Radiation Protection

Radiation Protection

Stat Ch 8 & 9

RHB – Rad Prot Syllabus

What is the difference betweenX-ray & Gamma?

RHB – Rad Prot – CH. IX p 51• ALARA (no minimum threshold)• STOCHASTIC EFFECTS –

NON TRESHOLD (CA + GENETIC)

• NON STHOCAHSTIC (DETERMINISTIC)SEVERITY OF EFFECTS VARIES WITH RADIATION DOSE (THRESHOLD)

(CATARACTS, SKIN, BONE MARROW, STERILITY

PERSONNEL PROTECTION

• SCATTER FROM THE PATIENT

• TABLE TOP, COLLIMATOR, TUBE HOUSING, BUCKY

• STRAY RADIATION – LEAKAGE OR SCATTER RADIATION

PERSONNEL PROTECTION

• STANDING BEHIND A PROTECTIVE PRIMARY (1/16TH pb) BARRIER:

• PRIMARY RADIATION EXPOSURE – 99.87% REDUCED

• PORTABLE BARRIER = 99 % REDUCTION

PERSONNEL PROTECTION

• PROTECTIVE APRONS –

• 0.25 PB = 97% ↓ TO SCATTER

• 0.5 PB = 99.9% ↓ TO SCATTER

• THYROID SHEILDS (0.25 & 0.5)

• GLOVES (0.25 & 0.5)

PERSONNEL PROTECTIONMONITORING

• FILM BADGE• TLD• POSL

• POCKET DOSIMETER

• RING BADGE

PERSONNEL PROTECTIONMONITORING

• DOSE LIMITS

• WHOLE BODY

• EYES

• EXTREMITIES (BELOW ELBOW/KNEES)

Occupational DoseANNUAL LIMITS

• WHOLE BODY = 5 REMS / 5000mRem

• LENS OF THE EYE = 15 REMS

• EXTREMITIES = 50 REMS

TLD

Ionization chamber

Report at least every quarterPreserved for a minimum of 3 years

RHB NOTIFICATION (EXP IN 24 HOURS)

• IMMEDIATE – WITHIN 24 HOURS

• TOTAL DOSE OF 25 rems

• Eye dose – 75 rem

• Extremity – 250 RADS

• OVEREXPOSURE – WITHIN 30 DAYS

• TOTAL DOSE OF 5 rems

• Eye dose – 15 rem

• Extremity - 50 REMS

LICENSE RENEWAL

• WITHIN 30 DAYS OF EXPRIATION

• NOTIFICATION OF CHANGE OF ADDRESS

• HIGH RADIAITON AREA –

• 100 mRem ( 0.1 rem / (1 msV)– @ 30 cm from the source of radiaton

• RADIAITON AREA –

• RHB: 5 mRem ( 0.005 rem / (.05 msV)– @ 30 cm from the source of radiation

• PUBLIC 2 mrem per week* (STAT)

RHB “RULES” RHB RP PG61

• LICENTIATES OF THE HEALING ARTS(MD, DO, DC, DPM)

• MUST HAVE A • RADIOLOGY SUPERVISOR &

OPERATORS PERMIT & CERTIFICATE• TO OPERATE OR SUPERVISE THE USE

OF X-RAYS ON HUMANS• SUPEVISORS MUST POST THEIR

LICENSES

RHB “RULES” RHB RP PG62

• ALL XRAYS MUST BE ORDERED BY A PHYSICIAN

• VERBAL OR WRITTEN PRESCRIPTION

• See Section C – “Technologist Restrictions”

CARDINAL RULES

• TIME

• DISTANCE

• SHEILDING

SHEILDING PG 72 RHB

• HVL – expressed 2 ways

• HOW MUCH IT REDUCES THE ORGINAL BEAM INTENSITY

• HOW MUCH IS REQUIRED FOR BARRIER THICKNESS (amount needed to attenuated the beam

Room SheildingCh. 9

• Workload Factor (W) -ma/sec/week

– how much time during the week is the beam on

• Occupancy Factor (T) - # of people in room - beyond the barrier

• Use Factor (U) - % of time beam will strike a barrier (table pg 242) Primary vs Secondary

• Leakage Radiation

Which type of radiation is predominant above 80 kvp?

• 10 day rule• No threshold for exposure• Leukemia , congential abnormailies

cander induction, resportion or death of the embryo and genetic effects

• Therapetuic Abortion “not justified”• 25 rads or less – no injury seen• ABSORBED DOSES – 50 RADS – could

result in a spontaneous abortion

DOSE TO FETUS VS ESE

Pregnancy & Embryo

Mother –

occupational worker (5 rem)

• Baby – (500 mRem)

• .5 rem/ year .05 rem/month

• 5 mSv .5 mSv / month

Declared Pregnant Worker• Must declare pregnancy – 2 badges provided• 1 worn at collar (Mother’s exposure)• 1 worn inside apron at waist level

Under 5 rad – negligible risk

Risk increases above 15 rad

Recommend abortion (spontaneous) 25 rad

• (“Baby exposure” approx 1/1000 of ESE)

• www.ntc.gov/NRC/RG/08/08-013.html