1. Radiation Safety Program
Dosimetry
Radiation Safety Program
This module meets the annual re-training requirement per Environment, Health and Safety’s Radiation Safety Program Policy. Use the buttons to navigate through the module.
In order to receive credit for reviewing this module, please follow the instructions at the conclusion of the slides.

2. Objectives
Identify the biological effects when ionizing radiation interacts with the human body.
Differentiate between various types of dosimetry.
Identify UCLA dosimetry policies, including proper badge usage.
Define radiation dose units and how they relate to annual dose limits set by the Nuclear Regulatory Commission (NRC).

3. Radiation Biology
DNA Single Strand break
To understand the purpose and function of dosimetry we must first understand the risks associated with working with radiation.
How does radiation affect our bodies?
Ionizing radiation transfers energy to electrons
Ionizing radiation has sufficient energy to break chemical bonds
Broken water molecules lead to free radicals which are chemically reactive
At the cell level, single and double strand breaks in DNA caused by ionizing radiation may lead to mutations, carcinogens, and cell death
DNA Double Strand break

4. Biological Effects
Biological effects from radiation can be broken down into two types:
Deterministic effects, which only occur above a certain dose threshold
Stochastic effects, which have a chance of occurring at any range of dose

5. Stochastic Effects
Whether you are working in a research or clinical environment, nearly all exposure to radiation will be at low doses, where stochastic effects can still occur.
A recent analysis of epidemiological studies of atomic bomb survivors, nuclear workers, and persons exposed to radiation for medical reasons predicts:
Approximately 42% of the population will be diagnosed with cancer from causes unrelated to radiation exposure.
A radiation dose of 10 mSv (1 rem) will increase the risk of developing cancer by 0.11% and fatal cancer by 0.056%1
1National Academies Council on Biological Effects of Ionizing Radiation (BEIR) VII.

6. Deterministic Effects
Deterministic Effects have a threshold, meaning that only above a threshold dose do these effects occur. The occupational limits of radiation exposure are well below any deterministic effect threshold.
If absorbed dose is greater than:
Possible Skin Effect Could be:
2 Gy
transient erythema (reddening of skin
6 Gy
erythema
3 to 5 Gy
temporary epilation (hair loss)
7 Gy
epilation can be permanent
10 Gy
dry desquamation (skin shedding)
15 Gy
moist desquamation

7. Scenario 1: What do you think?
Mark is about start working in a lab that works with P-32 to label DNA. As is typical with DNA labeling, Mark will be receiving low doses of radiation. Which effects should he be concerned with?
Both, deterministic and stochastic.
Deterministic effects.
Stochastic effects.
Click here to see the correct answer…

8. Scenario 1: What do you think?
Mark is about start working in a lab that works with P-32 to label DNA. As is typical with DNA labeling, Mark will be receiving low doses of radiation. Which effects should he be concerned with?
Both, deterministic and stochastic.
Determinist effects.
Stochastic effects.
Correct! A laboratory worker that handles P-32 for DNA labeling is not at risk of exceeding the 2 Gy deterministic effects threshold. A typical badge reading from a lab worker handling isotopes for DNA labeling is near background levels of radiation.

9. Dosimetry is the measurement of radiation dose received.
What is Dosimetry?
Dosimetry is the measurement of radiation dose received.
Dosimeters (e.g., badges, rings) measure the amount of radiation received by radiation workers and help Environment, Health and Safety monitor radiation dose to be sure workers do not exceed annual limits.
Badges and rings are administered to workers based on radioactive material shipment limits and/or specific radiation worker occupations.

10. Units of Dosimetry: Absorbed Dose
Absorbed Dose (D): a measure of the amount of energy from ionizing radiation deposited in a material. Human tissue is an example of such material.
Traditional unit: Radiation Absorbed Dose (rad), 1 rad = 100 erg/g
International unit: Gray (Gy), 1 Gray = 1000 joules/kg
1 Gray = 100 rads
How much dose did I get?
Energy in the form of radiation

11. Units of Dosimetry: Equivalent Dose
Equivalent Dose (H) is the absorbed dose (D) multiplied by a radiation weighting factor (WR)
H = D x WR
Equivalent dose is a more accurate measurement (compared to absorbed dose) of dose because it takes into consideration the type of radiation irradiating the matter. Each radiation type (e.g., alpha, beta, gamma, neutrons, x-rays) has a different degree of effectiveness in producing biological effects, hence the use of a radiation weighting factor (WR).
Traditional unit - Roentgen Equivalent Man (rem)
International unit - Sievert (Sv)
Radiation Type
Weighting factor (WR)
Gamma-rays/ X-rays/ Beta particles 1
Neutrons
5-20
Alpha Particles 20

