The Company conducts its Gamma Knife business through its 81% indirect interest in GKF. The remaining 19% interest is indirectly owned by Elekta. GKF, formed in October 1995, is managed by its policy committee. The policy committee is composed of one representative from the Company, Ernest A. Bates, M.D., ASHS’s Chairman and CEO, and one representative from Elekta. The policy committee sets the operating policy for GKF. The policy committee may act only with the unanimous approval of both of its members. The policy committee selects a manager to handle GKF’s daily operations. Craig K. Tagawa, Chief Executive Officer of GKF and Chief Operating and Financial Officer of ASHS, serves as GKF’s manager.

GKF’s profits and/or losses and any cash distributions are allocated based on membership interests. GKF’s operating agreement requires that it have a cash reserve of at least $50,000 before cash distributions are made to its members. From inception to December 31, 2016,2017, GKF has distributed $45,765,000$47,385,000 to the Company and $10,735,000$11,115,000 to the non-controlling member.

Image Guided Radiation Therapy Operations (“IGRT”)

The Company’s radiation therapy business currently consists of one IGRT system that began operation in September 2007 at an existing Gamma Knife customer site. A second IGRT system located in Turkey was sold in the second quarter of 2014. Revenue generated under IGRT services accounted for approximately 3% of the Company’s total revenue in 2016.2017.

IGRT technology integrates imaging and detection components into a state-of-the-art linear accelerator, allowing clinicians to plan treatment, verify positioning, and deliver treatment with a single device, providing faster, more effective radiation therapy with less damage to healthy tissue.  IGRT captures cone beam imaging, fluoroscopic and/or x-ray images on a daily basis, creating three-dimensional images that pinpoint the exact size, location and coordinates of tumors. Once tumors are pinpointed, the system delivers ultra-precise doses of radiation which ultimately leads to improved patient outcomes.

Based on the most recently available information, there are approximately 3,900 linear accelerator basedaccelerator-based radiation therapy units installed in the United States, and it is estimated that a majority of these units provide Intensity-Modulated Radiation Therapy (“IMRT”), IGRT or a combination of this advanced radiation therapy capability. Radiation therapy services are provided through approximately 2,300 hospital based and free-standing oncology centers.

Additional information on our operations can be found in Item 6–“Selected “Selected Financial Data”, Item 7–“Management’s “Management’s Discussion and Analysis of Financial Condition and Results of Operations” and Note 1 of our consolidated financial statements.

Proton Beam Radiation Therapy Operations

PBRT is an alternative to traditional external beam, photon basedphoton-based radiation delivered by linear accelerators. PBRT, first clinically introduced in the 1950s, has physics advantages compared to photon basedphoton-based systems which allow PBRT to deliver higher radiation doses to the tumor with less radiation to healthy tissue. PBRT currently treats prostate, brain, spine, head and neck, lung, breast, gastrointestinal tract and pediatric tumors. In excess of 130,000160,000 patients have been treated with protons worldwide.

Introduction of PBRT in the United States, until recently, has been limited due to the high capital costs of these projects. The Company believes that the current development of one and two treatment room PBRT systems at lower capital costs and the level of reimbursement for PBRT from the CMSCenters for Medicare and Medicaid Services (“CMS”) will help make this technology available to a larger segment of the market.

CUSTOMERS

The Company’s current business is the outsourcing of stereotactic radiosurgery services and radiation therapy services. The Company typically provides the equipment, as well as planning, installation, reimbursement and marketing support services. The majority of the Company’s customers pay the Company on a fee per use basis. The market for these services primarily consists of major urbanlarge and medium sized medical centers. The business is capital intensive; the total cost of a Gamma Knife or IGRT facility usually ranges from $3.0 million to $5.5 million, including equipment, site construction and installation; the total cost of a single room PBRT system usually ranges from $25.0M to $35.0M, inclusive of equipment, site construction and installation. The Company pays for the equipment and the medical center generally pays for site and installation costs. The following is a listing of the Company’s sites as of March 1, 2017:2018:

The Company’s typical fee per use agreement is for a ten yearten-year term. The fixed fee per use reimbursement amount that the Company receives from the customer is based on the Company’s cost to provide the service and the anticipated volume of the customer. The Gamma Knife contracts signed by the Company typically call for a fee ranging from $4,200$6,000 to $9,300 per procedure. There are no minimum volume guarantees required of the customer. In most cases, GKF is responsible for providing the Gamma Knife and related ongoing Gamma Knife equipment expenses (i.e., personal property taxes, insurance, and equipment maintenance) and also helps fund the customer’s Gamma Knife marketing. The customer generally is obligated to pay site and installation costs and the costs of operating the Gamma Knife. The customer can either renew the agreement or terminate the agreement at the end of the contractual term. If the customer chooses to terminate the agreement, then GKF removes the equipment from the medical center for possible placement at another site.

The Company’s typical revenue sharing agreements (“retail”) are for a period of ten years. Instead of receiving a fixed fee, the Company receives all or a percentage of the reimbursement (exclusive of physician fees) received by the customer. The Company is at risk for any reimbursement rate changes for radiosurgery or radiation therapy services by the government or otherthird partyother third-party payors. There are no minimum volume guarantees required of the customer.

One customer accounted for approximately 21%, 10%, and 10% of the Company’s total revenue. Inrevenue in 2017, 2016 and 2015, one customer accounted for approximately 10% of the Company’s total revenue. In 2014, no one customer accounted for more than 10% of the Company’s total revenue.respectively. At December 31, 2017 and 2016, three and 2015, two and three customers each accounted for more than 10% of total accounts receivable, respectively.

MARKETING

The Company markets its Gamma Knife services through its preferred provider status with Elekta and a direct sales effort led by its Vice President of Sales and Business Development, its Chief Operating Officer and its Chief Executive Officer. The Company markets its PBRT service through a direct sales effort led by its Vice President of Sales and Business Development, its Chief Operating Officer and its Chief Executive Officer. The major advantages to a health care provider in contracting with the Company for its services include:

FINANCING

The Company’s Gamma Knife business is operated through GKF. GKF generally finances its U.S. Gamma Knife units, upgrades and additions with loans or capital leases from various finance companies for typically 100% of the cost of each Gamma Knife, plus any sales tax, customs and duties. The financing is predominantly fully amortized over an 84 month84-month period and is collateralized by the equipment, customer contracts and accounts receivable, and is generally without recourse to the Company and Elekta. The loan to finance the Company’s unit in Peru is guaranteed by GKF and collateralized by the Company’s stock in the subsidiary, GKPeru. The lease financing obtained by Orlando is guaranteed by the Company and collateralized by the equipment, customer contract and accounts receivable related to this project.

COMPETITION

Conventional neurosurgery, radiation therapy and other radiosurgery devices are the primary competitors of Gamma Knife radiosurgery. Gamma Knife radiosurgery has gained acceptance as an alternative and/or adjunct to conventional surgery due to its more favorable morbidity outcomes for certain procedures as well as its non-invasiveness. Utilization of the Company’s Gamma Knife units is contingent on the acceptance of Gamma Knife radiosurgery by the customer’s neurosurgeons, radiation oncologists and referring physicians. In addition, the utilization of the Company’s Gamma Knife units is impacted by the proximity of competing Gamma Knife centers and providers using other radiosurgery devices.

Conventional linear accelerator basedaccelerator-based radiation therapy is the primary competitor of the Company’s proton therapy system at Orlando Health. Proton beam radiation therapy although available for many years is only recently emerging as a more clinically beneficial alternative to conventional linear accelerators for certain tumors. Utilization of the Company’s proton therapy system is dependent on the acceptance of this technology by Orlando Health’s radiation oncologists and referring physicians, as well as patient self-referrals. There are currently no competing proton therapy facilities in close proximity to the Company’s site.

There are several competing manufacturers of proton beamPBRT systems, including Mevion, IBA Particle Therapy Inc., Hitachi Ltd., Varian Medical Systems, Inc. (Accel), ProNova Solutions, LLC, Sumitomo Heavy Industries, ProTom International, Inc. and Mitsubishi Electric. The Company invested in Mevion by purchasinghas purchased one MEVION S250 and has made deposits towards the purchase of two additional MEVION S250 systems. The Mevion system potentially provides cancer centers the opportunity to introduce single treatment room PBRT services with a cost in the range of approximately $25 to $35 million versus four and five PBRT treatment room programs costing in excess of $120 million. The MEVION S250 system received FDA approval in the second quarter of 2012 and the first clinical treatment occurred in December 2013 at Barnes-Jewish Hospital. The MEVION S250i (Hyperscan) unit, which includes pencil beam scanning, was FDA approved in December 2017. The Company’s first MEVION S250 system in operation at Orlando Health treated its first patient in April 2016. The Company’sCompany currently does not have customer contracts for its second and third PBRT units will not begin construction until the Company identifies satisfactory placement sites.units.

