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        <OtherCostOrOtherBasisAmt>745300</OtherCostOrOtherBasisAmt>
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        <OtherCostOrOtherBasisAmt>2913040</OtherCostOrOtherBasisAmt>
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        <Amt>2988041</Amt>
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      <OtherLiabilitiesOrgGrp>
        <Desc>DEFERRED COMPENSATION LIABILITY</Desc>
        <Amt>471375</Amt>
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      <TotalLiabilityAmt>3459416</TotalLiabilityAmt>
      <FootnoteTextInd>X</FootnoteTextInd>
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      <InvestmentExpensesNotIncldAmt>110805</InvestmentExpensesNotIncldAmt>
      <RevenueNotReportedFinclStmtAmt>110805</RevenueNotReportedFinclStmtAmt>
      <TotalRevenuePerForm990Amt>23415351</TotalRevenuePerForm990Amt>
      <TotExpnsEtcAuditedFinclStmtAmt>22814538</TotExpnsEtcAuditedFinclStmtAmt>
      <ExpensesNotReportedAmt>0</ExpensesNotReportedAmt>
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      <SupplementalInformationDetail>
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        <ExplanationTxt>RETURN OF PRIOR YEAR GRANT FUNDS 104.</ExplanationTxt>
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          <CityNm>WINSTONSALEM</CityNm>
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        <NontaxableBenefitsFilingOrgAmt>15101</NontaxableBenefitsFilingOrgAmt>
        <NontaxableBenefitsRltdOrgsAmt>0</NontaxableBenefitsRltdOrgsAmt>
        <TotalCompensationFilingOrgAmt>173665</TotalCompensationFilingOrgAmt>
        <TotalCompensationRltdOrgsAmt>0</TotalCompensationRltdOrgsAmt>
        <CompReportPrior990FilingOrgAmt>0</CompReportPrior990FilingOrgAmt>
        <CompReportPrior990RltdOrgsAmt>0</CompReportPrior990RltdOrgsAmt>
      </RltdOrgOfficerTrstKeyEmplGrp>
      <RltdOrgOfficerTrstKeyEmplGrp>
        <PersonNm>SAMANTHA DAWES</PersonNm>
        <TitleTxt>DIRECTOR OF QUALITY IMPROVEMENT</TitleTxt>
        <BaseCompensationFilingOrgAmt>143645</BaseCompensationFilingOrgAmt>
        <CompensationBasedOnRltdOrgsAmt>0</CompensationBasedOnRltdOrgsAmt>
        <BonusFilingOrganizationAmount>2000</BonusFilingOrganizationAmount>
        <BonusRelatedOrganizationsAmt>0</BonusRelatedOrganizationsAmt>
        <OtherCompensationFilingOrgAmt>0</OtherCompensationFilingOrgAmt>
        <OtherCompensationRltdOrgsAmt>0</OtherCompensationRltdOrgsAmt>
        <DeferredCompensationFlngOrgAmt>14579</DeferredCompensationFlngOrgAmt>
        <DeferredCompRltdOrgsAmt>0</DeferredCompRltdOrgsAmt>
        <NontaxableBenefitsFilingOrgAmt>2917</NontaxableBenefitsFilingOrgAmt>
        <NontaxableBenefitsRltdOrgsAmt>0</NontaxableBenefitsRltdOrgsAmt>
        <TotalCompensationFilingOrgAmt>163141</TotalCompensationFilingOrgAmt>
        <TotalCompensationRltdOrgsAmt>0</TotalCompensationRltdOrgsAmt>
        <CompReportPrior990FilingOrgAmt>0</CompReportPrior990FilingOrgAmt>
        <CompReportPrior990RltdOrgsAmt>0</CompReportPrior990RltdOrgsAmt>
      </RltdOrgOfficerTrstKeyEmplGrp>
      <SupplementalInformationDetail>
        <FormAndLineReferenceDesc>PART I, LINE 4B</FormAndLineReferenceDesc>
