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        <ExclusionAmt>1060</ExclusionAmt>
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      <InfoInScheduleOPartIXInd>X</InfoInScheduleOPartIXInd>
      <GrantsToDomesticOrgsGrp>
        <TotalAmt>307000</TotalAmt>
      </GrantsToDomesticOrgsGrp>
      <GrantsToDomesticIndividualsGrp>
        <TotalAmt>44000</TotalAmt>
      </GrantsToDomesticIndividualsGrp>
      <FeesForServicesManagementGrp>
        <TotalAmt>647966</TotalAmt>
      </FeesForServicesManagementGrp>
      <FeesForServicesOtherGrp>
        <TotalAmt>229429</TotalAmt>
      </FeesForServicesOtherGrp>
      <AdvertisingGrp>
        <TotalAmt>2911</TotalAmt>
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      <OfficeExpensesGrp>
        <TotalAmt>37762</TotalAmt>
      </OfficeExpensesGrp>
      <InformationTechnologyGrp>
        <TotalAmt>8648</TotalAmt>
      </InformationTechnologyGrp>
      <TravelGrp>
        <TotalAmt>38364</TotalAmt>
      </TravelGrp>
      <ConferencesMeetingsGrp>
        <TotalAmt>473183</TotalAmt>
      </ConferencesMeetingsGrp>
      <InsuranceGrp>
        <TotalAmt>6070</TotalAmt>
      </InsuranceGrp>
      <OtherExpensesGrp>
        <Desc>LICENSES AND FEES</Desc>
        <TotalAmt>16623</TotalAmt>
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      <OtherExpensesGrp>
        <Desc>DUES AND SUBSCRIPTIONS</Desc>
        <TotalAmt>200</TotalAmt>
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      <TotalFunctionalExpensesGrp>
        <TotalAmt>1812156</TotalAmt>
      </TotalFunctionalExpensesGrp>
      <CashNonInterestBearingGrp>
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        <EOYAmt>486794</EOYAmt>
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      <SavingsAndTempCashInvstGrp>
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        <EOYAmt>332919</EOYAmt>
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      <PledgesAndGrantsReceivableGrp>
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        <EOYAmt>93670</EOYAmt>
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        <EOYAmt>158062</EOYAmt>
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        <EOYAmt>2071445</EOYAmt>
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      <AccountsPayableAccrExpnssGrp>
        <BOYAmt>3500</BOYAmt>
        <EOYAmt>62153</EOYAmt>
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      <GrantsPayableGrp>
        <BOYAmt>231800</BOYAmt>
        <EOYAmt>343800</EOYAmt>
      </GrantsPayableGrp>
      <DeferredRevenueGrp>
        <BOYAmt>274985</BOYAmt>
        <EOYAmt>108935</EOYAmt>
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      <TotalLiabilitiesGrp>
        <BOYAmt>510285</BOYAmt>
        <EOYAmt>514888</EOYAmt>
      </TotalLiabilitiesGrp>
      <OrganizationFollowsFASB117Ind>X</OrganizationFollowsFASB117Ind>
      <NoDonorRestrictionNetAssetsGrp>
        <BOYAmt>429280</BOYAmt>
        <EOYAmt>470023</EOYAmt>
      </NoDonorRestrictionNetAssetsGrp>
      <DonorRestrictionNetAssetsGrp>