The Company believes the business model it has developed for use in its Gamma Knife and IGRT placements can be tailored for the PBRT market segment. The Company is targeting large, hospital basedhospital-based cancer programs. The Company’s ability to develop a successful PBRT financing entity depends on the decision of cancer centers to self-fund or to fund the PBRT through conventional financing vehicles, the Company’s ability to capture market share from competing alternative PBRT financing entities, and the Company’s ability to raise capital to fund PBRT projects.

The Company’s ability to secure additional customers for Gamma Knife services and other proton beam radiation therapy services, or other equipment, is dependent on its ability to effectively compete against the manufacturermanufacturers of these systems selling directly to potential customers and other companies that outsource these services. The Company does not have an exclusive relationship with any manufacturer and has previously lost sales to customers that chose to purchase equipment directly from manufacturers. The Company may continue to lose future sales to such customers and may also lose sales to the Company’s competitors.

GOVERNMENT PROGRAMS

The Medicare program is administered by the Centers for Medicare and Medicaid Services (“CMS”)CMS of the U.S. Department of Health and Human Services (“DHHS”). Medicare is a health insurance program primarily for individuals 65 years of age and older, certain younger people with disabilities, and people with end-stage renal disease, and is provided without regard to income or assets.

The Medicare program is subject to statutory and regulatory changes, administrative rulings, interpretations and determinations, requirements for utilization review, and federal and state funding restrictions, all of which could materially increase or decrease payments from these government programs in the future, as well as affect the cost of providing services to patients and the timing of payments to our client hospitals.

The Company’s Gamma Knife, PBRT and IGRT customers receive payments for patient care from federal government and private insurer reimbursement programs. Currently in the United States, Gamma Knife, proton therapy and IGRT services are performed primarily on an out-patient basis. Gamma Knife patients with Medicare as their primary insurer, treated on either an in-patient or out-patient basis, comprise an estimated 35-45%35%-45% of the total Gamma Knife patients treated nationwide. PBRT and IGRT patients with Medicare as their primary insurer are treated primarily on an out-patient basis and comprise an estimated 45% to 50% of the total radiation therapy patients treated. The Company estimates that its percentage of patients with Medicare as their primary insurer approximates these national averages.

Congress enacted legislation in 2013 that significantly reduced the Medicare reimbursement rate for outpatient Gamma Knife treatment by setting it at the same amount paid for linear accelerator-based radio surgery treatment. Prior to April 1, 2013, Medicare’s reimbursement rate for Gamma Knife treatment had been relatively stable. Congress’s enactment of the American Taxpayer Relief Act of 2012, however, reduced Medicare’s Gamma Knife reimbursement rate from approximately $9,900 to $5,300, effective April 1, 2013. This change caused a substantial reduction in the Company’s revenues during 2013 and 2014. Effective January 1, 2015, the Centers for Medicare and Medicaid (CMS) established a Comprehensive Ambulatory Payment Classification for single session radiosurgery treatments, which increased the reimbursement rate byfrom approximately $4,100 to $9,700. The 2016 total CMS reimbursement rate of approximately $8,800 is scheduled to be increased to approximately $9,000 in 2017 and will increase to approximately $9,100 in 2018 for a Medicare beneficiary Gamma Knife treatment. The Company’s IGRT services are reimbursed by CMS and other insurers. Reimbursement for these services has remained fairly stable. See additional discussion under “Item 1A Risk Factors”.

The hospital based 2016 Medicare delivery code reimbursement rate for PBRT established by CMS is $506 for simple without compensation and $1,051 for simple with compensation, intermediate or complex treatments. The 2017 scheduled CMS rates are $494 for simple without compensation and $994 for simple with compensation, intermediate or complex treatments. The 2018 scheduled CMS rates are $522 for simple without compensation and $1,053 for simple with compensation, intermediate or complex treatments. Patients typically undergo 25-3025-40 delivery sessions. See additional discussion under “Item 1A Risk Factors– The Federal Reimbursement Rate for Gamma Knife Treatments Has Fluctuated”.

We are unable to predict the effect of future government health care funding policy changes on operations. If the rates paid by governmental payers are reduced, if the scope of services covered by governmental payers is limited, or if one or more of our hospital clients are excluded from participation in the Medicare program or any other government health care program, there could be a material adverse effect on our business.

Affordable Care Act

In March 2010, President Obama signed into law the Patient Protection and Affordable Care Act, as amended by the Health Care and Education Reconciliation Act of 2010, (“Affordable Care Act”), which has resulted in significant changes to the health care industry. The primary goal of the legislation was to extend health care coverage to approximately 32 million uninsured legal U.S. residents through both an expansion of public programs and reforms to private sector health insurance. According to the National Center for Health Statistics, in 2016 there were 28.6 million uninsured Americans down from more than 48.0 million in 2010. Of those covered by private insurance in 2016, 11.6 million had purchased their plans through federal or state-based exchanges established by the Affordable Care Act. The expansion of insurance coverage is expected to be funded in part by measures designed to promote quality and cost efficiency in health care delivery and by budgetary savings in the Medicare and Medicaid programs. Because the Company is not a health care provider, we are not directly affected by the law, but we could be indirectly affected principally as follows:

GOVERNMENT REGULATION

The payment of remuneration to induce the referral of health care business has been a subject of increasing governmental and regulatory focus in recent years. Section 1128B(b) of the Social Security Act (sometimes referred to as the "federal anti-kickback statute") provides criminal penalties for individuals or entities that offer, pay, solicit or receive remuneration in order to induce referrals for items or services for which payment may be made under the Medicare and Medicaid programs and certain other government funded programs. The Affordable Care Act amended the anti-kickback statute to eliminate the requirement of actual knowledge, or specific intent to commit a violation, of the anti-kickback statute. The Social Security Act provides authorizes the Office of Inspector General through civil proceedings to exclude an individual or entity from participation in the Medicare and state health programs if it is determined any such party has violated Section 1128B(b) of the Social Security Act. The Company believes that it is in compliance with the federal anti-kickback statute. Additionally, the Omnibus Budget Reconciliation Act of 1993, often referred to as "Stark II", bans physician self-referrals to providers of designated health services with which the physician has a financial relationship. On September 5, 2007, the third and final phase of the Stark regulations (Phase III) was published. The term "designated health services" includes, among others, radiation therapy services and in-patient and out-patient hospital services. On January 1, 1995, the Physician Ownership and Referral Act of 1993 became effective in California. This legislation prohibits physician self-referrals for covered goods and services, including radiation oncology, if the physician (or the physician's immediate family) concurrently has a financial interest in the entity receiving the referral. The Company believes that it is in compliance with these rules and regulations.

On August 19, 2008, the CMS published a final rule relating to inpatient hospital services paid under the Inpatient Prospective Payment System for discharges in the Fiscal Year 2009 (the “Final Rule”). Among other things, the Final Rule prohibits “per-click payments” to certain physician lessors for services rendered to patients who were referred by the physician lessor. This prohibition on per-click payments for leased equipment used in the treatment of a patient referred to a hospital lessee by a physician lessor applies regardless of whether the physician himself or herself is the lessor or whether the lessor is an entity in which the referring physician has an ownership or investment interest. The effective date of this prohibition was October 1, 2009. However, referrals made by a radiation oncologist for radiation therapy or ancillary services necessary for, and integral to, the provision of radiation therapy (such as Gamma Knife services) are not subject to this prohibition so long as certain conditions are met. GK Financing’s majority owned subsidiaries, Albuquerque GK Equipment, LLC (“AGKE”)AGKE and Jacksonville GK Equipment, LLC (“JGKE”)JGKE have minority ownership interests that are held solely by radiation oncologists, who are otherwise exempt from the referral prohibition under the Final Rule. The Company believes it is in compliance with the Final Rule.

A range of federal civil and criminal laws target false claims and fraudulent billing activities. One of the most significant is the Federal False Claims Act, which prohibits the submission of a false claim or the making of a false record or statement in order to secure a reimbursement from a government-sponsored program. In recent years, the federal government has launched several initiatives aimed at uncovering practices which violate false claims or fraudulent billing laws. Claims under these laws may be brought either by the government or by private individuals on behalf of the government, through a "whistleblower" or "qui tam" action. The Company believes that it is in compliance with the Federal False Claims Act; however, because such actions are filed under seal and may remain secret for years, there can be no assurance that the Company or one of its affiliates is not named in a material qui tam action.

