Ionizing Radiation In Medicine
• In the Beginning it wasX-Rays– Röntgen (1895)– Start of Development of
Non-Invasive Diagnostics
Medical Dose to Public• Accounts for > 40% of Public
Radiation Exposure– Internal and External Exposure
• Doses and Concentrations– Much Higher than Seen in the
RETS-REMP World• Radiopharmaceuticals
– Activity Administered to OneIndividual for One Procedure….
Annual Release from NPP
CAT Scan Radiation Dose
Head 200 mremChest 700 mremAbdomen 1,000 mremPelvis 1,000 mremWhole-Body 1,000 mrem
Radiopharmaceuticals• Worldwide The Most Commonly
Administered Radiopharmaceuticals Are:– Tc-99m (80% of all applications)– I-131
• 1996 – In U.S. ~ 8,000,000 ProceduresPerformed Using Radiopharmaceuticals
– Tc-99m: 6,900,000– I-131: 180,000
Radiopharmaceuticals in the U.S.
• Estimated Worldwide Use of I-131 inDeveloped Countries as of 2012– Hyperthyroid Treatment: 150 per million people.– Thyroid Cancer: 38 per million people
Radiopharmaceuticals – I-131
• Estimated Worldwide Use of I-131 inDeveloped Countries as of 2012– Hyperthyroid Treatment: 150 per million people.– Thyroid Cancer: 38 per million people
Radiopharmaceuticals – I-131
• Very High Activity May Be Administeredfor Aggressive Treatment
I-131 and Thyroid Cancer
– Enough to Kill DestroyThyroid Tissue
– Not Enough to KillPatient
• 10 CFR 20– 1301: Dose Limits for Individual Members of
the Public– 2003: Disposal by Release Into Sanitary
Sewerage• 10 CFR 35
– 75: Release of Individuals Containing UnsealedByproduct Material or Implants ContainingByproduct Material
U.S. Regulation of Radiopharmaceuticals
• 1301.(a)– 100 mrem TEDE
• 1301.(c)(1)– Visitors to an individual who cannot be released
under 10 CFR 35.75 can receive up to 500 mrem.– At the discretion of the “authorized user.”
10 CFR 20.1301Dose Limits for Individual Members of the Public
• 2003.(a)(2)– Average Monthly Concentration Not to Exceed
Concentration Limits of Part 20, App B, Table 3.• 2003.(b)
– “Excreta from individuals [i.e. patients]… are notsubject to the limitations contained in paragraph(a)…”
10 CFR 20.2003Disposal by Release to Sanitary Sewerage
• 75(a)– Release allowed if TEDE to any “other
individual” exposed to the patient is not likely toexceed 500 mrem.
• 75(b)– If dose to “other individual” likely to exceed 100
mrem, written instructions required to minimizedose to others.
10 CFR 35.75Release of Individuals Containing Unsealed Byproduct
Material or Implants containing Byproduct Material
Reg Guide 8.39Release of Patients Administered
Radioactive Materials• Release Criteria
– Administered Activity OR– Decayed Activity OR– 1-meter Dose Rate OR– Patient Specific Calculations
Patient Specific Calculations
• Minimize Dose to Others– Time, Distance and Shielding– Radiological and Biological Half-life
• Tools to Calculate Dose Readily Available– RADAR (www.doseinfo-radar.com)– Calculates Dose to Docs, Staff and Others that
are Exposed to an Individual AdministeredRadiopharmaceuticals
Release of Patients ReceivingRadiopharmaceuticals
• Patients routinely released under 35.75(a)– TEDE to any “other individual” exposed to the patient is
not likely to exceed 500 mrem.• Criteria Based on “Patient Specific” Calculations
– Doctors Assume Patient and Others Will FollowInstructions to Limit Dose
– Responsibility for Compliance Rests on Patient,Guardian, Care Giver…
Reg Guide 8.39 Release Criteria forTc-99m and I-131
Tc-99m I-131Reg Guide 8.39 Release Criteria
Administered Activity 760 mCi 33 mCiDecayed Activity 760 mCi 33 mCi
1-Meter Dose Rate 58 mrem/hr 7 mrem/hr
Typical Administered Activity
Diagnostic 20 mCi 10 mCiTherapeutic - 300 mCi or greater
Release of Patients ReceivingTherapeutic Doses of I-131
• Problems– Administered therapeutic activity of I-131
exceeds RG 8.39 guidance.– Medical facilities must minimize dose to staff.– Rad waste holdup is expensive for medical
facilities.
I-131 Clears Quickly• 50% Clears in the First 24 Hours• 80% - 90% of Administered Excreted Over the
Next 3-5 Days• Eliminated Primarily in Urine• Sooooo – Where Does It Go?
