Radiation Safety Program Overview and Terminology Robert Forrest, CHP Radiation Safety Officer Environmental Health and Radiation Safety

Remember Don’t be the RSO!

Who gets the blame? “The licensee, through its Radiation Safety Officer, failed to ensure that radiation safety activities were being performed in accordance with the established procedures.”

Radiation Symbol

New ISO Radiation Symbol

Public Perceptions Nuclear Weapons Cancer Invisible, industrial hazard

Recommending Groups ICRP- International Commission on Radiological Protection NCRP- National Council on Radiological Protection ICRU- International Commission on Radiological Units BEIR - Biological Effects of Ionizing Radiation Committee

Regulatory Agencies NRC DOE DOT EPA FDA OSHA Naval Reactors US Post Office States Local Municipalities

Main Regulatory Authorities NRC regulates: Byproduct material Reactors and Fuel State regulates: Accelerator material Energized Equipment

Agreement States vs. NRC State accepts NRC rules State can be more restrictive NRC retains control of Reactors and Fuel

Radiation Safety Program Commensurate with scope of activities Governed by: Regulations License Conditions Local Policies and Procedures

NRC Licenses License authorizes who, what, where and how Requirements above and beyond regulations Includes all correspondence back and forth between licensee and regulatory agency

NRC Licenses Specific License Names authorized users Requires amendments to change small items Broad Scope License Licensee can designate authorized users Licensee can modify “ministerial” items

Organizational Responsibilities Executive Management Radiation Safety Committee Radiation Safety Officer

Terminology Radioactive Material Radiation Contamination Half-life Activity

Radioactive Material (unstable material which spontaneously transforms usually emitting some type of radiation)

Radiation (particulate or electromagnetic energy emitted during radioactive decay)

Contamination (radioactive material spread into an unwanted place)

Half-Life The time required for any given radioisotope to decrease to one half of its original activity. T 1/2 = ln 2 / The radiological half-lives for Tc-99m and I-131 are 6 hours and 8 days, respectively.

Half life

Activity the rate of decay * the number of atoms A = *N Current Unit Curie (Ci) 1Ci = 3.7 E 10 Bq SI Unit Becquerel (Bq) 1 Bq = 1 d/s 1 Bq = 2.7 E -11 Ci

Activity A = *N If N = 1x10 9 atoms Tc-99m, A = (0.116 hr -1 )(1x10 9 atoms) A = 3.22 x 10 4 Bq (0.87 μCi) I-131, A = (3.61x10 -3 hr -1 )(1x10 9 atoms) A = 1 x 10 3 Bq (0.027 μCi)

Activity Biomedical Research uses  Ci quantities Nuclear Medicine uses mCi quantities –Bone Scan uses 25 mCi of Tc-99m Radiation Oncology uses mCi-Ci quantities –LDR implants use mCi of Cs-137 –HDR implants use 10 Ci Ir-192

Sources used in Radiation Work Biomedical Research C-14, H-3, I-125, P-32, S-35 Nuclear Medicine Tc-99m and I-131 both use unsealed sources contamination usually biggest problem

Sources Used in Radiation Work Radiology x-ray equipment Oncology Cs-137, Ir-192, Pd-103, x-ray equip. & linacs machine and sealed sources external exposure is the biggest concern

Annual Average Background Dose Distribution (total =360 mrem)

Acute Radiation Effects Minor blood changes25,000 mrem Hemopoietic Syndrome200,000 mrem Erythema ,000 mrem LD 50,30 450,000 mrem

Delayed Radiation Effects Cancer Genetic Effects

Extrapolating Risk Factors Known Effects X X X X X X Effect Radiation Dose Extrapolated Risk Occupational Dose Levels

Dose Limits (10 CFR ) Total Effective Dose Equivalent5000 mrem Total Organ Dose Equivalent50,000 mrem Lens of the Eye15,000 mrem Skin and Extremities50,000 mrem Declared Pregnant Worker500 mrem Minor500 mrem General Public100 mrem

Declared Pregnant Worker a woman who has voluntarily informed her employer, in writing, of her pregnancy and the estimated date of conception. licensee shall make efforts to avoid substantial variations in monthly exposures

