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        <FormAndLineReferenceDesc>PART IV, SECTION A, LINE 3B:</FormAndLineReferenceDesc>
        <ExplanationTxt>ROI IS THE SUPPORTING ORGANIZATION FOR THE AMERICAN SOCIETY FOR RADIATION ONCOLOGY (ASTRO), A 501(C)(6) ORGANIZATION. ROI PERFORMED THE 509(A)(2) TEST FOR ASTRO AND FOUND THAT ASTRO'S SUPPORT PERCENTAGE EXCEEDS THE 33% MINIMUM OF PUBLIC SUPPORT THAT WOULD BE A REQUIREMENT IF ASTRO WERE DESCRIBED AS SUCH AN ENTITY. ACCORDINGLY, ROI IS ELIGIBLE TO SUPPORT ASTRO.</ExplanationTxt>
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          <AddressLine2>RESTRICTED</AddressLine2>
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          <State>RESTRICTED</State>
          <ZIPCode>RESTRICTED</ZIPCode>
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        <InvestmentEarningsOrLossesAmt>1281972</InvestmentEarningsOrLossesAmt>
        <OtherExpendituresAmt>192224</OtherExpendituresAmt>
        <EndYearBalanceAmt>10457820</EndYearBalanceAmt>
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        <BeginningYearBalanceAmt>9117677</BeginningYearBalanceAmt>
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        <InvestmentEarningsOrLossesAmt>414950</InvestmentEarningsOrLossesAmt>
        <OtherExpendituresAmt>521209</OtherExpendituresAmt>
        <EndYearBalanceAmt>9169439</EndYearBalanceAmt>
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        <BeginningYearBalanceAmt>9431266</BeginningYearBalanceAmt>
        <ContributionsAmt>272097</ContributionsAmt>
        <InvestmentEarningsOrLossesAmt>-172985</InvestmentEarningsOrLossesAmt>
        <OtherExpendituresAmt>412701</OtherExpendituresAmt>
        <EndYearBalanceAmt>9117677</EndYearBalanceAmt>
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        <BeginningYearBalanceAmt>9041538</BeginningYearBalanceAmt>
        <ContributionsAmt>361072</ContributionsAmt>
        <InvestmentEarningsOrLossesAmt>441358</InvestmentEarningsOrLossesAmt>
        <OtherExpendituresAmt>412702</OtherExpendituresAmt>
        <EndYearBalanceAmt>9431266</EndYearBalanceAmt>
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        <BeginningYearBalanceAmt>8335418</BeginningYearBalanceAmt>
        <ContributionsAmt>521273</ContributionsAmt>
        <InvestmentEarningsOrLossesAmt>1201604</InvestmentEarningsOrLossesAmt>
        <OtherExpendituresAmt>976994</OtherExpendituresAmt>
        <EndYearBalanceAmt>9081301</EndYearBalanceAmt>
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      <EndowmentsHeldRelatedOrgInd>0</EndowmentsHeldRelatedOrgInd>
      <TotalBookValueLandBuildingsAmt>0</TotalBookValueLandBuildingsAmt>
      <FootnoteTextInd>X</FootnoteTextInd>
      <TotalRevEtcAuditedFinclStmtAmt>2100687</TotalRevEtcAuditedFinclStmtAmt>
      <NetUnrealizedGainsInvstAmt>953853</NetUnrealizedGainsInvstAmt>
      <DonatedServicesAndUseFcltsAmt>22919</DonatedServicesAndUseFcltsAmt>
      <RevenueNotReportedAmt>976772</RevenueNotReportedAmt>
      <RevenueSubtotalAmt>1123915</RevenueSubtotalAmt>
      <InvestmentExpensesNotIncldAmt>38243</InvestmentExpensesNotIncldAmt>
      <RevenueNotReportedFinclStmtAmt>38243</RevenueNotReportedFinclStmtAmt>
      <TotalRevenuePerForm990Amt>1162158</TotalRevenuePerForm990Amt>
      <TotExpnsEtcAuditedFinclStmtAmt>641939</TotExpnsEtcAuditedFinclStmtAmt>
      <DonatedServicesUseFcltsAmt>22919</DonatedServicesUseFcltsAmt>
      <ExpensesNotReportedAmt>22919</ExpensesNotReportedAmt>
      <ExpensesSubtotalAmt>619020</ExpensesSubtotalAmt>
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      <SupplementalInformationDetail>
        <FormAndLineReferenceDesc>PART V, LINE 4:</FormAndLineReferenceDesc>
        <ExplanationTxt>CURRENTLY, THE ENDOWMENT FUND IS A PERMANENTLY RESTRICTED FUND WHICH IS NOT AVAILABLE FOR USE.</ExplanationTxt>
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      <SupplementalInformationDetail>
        <FormAndLineReferenceDesc>PART X, LINE 2:</FormAndLineReferenceDesc>
        <ExplanationTxt>ROI PERFORMED AN EVALUATION OF UNCERTAINTY IN INCOME TAXES FOR THE YEAR ENDED DECEMBER 31, 2017, AND DETERMINED THAT THERE ARE NO MATTERS THAT WOULD REQUIRE RECOGNITION IN THE FINANCIAL STATEMENTS OR THAT MAY HAVE ANY EFFECT ON ITS TAX-EXEMPT STATUS.</ExplanationTxt>
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          <BusinessNameLine1Txt>JOHN HOPKINS UNIVERSITY</BusinessNameLine1Txt>
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        <USAddress>
          <AddressLine1Txt>3910 KESWICK ROAD N4327-B</AddressLine1Txt>
          <CityNm>BALTIMORE</CityNm>
          <StateAbbreviationCd>MD</StateAbbreviationCd>
          <ZIPCd>21211</ZIPCd>
        </USAddress>
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        <PurposeOfGrantTxt>RESEARCH GRANT</PurposeOfGrantTxt>
