Medical Radionuclides in theEnvironment

Jim KeyKey Solutions, Inc.

2014 RETS-REMP WorkshopSavannah

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

PET Scan Radiation Dose

Brain PET Scan – 1,410 mrem

CAT Scan Radiation Dose

Head 200 mremChest 700 mremAbdomen 1,000 mremPelvis 1,000 mremWhole-Body 1,000 mrem

Radiation Dose for Fused CT-PET Scan

Combined Exposure from CAT and PET Dose ?

Radiation Doses for Cardiac Stress Test• Tc-99m 940 mrem• Tl-201 4,100 mrem

Veterinary Medicine

• CAT Scan of Pet– External Dose

• PET Scan of Cat– Internal Dose

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

Where Does it End Up?

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