RT 123INTRODUCTION & Review of

Radiation Protection(Merrills Ch. 2)

WK #3

http://www.tsgxray.com/XrayOnLt1.jpg

MARIE & PIERRE CURIE

• 1898

• “NAMED RADIOACTIVITY”

• DEVELOPED A RADIATION DETECTOR

• 1914 (WW1) DEVELOPED A MOBILE RADIOGRAPHY X-RAY “CAR” TO TAKE XRAY IN THE BATTLE FRONTS

• TRAINED 150 “TECHNICIANS” TO OPERATED CARS

Early measurement of Radiation

• Skin dryness & erythema– AKA radiodermatitis

• Ulcers formed

• Cataracts• Cancers

DIAGNOSTICRADIOLOGY

• STATIC – STILL SHOTS

• DYNAMIC

• XRAYS IN MOTION

• FLUOROSCOPY

STANDARD VS SI UNITS

•R - C/kg

•Rem - Sievert

•Rad - Gray

measurement

100 R = 1 C/kg1Rad = 1/100 Gray1 Rem = .01 Sievert(Rad + QF = REM)1 REM = 10 mSv

1 Rem = 1000mRem

Quality Factor

• How dangerous the type of radiation is

• Alpha + fast neutrons = 20

• X-ray, Beta, Gamma . = 1

REM

• IS A PRODUCT OF THE

• QF x RAD

Why did the bunny die??

BUNNY A

• Received 200 rads

BUNNY B

• Received 200 rads

Why did the bunny die??

BUNNY A

200 rads of X-RAY = 200 RADS

BUNNY B

200 rads of alpha =

4000 rads

Permissible Occupational Dose

• Annual dose:

• 5 Rem / year 50 mSv / year

• Cumulative Dose

• 1rem x age 10mSv X age

Occupational DoseANNUAL LIMITS

• WHOLE BODY = 5 REMS / 5000mRem

• LENS OF THE EYE = 15 REMS

• EXTREMITIES = 50 REMS

OCCUPATIONAL EXPOSURES

• 5 REMS / YEAR BUT NOT TO EXCEED 1.25

REM/QUARTER

AVERAGE ACTUAL EXPOUSRE IS APPROXIMATELY 50 mrem/year

• OLD “MPD 5(Age – 18)”

PUBLIC EXPOSURE

• 10 % OF OCCUPATIONAL

• NON MEDICAL EXPOSURE

• .5 RAD OR 500 MRAD

• UNDER AGE 18 AND STUDENT

• .1 rem 1 mSv• Pg 98 RTA BOOK

CARDINAL RULESOF RADIATION PROTECTION

•TIME

•DISTANCE

•SHIELDING

ROOM SHIELDING

• PRIMARY SHIELD – • PRIMARY BEAM DIRECTED

AT WALL• 1/16 LEAD - 7 FEET HIGH

ROOM SHIELDING

• SECONDARY – NO PRIMARY BEAM

• 1/32 LEAD

• CONTROL BOOTH (SECONDARY)

• BEAM SCATTERS 2X BEFORE HITTING

• LEAD WINDOW – 1.5MM LEAD EQ

MONITORING

• CONTROLLED AREA – Used by occupationally exposed personnel (monitored)

• 100mrem / WEEK

• UNCONTROLLED AREA – PUBLIC

• 2 mrem per week*

SHEILDING

TECHNOLOGIST . 25 mm LEAD

• LEAD APRON, GLOVES

• THYROID SHIELD, GLASSES

PATIENT –

GONAD SHEILDING

. 5 mm LEAD

GONAD SHIELDING

• MUST BE . 5 MM OF LEAD

• MUST BE USED WHEN GONADS WILL LIE WITHING 5 CM OF THE COLLIMATED AREA (RHB)

• KUB. Lumbar Spine Pelvis

• male vs female shielding

TYPES OF SHEILDING

•FLAT /CONTACT

•SHAPED

•SHADOW

               

                

  

http://lumax.kiranxray.com/img/mini_appron.jpg

Personnel Monitoring Devices

•Film Badges•TLD / POSL•Pocket Dosimeter•Ring Badge

MEASUREMENT

• FILM BADGE

• TLD• POSL• POCKET

DOSIMETER

• ABOVE 10 MREM

• ABOVE 5 MREM

• 1 MREM

• NOT ACCURATE

REM

• IS A PRODUCT OF THE

• QF x RAD

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

Pregnant patient

• ALWAYS ASK LMP before exposure made

• “10-day Rule” No longer used

• “Grace period” of implantation

• STATE – Beam 5 cm within gonads

PREGNANT PATIENTS

• ASCERTAIN LMP - IF FETUS IS EXPOSED• PHYSICSTS WILL NEED INFORMATION:• WHICH XRAY MACHINE USED (MR/MAS)• # OF PROJECTIONS (INC REPEATS)• TECHNIQUE FOR EACH EXPOSURE• SID • PATIENT MEASUREMENT AT C/R• FLUORO TIME & TECHNIQUE USED• PHYSICIST WILL CALCULATE FETAL DOSE

RADIATION DOSE TO PATIENTS

• ESE - ENTRACE SKIN EXPOSURE (MEASURED BY A TLD)

• SKIN DOSE• GONADAL DOSE• BONE MARROW DOSE• (MEAN GLADULAR DOSE- MAMMO)

AP VS PA EXPOSURE/ESE

SOMATIC & GENETICSTOCHASTIC VS NON STOCHASTIC

• A = STOCHASTIC• “CHANCE” EFFECTS GENETIC, LEUKEMIA,

CANCERDIAGNOSTIC RADIOLOGY

B= NON-STOCHASTICTHRESHOLD EFFECTSDETERMINISTICSOMATIC EFFECTSSKIN ERYTHEMA,

CATARACTS, STERILITYRAD -MALIGNANCIES

GSD• GENETICALY SIGNIFICANT DOSE

• Takes all of the population into account

• Annual AVERAGE gonadal dose to population of childbearing age

• 0. 20 mSv or 20 millirem • rem or rad???

REDUCING REPEATS

• TECHNIQUE CHARTS

• CAREFUL REVIEW OF TECHNICAL FACTORS

• REFER TO TECHNIQUE BOOK AND

• ASK WHEN YOU ARE NOT SURE!

Carlton Ch 13 - p. 208 & 210 & 214

• “AVE” CHEST EXPOSURE - 2 IMAGES

• (Ave – Pt meas 23cm pa 40cm lat)

• PA 110 KVP 5 MAS 16:1 GRID 400RS 72”

• LAT 110 KVP 20 MAS 16:1 GRID 400 RS 72”

• WHAT IS THE PATIENT’S DOSE??

PEDIATRIC EXPOSURE

• MORE SENSITIVE TO RADIATION THAN ADULTS

• LIMIT BEAM TIME • MAY REMOVE GRID (REDUCE

EXPOSURE)• AP VS PA• COLLIMATION & SHIELDING !!!!!!!!!!!!!!!• GENDER DIFFERENCES• IMMOBILATION