You Guessed It!• Single Individual Could Pass
100-200 mCi of I-131 intoSewer System in One WeeksTime
• In Large Hospital 3-5Therapeutic and 40-50Diagnostic Administrationsper Week
• A Lot of I-131 is Entering theEnvironment
Is This a Problem?Medical Radionuclides Detected in Sewage Systems
• Cr-51• Ga-67• Se-75• Tc-99m
• I-123• I-125• I-131• Tl-201• Au-198
Contaminants Present in Radiopharmaceuticals
Radiopharmaceutical PotentialContaminants Half-life
I-123 13 hI-124 4 dI-125 60 dI-126 13 dI-130 12 h
Te-121 17 dNa-24 15 h
Contaminants Present in Radiopharmaceuticals
Radiopharmaceutical PotentialContaminants Half-life
Ga-67 3.3 dGa-66 10 hZn-65 244 d
Tc-99m 6 hMo-99 66 h
Tl-201 73 hTl-200 26 hTl-202 12 d
Stabin M, Schlatke-Stelson A. A List Of Nuclear Medicine Radionuclides And Potential Contaminants For Operators OfIn-Vivo Counters. Health Physics. 1991 September;61(3):427-430.
Does Anyone Really Care?• 40 CFR 257
– Criteria for Classification of Solid Waste Disposal Facilities and Practices
• 40 CFR 503– Regulation of Sewage Sludge Disposal
• NUREG/CR-5814– Evaluation of Exposure Pathways to Man From Disposal of Radioactive
Materials Into Sanitary Sewer Systems. Washington: USNRC; 1992Nuclear Regulatory Commission.
• NUREG/CR-6289– Reconcentration of Radioactive Material Released to Sanitary Sewers in
Accordance with 10 CFR Part 20.
• And a lot of published research…..
NUREG/CR-5814Evaluation of Exposure Pathways to Man From
Disposal of Radioactive Materials Into Sanitary Sewer Systems
• General Dose Scenarios Examined– Sewage Treatment Process– Sludge Treatment and Disposal– Post-Sewage Sludge Removal
• Exposure Pathways– External– Internal
• Exposed Groups– Waste Treatment Facility Worker– Member of the Public
NUREG/CR-5814Evaluation of Exposure Pathways to Man From
Disposal of Radioactive Materials Into Sanitary Sewer Systems
– H-3– Hard To Detects
• Fe-55• Ni-63• Sr-89• Sr-90
– Most Commonly Used Radiopharmaceuticals• Tc-99m• I-131
Radionuclide Source Term
Doses for H-310 CFR 20 – Effluent Concentration Limit
(1.0E-03 uCi/ml)
Scenario ExposedIndividual
TEDE Dose(mrem)
Sewage Treatment Process Operations Worker 1.8E-10
Incineration of STP Sludge Worker 3.2E-09
Incinerated Sludge Ash Disposal Worker 1.5E-10
Application for Agricultural Use Public < 1.0E-10
Land Fill – Public Use Public < 1.0E-10
Doses for Fe-5510 CFR 20 – Effluent Concentration Limit
(1.0E-04 uCi/ml)
Scenario ExposedIndividual
TEDE Dose(mrem)
Sewage Treatment Process Operations Worker 2.7E-07
Incineration of STP Sludge Worker 5.0E-07
Incinerated Sludge Ash Disposal Worker 4.3E-09
Application for Agricultural Use Public 7.8E-10
Land Fill – Public Use Public 8.8E-10
Doses for Ni-6310 CFR 20 – Effluent Concentration Limit
(1.0E-04 uCi/ml)
Scenario ExposedIndividual
TEDE Dose(mrem)
Sewage Treatment Process Operations Worker 8.8E-09
Incineration of STP Sludge Worker 1.6E-07
Incinerated Sludge Ash Disposal Worker 7.2E-09
Application for Agricultural Use Public < 1.0E-10
Land Fill – Public Use Public < 1.0E-10
Doses for Sr-8910 CFR 20 – Effluent Concentration Limit
(8.0E-08 uCi/ml)
Scenario ExposedIndividual
TEDE Dose(mrem)
Sewage Treatment Process Operations Worker 2.8E-05
Incineration of STP Sludge Worker 2.6E-05
Incinerated Sludge Ash Disposal Worker 6.3E-06
Application for Agricultural Use Public 4.8E-05
Land Fill – Public Use Public 3.4E-06
Doses for Sr-9010 CFR 20 – Effluent Concentration Limit
(5.0E-07 uCi/ml)
Scenario ExposedIndividual
TEDE Dose(mrem)
Sewage Treatment Process Operations Worker 2.2E-06
Incineration of STP Sludge Worker 1.7E-05
Incinerated Sludge Ash Disposal Worker 8.5E-07
Application for Agricultural Use Public 1.7E-04
Land Fill – Public Use Public 4.3E-08
Doses for Tc-99m10 CFR 20 – Effluent Concentration Limit
(1.0E-03 uCi/ml)
Scenario ExposedIndividual
TEDE Dose(mrem)
Sewage Treatment Process Operations Worker 2.2E-07
Incineration of STP Sludge Worker 2.2E-07
Incinerated Sludge Ash Disposal Worker 2.5E-08
Application for Agricultural Use Public < 1.0E-10
Land Fill – Public Use Public < 1.0E-10
Doses for I-13110 CFR 20 – Effluent Concentration Limit
(1.0E-06 uCi/ml)
Scenario ExposedIndividual
TEDE Dose(mrem)
Sewage Treatment Process Operations Worker 3.9E-03
Incineration of STP Sludge Worker 3.6E-03
Incinerated Sludge Ash Disposal Worker 1.1E-03
Application for Agricultural Use Public 3.0E-05
Land Fill – Public Use Public 7.3E-04