        <ExplanationTxt>DURING THE YEAR ENDED DECEMBER 31, 2019, LAURA THEVENOT, CEO, PARTICIPATED IN A 457(F) NONQUALIFIED PLAN, WITH CONTRIBUTIONS TO THE PLAN OF $11,000.</ExplanationTxt>
      </SupplementalInformationDetail>
    </IRS990ScheduleJ>
    <IRS990ScheduleO documentId="RetDoc1044400001">
      <SupplementalInformationDetail>
        <FormAndLineReferenceDesc>FORM 990, PART VI, SECTION A, LINE 6</FormAndLineReferenceDesc>
        <ExplanationTxt>ASTRO'S NOMINATING COMMITTEE IS COMPRISED OF 12 MEMBERS, INCLUDING 6 BOARD MEMBERS AND 6 PERSONS ELECTED FROM ITS MEMBERSHIP. THE NOMINATING COMMITTEE IS RESPONSIBLE FOR FINALIZING THE SLATE OF CANDIDATES FOR THE BOARD OF DIRECTORS.</ExplanationTxt>
      </SupplementalInformationDetail>
      <SupplementalInformationDetail>
        <FormAndLineReferenceDesc>FORM 990, PART VI, SECTION A, LINE 7A</FormAndLineReferenceDesc>
        <ExplanationTxt>REFER TO EXPLANATION PROVIDED IN RESPONSE TO LINE 6 FOR A DESCRIPTION OF THE MEMBERS WITH THE RIGHT TO ELECT THE GOVERNING BODY.</ExplanationTxt>
      </SupplementalInformationDetail>
      <SupplementalInformationDetail>
        <FormAndLineReferenceDesc>FORM 990, PART VI, SECTION A, LINE 7B</FormAndLineReferenceDesc>
        <ExplanationTxt>REFER TO EXPLANATION PROVIDED IN RESPONSE TO LINE 6 FOR A DESCRIPTION OF THE MEMBERS WITH THE RIGHT TO PARTICIPATE IN ASTRO'S GOVERNANCE.</ExplanationTxt>
      </SupplementalInformationDetail>
      <SupplementalInformationDetail>
        <FormAndLineReferenceDesc>FORM 990, PART VI, SECTION B, LINE 11B</FormAndLineReferenceDesc>
        <ExplanationTxt>THE FEDERAL FORM 990 IS PREPARED BY OUR EXTERNAL TAX ACCOUNTANTS. THE DRAFT IS PROVIDED TO OUR FINANCE STAFF FOR REVIEW BEFORE BEING SUBMITTED TO THE VP FINANCE &amp; ADMINISTRATION, CEO, AND TREASURER FOR THEIR REVIEW AND APPROVAL. THE REVISED DRAFT IS THEN PROVIDED TO THE FULL BOARD OF DIRECTORS FOR THEIR REVIEW PRIOR TO FILING WITH THE INTERNAL REVENUE SERVICE.</ExplanationTxt>
      </SupplementalInformationDetail>
      <SupplementalInformationDetail>
        <FormAndLineReferenceDesc>FORM 990, PART VI, SECTION B, LINE 12C</FormAndLineReferenceDesc>
        <ExplanationTxt>ASTRO'S OFFICERS, DIRECTORS, KEY EMPLOYEES AND VOLUNTEERS ARE REQUIRED TO FILL OUT DISCLOSURE FORMS ON AN ANNUAL BASIS AND TO UPDATE THEIR DISCLOSURE FORMS UPON ANY MATERIAL CHANGE IN THE INTERIM. THESE DISCLOSURE FORMS ARE REVIEWED IN ORDER TO IDENTIFY AND ADDRESS ANY POTENTIAL CONFLICTS OF INTERESTS FOR THESE INDIVIDUALS.</ExplanationTxt>
      </SupplementalInformationDetail>
      <SupplementalInformationDetail>
        <FormAndLineReferenceDesc>FORM 990, PART VI, SECTION B, LINE 15</FormAndLineReferenceDesc>
        <ExplanationTxt>AN INDEPENDENT CONSULTANT PERFORMED MARKET SURVEY TO DEVELOP SALARY STRUCTURE AND RANGES. ASTRO'S PRACTICE IS TO COMPLETE A MARKET SURVEY EVERY THREE YEARS; THIS WAS LAST COMPLETED FOR THE CEO IN 2019. THE CEO'S COMPENSATION IS DETERMINED BY A SUBCOMMITTEE OF THE BOARD USING COMPARABLE SALARIES OF SIMILAR CEO POSITIONS OF NONPROFIT MEDICAL ORGANIZATIONS. THIS REVIEW WAS DISCUSSED WITH THE BOARD OF DIRECTORS AND RECEIVED THEIR APPROVAL. ANNUALLY, BUDGET GUIDELINES ARE SET FOR ANY ADDITIONS TO STAFF AND SALARY INCREASES. MANAGERS MAKE RECOMMENDATIONS FOR ANNUAL INCREASES AND PROMOTIONS WHICH ARE REVIEWED BY HUMAN RESOURCES AND THE DIVISION VICE PRESIDENTS. ALL PROMOTIONS ARE APPROVED BY THE CHIEF EXECUTIVE OFFICER.</ExplanationTxt>