Legislation in various jurisdictions requires that health facilities obtain a Certificate of Need ("CON") prior to making expenditures for medical technology in excess of specified amounts. Four of the Company’s existing customers were required to obtain a CON or its equivalent. The CON procedure can be expensive and time consuming and may impact the length of time before Gamma Knife services commence. CON requirements vary from state to state in their application to the operations of both the Company and its customers. In some jurisdictions the Company is required to comply with CON procedures to provide its services and in other jurisdictions customers must comply with CON procedures before using the Company's services. The Company is unable to predict if any jurisdiction will eliminate or alter its CON requirements in a manner that will increase competition and, thereby, affect the Company's competitive position.

The Company's Gamma Knife units contain Cobalt 60 radioactive sources. The medical centers that house the Company's Gamma Knife units are responsible for obtaining possession and user's licenses for the Cobalt 60 source from the Nuclear Regulatory Commission. The Company’s Gamma Knife center in Peru was responsible for obtaining possession and user’s licenses for the Cobalt-60 sources from the Peruvian Regulatory Agencies.

Standard linear accelerator equipment utilized to treat patients is regulated by the FDA. The licensing is obtained by the individual medical center operating the equipment.

The Company believes it is in substantial compliance with the various rules and regulations that affect its businesses.

INSURANCE AND INDEMNIFICATION

The Company's contracts with equipment vendors generally do not contain indemnification provisions. The Company maintains a comprehensive insurance program covering the value of its property and equipment, subject to deductibles, which the Company believes are reasonable.

The Company's customer contracts generally contain mutual indemnification provisions. The Company maintains general and professional liability insurance.insurance in the United States. The Company is not involved in the practice of medicine and therefore believes its present insurance coverage and indemnification agreements are adequate for its business. The Company’s Peruvian Gamma Knife center is a free-standing facility operated by GKPeru. GKPeru’s treating physicians and clinical staff are independent contractors. The Company maintains general and professional liability insurance consistent with the operations of this facility and believes its present coverage is adequate for its business.

EMPLOYEES

At December 31, 2016,2017, the Company employed eight (8)nine (9) people on a full-time basis and one (1) on a part-time basis. None of these employees is subject to a collective bargaining agreement and there is no union representation within the Company. The Company maintains various employee benefit plans and believes that its employee relations are good.

EXECUTIVE OFFICERS OF THE COMPANY

The following table provides current information concerning those persons who serve as executive officers of the Company. The executive officers were appointed by the Board of Directors and serve at the discretion of the Board of Directors.

Ernest A. Bates, M.D., founder of the Company, has served in the positions listed above since the incorporation of the Company. A board-certified neurosurgeon, Dr. Bates is Emeritus Vice Chairman of the Board of Trustees at Johns Hopkins University and serves on the Johns Hopkins Neurosurgery Advisory Board. He also serves on the boards of Shared Imaging and The School of Nursing Dean’s Advisory Council at UCSF .UCSF. Dr. Bates currently serves as President and Director of the Ernest Bates Foundation. Dr. Bates previously served on the California Commission for Jobs and Economic Growth and the Magistrate Judge Merit Selection Panel. From 1981-1987 he was a member of the Board of Governors of the California Community Colleges, and he served on the California High Speed Rail Authority from 1997 to 2003. Dr. Bates is a member of the Board of Overseers at the University of California, San Francisco, School of Nursing. He is a graduate of the School of Arts and Sciences of the Johns Hopkins University, and he earned his medical degree at the University of Rochester School of Medicine and Dentistry.

Craig K. Tagawa has served as Chief Operating Officer since February 1999 in addition to serving as Chief Financial Officer since May 1996. Mr. Tagawa also served as Chief Financial Officer from January 1992 through October 1995. Previously a Vice President in such capacity, Mr. Tagawa became a Senior Vice President on February 28, 1993. He is also the Chief Executive Officer of GKF. From September 1988 through January 1992, Mr. Tagawa served in various positions with the Company. Mr. Tagawa currently serves as Chief Financial Officer and Secretary of the Ernest Bates Foundation. He is a former Chair of the Industrial Policy Advisory Committee of the Engineering Research Center for Computer-Integrated Surgical Systems and Technology at The Johns Hopkins University. He received his undergraduate degree from the University of California at Berkeley and his M.B.A. from Cornell University.

Ernest R. Bates joined the Company in January 2007 as Vice President of Sales and Business Development. He was on the Board of Directors of the Company from 2004 through February 2007. Prior to joining the Company, he had been Managing Director, Institutional Fixed Income Sales of HSBC Securities (USA), Inc. since 2003. Mr. Bates has also served as Managing Director, Head of Asian Product for HSBC Securities (USA) Inc. from 1999 to 2003. From 1993 through 1999, Mr. Bates held various positions with Merrill Lynch, last serving as Vice President, European Syndicate for Merrill Lynch International. He received his undergraduate degree from Brown University and a M.B.A. degree from The Wharton Business School. Ernest R. Bates is the son of Chairman of the Board and Chief Executive Officer Dr. Ernest A. Bates.

AVAILABLE INFORMATION

Our Internet address iswww.ashs.com. We make available free of charge, through our Internet website under the “Investor Center” tab in the “Corporate” section, our annual report on Form 10-K, quarterly reports on Form 10-Q, current reports on Form 8-K, and amendments to those reports filed or furnished pursuant to Section 13(a) or 15(d) of the Securities Exchange Act of 1934 (“Exchange Act”) as soon as reasonably practicable after such material is electronically filed with or furnished to the SEC. The information contained on our Internet website is not part of this document.

ITEM 1A. RISK FACTORS

In addition to the other information in this report, the following factors could affect our future business, results of operations, cash flows or financial position, and could cause future results to differ materially from those expressed in any of the forward-looking statements contained in this report.

The Federal Reimbursement Rate for Gamma Knife Treatments Has Fluctuated

Congress enacted legislation in 2013 that significantly reduced the Medicare reimbursement rate for outpatient Gamma Knife treatment by setting it at the same amount paid for linear accelerator-based radiosurgery treatment. Prior to April 1, 2013, Medicare’s reimbursement rate for Gamma Knife treatment had been relatively stable. In April 2013, the Medicare reimbursement rate for Gamma Knife treatment was lowered from approximately $9,900 to $5,300 per treatment session. This sudden reduction in a rate that had historically been stable resulted in a significant decrease in the Company’s revenues from all of our revenue sharing and some of our fixed fee medical centers. The reimbursement rate was subsequently increased to approximately $5,600 in 2014. Effective January 1, 2015, CMS established a comprehensive Ambulatory Payment Classification (APC) for both Gamma Knife and LINAC one session cranial radiosurgery at a reimbursement rate of approximately $9,700. This represents an estimated increase of $4,100 per Medicare Gamma Knife treatment (exclusive of co-insurance and other adjustments) effective January 1, 2015 compared to the 2014 Medicare reimbursement rate. The 2016 reimbursement level was reduced by CMS to approximately $8,800 but is scheduled to increaseincreased to approximately $9,000 in 2017.2017 and increased again to $9,100 in 2018. There can be no assurance that CMS reimbursement levels will be maintained at levels providing the Company an adequate return on its investment. Any future reductions in the reimbursement rate would adversely affect the Company’s revenues and financial results.

The average Medicare reimbursement rate trends from 20132014 to 20172018 are outlined below:

Average Medicare Reimbursement Rate Trends

The Company’s Capital Investment at Each Site is Substantial

Each Gamma Knife, PBRT or IGRT device requires a substantial capital investment. In some cases, we contribute additional funds for capital costs and/or annual operating and equipment related costs such as marketing, maintenance, insurance and property taxes. Due to the structure of our contracts with medical centers, there can be no assurance that these costs will be fully recovered or that we will earn a satisfactory return on our investment.

The Market for the Gamma Knife is Limited

There is a limited market for the Gamma Knife, and the market in the United States may be mature. The Company has begun operation at only four (4)nine (9) new Gamma Knife sites in the United States since 2011. An additional new site is scheduled to begin operation in the second half of 2017. Due to the substantial costs of acquiring a Gamma Knife unit, we must identify medical centers that possess neurosurgery and radiation oncology departments capable of performing a large number of Gamma Knife procedures. As of December 31, 2016,2017, there were approximately 123118 operating Gamma Knife units in the United States, of which 17sixteen (16) units were owned by the Company. As of December 31, 2016,2017, the Company has twoone idle Gamma Knife unitsunit with a cumulative net book value of $1,483,000. One$729,000. There are currently no plans to place into service or trade this unit was traded in during 2016 to place a new unit at a new customer site in 2017. The Company plans to trade the second unit in for a new unit or place this units at a new site.2018. There can be no assurance that we will be successful in placing these idle units or additional units at any sites in the future. The Company’s existing contracts with its customers are fixed in length and there can be no assurance that the customers will wish to extend the contract beyond the end of the term.