        <BOYAmt>95161</BOYAmt>
        <EOYAmt>1086534</EOYAmt>
      </DonorRestrictionNetAssetsGrp>
      <TotalNetAssetsFundBalanceGrp>
        <BOYAmt>524441</BOYAmt>
        <EOYAmt>1556557</EOYAmt>
      </TotalNetAssetsFundBalanceGrp>
      <TotLiabNetAssetsFundBalanceGrp>
        <BOYAmt>1034726</BOYAmt>
        <EOYAmt>2071445</EOYAmt>
      </TotLiabNetAssetsFundBalanceGrp>
      <ReconcilationRevenueExpnssAmt>1032116</ReconcilationRevenueExpnssAmt>
      <OtherChangesInNetAssetsAmt>0</OtherChangesInNetAssetsAmt>
      <InfoInScheduleOPartXIIInd>X</InfoInScheduleOPartXIIInd>
      <MethodOfAccountingAccrualInd>X</MethodOfAccountingAccrualInd>
      <AccountantCompileOrReviewInd>0</AccountantCompileOrReviewInd>
      <FSAuditedInd>1</FSAuditedInd>
      <FSAuditedBasisGrp>
        <SeparateBasisFinclStmtInd>X</SeparateBasisFinclStmtInd>
      </FSAuditedBasisGrp>
      <AuditCommitteeInd>1</AuditCommitteeInd>
      <FederalGrantAuditRequiredInd>0</FederalGrantAuditRequiredInd>
    </IRS990>
    <IRS990ScheduleB documentId="RetDoc1234500001">
      <ContributorInformationGrp>
        <ContributorNum>RESTRICTED</ContributorNum>
        <ContributorBusinessName>
          <BusinessNameLine1>RESTRICTED</BusinessNameLine1>
        </ContributorBusinessName>
        <ContributorUSAddress>
          <AddressLine1>RESTRICTED</AddressLine1>
          <AddressLine2>RESTRICTED</AddressLine2>
          <City>RESTRICTED</City>
          <State>RESTRICTED</State>
          <ZIPCode>RESTRICTED</ZIPCode>
        </ContributorUSAddress>
        <TotalContributionsAmt>RESTRICTED</TotalContributionsAmt>
      </ContributorInformationGrp>
    </IRS990ScheduleB>
    <IRS990ScheduleC documentId="RetDoc1039700001">
      <SubstantiallyAllDuesNondedInd>0</SubstantiallyAllDuesNondedInd>
      <OnlyInHouseLobbyingInd>1</OnlyInHouseLobbyingInd>
      <AgreeCarryoverPriorYearInd>0</AgreeCarryoverPriorYearInd>
    </IRS990ScheduleC>
    <IRS990ScheduleD documentId="RetDoc1040000001">
      <TotalBookValueLandBuildingsAmt>0</TotalBookValueLandBuildingsAmt>
      <FootnoteTextInd>X</FootnoteTextInd>
      <TotalRevEtcAuditedFinclStmtAmt>2844272</TotalRevEtcAuditedFinclStmtAmt>
      <RevenueNotReportedAmt>0</RevenueNotReportedAmt>
      <RevenueSubtotalAmt>2844272</RevenueSubtotalAmt>
      <RevenueNotReportedFinclStmtAmt>0</RevenueNotReportedFinclStmtAmt>
      <TotalRevenuePerForm990Amt>2844272</TotalRevenuePerForm990Amt>
      <TotExpnsEtcAuditedFinclStmtAmt>1812156</TotExpnsEtcAuditedFinclStmtAmt>
      <ExpensesNotReportedAmt>0</ExpensesNotReportedAmt>
      <ExpensesSubtotalAmt>1812156</ExpensesSubtotalAmt>
      <ExpensesNotRptFinclStmtAmt>0</ExpensesNotRptFinclStmtAmt>
      <TotalExpensesPerForm990Amt>1812156</TotalExpensesPerForm990Amt>
      <SupplementalInformationDetail>
        <FormAndLineReferenceDesc>PART X, LINE 2:</FormAndLineReferenceDesc>
