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Radiation Safety Program Overview and Terminology

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Robert Forrest, CHP Radiation Safety Officer Environmental Health and Radiation Safety Remember Don t be the RSO! Radiation Symbol New ISO Radiation Symbol Public ... – PowerPoint PPT presentation

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Title: Radiation Safety Program Overview and Terminology


1
Radiation Safety Program Overview and Terminology
  • Robert Forrest, CHP
  • Radiation Safety Officer

Environmental Health and Radiation Safety
2
Remember
  • Dont be the RSO!

3
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.
4
(No Transcript)
5
Radiation Symbol
6
New ISO Radiation Symbol
7
Public Perceptions
  • Nuclear Weapons
  • Cancer
  • Invisible, industrial hazard

8
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

9
Regulatory Agencies
  • NRC
  • DOE
  • DOT
  • EPA
  • FDA
  • OSHA
  • Naval Reactors
  • US Post Office
  • States
  • Local Municipalities

10
Main Regulatory Authorities
  • NRC regulates
  • Byproduct material
  • Reactors and Fuel
  • State regulates
  • Accelerator material
  • Energized Equipment

11
Agreement States vs. NRC
  • State accepts NRC rules
  • State can be more restrictive
  • NRC retains control of Reactors and Fuel

12
(No Transcript)
13
Radiation Safety Program
  • Commensurate with scope of activities
  • Governed by
  • Regulations
  • License Conditions
  • Local Policies and Procedures

14
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

15
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

16
(No Transcript)
17
Organizational Responsibilities
Executive Management
Radiation Safety Committee
Radiation Safety Officer
18
Terminology
  • Radioactive Material
  • Radiation
  • Contamination
  • Half-life
  • Activity

19
Radioactive Material (unstable material which
spontaneously transforms usually emitting some
type of radiation)
20
Radiation (particulate or electromagnetic energy
emitted during radioactive decay)
21
Contamination (radioactive material spread into
an unwanted place)
22
Half-Life
  • The time required for any given radioisotope to
    decrease to one half of its original activity.
  • T1/2 ln 2 / ?
  • The radiological half-lives for Tc-99m and
  • I-131 are 6 hours and 8 days, respectively.

23
Half life
24
Half life
25
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

26
Activity
  • A ?N
  • If N 1x109 atoms
  • Tc-99m, A (0.116 hr-1)(1x109 atoms)
  • A 3.22 x 104 Bq (0.87 µCi)
  • I-131, A (3.61x10-3 hr-1)(1x109 atoms)
  • A 1 x 103 Bq (0.027 µCi)

27
Activity
  • Biomedical Research uses mCi quantities
  • Nuclear Medicine uses mCi quantities
  • Bone Scan uses 25 mCi of Tc-99m
  • Radiation Oncology uses mCi-Ci quantities
  • LDR implants use 100-200 mCi of Cs-137
  • HDR implants use 10 Ci Ir-192

28
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

29
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

30
Annual Average Background Dose Distribution (total
360 mrem)
31
Acute Radiation Effects
  • Minor blood changes 25,000 mrem
  • Hemopoietic Syndrome 200,000 mrem
  • Erythema 200-300,000 mrem
  • LD50,30 450,000 mrem

32
Delayed Radiation Effects
  • Cancer
  • Genetic Effects

33
Extrapolating Risk Factors
34
Dose Limits (10 CFR 20.1201-8)
  • Total Effective Dose Equivalent 5000 mrem
  • Total Organ Dose Equivalent 50,000 mrem
  • Lens of the Eye 15,000 mrem
  • Skin and Extremities 50,000 mrem
  • Declared Pregnant Worker 500 mrem
  • Minor 500 mrem
  • General Public 100 mrem

35
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

36
Dosimeter Filters
Open window
Copper
Al2O3 strip
Tin
Image filter
37
Low energy - static
  • Radiation

38
Low energy - dynamic
Radiation
39
Pregnant Patient
  • Get and read Wagners book
  • If clinically indicated, do the study
  • Steps should be taken to lower dose if possible
  • When counseling, use numbers that are
    understandable

40
Pregnant Patient
41
Effective Doses to Patients from Diagnostic
Studies
  • DEXA lt 1mrem
  • Chest x-ray 10 mrem
  • AP abdomen 70 mrem
  • Upper GI 300 mrem
  • CT abdomen 700-1000 mrem
  • Coron. Angioplasty 2200 mrem
  • Source Hall, Radiobiology for the Radiologist,
    5th edition

42
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

43
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

44
Radiation-Induced Skin Injuries 14, 17
Figure from 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?

45
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
46
estimated 25 Gy dose Erythemia at 3 weeks
47
Ulceration at 5 months
48
Debridement at 6.5 months
49
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

50
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

51
Medical Event (formerly misadministration)
  • An administration involving the wrong
    individual, wrong radiopharmaceutical, wrong
    route of administration
  • AND
  • the dose to the patient gt5 rem EDE or 50 rem to
    any organ.

52
Medical Event (formerly misadministration)
  • An administration to the correct patient when
    the total dosage gt /- 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.

53
Medical Event Examples
  • 1) Therapy dose mishaps are generally medical
    events
  • 2) Diagnostic dose events are generally not
    medical events.

54
General Radiation Safety
  • External Exposure Control
  • Time
  • Distance
  • Shielding
  • Internal Exposure Control
  • Contamination prevention

55
Time
  • Minimize time spent with patients after being
    dosed
  • may not be practical

56
Distance
  • Maximize distance from patient to greatest extent
    possible
  • monitor with electronic dosimeter to find where
    max. dose is received

57
Distance
  • Maximize distance from patient to greatest extent
    possible
  • monitor with electronic dosimeter to find where
    max. dose is received

58
Distance - example
  • From a patient with a typical stress dosage, a
    worker at edge of treadmill receives about 9
    mR/hr.

59
Distance - example
  • At 1 meter from the treadmill, the exposure rate
    is about 2 mR/hr.

60
Shielding
  • Beta Shielding
  • low Z material (plexi-glass)
  • thickness gt beta particle range
  • Gamma Shielding
  • high Z material
  • calculate required thickness

61
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 gt95

62
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.

63
Inspections
  • Be honest
  • Answer questions which are asked
  • Have organized records

64
Emergencies
  • Spills are the most common problem
  • Must have procedures in place
  • Will demonstrate program weaknesses

65
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

66
Remember
  • Dont be the RSO!
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