WEEK 7 RADIATION BIOLOGY & PROTECTION Part 1 FINAL

Sources of Ionizing Radiation

Electromagnetic Spectrum – shows ranges in intensity

Background Radiation has been around a long time….

Radon & Uranium most common sources

AVE population exposure= 20 – 30 mrem/year In some places in United States average ________mrem/yr Majority due to _________ gas   Many places on earth receive more than _________ mrem/yr from radon Some natural background in the United States average 200 - 300 mrem/yr with the majority due to radon gas, a daughter product of uranium decay.  However, many places on earth receive more than 1000 mrem/yr from radon.

________ ________radiation MEDICAL IMAGING __________________x-rays _________________ x-rays Greatest source of ________ ________radiation

What is the difference between x-rays and gamma rays???? Their______________________ X-rays are _______ __________ Gamma comes from the ______ of the atom

Terminology to cover Units of Measurement ALARA DOSE – Target theory Cumulative Annual Target theory Direct vs. Indirect Hit Somatic vs. genetic

UNITS OF RADIATION MEASUREMENT To ______________the amount of radiation A: Received by _________________

Conventional vs. SI units New system developed in 1948 System of Units based on Metric measurements developed by International Committee for Weights and Measures 1985- officially adopted British units used since 1920’s United States still uses this system

Conv. Units SI Units RADS REMS R - ROENTGEN _______ Not equal in amount

Comparsion of Units

REMS OCCUPATIONAL EXPOSURE R - ROENTGENS RADS – PATIENT DOSE

Convenetional Unit of ROENTGEN (R) SI unit =__________ The quantity of radiation exposure in_______________ Measures __________of the x-ray tube Does not indicate the actual ________________________________

RADIATION ABSORBED DOSE (RAD) SI = GRAY (Gy) Measures the _____________ of energy ___________ by any medium (__________) 1 Gray (Gy) = 100 _______ 1/100 Gy = 1 _______

RAD to GRAY 100 rad = 1 Gy =1000 mGy 10 rad = .1 Gy = = 100 mGy 1000 mRad = 1 rad = .01 Gy = 10 mGy

Radiation Equivalent Man Used for ________ Traditional Unit = _________ SI Unit = ____________ (Sv) 1 Sv = 100 __________ 1/100 Sv =1 _________

RADIATION EQUIVALENT MAN (REMS) SI UNITS = SIEVERT Different _________ of radiation produce different responses The unit of dose ___________, expressed as __________________________________ Used for ____________(employee) exposures Can be used when for dose of patient Not all types of radiation produce the same responses in living tissue The unit of dose equivalence, expressed as the product of the absorbed dose in rad (or gray) and quality factor. RAD x QF = REM used for occupational exposures can be used when for dose of patient

QUALITY FACTOR Qualifies what the damage is from different types of radiation Example: QF for X-ray is 1 QF for alpha is 20 Alpha is 20 x more damaging to tissue

Rad VS. Rem QF of x-ray is 1 1 RAD X QF = 1 REM 1 GRAY X QF = 1 SIEVERT

Very low energy = More destructive

Why did the bunny die?? BUNNY A Received 200 rads BUNNY B

Why did the bunny die?? BUNNY A 200 rads x 1 for X-RAY = 200 RADS BUNNY B 200 rads x 20 for alpha = 4000 rads

REM to Sievert 100 rem = 1 sV =1000 msv 10 rem = .1 sV = = 100 msv 1000 mRem = 1 rem = .01 sV = 10 msv

RADS REMS RADS GRAYS Patient absorbed dose REMS SIEVERTS Employee (technologists) =

Cell Response to Radiation

Response of cells to radiation Cell sensitivity is dependant on: Type of cell Type of damage received Type of radiation exposed to

Sensitivity to radiation based on sex

Which (Male or Female) GONADs are external vs internal?

Which gender has gonads from birth?

Which gender constantly produces new reproductivecells?

Which GENDER is more sensitive to radiation at birth? Why?

Dose limits

Permissible Occupational Dose Annual dose : 5 Rem/year 50mSv/year (5000 mrem) Cumulative Dose 1 rem x age 10mSv x age

Allowable DOSE - ANNUAL BRITISH UNIT 5 REMS SI UNIT 5O mSv

OCCUPATIONAL EXPOSURES 5 REMS / YEAR BUT NOT TO EXCEED 1.25 REM/QUARTER

Allowable DOSE – TOTAL CUMMULATIVE SI UNIT Age x 10msv BRITISH UNIT Age x 1 rem Old MPD dose 5(age-18)

Declared Pregnant Worker ____ badges provided 1 worn at collar (___________________exposure) 1 worn inside apron at waist level (____ exposure) Under 5 rem – _____________________ risk Risk _____________________ above 15 rem Recommend ________ (spontaneous) 25 rem (“Baby exposure” approx 1/1000 of ESE) www.ntc.gov/NRC/RG/08/08-013.html 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

Pregnancy & Embryo Mother __________worker Baby (5 rem) 500_______.5 rem/ year .05 rem/____________ 5______ .5 mSv / ________

Fetus Exposure Radiation exposure is most harmful during the __________ trimester of pregnancy ______________ Exposure limit 0.05 rem or 0.5 mSv PER MONTH 0.5 rem or 5 mSv total gestation

Education and Training Exposures Student’s must never hold patients during exposures Effective dose limit (Annual) 0.1 rem or 1 mSv (1/50 of Technologist’s dose)

PUBLIC EXPOSURE NON MEDICAL EXPOSURE 10 % of Occupational exposure 0.5 rad or 500 mrad or 50mgray Under age 18 and Students 0.1 rem 10 mrem 1mSv

Review

Radiation Monitoring

Radiation Monitoring Monitors measure the quantity of radiation received. Any radiation worker must be monitored to determine estimated dose exposure

Personnel Monitoring Devices Film Badges Thermoluminescent Dosimeters (TLD) Pocket Dosimeters Optically Stimulated Luminescence (OSL Dosimeters)

TLD

Film Badges – changed monthly

POSL

Field Survey Instruments “Cutie Pie” Ionization Chamber Geiger Muller counter

Q = t x תּ CUTIE PIE

Review What is the annual allowable dose for a 32 year old Technologist?

What is the cummulative allowable dose for a 32 year old Technologist?

Regulatory Agencies NCRP – NRC – National Council on Radiation Protection NRC – Nuclear Regulatory Committee

REGULATORY AGENCIES NCRP - Reviews recommendation for radiation protection & safety. Distributes information re: radiation awareness NRC Makes LAWS & enforces regulations

QUESTIONS ?