The Company Has a High Level of Debt

The Company’s business is capital intensive. The Company finances its Gamma Knife units through its GKF subsidiary. The amounts financed through GKF have been generally non-recourse to ASHS. The Company financed its first proton therapy unit through its wholly ownedwholly-owned subsidiary, Orlando, and guaranteed the lease financing. The Company’s combined long termlong-term debt and capital leases totaled $27,036,000$23,143,000 as of December 31, 20162017 and is collateralized by its Gamma Knife, MEVION S250 and other assets, including accounts receivable and future proceeds from any contract between the Company and any end user of the financed equipment. This high level of debt may adversely affect the Company’s ability to secure additional credit in the future, and as a result may affect operations and profitability. If default on debt occurs in the future, the Company’s creditors would have the ability to accelerate the defaulted loan, to seize the Gamma Knife or MEVION S250 units or other equipment with respect to which default has occurred, and to apply any collateral they may have at the time to cure the default.

A Small Number of Customers Account for a Major Portion of our Revenues

A limited number of customers have historically accounted for a substantial portion of the Company’s total revenue, and the Company expects such customer concentration to continue for the foreseeable future. For example, in 2016, seven (7)2017, five (5) customers in total accounted for more than 50% of the Company’s revenue. The loss of a significant customer or a significant decline in the business from the Company’s largest customers could have a material adverse effect on the Company’s business and results of operations. During 2016, one of the Company’s seven largest customers provided notice of their intent to exercise the option to purchase the Gamma Knife unit at their hospital at the end of the lease term in April 2017. The Company is placing two other Gamma Knife units in the second half of 2017, but the loss of the contract could cause fluctuations in revenue from quarter to quarter.

The Market for the Company’s Services is Competitive

The Company estimates that there are two other companies that actively provide alternative, non-conventional Gamma Knife financing to potential customers. We believe there are no competitor companies that currently have more than three (3) Gamma Knife units in operation. The Company’s relationship with Elekta, the manufacturer of the Leksell Gamma Knife unit, is non-exclusive, and in the past the Company has lost sales to customers that chose to purchase a Gamma Knife unit directly from Elekta. The Company also has several competitors in the financing of proton therapy projects. The Company’s business model differs from its competitors, but there can be no assurances that the Company will not lose placements to its competitors. In addition, the Company may continue to lose future sales to customers purchasing equipment directly from manufacturers. There can be no assurance that the Company will be able to successfully compete against others in placing future units.

There are Alternatives to the Gamma Knife

Other radiosurgery devices and conventional neurosurgery compete against the Gamma Knife. Each of the medical centers targeted by the Company could decide to acquire another radiosurgery device instead of a Gamma Knife. In addition, neurosurgeons who are responsible for referring patients for Gamma Knife surgery may not be willing to make such referrals for various reasons, instead opting for invasive surgery. There can be no assurance that the Company will be able to secure a sufficient number of future sites or Gamma Knife procedures to sustain its profitability and growth.

International Operations

The Company has plans to install, in 2017,installed a Gamma Knife in Peru. The Company sold its operationsLima, Peru in Turkey on June 10, 2014.2017. International operations can be subject to exchange rate volatility which could have an adverse effect on our financial results and cash flows. In addition, international operations can be subject to legal and regulatory uncertainty and political and economic instability, which could result in problems asserting property or contractual rights, potential tariffs, increased compliance costs, increased regulatory scrutiny, potential adverse tax consequences, the inability to repatriate funds to the United States, and the Company’s inability to operate in those locations.

New Technology and Products Could Result in Equipment Obsolescence

There is constant change and innovation in the market for highly sophisticated medical equipment. New and improved medical equipment can be introduced that could make the Gamma Knife technology obsolete and that would make it uneconomical to operate. During 2000, Elekta introduced an upgraded Gamma Knife which cost approximately $3.6 million plus applicable tax and duties. This upgrade includes an Automatic Positioning System™ (“APS”), and therefore involved less health care provider intervention. In early 2005, Elekta introduced a new upgrade, the Gamma Knife Model 4C (“Model 4C”). The cost to upgrade existing units to the Model 4C with APS was approximately $200,000 to $1,000,000, depending on the current Gamma Knife configuration. In 2006 Elekta introduced a new model of the Gamma Knife, the Perfexion, which costs approximately $4.5 million plus applicable taxes and duties. The Perfexion can perform procedures faster than previous Gamma Knife models and it involves less health care personnel intervention. In 2015, Elekta introduced the Leksell Gamma Knife Icon^TM. The Perfexion is upgradeable to the Icon platforms which has enhanced imaging capabilities allowing for treatment without a head frame and the treatment of larger tumors. Existing model 4Cs of the Gamma Knife are not upgradeable to the Perfexion model. As of March 1, 2017,2018, 14 of the Company’s Gamma Knife units are Perfexion models; of the Company’s remaining Gamma Knife units, two (2) are Model 4Cs with APS and one is upgradeable to a more advanced Model 4C unit. The failure to acquire or use new technology and products could have a material adverse effect on our business and results of operations.

In addition, there are constant advances made in radiation therapy equipment. The Company purchased IGRT and CT Simulator systems in 2006 with a list price of approximately $8,300,000. As in the Gamma Knife business, new and improved IGRT equipment can be introduced that could make the existing technology obsolete and that would make it uneconomical to operate.

The Company Has Invested in a Proton Beam Business

We have committed a substantial amount of our financial resources to next-generation proton beam technology. The first MEVION S250 system began treating patients in December 2013. The Company’s first MEVION S250 system began treating patients in April 2016. The Company has committed to purchase two (2) additional MEVION S250 systems and has already made deposits of $2,000,000 towards this commitment. There can be no assurance that we will be able to finance the two additional systems and if we do, that we will recover this investment or future investments, or our $2,709,000 common stock investment in Mevion, which was written down to approximately $579,000 as of December 31, 2015.systems.

The Trading Volume of Our Common Stock is Low

Although our common stock is listed on the NYSE MKT, our common stock has historically experienced low trading volume. Reported average daily trading volume in our common stock for the three-month period ended December 31, 20162017 was approximately 10,80016,000 shares. There is no reason to think that a more significant active trading market in our common stock will develop in the future. Limited trading volume subjects our common stock to greater price volatility and may make it difficult for you to sell your shares in a quantity or at a price that is attractive to you.

ITEM 1B. UNRESOLVED STAFF COMMENTS

None.

ITEM 2. PROPERTIES

The Company's corporate offices are located at Two Embarcadero Center, Suite 410, San Francisco, California, where it leases approximately 3,253 square feet for $18,434$18,986 per month with a lease expiration date in August 2023. Prior to the Company’s relocation in 2016, it leased approximately 4,640 square feet for $25,128 per month and subleased approximately 3,500 square feet of the office space for $16,042 per month. The sublease expired in May 2016. The Company also has a satellite office in Fairfield, California, where it leases 895 square feet for $2,505$2,629 per month with a lease expiration date in April 2018.2020.

For the year ended December 31, 20162017 the Company's aggregate net rental expenses for all properties were approximately $231,000, net of sublease income of $76,000.$308,000.

ITEM 3. LEGAL PROCEEDINGS

There are no material pending legal proceedings involving the Company or any of its property. The Company knows of no legal or administrative proceedings against the Company contemplated by governmental authorities.

ITEM 4. MINE SAFETY DISCLOSURES

Not applicable.

PART II

ITEM 5. MARKET FOR REGISTRANT'S COMMON EQUITY, RELATED STOCKHOLDER MATTERS AND ISSUER PURCHASES OF EQUITY SECURITIES

Market Information and Dividend Policy

The Company's common shares, no par value (the "Common Shares"), are currently traded on the New York Stock Exchange. At December 31, 2016,2017, the Company had 5,468,0005,710,000 issued and outstanding common shares, 625,000615,000 common shares reserved for options, 4,000 unvested restricted stock units issued, 215,000237,000 vested restricted stock units and 129,000 restricted stock awards reserved for issuance and warrants to issue 100,000 shares of common stock.issuance.

The following table sets forth the high and low closing sale prices of the Common Shares of the Company on the New York Stock Exchange for each full quarter for the last two fiscal years.

The Company estimates that there were approximately 1,400 beneficial holders of its Common Shares at December 31, 2016.2017.

