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            <State>MD</State>
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        <NameOfContractor>
          <NameBusiness>
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            <State>IL</State>
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        </AddressOfContractor>
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      <ContractorCompensation>
        <NameOfContractor>
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            <State>MA</State>
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        </AddressOfContractor>
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      <Equipment>
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      <OtherLiabilities>
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      <ExpensesSubtotal>18676295</ExpensesSubtotal>
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      <TotalExpensesPerForm990>18676295</TotalExpensesPerForm990>
      <Form990ScheduleDPartXIII>
        <Identifier>DESCRIPTION OF INTENDED USE OF ENDOWMENT FUNDS:</Identifier>
        <ReturnReference>PART V, LINE 4:</ReturnReference>
        <Explanation>ASTRO'S BOARD DESIGNATED NET ASSETS HAVE BEEN BOARD APPROVED FOR VARIOUS PURPOSES INCLUDING: 1) ITS COMMITMENT TO ITS AFFILIATE'S VISION OF VALUE CAMPAIGN, 2)RESERVE FOR AN UNANTICIPATED CANCELLATION OF A FUTURE ANNUAL CONFERENCE, 3) A PRACTICE ACCREDITATION PROGRAM AND 4) OTHER PROGRAMS.</Explanation>
      </Form990ScheduleDPartXIII>
      <Form990ScheduleDPartXIII>
        <Explanation>BOTH ASTRO AND ROI COMPLY WITH THE PROVISIONS OF FINANCIAL ACCOUNTING STANDARDS BOARD CODIFICATION TOPIC ACCOUNTING FOR UNCERTAINTY IN INCOME TAXES. FOR THE YEARS ENDED DECEMBER 31, 2012 AND 2011, NO UNRECOGNIZED TAX PROVISION OR BENEFIT EXISTS FOR EITHER ORGANIZATION.</Explanation>
      </Form990ScheduleDPartXIII>
    </IRS990ScheduleD>
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          <BusinessNameLine1>RADIATION ONCOLOGY INSTITUTE</BusinessNameLine1>
        </RecipientNameBusiness>
        <AddressUS>
          <AddressLine1>8280 WILLOW OAKS CORPORATE DR STE</AddressLine1>
          <AddressLine2>500</AddressLine2>
          <City>FAIRFAX</City>
          <State>VA</State>
          <ZIPCode>22031</ZIPCode>
        </AddressUS>
        <EINOfRecipient>510178702</EINOfRecipient>
        <IRCSection>501C(3)</IRCSection>
        <AmountOfCashGrant>825358</AmountOfCashGrant>
        <PurposeOfGrant>SCIENTIFIC GRANT</PurposeOfGrant>
      </RecipientTable>
      <Form990ScheduleIPartIII>
        <TypeOfGrant>JUNIOR FACULTY CAREER RESEARCH TRAINING AWARD</TypeOfGrant>
        <NumberOfRecipients>16</NumberOfRecipients>
        <AmountOfCashGrant>400000</AmountOfCashGrant>
        <DescriptionOfNonCashAssistance>SCIENTIFIC GRANTS</DescriptionOfNonCashAssistance>
      </Form990ScheduleIPartIII>
      <Form990ScheduleIPartIII>
        <TypeOfGrant>SEED GRANT</TypeOfGrant>
        <NumberOfRecipients>6</NumberOfRecipients>
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        <DescriptionOfNonCashAssistance>SCIENTIFIC GRANTS</DescriptionOfNonCashAssistance>
      </Form990ScheduleIPartIII>
      <Form990ScheduleIPartIII>
