RADIOBIOLOGY AND RAD PROTECTION CD #6 2006 WEEK 7 RT 244 1
RADIATION DETECTION
3
– RADIATION EXPOSURE
3 TYPES
OCCUPATIONAL (WORKERS)
MEDICAL
– TESTS/EXAMS
PUBLIC
– ALL OTHER TYPES (INCLUDING BACKGROUND)
5 EXPOSURE RATE (EXPOSURE MEASURED IN R OR C/KG)
EXPOSURE RATE = EXPOSURE TO PT / UNIT OF TIME
Surface Intregral Exposure = EXPOSURE X AREA OF RADIATION BEAM
6
– EXPOSURE IS NOT AMOUT PT RECEIVED – THIS IS ABSORED DOSE
MEASURED IN RAD OR GRAY = AMOUNT OF PHOTONS ENTERED SUBTRACT
AMOUNT EXIT = ABSORBED DOSE
1 GRAY = 100 RAD 1 cGY = 1 rad 1 mGy (milligra) = 100 mRad (millirad)
8 = QUALITY FACTOR
AMOUNT OF DAMAGE DEPENDS OF TYPE AND ENERGY OF PHOTON
ALPHA MORE DAMAGING THAN XRAY
(HIGH LET) (LOW LET)
DOSE EQUIVALENT - REMS – SIEVERTS
(OCCUPATIONAL EXPOSURE)
To CALCULATE DE (DOSE EQUIVALENT) A QUALITY FACTOR IS USED
XRAY / GAMMA/ BETA = 1 FAST NEUTRONS & ALPHA = 20
DOSE EQIVALANT VALUE = ABSORBED DOSE X QUALITY FACTOR
RAD X QF GRAY X QF
9 = SOME ORGANS MORE SENSITIVE TO RADIATION
– SEE CHART Tissue Weighing Factors
GONAD .2 COLON/LUNG/STOMACH .12 BREAST/LIVER .05
12
– NCRP LIMITS
STOCHASTIC EFFECTS ARE NONTHRESHOLD / RANDOMMLY OCCURING BIOLOGICAL
SOMATIC CHANGES IN WHICH THE CHANCE OF OCCURANCE (NOT THE SEVERITY OF THE
EFFECT) IS PROPORTIONAL TO THE DOSE OF RADIATION
INCREASED DOSE LEADS TO AN INCREASED CHANCE OF CANCER
NON - STOCHASTIC EFFECTS (AKA
– DETERMINISTIC) HAVE A THRESHOLD WHERE NO
EFFECT IS SEEN - THEN THE SEVERITY INCREASES AS THE DOSE INCREASES –
USUALLY FROM HIGH DOSES
GI SYNDROME / BONE MARROW SYNDROME / CNS
COMMON EARLY EFFECTS =ERYTHEMIA LOW WBC EPILATION
LATE EFFECTS – CATARCTS, INFERTILITY
LOW DOSES CAN CAUSE BIOLOGIC DAMAGE AS WELL
OCCUPATIONAL DOSE LIMITS
EFFECTIVE DOSE EQUIV (DE) = 50 mSv (5 REM) PER YEAR

RADIOBIOLOGY AND RAD PROTECTION CD #6 2006 WEEK 7 RT 244 2
RADIATION DETECTION
WHOLE BODY
LENS OF EYE 150 mSv (15 REM)
ALL OTHER 500 mSv (50 REM)
Long term accumulation 10mSv X age(year) (1 REM x AGE)‘
CUMULATIVE – LIFETME NOT TO EXCEED
13
–
ALARA
14 SUMMARY OF RADIATION QUANTITIES & UNITS – CHART
16 – PERSONNEL MONITORING Badge on COLLAR – outside of apron receive 1% of the annual total DE for any single month
1% = (.5 rem / .005 mSv)
MONTHLY LIMITS (50 mrem or .5mSv) OR any person portable radiography or fluoro
18 – OCCUPATIONAL EXPOSURES - RADIATION WORKERS 1.5 mSv = _______ rem
18 – occupational workers average 1.5mSv or .15 rem (150mrem)
(according to Merrills CH. 2 – 50 mrem/yr)
21 FILM BADGES= film inside
FILM BADGE
– SENSITIVE 10 MREM – 500 REM
. 1 mSv to 5 sieverts
22 – read with a DENSITOMETER
AMOUNT OF DENSITY OF FILM PROPORTIONAL TO EXPOSURE
24 –( audio)
ADVANTAGES - INEXPENSIVE, MONTHLY RECORD PERMANENT
DISADAVANTAGE
– TAKES A WHILE TO SEE REPORT FOR EXPOSURE
ONLY RECORDS IN BODY AREA WORN
ACCURACY + OR – 20 %
MUST BE CHANGED EACH MONTH
25/26
– TLD / POSL - LITHIUM FLORIDE CRYSTAL OR CHIP EXCITED – VISIBLE LIGHT
EMMITTED – TEMP PLOTTED ON A CURVE PROP TO EXPOSURE
MORE ACCURATE MORE SENSITIVE MEASURE 5mR minimum TO 200Mr (measures ionization)
HIGH COST – BUT CHANGED IN 3 MONTHS = LATER = COST
ONCE READ NOT PERMANENT – BUT RECORD IS
28 – pocket dosimeter – not permanent (0 – 200 mR) immediate exposure readout
30 where to wear badge
33 - film badge report - review and turn in *** look at film badge report = listed in mrem
35 – Survey instruments
TURN IN A CURRENT FILM BADGE REPORT
36 RADIATION MONITORS
37 Cutie pie Ionization chamber BY IONIZATION Q = T X
תּ3.14 (pie) LOW – HIGH reading
1) Diagnostic Radiaiton when 2 sec or more is used 2) Pt ingestion of radioisotope
38 or Geiger Muller detector Used in Nuclear Med for radioactive particles
39 Scintillation Detectors
– Gamma Camera (CT and Nuclear Med)