There were no dividends declared or paid during 2017, 2016, 2015, or 2014.2015. Dividends had been paid by the Company from 2001 to 2007, but during 2007 the Board of Directors suspended dividends for the purpose of preserving cash for the development of its PBRT business. The Company did not pay cash dividends prior to 2001.

Stock Repurchase Program

In 1999 and 2001, the Board of Directors approved resolutions authorizing the Company to repurchase up to a total of 1,000,000 shares of its common stock on the open market from time to time at prevailing prices, and in 2008 the Board of Directors reaffirmed these authorizations. In 2017, 2016, and 2015 there were no shares repurchased by the Company. In 2014, there were approximately 1,000 shares repurchased at a cost of approximately $2,000. A total of approximately 928,000 shares have been repurchased in the open market pursuant to these authorizations at a cost of approximately $1,957,000. As of December 31, 2016,2017, there were approximately 72,000 shares remaining under the repurchase authorizations.

Shareholder Rights Plan

On March 22, 1999, the Company adopted a Shareholder Rights Plan (“Plan”). Under the Plan, the Company made a dividend distribution of one Right for each outstanding share of the Company’s common stock as of the close of business on April 1, 1999. The Rights become exercisable only if any person or group, with certain exceptions, becomes an “acquiring person” (acquires 15% or more of the Company’s outstanding common stock) or announces a tender or exchange offer to acquire 15% or more of the Company’s outstanding common stock. The Company’s Board of Directors adopted the Plan to protect shareholders against a coercive or inadequate takeover offer. On March 12, 2009, the Board of Directors approved the First Amendment to the Plan which, among other things, extended the final date on which the Rights are exercisable until the close of business on April 1, 2019.

Equity Compensation Plans

During 2016,2017, 4,000 restricted stock units, 37,00018,000 restricted stock units for deferred compensation and 20,00027,000 options were issued. Additional information regarding our equity compensation plans is incorporated herein by reference from the 20172018 Proxy Statement. Also, see Note 9-“Shareholders’8 - “Shareholders’ Equity to the Consolidated Financial Statements”.

Recent Sales of Unregistered Securities

The Company sold 750,000 shares of common stock to members of the Board of Directors in two private placement transactions in 2014 that were exempt under Section 4(a)(2) of the Securities Act.

ITEM 6. SELECTED FINANCIAL DATA

See accompanying note (1)

See accompanying note (1)

(1) In 1995, the Company entered into an operating agreement granting to American Shared Radiosurgery Services (a California corporation and a wholly-owned subsidiary of the Company) an 81% ownership interest in GKF. During 2010 and 2011, GKF established new operating subsidiaries, EWRS, EWRS Turkey, GKPeru, AGKE, and JGKE, and other subsidiaries that are not yet operational. On June 10, 2014, the Company sold EWRS Turkey. Accordingly, the financial data for the Company presented above include the results of GKF and its subsidiaries for the periods 20122013 through 2016.2017.

This financial data as of December 31, 2016, 20152017 and 20142016 and for the years ended December 31, 2016, 20152017 and 20142016 should be read in conjunction with our consolidated financial statements and the notes thereto beginning on page A-1 of this report and with Item 7–“Management’s “Management’s Discussion and Analysis of Financial Condition and Results of Operations.”

ITEM 7. MANAGEMENT'S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS

APPLICATION OF CRITICAL ACCOUNTING POLICIES

The Company’s consolidated financial statements are prepared in accordance with generally accepted accounting principles and follow general practices within the industry in which it operates. Application of these principles requires management to make estimates, assumptions and judgments that affect the amounts reported in the financial statements and accompanying notes. These estimates, assumptions and judgments are based on information available as of the date of the financial statements; accordingly, as this information changes, the financial statements could reflect different estimates, assumptions and judgments. Certain policies inherently have a greater reliance on the use of estimates, assumptions and judgments and as such have a greater possibility of producing results that could be materially different than originally reported.

The most significant accounting policies followed by the Company are presented in Note 2 to the consolidated financial statements. These policies along with the disclosures presented in the other financial statement notes and, in this discussion, and analysis, provide information on how significant assets and liabilities are valued in the financial statements and how those values are determined. Based on the valuation techniques used and the sensitivity of financial statement amounts, and the methods, assumptions and estimates underlying those amounts, management has identified revenue recognition and costs of sales for turn-key and revenue sharing arrangements, carrying value of fixed assets and useful lives, and the carrying value of its Mevion investment to be the areas that required the most subjective or complex judgments, and as such could be most subject to revision as new information becomes available. The following are our critical accounting policies in which management’s estimates, assumptions and judgments most directly and materially affect the financial statements:

Revenue Recognition

The Company has one revenue-generating activity, which consists of equipment leasing to hospitals, and includes the operation of Gamma Knife units by GKF, the operation of one proton therapy unit by Orlando, and the operation of one IGRT site by ASHS. During 2014, the Company entered into a lease agreement where the lessee gave the Company a piece of equipment for $1. The Company estimated and recorded the fair market value of the equipment received and recognized deferred revenue. As of December 31, 2014, the fair market value of the equipment received during the year was $700,000.

Revenue is recognized when services have been rendered and collectability is reasonably assured, on either a fee per use or revenue sharing basis. During 2016,2017, the Company had ten (10) fee per use arrangements and nine (9)ten(10) retail service arrangements. Under both of these types of agreements, the hospital is responsible for billing patients and collecting technical component fees for services performed. Revenue associated with installation of the Gamma Knife, PBRT, and IGRT units, if any, is a part of the negotiated lease amount and not a distinctly identifiable amount. The costs, if any, associated with installation of the units are amortized over the period of the related lease to match revenue recognition of these costs.

For fee per use agreements, revenue is not estimated because these contracts provide for a fixed fee per procedure and are typically for a ten yearten-year term. Revenue is recognized at the time the procedures are performed, based on each hospital’s contracted rate. There is no guaranteed minimum payment. Costs related to operating the units are charged to costs of operations as incurred, which approximates the recognition of the related revenue. Revenue under fee per use agreements is recorded in accordance with the contract terms.

During 2016,2017, ASHS had one (1) agreement, Orlando had one (1) agreement, and GKF had seven (7)eight (8) agreements that are based on revenue sharing.retail service arrangements. These can be further classified as either “turn-key” arrangements or “revenue sharing” arrangements. For GKF’s four (4)five (5) turn-key sites, GKF is solely responsible for the costs to acquire and install the Gamma Knife. In return, GKF receives payment from the hospital in the amount of its reimbursement from third party payors. Revenue is recognized by the Company during the period in which the procedure is performed and is estimated based on what can be reasonably expected to be paid by the third partythird-party payor to the hospital. The estimate is primarily determined from historical experience and hospital contracts with third party payors. These estimates are reviewed on a regular basis and adjusted as necessary to more accurately reflect the expected payment amount. The Company also records an estimate of operating costs associated with each procedure during the period in which the procedure is performed. For two of the turn-key sites, the Company also shares a percentage of net operating profit. The Company records an estimate of net operating profit based on estimated revenues, less estimated operating costs. Costs are determined primarily based on historical treatment protocols and cost schedules with the hospital. The Company’s estimated operating costs are reviewed on a regular basis and adjusted as necessary to more accurately reflect the actual operating costs. Revenue for turn-key sites is recorded on a gross basis, and the operating expenses the Company reimburses to the hospital are recorded in other operating costs.

Under revenue sharing arrangements the hospital shares in the responsibility and risk with the Company for the capital investment to acquire and install the equipment. Unlike our turn-key arrangement, the lease payment under a revenue sharing arrangement is a percentage of reimbursed revenue. Payments are made by the hospital, generally on a monthly basis, to the Company based on an agreed upon percentage allocation of cash collected. Revenue is recognized during the period in which procedures are performed and is estimated based on the reimbursement amount that the Company expects to receive from the hospital for those procedures. This estimate is reviewed on a regular basis and adjusted as necessary to more accurately reflect the expected payment amount.

Revenue from retail arrangements amounted to approximately 57%64%, 47%57% and 42%47% of total revenue for the years ended December 31, 2017, 2016 2015 and 2014,2015, respectively. Because the revenue estimates are reviewed on a quarterly basis, any adjustments required for past revenue estimates would result in an increase or reduction in revenue during the current quarterly period.