        <TypeOfGrant>SURVIVOR CIRCLE GRANT</TypeOfGrant>
        <NumberOfRecipients>2</NumberOfRecipients>
        <AmountOfCashGrant>20000</AmountOfCashGrant>
        <DescriptionOfNonCashAssistance>SCIENTIFIC GRANTS</DescriptionOfNonCashAssistance>
      </Form990ScheduleIPartIII>
      <Form990ScheduleIPartIV>
        <Identifier>PROCEDURE FOR MONITORING GRANTS IN THE U.S.:</Identifier>
        <ReturnReference>PART I, LINE 2:</ReturnReference>
        <Explanation>SCHEDULE I, PART I, LINE 2: SCIENTIFIC GRANTS MONITORED BY SIX MONTH PROGRESS REPORTS AND FINAL REPORT</Explanation>
      </Form990ScheduleIPartIV>
    </IRS990ScheduleI>
    <IRS990ScheduleJ documentId="RetDoc1042400001">
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      <WrittenPolicyReTAndEExpenses>1</WrittenPolicyReTAndEExpenses>
      <SubstantiationRequired>1</SubstantiationRequired>
      <CompensationCommittee>X</CompensationCommittee>
      <IndependentConsultant>X</IndependentConsultant>
      <WrittenEmploymentContract>X</WrittenEmploymentContract>
      <CompensationSurvey>X</CompensationSurvey>
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      <SeverancePayment>0</SeverancePayment>
      <SupplementalNonqualRetirePlan>1</SupplementalNonqualRetirePlan>
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      <Form990ScheduleJPartII>
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        <Title>CEO</Title>
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      <GeneralExplanation>
        <ReturnReference>FORM 990, PART VI, SECTION A, LINE 6</ReturnReference>
        <Explanation>ASTRO IS A NOT-FOR-PROFIT WITH MEMBERS.</Explanation>
      </GeneralExplanation>
      <GeneralExplanation>
        <ReturnReference>FORM 990, PART VI, SECTION A, LINE 7A</ReturnReference>
        <Explanation>MEMBERS ELECT THE BOARD OF DIRECTORS.</Explanation>
      </GeneralExplanation>
      <GeneralExplanation>
        <ReturnReference>FORM 990, PART VI, SECTION A, LINE 7B</ReturnReference>
        <Explanation>CHANGES TO THE BYLAWS.</Explanation>
      </GeneralExplanation>
      <GeneralExplanation>
        <ReturnReference>FORM 990, PART VI, SECTION B, LINE 11</ReturnReference>
        <Explanation>DEVELOPED BY AUDITORS; REVIEWED BY FINANCE STAFF; APPROVED BY CFO AND CEO.</Explanation>
      </GeneralExplanation>
      <GeneralExplanation>
        <ReturnReference>FORM 990, PART VI, SECTION B, LINE 12C</ReturnReference>
        <Explanation>POLICY REVIEWED ON YEARLY BASIS.</Explanation>
      </GeneralExplanation>
      <GeneralExplanation>
        <ReturnReference>FORM 990, PART VI, SECTION B, LINE 15</ReturnReference>
        <Explanation>INDEPENDENT CONSULTANT PERFORMED SALARY SURVEY TO DEVELOP SALARY STRUCTURE AND RANGES.</Explanation>
      </GeneralExplanation>
      <GeneralExplanation>
        <ReturnReference>FORM 990, PART VI, SECTION C, LINE 18</ReturnReference>
        <Explanation>ANNUAL REPORT WITH SUMMARY FINANCIAL STATEMENTS DISTRIBUTED TO MEMBERS AND AVAILABLE TO MEMEBERS ON ASTRO WEB SITE, GOVERNING DOCUMENTS AND CONFLICT OF INTEREST POLICY AVAIALABLE TO MEMBERS ON ASRTO WEBSITE.</Explanation>
      </GeneralExplanation>
      <GeneralExplanation>
