WEEK 7 RADIATION BIOLOGY & PROTECTION Part 1

WEEK 7
RADIATION BIOLOGY & PROTECTION Part 1

FINAL

Sources of Ionizing Radiation

______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

MEDICAL IMAGING

______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 –

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

British units used since 1920’s

United States still uses this system

New system developed in 1948

System of Units based on Metric measurements developed by International Committee for Weights and Measures

1985- officially adopted

Conv. Units SI Units

RADS

REMS

R - ROENTGEN

______

Comparsion of Units

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

1/100 Gy = 1 rad

 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

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

Why did the bunny die??

BUNNY A

Received 200 rads

BUNNY B

Received 200 rads

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

BRITISH UNIT

Age x 1 rem

Old MPD dose 5(age-18)

SI UNIT

Age x 10msv

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)

Pregnancy & Embryo

Mother ______worker

(5 rem)

Baby

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

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

Geiger Muller counter

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 –

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 ?