Carrying Value of Mevion Investment

The Company has carried its investment in Mevion at cost and reviews it for impairment on a quarterly basis, or as events or circumstances might indicate that the carrying value of the investment may be below its cost basis on an, other-than-temporary impairment basis. During the year ended December 31, 2015, due to Mevion’s cancellation of its planned IPO on July 27, 2015 and its announcement on August 4, 2015 of an investment of up to $200M by new investors, the Company determined that its Mevion common stock investment was impaired on an other-than-temporary basis. The fair value of the Company’s investment in Mevion was approximately $579,000 as of December 31, 2015 with an impairment loss for the year then ended of $2,140,000. During the year ended December 31, 2017, the Company reviewed its investment in Mevion and determined the fair value of its investment was $0. Based on the Company’s assessment of its investment in Mevion, the Company recognized an impairment loss for the year then ended December 31, 2017 of $579,000. For additional information, see “Impairment Analysis of Investment in Equity Securities.”

20162017 Results

For the year ended December 31, 2017, 76% of the Company’s revenue was derived from its Gamma Knife business, 21% was derived from the PBRT system, and the remaining 3% from its IGRT business. For the year ended December 31, 2016, 86% of the Company’s revenue was derived from its Gamma Knife business, 12% was derived from the PBRT system, and the remaining 2% from its IGRT business. For the year ended December 31, 2015, 97% of the Company’s revenue was derived from its Gamma Knife business, and the remaining 3% from its IGRT business. For the year ended December 31, 2014, 94% of the Company’s revenue was derived from its Gamma Knife business, and the remaining 6% from its IGRT business.

TOTAL REVENUE

Total revenue increased 4.6% and 13.0% compared to 2016 and 2015, due to the Company’s new PBRT unit which became operational in April 2016. Total revenue in 2015 increased 7.3% compared to 2014, due to an increase in Gamma Knife revenue, offset by a decrease in IGRT revenue.

Gamma Knife Revenue

Gamma Knife revenue for 2017 was $14,848,000 compared to $16,076,000 in 2016. Gamma Knife revenue for 2017 decreased $1,228,000 compared to 2016, due to two customer contracts that expired in April and August 2017, respectively. Total Gamma Knife revenue for 2016 was $16,076,000 compared to $16,077,000 in 2015. Total Gamma Knife revenue for 2015 increased 10.7% to $16,077,000 compared to $14,521,000 in 2014. Total Gamma Knife revenue for 2014 decreased 10.0% to $14,521,000 compared to $16,127,000 in 2013. The Company had seventeen seventeen, and twenty Gamma Knife units in operation at December 31, 2017, 2016 2015 and 2014, respectively.2015.

The total number of Gamma Knife procedures performed in 2017 decreased 291 compared to 2016, due to two customer contracts that expired in April and August 2017, respectively. The number of Gamma Knife procedures performed in 2016 was consistent with prior year, excludingdecreased 25 compared to 2015, due to one customer contract that expired in March 2015. The number of Gamma Knife procedures performed in 2015 increased 125, excluding procedures performed in Turkey in 2014. This increase was due to a new site which treated its first patient in December 2014, and increased volume at existing sites, offset by one contract which ended March 31, 2015.

Revenue per procedure increased by $740 and $107 in 2016, $1,160 in 20152017 and $599 in 20142016 compared to 2016 and 2015, and 2014, respectively. For 2017, the increase was primarily due to the expiration of a high volume, low reimbursement rate customer contract. For 2016, the increase was due to a favorable payor mix at the Company’s retail sites. For 2015, the increase was due to a favorable payor mix, increased reimbursement for Medicare procedures, effective January 1, 2015, and the sale of EWRS Turkey units which were reimbursed at lower rates compared to the Company’s other units.

Proton Therapy Revenue

*Not meaningful

Total PBRT revenue for 20162017 was $2,149,000$4,120,000 compared to $2,149,000 and $0 in 2016 and 2015, and 2014.respectively. The number of PBRT fractions performed in 20162017 was 2,3304,554 compared to 2,330 and 0 in 20152016 and 2014.2015. Revenue per fraction in 20162017 was $922$905 compared to $922 and $0 in 2016 and 2015, and 2014.respectively. The Company’s first MEVION S250 system was place at Orlando Health and treated its first patient in April 2016.

IGRT Revenue

IGRT revenue for 2017 was $588,000 compared to $475,000 and $471,000 in 2016 and 2015, respectively. IGRT revenue increased for 2017 due to increased volumes at the Company’s existing site.

Medical services revenue from the Company’s IGRT contract for 2016 increased 0.8% to $475,000 compared to $471,000 in 2015. Medical services revenue from the Company’s IGRT contracts for 2015 decreased 47.4% to $471,000 compared to $896,000 in 2014. The sale of EWRS Turkey in 2014 contributed $208,000 to the decline, in addition to lower volume at the Company’s existing site.

COSTS OF REVENUE

The Company's costs of revenue, consisting of maintenance and supplies, depreciation and amortization, and other operating expenses (such as insurance, property taxes, sales taxes, marketing costs and operating costs from the Company’s retail sites) increased by $988,000 in 2017 and $72,000 in 2016 compared to 2016 and 2015, and decreased by $305,000 in 2015 compared to 2014.respectively.

The Company's maintenance and supplies costs were 6.9% of total revenue in 2017, 4.7% of total revenue in 2016, and 6.6% of total revenue in 2015, and 11.0% of total revenue in 2014.2015. Maintenance and supplies costs increased by $485,000 and decreased by $215,000 in 2017 and $602,000 in2016 compared to 2016 and 2015, respectively. The increase in 2017 compared to 2015 and 2014, respectively.2016 was due to the Company’s PBRT maintenance contract which began September 2017. The decrease in 2016 compared to 2015 was due to the expiration of fixed fee maintenance contracts at existing sites. The decrease in 2015 compared to 2014 was due to the expiration of fixed fee maintenance contracts at existing sites and the sale of the Company’s units in Turkey, which also had fixed fee maintenance contracts. The existing sites with fixed fee maintenance contracts that expired, now receive maintenance on a scheduled and on an as needed basis, which can be more cost effective.

Depreciation and amortization costs as a percentage of total revenue were 33.5%33.8%, 37.1%33.5%, and 40.0%,37.1% in 2017, 2016 2015 and 2014,2015, respectively. Depreciation and amortization costs increased $339,000 and $123,000 in 2017 and 2016 compared to 20152016 and decreased $32,000 in 2015, compared to 2015 and 2014, respectively. The increase in 2017 and 2016 compared to 2016 and 2015 iswas due to depreciation incurred on the PBRT system. The decrease in 2015 compared to 2014 is due to the sale of EWRS Turkey in 2014, offset by increased depreciation in 2015 for the Company’s new site, which started in December 2014, and two Cobalt-60 reloads, which occurred during the second and third quarters 2015.system, respectively.

Other direct operating costs as a percentage of total revenue were 14.8%15.0%, 15.7%14.8%, and 14.8%15.7% in 2017, 2016 2015 and 2014,2015, respectively. Other direct operating costs increased by $164,000 in 2017 and 2016 compared to 2016 and 2015, respectively. The increase in 2017 is due to property taxes and increased $329,000operating costs for the Company’s PBRT system and operating costs for the Company’s new Gamma Knife site in 2015 compared to 2014.Peru. The increase in 2016 is due to marketing costs for the new PBRT site and increased marketing costs at an existing customer site, offset by a decrease in operating costs at the Company’s retail sites. The increase in 2015 is due to increased operating costs at the Company’s retail sites, offset slightly by lower insurance costs.

SELLING AND ADMINISTRATIVE EXPENSE

The Company's selling and administrative costs increased $521,000 and $306,000 in 2017 and 2016 compared to 2016 and 2015, respectively. The increase in 2017 was driven by start-up costs for the Company’s new site in Peru, legal fees, consulting fees, travel costs, severance expense and decreased $134,000 in 2015 comparedbuilding rent. The Company moved offices on August 31, 2016. Prior to 2014.the move, the Company subleased a portion of its existing office space. The Company also recorded approximately $108,000 of stock-based compensation expense to recognize performance awards for the year ended December 31, 2017. These performance awards had certain vesting targets tied to performance metrics which were achieved for the year ended. The increase in 2016 is due to a write-off of deferred legal fees and increased rent expense. The increase in rent expense is primarily due to the expiration of the sublease at the Company’s prior office space, which offset total rent. The decrease in 2015 is due to consulting fees that were expensed in 2014, a decrease in state and local taxes paid, offset by an increase in stock-based compensation expense.

INTEREST EXPENSE

The Company's interest expense increased $220,000 and $468,000 in 2017 and 2016 compared to 2016 and 2015, and decreased $460,000 in 2015 compared to 2014.respectively. The increase in 2017 and 2016 compared to 2016 and 2015 is primarily due to interest incurred on PBRT lease financing, offset by a lower average principal base for the Company’s Gamma Knife portfolio, effectively reducing interest expense. The decrease in 2015 compared to 2014 is due, in part, to the sale of EWRS Turkey in 2014, which accounted for approximately $100,000 of expense in 2014. In addition, the Company had a lower average principal base in 2015, effectively reducing interest expense.