        <ReturnReference>FORM 990, PART VI, SECTION C, LINE 19</ReturnReference>
        <Explanation>NOT AVAILABLE TO THE PUBLIC.</Explanation>
      </GeneralExplanation>
    </IRS990ScheduleO>
    <IRS990ScheduleR documentId="RetDoc1043400001">
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          <BusinessNameLine1>RADIATION ONCOLOGY INSTITUTE</BusinessNameLine1>
        </NameOfDisregardedEntity>
        <AddressUS>
          <AddressLine1>8280 WILLOW OAKS CORPORATE DRIVE SU</AddressLine1>
          <City>FAIRFAX</City>
          <State>VA</State>
          <ZIPCode>22031</ZIPCode>
        </AddressUS>
        <EIN>510178702</EIN>
        <LegalDomicileState>VA</LegalDomicileState>
        <ExemptCodeSection>501(C)(3)</ExemptCodeSection>
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      <GiftGrantOrCapContrToOtherOrg>1</GiftGrantOrCapContrToOtherOrg>
      <GiftGrantOrCapContrFrOtherOrg>1</GiftGrantOrCapContrFrOtherOrg>
      <LoansOrGuaranteesToOtherOrg>0</LoansOrGuaranteesToOtherOrg>
      <LoansOrGuaranteesFromOtherOrg>0</LoansOrGuaranteesFromOtherOrg>
      <DividendsRelatedOrganization>0</DividendsRelatedOrganization>
      <SaleOfAssetsToOtherOrg>0</SaleOfAssetsToOtherOrg>
      <PurchaseOfAssetsFromOtherOrg>0</PurchaseOfAssetsFromOtherOrg>
      <ExchangeOfAssets>0</ExchangeOfAssets>
      <RentalOfFacilitiesToOtherOrgs>0</RentalOfFacilitiesToOtherOrgs>
      <RentalOfFacilitiesFrOtherOrgs>0</RentalOfFacilitiesFrOtherOrgs>
      <PerformOfServicesForOtherOrgs>0</PerformOfServicesForOtherOrgs>
      <PerformOfServicesByOtherOrgs>0</PerformOfServicesByOtherOrgs>
      <SharingOfFacilities>0</SharingOfFacilities>
      <SharingOfPaidEmployees>1</SharingOfPaidEmployees>
      <ReimbursementPaidToOtherOrg>0</ReimbursementPaidToOtherOrg>
      <ReimbursementPaidByOtherOrg>1</ReimbursementPaidByOtherOrg>
      <OtherTransferToOtherOrg>0</OtherTransferToOtherOrg>
      <OtherTransferFromOtherOrg>0</OtherTransferFromOtherOrg>
      <TransactionsRelatedOrgsTable>
        <NameOfOtherOrganization>
          <BusinessNameLine1>RADIATION ONCOLOGY INSTITUTE</BusinessNameLine1>
        </NameOfOtherOrganization>
        <TransactionType>B</TransactionType>
        <AmountInvolved>825358</AmountInvolved>
      </TransactionsRelatedOrgsTable>
      <TransactionsRelatedOrgsTable>
        <NameOfOtherOrganization>
          <BusinessNameLine1>RADIATION ONCOLOGY INSTITUTE</BusinessNameLine1>
        </NameOfOtherOrganization>
        <TransactionType>O</TransactionType>
        <AmountInvolved>232246</AmountInvolved>
      </TransactionsRelatedOrgsTable>
      <TransactionsRelatedOrgsTable>
        <NameOfOtherOrganization>
          <BusinessNameLine1>RADIATION ONCOLOGY INSTITUTE</BusinessNameLine1>
        </NameOfOtherOrganization>
        <TransactionType>Q</TransactionType>
        <AmountInvolved>144078</AmountInvolved>
      </TransactionsRelatedOrgsTable>
      <TransactionsRelatedOrgsTable>
        <NameOfOtherOrganization>
          <BusinessNameLine1>RADIATION ONCOLOGY INSTITUTE</BusinessNameLine1>
        </NameOfOtherOrganization>
        <TransactionType>C</TransactionType>
        <AmountInvolved>10000</AmountInvolved>
      </TransactionsRelatedOrgsTable>
    </IRS990ScheduleR>
  </ReturnData>
</Return>