        <ExplanationTxt>SIO BELIEVES THAT IT HAS APPROPRIATE SUPPORT FOR ANY TAX POSITIONS TAKEN, AND AS SUCH, DOES NOT HAVE ANY UNCERTAIN TAX POSITIONS THAT ARE MATERIAL TO THE FINANCIAL STATEMENTS OR THAT WOULD HAVE AN EFFECT ON ITS TAX-EXEMPT STATUS. THERE ARE NO UNRECOGNIZED TAX BENEFITS OR LIABILITIES THAT NEED TO BE RECORDED.</ExplanationTxt>
      </SupplementalInformationDetail>
    </IRS990ScheduleD>
    <IRS990ScheduleI documentId="RetDoc1041900001">
      <GrantRecordsMaintainedInd>1</GrantRecordsMaintainedInd>
      <RecipientTable>
        <RecipientBusinessName>
          <BusinessNameLine1Txt>UNIVERSITY OF TEXAS</BusinessNameLine1Txt>
        </RecipientBusinessName>
        <USAddress>
          <AddressLine1Txt>5323 HARRY HINES BLVD</AddressLine1Txt>
          <CityNm>DALLAS</CityNm>
          <StateAbbreviationCd>TX</StateAbbreviationCd>
          <ZIPCd>75390</ZIPCd>
        </USAddress>
        <RecipientEIN>756002868</RecipientEIN>
        <IRCSectionDesc>N/A</IRCSectionDesc>
        <CashGrantAmt>100000</CashGrantAmt>
        <PurposeOfGrantTxt>RESEARCH GRANT</PurposeOfGrantTxt>
      </RecipientTable>
      <RecipientTable>
        <RecipientBusinessName>
          <BusinessNameLine1Txt>YALE UNIVERSITY</BusinessNameLine1Txt>
        </RecipientBusinessName>
        <USAddress>
          <AddressLine1Txt>PO BOX 2038</AddressLine1Txt>
          <CityNm>NEW HAVEN</CityNm>
          <StateAbbreviationCd>CT</StateAbbreviationCd>
          <ZIPCd>06521</ZIPCd>
        </USAddress>
        <RecipientEIN>060646973</RecipientEIN>
        <IRCSectionDesc>501(C)(3)</IRCSectionDesc>
        <CashGrantAmt>100000</CashGrantAmt>
        <PurposeOfGrantTxt>RESEARCH GRANT</PurposeOfGrantTxt>
      </RecipientTable>
      <RecipientTable>
        <RecipientBusinessName>
          <BusinessNameLine1Txt>NORTHWESTERN UNIVERSITY</BusinessNameLine1Txt>
        </RecipientBusinessName>
        <USAddress>
          <AddressLine1Txt>633 CLARK ST</AddressLine1Txt>
          <CityNm>EVANSTON</CityNm>
          <StateAbbreviationCd>IL</StateAbbreviationCd>
          <ZIPCd>60208</ZIPCd>
        </USAddress>
        <RecipientEIN>362167817</RecipientEIN>
        <IRCSectionDesc>501(C)(3)</IRCSectionDesc>
        <CashGrantAmt>100000</CashGrantAmt>
        <PurposeOfGrantTxt>RESEARCH GRANT</PurposeOfGrantTxt>
      </RecipientTable>
      <RecipientTable>
        <RecipientBusinessName>
          <BusinessNameLine1Txt>BRIGHAM AND WOMEN'S HOSPITAL</BusinessNameLine1Txt>
        </RecipientBusinessName>
        <USAddress>
          <AddressLine1Txt>75 FRANCIS ST</AddressLine1Txt>
          <CityNm>BOSTON</CityNm>
          <StateAbbreviationCd>MA</StateAbbreviationCd>
          <ZIPCd>02115</ZIPCd>
        </USAddress>
        <RecipientEIN>043277859</RecipientEIN>
        <IRCSectionDesc>501(C)(3)</IRCSectionDesc>
        <CashGrantAmt>7000</CashGrantAmt>
        <PurposeOfGrantTxt>RESEARCH GRANT</PurposeOfGrantTxt>
      </RecipientTable>
      <Total501c3OrgCnt>3</Total501c3OrgCnt>
      <TotalOtherOrgCnt>1</TotalOtherOrgCnt>
      <GrantsOtherAsstToIndivInUSGrp>
        <GrantTypeTxt>FELLOW TRAVEL GRANTS</GrantTypeTxt>
        <RecipientCnt>52</RecipientCnt>