      </SupplementalInformationDetail>
      <SupplementalInformationDetail>
        <FormAndLineReferenceDesc>FORM 990, PART VI, SECTION C, LINE 19</FormAndLineReferenceDesc>
        <ExplanationTxt>THE SUMMARY FINANCIAL STATEMENTS ARE AVAILABLE UPON REQUEST. GOVERNING DOCUMENTS AND CONFLICT OF INTEREST POLICY ARE AVAILABLE ON OUR WEBSITE.</ExplanationTxt>
      </SupplementalInformationDetail>
      <SupplementalInformationDetail>
        <FormAndLineReferenceDesc>FORM 990, PART IX, LINE 11G</FormAndLineReferenceDesc>
        <ExplanationTxt>CONSULTING FEES 2,035,271. OTHER PROFESSIONAL FEES 361,051.</ExplanationTxt>
      </SupplementalInformationDetail>
      <SupplementalInformationDetail>
        <FormAndLineReferenceDesc>FORM 990, PART XI, LINE 9:</FormAndLineReferenceDesc>
        <ExplanationTxt>RETURN OF PRIOR YEAR GRANT FUNDS 104.</ExplanationTxt>
      </SupplementalInformationDetail>
    </IRS990ScheduleO>
    <IRS990ScheduleR documentId="RetDoc1043400001">
      <IdRelatedTaxExemptOrgGrp>
        <DisregardedEntityName>
          <BusinessNameLine1Txt>RADIATION ONCOLOGY INSTITUTE</BusinessNameLine1Txt>
        </DisregardedEntityName>
        <USAddress>
          <AddressLine1Txt>251 18TH STREET SOUTH 8TH FLOOR</AddressLine1Txt>
          <CityNm>ARLINGTON</CityNm>
          <StateAbbreviationCd>VA</StateAbbreviationCd>
          <ZIPCd>22202</ZIPCd>
        </USAddress>
        <EIN>510178702</EIN>
        <PrimaryActivitiesTxt>TO SUPPORT AND CONDUCT RESEARCH AND EDUCATIONAL ACTIVITIES</PrimaryActivitiesTxt>
        <LegalDomicileStateCd>IL</LegalDomicileStateCd>
        <ExemptCodeSectionTxt>501(C)(3)</ExemptCodeSectionTxt>
        <PublicCharityStatusTxt>LINE 12B, II</PublicCharityStatusTxt>
        <DirectControllingEntityName>
          <BusinessNameLine1Txt>ASTRO</BusinessNameLine1Txt>
        </DirectControllingEntityName>
        <ControlledOrganizationInd>1</ControlledOrganizationInd>
      </IdRelatedTaxExemptOrgGrp>
      <IdRelatedTaxExemptOrgGrp>
        <DisregardedEntityName>
          <BusinessNameLine1Txt>ASTRO PAC</BusinessNameLine1Txt>
        </DisregardedEntityName>
        <USAddress>
          <AddressLine1Txt>251 18TH STREET SOUTH 8TH FLOOR</AddressLine1Txt>
          <CityNm>ARLINGTON</CityNm>
          <StateAbbreviationCd>VA</StateAbbreviationCd>
          <ZIPCd>22202</ZIPCd>
        </USAddress>
        <EIN>061673960</EIN>
        <PrimaryActivitiesTxt>POLITICAL ACTION COMMITTEE</PrimaryActivitiesTxt>
        <LegalDomicileStateCd>VA</LegalDomicileStateCd>
        <ExemptCodeSectionTxt>527</ExemptCodeSectionTxt>
        <DirectControllingEntityName>
          <BusinessNameLine1Txt>ASTRO</BusinessNameLine1Txt>
        </DirectControllingEntityName>
        <ControlledOrganizationInd>1</ControlledOrganizationInd>
      </IdRelatedTaxExemptOrgGrp>
      <ReceiptOfIntAnntsRntsRyltsInd>0</ReceiptOfIntAnntsRntsRyltsInd>