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      <RecipientTable>
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          <BusinessNameLine1Txt>MD ANDERSON CANCER CENTER</BusinessNameLine1Txt>
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        <USAddress>
          <AddressLine1Txt>1515 HOLCOMBE BOULEVARD</AddressLine1Txt>
          <CityNm>HOUSTON</CityNm>
          <StateAbbreviationCd>TX</StateAbbreviationCd>
          <ZIPCd>77230</ZIPCd>
        </USAddress>
        <RecipientEIN>746001118</RecipientEIN>
        <IRCSectionDesc>501(C)(3)</IRCSectionDesc>
        <CashGrantAmt>49990</CashGrantAmt>
        <PurposeOfGrantTxt>RESEARCH GRANT</PurposeOfGrantTxt>
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      <RecipientTable>
        <RecipientBusinessName>
          <BusinessNameLine1Txt>ALBERT EINSTEIN COLLEGE OF MEDICINE</BusinessNameLine1Txt>
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        <USAddress>
          <AddressLine1Txt>1300 MORRIS PARK AVENUE</AddressLine1Txt>
          <CityNm>BRONX</CityNm>
          <StateAbbreviationCd>NY</StateAbbreviationCd>
          <ZIPCd>10461</ZIPCd>
        </USAddress>
        <RecipientEIN>472209056</RecipientEIN>
        <IRCSectionDesc>501(C)(3)</IRCSectionDesc>
        <CashGrantAmt>23682</CashGrantAmt>
        <PurposeOfGrantTxt>RESEARCH GRANT</PurposeOfGrantTxt>
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      <RecipientTable>
        <RecipientBusinessName>
          <BusinessNameLine1Txt>AMERICAN SOCIETY FOR RADIATION ONCOLOGY</BusinessNameLine1Txt>
        </RecipientBusinessName>
        <USAddress>
          <AddressLine1Txt>251 18TH STREET SOUTH 8TH FLOOR</AddressLine1Txt>
          <CityNm>ARLINGTON</CityNm>
          <StateAbbreviationCd>VA</StateAbbreviationCd>
          <ZIPCd>22202</ZIPCd>
        </USAddress>
        <RecipientEIN>420943164</RecipientEIN>
        <IRCSectionDesc>501(C)(6)</IRCSectionDesc>
        <CashGrantAmt>10000</CashGrantAmt>
        <PurposeOfGrantTxt>GENERAL SUPPORT</PurposeOfGrantTxt>
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      <SupplementalInformationDetail>
        <FormAndLineReferenceDesc>PART I, LINE 2:</FormAndLineReferenceDesc>
        <ExplanationTxt>AS PER A SIGNED AGREEMENT LETTER, ROI REQUIRES ANY DEVIATION FROM THE FUNDED GRANT PROPOSAL TO BE SUBMITTED IMMEDIATELY IN WRITING TO ROI. IN ADDITION, AN INTERIM PROGRESS REPORT AND A FINAL REPORT ARE COLLECTED WHICH SUMMARIZE PROGRESS MADE AND EXPENDITURES.</ExplanationTxt>
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        <NontaxableBenefitsRltdOrgsAmt>36975</NontaxableBenefitsRltdOrgsAmt>
        <TotalCompensationFilingOrgAmt>0</TotalCompensationFilingOrgAmt>
        <TotalCompensationRltdOrgsAmt>798971</TotalCompensationRltdOrgsAmt>
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      <SupplementalInformationDetail>
        <FormAndLineReferenceDesc>PART I, LINE 3</FormAndLineReferenceDesc>
        <ExplanationTxt>ROI DOES NOT DIRECTLY HIRE OR COMPENSATE EMPLOYEES. ALL EMPLOYEES ARE EMPLOYEES OF THE AMERICAN SOCIETY FOR RADIATION ONCOLOGY (ASTRO), A RELATED ORGANIZATION EXEMPT UNDER SECTION 501(C)(6). AN INDEPENDENT CONSULTANT PERFORMED A 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 EX-OFFICIO, EXECUTIVE DIRECTOR IN 2016. THE EX-OFFICIO, EXECUTIVE DIRECTOR'S COMPENSATION IS DETERMINED BY A SUBCOMMITTEE OF THE BOARD USING COMPARABLE SALARIES OF SIMILAR EXECUTIVE DIRECTOR POSITIONS OF NONPROFIT MEDICAL ORGANIZATIONS. THIS REVIEW WAS DISCUSSED WITH THE BOARD OF DIRECTORS AND THE FINAL DETERMINATION WAS MADE BY THE EXECUTIVE COMMITTEE.</ExplanationTxt>
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      <SupplementalInformationDetail>
        <FormAndLineReferenceDesc>FORM 990, PART VI, SECTION A, LINE 3</FormAndLineReferenceDesc>
        <ExplanationTxt>ALL MANAGEMENT FUNCTIONS OF ROI ARE CONTROLLED BY THE AMERICAN SOCIETY FOR RADIATION ONCOLOGY (ASTRO), A RELATED ORGANIZATION EXEMPT UNDER SECTION 501(C)(6).</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 OF ASTRO FOR THEIR REVIEW AND APPROVAL. THE REVISED DRAFT IS THEN PROVIDED TO THE FULL BOARD OF DIRECTORS PRIOR TO FILING WITH THE INTERNAL REVENUE SERVICE.</ExplanationTxt>
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      <SupplementalInformationDetail>
        <FormAndLineReferenceDesc>FORM 990, PART VI, SECTION B, LINE 12C</FormAndLineReferenceDesc>
        <ExplanationTxt>ROI'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 THESE INDIVIDUALS.</ExplanationTxt>
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      <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>
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