        <CashGrantAmt>44000</CashGrantAmt>
      </GrantsOtherAsstToIndivInUSGrp>
      <SupplementalInformationDetail>
        <FormAndLineReferenceDesc>PART I, LINE 2:</FormAndLineReferenceDesc>
        <ExplanationTxt>SIO AND THE WCIO CONFERENCE INVESTS IN THE SUCCESS OF THE INTERVENTIONAL ONCOLOGY (IO) FIELD BY OFFERING FUTURE IO PROFESSIONALS THE OPPORTUNITY TO ATTEND AND ENGAGE IN WCIO ANNUAL CONFERENCES THROUGH THE WCIO ANNUAL MEETING SCHOLARSHIP. THE SCHOLARSHIP IS OPEN TO ALL INTERVENTIONAL RADIOLOGY FELLOWS, DIAGNOSTIC RADIOLOGY RESIDENTS AND POST-GRADUATE MEDICAL STUDENTS WITHIN THE UNITED STATES. AN APPLICANT MUST BE IN THEIR ACGME INTERVENTIONAL RADIOLOGY FELLOWSHIP OR ACGME DIAGNOSTIC RADIOLOGY RESIDENCY AT THE TIME OF APPLICATION, OR BE A POST-GRADUATE MEDICAL STUDENT WITHIN THE IO FIELD. MINIMAL MONITORING IS REQUIRED.</ExplanationTxt>
      </SupplementalInformationDetail>
    </IRS990ScheduleI>
    <IRS990ScheduleO documentId="RetDoc1044400001">
      <SupplementalInformationDetail>
        <FormAndLineReferenceDesc>FORM 990, PART III, LINE 2</FormAndLineReferenceDesc>
        <ExplanationTxt>THE FOLLOWING PROGRAMS WERE NOT LISTED ON THE PRIOR YEAR 990, BUT HAVE BEEN ONGOING PROGRAMS: EDUCATION AND TRAINING, PUBLICATIONS, ONLINE COMMUNITY, AND RESEARCH GRANTS. SEE FORM 990, PART III, LINE 4 AND SCHEDULE O FOR THE PROGRAM DESCRIPTIONS. OTHER MEETINGS IS NEW IN 2020.</ExplanationTxt>
      </SupplementalInformationDetail>
      <SupplementalInformationDetail>
        <FormAndLineReferenceDesc>FORM 990, PART VI, SECTION A, LINE 1</FormAndLineReferenceDesc>
        <ExplanationTxt>THE EXECUTIVE COMMITTEE SHALL BE COMPRISED OF THE ELECTED OFFICERS OF THE ORGANIZATION, THE CHAIR, VICE-CHAIR AND PAST-CHAIR. THE COMMITTEE SHALL MEET REGULARLY AS OUTLINED IN THE BOARD POLICY. THE EXECUTIVE COMMITTEE SHALL ACT FOR THE BOARD OF DIRECTORS IN THE INTERIM BETWEEN MEETINGS OF THE BOARD BY A TWO-THIRDS VOTE. ALL DIRECTORS SHALL BE SENT ELECTRONIC NOTICE OF AN EXECUTIVE COMMITTEE VOTE WITHIN FIVE (5) BUSINESS DAYS OF SUCH VOTE, ALONG WITH THE OPPORTUNITY TO NOTIFY THE CHIEF EXECUTIVE OFFICER ELECTRONICALLY WITHIN A DATE SPECIFIED IN SUCH NOTICE (SAID DATE NOT TO BE LESS THAN FIVE (5) BUSINESS DAYS AFTER THE DATE OF SUCH NOTICE) IF THEY WISH THE EXECUTIVE COMMITTEE VOTE TO BE SUBJECT TO RATIFICATION BY THE BOARD OF DIRECTORS.</ExplanationTxt>
      </SupplementalInformationDetail>
      <SupplementalInformationDetail>
        <FormAndLineReferenceDesc>FORM 990, PART VI, SECTION A, LINE 3</FormAndLineReferenceDesc>
        <ExplanationTxt>THE ORGANIZATION HAS ENTERED INTO A MANAGEMENT CONTRACT WITH SMITHBUCKLIN CORPORATION. UNDER THE TERMS OF THIS CONTRACT, SIO MAKES PAYMENTS TO SMITHBUCKLIN WHICH COVER STAFF SALARIES AND OTHER OVERHEAD EXPENSES. SMITHBUCKLIN'S PERFORMANCE UNDER THIS AGREEMENT IS MONITORED BY THE BOARD OF SIO. THE FEES INCURRED BY SIO DURING THE YEAR ENDED DECEMBER 31, 2020 WERE $647,966 FOR THE FOLLOWING: EXECUTIVE MANAGEMENT OF $120,000, MEMBERSHIP AND OPERATIONS SERVICES, EVENT SERVICES, MARKETING AND COMMUNICATIONS SERVICES, CREATIVE AND DESIGN SERVICES, EDUCATION AND LEARNING SERVICES, FINANCIAL MANAGEMENT AND ACCOUNTING SERVICES, INFORMATION TECHNOLOGY SERVICES AND VALUE ADDED SERVICES. SMITHBUCKLIN'S PERFORMANCE UNDER THIS AGREEMENT IS MONITORED BY THE BOARD OF SIO.</ExplanationTxt>