      <GiftGrntOrCapContriToOthOrgInd>1</GiftGrntOrCapContriToOthOrgInd>
      <GiftGrntCapContriFromOthOrgInd>1</GiftGrntCapContriFromOthOrgInd>
      <LoansOrGuaranteesToOtherOrgInd>0</LoansOrGuaranteesToOtherOrgInd>
      <LoansOrGuaranteesFromOthOrgInd>0</LoansOrGuaranteesFromOthOrgInd>
      <DivRelatedOrganizationInd>0</DivRelatedOrganizationInd>
      <AssetSaleToOtherOrgInd>0</AssetSaleToOtherOrgInd>
      <AssetPurchaseFromOtherOrgInd>0</AssetPurchaseFromOtherOrgInd>
      <AssetExchangeInd>0</AssetExchangeInd>
      <RentalOfFacilitiesToOthOrgInd>0</RentalOfFacilitiesToOthOrgInd>
      <RentalOfFcltsFromOthOrgInd>0</RentalOfFcltsFromOthOrgInd>
      <PerformOfServicesForOthOrgInd>0</PerformOfServicesForOthOrgInd>
      <PerformOfServicesByOtherOrgInd>0</PerformOfServicesByOtherOrgInd>
      <SharingOfFacilitiesInd>1</SharingOfFacilitiesInd>
      <PaidEmployeesSharingInd>1</PaidEmployeesSharingInd>
      <ReimbursementPaidToOtherOrgInd>1</ReimbursementPaidToOtherOrgInd>
      <ReimbursementPaidByOtherOrgInd>1</ReimbursementPaidByOtherOrgInd>
      <TransferToOtherOrgInd>0</TransferToOtherOrgInd>
      <TransferFromOtherOrgInd>0</TransferFromOtherOrgInd>
      <TransactionsRelatedOrgGrp>
        <OtherOrganizationName>
          <BusinessNameLine1Txt>RADIATION ONCOLOGY INSTITUTE</BusinessNameLine1Txt>
        </OtherOrganizationName>
        <TransactionTypeTxt>B</TransactionTypeTxt>
        <InvolvedAmt>88600</InvolvedAmt>
        <MethodOfAmountDeterminationTxt>ACTUAL</MethodOfAmountDeterminationTxt>
      </TransactionsRelatedOrgGrp>
      <TransactionsRelatedOrgGrp>
        <OtherOrganizationName>
          <BusinessNameLine1Txt>RADIATION ONCOLOGY INSTITUTE</BusinessNameLine1Txt>
        </OtherOrganizationName>
        <TransactionTypeTxt>N</TransactionTypeTxt>
        <InvolvedAmt>96070</InvolvedAmt>
        <MethodOfAmountDeterminationTxt>FMV</MethodOfAmountDeterminationTxt>
      </TransactionsRelatedOrgGrp>
      <TransactionsRelatedOrgGrp>
        <OtherOrganizationName>
          <BusinessNameLine1Txt>RADIATION ONCOLOGY INSTITUTE</BusinessNameLine1Txt>
        </OtherOrganizationName>
        <TransactionTypeTxt>O</TransactionTypeTxt>
        <InvolvedAmt>347393</InvolvedAmt>
        <MethodOfAmountDeterminationTxt>FMV</MethodOfAmountDeterminationTxt>
      </TransactionsRelatedOrgGrp>
      <TransactionsRelatedOrgGrp>
        <OtherOrganizationName>
          <BusinessNameLine1Txt>RADIATION ONCOLOGY INSTITUTE</BusinessNameLine1Txt>
        </OtherOrganizationName>
        <TransactionTypeTxt>P</TransactionTypeTxt>
        <InvolvedAmt>71011</InvolvedAmt>
        <MethodOfAmountDeterminationTxt>ACTUAL</MethodOfAmountDeterminationTxt>
      </TransactionsRelatedOrgGrp>
      <SupplementalInformationDetail>
        <FormAndLineReferenceDesc>SCHEDULE R, PART V, LINE 2</FormAndLineReferenceDesc>
        <ExplanationTxt>THE $71,011 IS A FINAL BALANCE OF THE DUE TO/FROM ACCOUNT THAT IS A COMBINATION OF OVERHEAD, CREDIT CARD DONATION PAID THROUGH ASTRO FOR ROI, AND JOINT INVOICES PAID THROUGH ASTRO FOR ROI.</ExplanationTxt>
      </SupplementalInformationDetail>
    </IRS990ScheduleR>
  </ReturnData>
</Return>