Dosimeter Filters Open window Copper Tin Image filter Al 2 O 3 strip

Low energy - static Radiation

Low energy - dynamic Radiation

Pregnant Patient Get and read Wagner’s book If clinically indicated, do the study Steps should be taken to lower dose if possible When counseling, use numbers that are understandable

Pregnant Patient

Effective Doses to Patients from Diagnostic Studies DEXA < 1mrem Chest x-ray ~ 10 mrem AP abdomen ~ 70 mrem Upper GI ~ 300 mrem CT abdomen ~ mrem Coron. Angioplasty ~ 2200 mrem Source: Hall, Radiobiology for the Radiologist, 5 th edition

Effective Doses to Patients from Diagnostic Studies 4 mCi Tc MAA~ 160 mrem 15 mCi Tc DTPA~ 270 mrem 25 mCi Tc MDP~ 525 mrem 15/40 mCi Tc Mibi~ 1700 mrem 10 mCi 18F-FDG~ 700 mrem 15 mCi FDG PET/CT~2500 mrem Source: ICRP 80, Radiation Dose to Patients from Radiopharmaceuticals

Radiation Induced Skin Injuries from Fluoroscopy Skin injuries are the most likely injury resulting from diagnostic procedures. Fluoro unit outputs average to 1-2 R/min Fluoro unit outputs can go up to 10 R/min High Dose modes can go up to 20 R/min No limits on Cine or digital recordings Transient erythema at 200 rads

Radiation-Induced Skin Injuries [14, 17] Skin “burns” are rare but possible for prolonged fluorocardio & other interventions FDA has received 60 reports of burns since 1994  ~ 8.6 reported burns per year How many radiation burns are not reported? Figure from [17]

Example of chronic skin injury due to cumulative skin dose of ~20,000 mGy (20 Gy) from coronary angiography and x2 angioplasties 21 months after first procedure, base of ulcer exposes spinous process

estimated 25 Gy dose Erythemia at 3 weeks estimated 25 Gy dose Erythemia at 3 weeks

Ulceration at 5 months

Debridement at 6.5 months

Nuclear Medicine Authorized Users Requirements in 10 CFR 35 You are NOT an Authorized User UNTIL approved: specific license: NRC broad scope license: Rad. Safety Committee

Accurate Administrations The department must have a program in place to ensure that the following are correct, as directed by the Authorized User: patient identity radiopharmaceutical dosage

Medical Event (formerly misadministration) An administration involving the wrong individual, wrong radiopharmaceutical, wrong route of administration AND the dose to the patient >5 rem EDE or 50 rem to any organ.

Medical Event (formerly misadministration) An administration to the correct patient when the total dosage > +/- 20% of the prescribed dosage or the prescribed dosage range AND the dose to the patient differs by more than 5 rem EDE or 50 rem to any organ than would have resulted from the prescribed dosage.

Medical Event Examples 1) Therapy dose mishaps are generally medical events 2) Diagnostic dose events are generally not medical events.

General Radiation Safety External Exposure Control: Time Distance Shielding Internal Exposure Control Contamination prevention

Time Minimize time spent with patients after being dosed may not be practical

Distance Maximize distance from patient to greatest extent possible monitor with electronic dosimeter to find where max. dose is received

Distance Maximize distance from patient to greatest extent possible monitor with electronic dosimeter to find where max. dose is received

Distance - example From a patient with a typical stress dosage, a worker at edge of treadmill receives about 9 mR/hr.

Distance - example At 1 meter from the treadmill, the exposure rate is about 2 mR/hr.

Shielding Beta Shielding low Z material (plexi-glass) thickness > beta particle range Gamma Shielding high Z material calculate required thickness

Lead Apron Standard apron thickness is 0.5 mm Pb equival. PA requires at least 0.25 mm. Attenuation of 0.5 mm Pb: Cs-137=6% Tc-99m=74% x-rays=>95%

Internal Exposure Control: Contamination Prevention Gloves and lab coat Personnel surveys: hands, feet, clothing No eating, drinking, smoking, or applying cosmetics in licensed areas. Make sure all radioactive material containers are properly closed and carefully handled.

Inspections Be honest Answer questions which are asked Have organized records

Emergencies Spills are the most common problem Must have procedures in place Will demonstrate program weaknesses

Summary Know the regulations Know license requirements and minimize commitments Know the regulators Get program support Stay organized Be honest and admit your mistakes When in doubt, ask your RSO

Remember Don’t be the RSO!