      </SupplementalInformationDetail>
      <SupplementalInformationDetail>
        <FormAndLineReferenceDesc>FORM 990, PART VI, SECTION A, LINE 6</FormAndLineReferenceDesc>
        <ExplanationTxt>THE MEMBERHSIP OF THE SOCIETY SHALL CONSIST OF: ACTIVE - DUES PAYING INDIVIDUALS WHO ARE PHYSICIANS WHO PRACTICE INTERVENTIONAL ONCOLOGY OR A RELATED FIELD AND PHD LEVEL SCIENTISTS. ACTIVE MEMBERS ARE VOTING MEMBERS WHO CAN HOLD OFFICE OR SERVE AS COMMITTEE CHAIRS. AFFILIATE - DUES PAYING INDIVIDUALS WHO ARE NOT PHYSICIANS, BUT ARE RELATED MEDICAL PROFESSIONALS, RESEARCH ASSISTANTS, OR HEALTH SPECIALISTS WHO SUPPORT ACTIVITIES RELATED TO INTERVENTIONAL ONCOLOGY. AFFILIATE MEMBERS CANNOT VOTE OR HOLD OFFICE, BUT CAN SERVE ON A COMMITTEE. RESIDENT/FELLOW - DUES PAYING INDIVIDUALS IN THEIR RESIDENCY OR FELLOWSHIP. RESIDENTS AND FELLOWS CANNOT VOTE, SERVE ON A COMMITTEE OR HOLD OFFICE. STUDENT - DUES PAYING INDIVIDUALS WHO ARE STUDENTS OF INTERVENTIONAL ONCOLOGY OR RELATED FIELD. STUDENTS CANNOT VOTE, SERVE ON A COMMITTEE OR HOLD OFFICE.</ExplanationTxt>
      </SupplementalInformationDetail>
      <SupplementalInformationDetail>
        <FormAndLineReferenceDesc>FORM 990, PART VI, SECTION A, LINE 7A</FormAndLineReferenceDesc>
        <ExplanationTxt>THE ORGANIZATION'S MEMBERS ELECT THE MEMBERS OF THE BOARD OF DIRECTORS.</ExplanationTxt>
      </SupplementalInformationDetail>
      <SupplementalInformationDetail>
        <FormAndLineReferenceDesc>FORM 990, PART VI, SECTION B, LINE 11B</FormAndLineReferenceDesc>
        <ExplanationTxt>THE FORM 990 IS REVIEWED BY THE STAFF OF THE MANAGEMENT COMPANY, INCLUDING THE EXECUTIVE DIRECTOR, AND A COPY IS PROVIDED TO THE ENTIRE BOARD PRIOR TO FILING.</ExplanationTxt>
      </SupplementalInformationDetail>
      <SupplementalInformationDetail>
        <FormAndLineReferenceDesc>FORM 990, PART VI, SECTION C, LINE 19</FormAndLineReferenceDesc>
        <ExplanationTxt>THE ORGANIZATION MAKES ITS GOVERNING DOCUMENTS AND FINANCIAL STATEMENTS AVAILABLE TO THE PUBLIC UPON REQUEST.</ExplanationTxt>
      </SupplementalInformationDetail>
      <SupplementalInformationDetail>
        <FormAndLineReferenceDesc>FORM 990, PART IX, LINE 11G</FormAndLineReferenceDesc>
        <ExplanationTxt>SPEAKER FEE 54,481. OTHER PROFESSIONAL FEES 174,948.</ExplanationTxt>
      </SupplementalInformationDetail>
      <SupplementalInformationDetail>
        <FormAndLineReferenceDesc>FORM 990, PART XII, LINE 2C:</FormAndLineReferenceDesc>
        <ExplanationTxt>THE ORGANIZATION HAS NOT CHANGED ITS OVERSIGHT PROCESS OR SELECTION PROCESS OF AN INDEPENDENT ACCOUNTANT DURING THE TAX YEAR.</ExplanationTxt>
      </SupplementalInformationDetail>
    </IRS990ScheduleO>
  </ReturnData>
</Return>