(LOSS) ON EARLY EXTINGUISHMENT OF DEBT

*Not meaningful

(Loss) on early extinguishment of debt was $0 in 2017 compared to $108,000 in 2016 compared toand $0 in 2015 and 2014.2015. In February 2016, the Company used a portion of the proceeds from the lease financing for its first MEVION S250 to pay down the $1,000,000 of Promissory Notes that were issued pursuant to the Note and Warrant Purchase Agreements (the “Agreements”) between the Company and four members of the Company’s Board of Directors. The Agreements permit for early payment without penalty to the Company. The Notes were issued with common stock warrants with an estimated fair value of $145,000. The unamortized balance of the discount on the Notes, of $80,000, and deferred fees incurred from the issuance of the Note of approximately $28,000, were recorded as a loss on early extinguishment of debt on the Company’s condensed consolidated statement of operations.

(LOSS) ON WRITE DOWN INVESTMENT IN EQUITY SECURITIES

*Not meaningful

(Loss) on the write down of the Company’s investment in equity securities was $579,000 in 2017 compared to $0 in 2016 comparedand $2,140,000 in 2015. For 2017, the (loss) on the write down of investment in equity securities is due to $2,140the other-than-temporary assessment performed at December 31, 2017. The Company adjusted the carrying value of its investment in Mevion to the determined fair value of $0 and recorded a $579,000 impairment loss. For 2015, and $0 in 2014. Thethe (loss) on the write down of investment in equity securities is due to the other-than-temporary impairment assessment performed at June 30, 2015.At2015. At June 30, 2015, the Company adjusted the carrying value of its investment in Mevion to the determined fair value of $600,000 and recorded a $2,114,000 impairment loss. Subsequently, the Company engaged a third partythird-party expert to review its assessment of the fair value of the Company’s common stock in Mevion and as a result, adjusted the impairment loss an additional $26,000. For the year ended December 31, 2015 the impairment loss was $2,140,000 and the fair value was approximately $579,000.

This transaction is treated as a capital loss for tax purposes which may be deducted only to the extent the Company has capital gains. The Company is not aware of any event or transaction planned where the Company would generate a capital gain. Therefore, a full valuation allowance was recorded against the income tax benefit from the impairment loss, and the net impact to the income tax provision is $0.

(LOSS) ON SALE OF SUBSIDIARY

INTEREST AND OTHER INCOME

Interest and other income decreased $12,000 and $3,000 in 2017 and $10,000 in2016 compared to 2016 and 2015, compared to 2015 and 2014, respectively. The decrease in 2015 was due to lower interest income because the Company closed out the certificate of deposit on January 2, 2015.

INCOME TAX EXPENSE

Income tax expense decreased $2,046,000 and increased $509,000 in 2017 and $305,000 in 2016 and 2015 compared to 20152017 and 2014,2016, respectively. On December 22, 2017, the U.S. government enacted comprehensive tax legislation commonly referred to as the Tax Cuts and Jobs Act (the "Tax Act"). The Tax Act makes broad and complex changes to the U.S. tax code that affect fiscal 2017, including, but not limited to requiring a one-time transition tax on certain unrepatriated earnings of foreign subsidiaries that is payable over eight years. The Tax Act also establishes new tax laws that will affect 2018 and later years, including, but not limited to, a reduction of the U.S. federal corporate tax rate from 34% to 21%, a general elimination of U.S. federal income taxes on dividends from foreign subsidiaries, net operating loss deduction limitations, a base erosion, anti-tax abuse tax and a deduction for foreign-derived intangible income and a new provision designed to tax global intangible low-taxed income. As these provisions do not apply until 2018 the Company continues to evaluate the impact of such provisions of the Tax Act. As a result of the Tax Act, the Company revalued its federal and state deferred tax liabilities based on a 21% tax rate as opposed to a 34% tax rate. The net effect of this change on the Company’s income tax provision for the year ended December 31, 2017 was a tax benefit of $1,546,000.

The increase in 2016 is due to income from the PBRT system and operations of the Company’s subsidiaries. The increase in 2015 is due to income from operations of the Company’s subsidiaries. The loss incurred on the write-down of the Company’s investment in equity securities is a capital loss which is treated as non-deducible expense for income tax provision purposes and as such, a full valuation allowance was recorded against this loss and the net impact to the provision was $0.

The Company anticipates that it will continue to record income tax expense if it operates profitably in the future. Currently there are state income tax payments required for most states in which the Company operates. However, there are minimal current federal income tax payments required due to net operating loss carryforwards and other deferred tax assets available for federal tax purposes.

The Company had a net operating loss carryforward for federal income tax return purposes at December 31, 20162017 of approximately $7,589,000.$5,928,000.

NET INCOME ATTRIBUTABLE TO NON-CONTROLLING INTERESTS

Net income attributable to non-controlling interests decreased $303,000 and increased $374,000 in 2017 and $556,000 in2016 compared to 2016 and 2015, compared to 2015 and 2014, respectively. Net income attributable to non-controlling interests represents the pre-tax income earned by the 19% non-controlling interest in GKF, and the pre-tax income or losses of the non-controlling interests in various subsidiaries controlled by GKF. The decrease or increase in net income attributable to non-controlling interests reflects the relative profitability of GKF.

NET INCOME (LOSS) ATTRIBUTABLE TO AMERICAN SHARED HOSPITAL SERVICES

Net income attributable to American Shared Hospital Services was $1,923,000 in 2017 compared to $930,000 in 2016, compared toand a net loss of $1,522,000 in 2015,2015. Excluding the adjustment to the Company’s income tax provision, because of the Tax Act of $1,546,000, and athe write-down of the Company’s investment in Mevion of $579,000 in 2017, and the loss on early extinguishment of debt of $108,000, net loss of $952,000estimated taxes in 2014.2016, net income decreased $38,000 in 2017 compared to 2016. Excluding the loss on early extinguishment of debt of $108,000, net of estimated taxes, in 2016, and the write-down of the Company’s investment in Mevion of $2,140,000 in 2015, net income increased $376,000.$376,000 in 2016 compared to 2015. This increase was due to the new PBRT system which began operations in April 2016. Excluding the write-down of the Company’s investment in Mevion of $2,140,000 in 2015, and the loss on sale of subsidiary of $572,000 and foreign currency gains of $161,000 in 2014, net income increased $1,159,000 in 2015 compared to 2014. The increase in net income in 2015 compared to 2014 is due to increased volumes and average reimbursement per procedures, in addition to lower costs of revenue.

IMPAIRMENT ANALYSIS OF INVESTMENT IN EQUITY SECURITIES

As of December 31, 2016,2017, and December 31, 20152016 the Company had a $0 and $579,000 investment in the common stock of Mevion, respectively, representing an approximate 0.46% interest in Mevion. The Company accounts for this investment under the cost method. The Company carries its investment in Mevion at cost and reviews it for impairment on a quarterly basis, or as events or circumstances might indicate that the carrying value of the investment may not be recoverable.

Based on guidance provided in Accounting Standards Codification (“ASC”) 320 Investments–Debt and Equity Securities (“ASC 320”) and Staff Accounting Bulletins (“SAB”) Topic 5M Other Than Temporary Impairment (“OTTI”) of Certain Investments in Equity Securities (“SAB Topic 5M”), the Company analyzed the related events of Mevion, that occurred in the second and third quarters of 2015 and its impact on the Company’s investment. The Company determined that these circumstances indicated a decline in value of its Mevion investment that was other-than-temporary and concluded that a write-down of the carrying value should be recognized. As of June 30, 2015, the Company adjusted its investment in Mevion to the estimated fair value of $600,000 and recorded a $2,114,000 impairment loss. The $2,114,000 other than temporary impairment of its investment in Mevion is recorded in other income (loss) on the Company’s Condensed Consolidated Statement of Operations.

During the period ended December 31, 2015, the Company engaged a third-party expert to review and corroborate its assessment of the fair value of the Mevion investment. Based on the third-party analysis, an additional impairment loss of $26,000 was recognized by the Company during the three months ended December 31, 2015. The fair value of the Company’s investment in Mevion, as of December 31, 2015 and September 30, 2016 was approximately $579,000. The impairment loss for the year ended December 31, 2015 was $2,140,000.

TheDuring the year ended December 31, 2017, the Company reviewed thisits investment atin Mevion and determined the fair value of its investment was $0. Based on the Company’s assessment of its investment in Mevion, the Company recognized an impairment loss for the year then ended December 31, 2016 in light2017 of both current market conditions and the ongoing needs of Mevion to raise cash to continue its development of the first compact, single room PBRT system. Based on its analysis, the Company determined no additional impairment needs to be recognized as of December 31, 2016.$579,000.

LIQUIDITY AND CAPITAL RESOURCES

The Company had cash and cash equivalents of $2,152,000 at December 31, 2017 compared to $2,871,000 at December 31, 2016, compared to $2,209,000 at December 31, 2015, an increasea decrease of $662,000.$719,000. The Company’s expected primary cash needs on both a short and long-term basis are for capital expenditures, business expansion, working capital, and other general corporate purposes.

Restricted cash of $250,000$350,000 at December 31, 20162017 increased $200,000$100,000 compared to December 31, 2015.2016. The increase in 20162017 is due to restricted cash requirements per Orlando’s lease financing agreement. Existing restricted cash reflects cash that may only be used for the operations of GKF.

Operating activities provided cash of $8,378,000$7,853,000 in 2016,2017, which was driven by net income of $2,250,000,$2,940,000, non-cash charges for depreciation and amortization of $6,327,000, the$6,677,000, loss on early extinguishmentdisposal of debtassets of $108,000, deferred income tax$15,000, loss on the write-down of $772,000,the Company’s investment in equity securities of $579,000, net accrued interest on lease financing of $414,000,$113,000, stock-based compensation expense of $215,000,$323,000, and changes in accounts payable, other non-cash itemsaccrued liabilities and deferred revenue of $4,000.$125,000. These were partially offset by changes in receivables of $1,230,000,$860,000, changes in prepaid and other assets of $283,000,$793,000, and changes in accounts payable and accrued liabilitiesdeferred income tax benefit of $199,000.$1,266,000.

The Company’s trade accounts receivable increased by $1,047,000$934,000 to $5,019,000 at December 31, 2017 from $4,085,000 at December 31, 2016, from $3,038,000 at December 31, 2015, primarily due to accounts receivable related to the new PBRT system which began operations in April 2016. The number of days revenue (sales) outstanding (“DSO”) in accounts receivable as of December 31, 20162017 increased to 8094 days compared to 6780 days at December 31, 2015.2016. DSO can and does fluctuate depending on timing of customer payments received and the mix of fee per use versus retail customers. Retail sites generally have longer collection periods than fee per use sites.

Investing activities used $1,612,000$653,000 of cash in 20162017 due to payments made towards the purchase of property and equipment of $1,612,000.$803,000, offset by proceeds from sale of equipment of $150,000.

Financing activities used $6,104,000$7,919,000 of cash during 2016,2017, primarily due to principal payments on long-term debt of $2,968,000,$2,314,000, principal payments towards capital leases of $4,171,000,$4,954,000, distributions to non-controlling interests of $699,000,$666,000, and restricted cash of $200,000. This was$100,000. These were partially offset by long term debt financing on equipment of $570,000, capital contributions from non-controlling interests in subsidiaries of the Company of $7,000, proceeds from warrants and options exercised of $220,000, and proceeds from capital lease financing for reimbursement of payments for acquisition of equipment of $1,137,000.$115,000.

The Company had negative working capital at December 31, 20162017 of $293,000$114,000 compared to negative working capital of $2,691,000$815,000 at December 31, 2015.2016. The $2,398,000$701,000 increase in net working capital was due to an increase in cash and restricted cash of $662,000 and $200,000, respectively,$100,000, increases in accounts receivable of $1,047,000, increases in other accounts receivable of $183,000,$934,000, increases in prepaid and other assets of $289,000, increases in employee compensation expenses of $28,000,$786,000, and a net increasedecrease in the current portion of long term debt and capital leases of $73,000.$59,000. This was offset by a decrease in cash of $719,000, decrease in other accounts receivable of $74,000, increase in accounts payable of $56,000$40,000, increase in employee compensation and decreasesbenefits of $3,000, increase in other accrued liabilities of $62,000.$88,000, and an increase in long-term debt of $254,000. The Company believes that its cash flow from cash on hand, operations, and other cash resources are adequate to meet its scheduled debt and capital lease obligations during the next 12 months. See additional discussion below related to commitments.

The Company, in the past, has secured financing for its Gamma Knife and radiation therapy units. The Company has secured financing for its projects from several lenders and anticipates that it will be able to secure financing on future projects from these or other lending sources, but there can be no assurance that financing will continue to be available on acceptable terms.

IMPACT OF INFLATION AND CHANGING PRICES

The Company does not believe that inflation has had a significant impact on operations because a substantial majority of the costs that it incurs under its customer contracts are fixed through the term of the contract.

CONTRACTUAL OBLIGATIONS, COMMITMENTS, CONTINGENT LIABILITIES AND OFF BALANCEOFF-BALANCE SHEET ARRANGEMENTS

The following table presents, as of December 31, 2016,2017, the Company’s significant fixed and determinable contractual obligations by payment date. The payment amounts represent those amounts contractually due to the recipient and do not include any unamortized premiums or discounts, hedge basis adjustments, or other similar carrying value adjustments. Further discussion of the nature of each obligation is included in the notes to the consolidated financial statements referenced below. For purposes of this table, these commitments are listed in the less than 1 year and 1-3 year1-3-year categories.

Further discussion of the long-term debt commitment is included in Note 5, capital leases in Note 6, and operating leases in Note 11 of the consolidated financial statements.

As of December 31, 2016,2017, the Company had commitments to purchase two MEVION S250 PBRT systems for $25,800,000 and the Company had $2,000,000 in non-refundable deposits toward the purchase of these two PBRT systems from Mevion. The non-refundable deposits are recorded in the consolidated balance sheetsCondensed Consolidated Balance Sheets as deposits and construction in progress. The

On July 21, 2017, the Company signed First Amendments to two System Build Agreements (the “Amendments”) for the Company’s first MEVION S250second and third Mevion PBRT treated its first patient in April 2016.units. The Company and Mevion have not agreed on preliminary construction and delivery timetables for the second and third PBRT units for which the Company has purchase commitments. The Company’s delivery timeframe is triggered by USFDA 510K clearance of Mevion’s recently developed treatment nozzle. The Company is actively seeking sites for these units but, to date, has not entered into agreements with any party for either placement of a PBRT unit or the related financing. InThe Company projects that it will be required to take delivery of the past,second and third PBRT units no later than 2019 and 2020, respectively.

On July 21, 2017, the Company entered into a Maintenance and Support Agreement (the “Mevion Service Agreement”) with Mevion, have established constructionwhich provides for maintenance and delivery timetables, and therefore progress payment dates, only after the Company has notified Mevion that there is a proposed site for the unit. Accordingly, the timing of the required payments for the remaining $25,800,000support of the Company’s purchase commitments remains uncertain.PBRT unit at Orlando Health. The Company’s positionMevion Service Agreement began September 5, 2017 and required an upfront payment of $1,000,000 which was made on August 4, 2017, and further requires payments over the next 11 months. This payment portion was recorded as a prepaid contract and will be amortized over the one-year service period. The Mevion Service Agreement is that these payments should not commence until a site is available for a PBRT unit and the related financing is in place.five (5) year period.

As of December 31, 2016,2017, the Company had commitments to purchase oneperform two Cobtalt-60 reloads at existing Gamma Knife Perfexion system, one Cobalt-60 reload, and is scheduled to install one Gamma Knife Model 4C system, which the Company previously financed and owns.customer sites. Total Gamma Knife commitments as of December 31, 2016,2017 were $3,160,000.$1,500,000. The Model 4C unit isCobalt-60 reloads are scheduled to be installedoccur in the third quarter of 2017 at the Company’s new customer site in Peru. There are cash requirements for the Peru commitment in the next 12 months of approximately $200,000. The Company believes that cash flow from cash on hand and operations will be sufficient to cover this payment. The Perfexion unit is for a new site the Company expects to start treating patients in the latterfirst half of 2017.2018. The Company has secured financing for this unit. The Cobalt-60 reload is for an existing customer and occurred in the first quarter of 2017. The Company obtained financing for this reload as well.these reloads. There are no other significant cash requirements, pending financing for the Cobalt-60 reloads in the next 12 months. There can be no assurance that financing will be available for the Company’s current or future projects, or at terms that are acceptable to the Company.

The Company estimates the following commitments for each of the equipment systems, with expected timing of payments as follows as of December 31, 2016:2017:

ITEM 7A. QUANTITATIVE AND QUALITATIVE DISCLOSURES ABOUT MARKET RISK

The table below presents information about certain market-sensitive financial instruments as of December 31, 2016.2017. The fair values were determined based on quoted market prices for the same or similar instruments.