12. Units of Dosimetry: Effective Dose
Effective Dose (E) is the equivalent dose (H) multiplied by a tissue weighing factor (WT)
E = H x WT
Effective dose is the most accurate measurement of biological damage because it takes into consideration the type of radiation and the type of tissue being irradiated.
Traditional unit is the rem,
International unit is the Sievert (Sv)
The regulations are based on effective dose
Tissue Type
Weighing factor (WT)1
Bone marrow
0.12
Colon
Lung
Stomach
Breast
Gonads
0.08
Bladder
0.04
Esophagus
Liver
Thyroid
Bone surfaces
0.01
Brain
Salivary Glands
Skin
1From ICRP 103 (2008)

13. (below knees and elbows)
Annual Dose Limits
Skin
0.5 Sv
50 rem
Per NRC regulations, if a radiation worker is likely to get 10% of the annual dose limits (shown on the right), they must be issued dosimetry.
Eyes
0.15 Sv
(15 rem)
Total Effective Dose
(whole body)
0.05 Sv
(5 rem)
Extremities
(below knees and elbows)
0.5 Sv
(50 rem)
Internal Organs
0.5 Sv
(50 rem)

14. ALARA Limits at UCLA
UCLA has established its own, more stringent annual dose limits in order to keep doses As Low As Reasonably Achievable (ALARA).
The EH&S Radiation Safety Program has ALARA I, II, and III limits, which represent 24%, 48%, and 96% of the NRC annual dose limits, respectively.
If a dose is reported that exceeds the ALARA II or III limits, you will receive a notice from the Radiation Safety Program. EH&S will also investigate the matter to keep doses as low as reasonably achievable.

15. ALARA Limits Specific to UCLA
Look at the chart below to determine how much dose you can receive in different areas of your body per month, and how that relates to your ALARA limits.
Area of Body (location of dose measurement)
ALARA I
(mrem/ month)
ALARA II
ALARA III
Deep-Dose: whole body exposure (tissue depth of 1 cm)
100
200
400
Lens of Eye Dose: external exposure of the lens of the eye (tissue depth of 0.3 cm)
300
600
1200
Shallow/ Extremity Dose: external exposure of the skin or an extremity (tissue depth of cm, averaged over an area of 1 cm2.)
1000
2000
4000
Fetal Dose: exposure of the fetus/embryo during the gestation period. 12 24 48

16. Scenario 2: What do you think?
Sue works with F-18, her exposure report read 405 mrem to the whole body for the month of January which puts her over ALARA III limits under UCLA policy. What can she expect?
Nothing will happen, she is on pace to be under the annual limit of 5,000 mrem.
She will get a notice from the Radiation Safety Program.
Since she exceeded ALARA III limits, she will receive a letter that she can no longer work with radiation for the rest of the year.
Click here to see the correct answer…

17. Scenario 2: What do you think?
Sue works with F-18, her exposure report read 405 mrem to the whole body for the month of January which puts her over ALARA III limits under UCLA policy. What can she expect?
Nothing will happen, she is on pace to be under the annual limit of 5,000 mrem.
She will get a notice from the Radiation Safety Program.
Since she exceeded ALARA III limits, she will receive a letter that she can no longer work with radiation for the rest of the year.
Correct! The Radiation Safety Program will be in contact with Sue to help minimize her dose by analyzing work practices.

18. Dosimeters
Dosimeters measure the amount of radiation dose received by wearers. At UCLA, various types of dosimeters are used:
Optical-Stimulated Luminescence dosimeters (OSL)
Thermoluminescent dosimeters (TLD)
Pocket dosimeters
Electronic dosimeters

19. Dosimeters: OSL Badges
Optical Stimulated Luminescence (OSL) badges measure whole body, lens of the eyes and shallow dose.
How are OSL Badges read?
OSL badges contain aluminum oxide (Al2O3) crystals which are read by a specific wavelength of laser light. The released light indicates the amount of radiation dose.
OSL badge have limitations:
For x-ray, gammas only > 5 keV photons can be read, dose measurement range of 1 mrem to 1000 rem
For beta particles only > 150 keV particles can be read, dose measurement range of 10 mrem to 1000 rem.

20. Dosimeters: TLD Rings
Thermoluminescent dosimeter (TLD) rings assess extremity (e.g., below the elbow) doses.
How are TLD rings read?
TLD badges have a lithium fluoride chip inside the engraved ring cover which when heated causes a luminescence in proportion to the amount of radiation exposure.
TLD rings have limitations:
For gammas, x-rays only >15 keV photos can be read, dose measurement range from 30 mrem to 1000 mrem
For betas only > 200 keV particles can be read, dose measurement range from 40 mrem to 1000 mrem
Affected by heat, moisture, and pressure, cannot be re-read, unlike OSL badges.

21. Dosimeters: Pocket
Pocket dosimeters, used by cyclotron users and in emergency situations, are issued less frequently. Pocket dosimeters allow for instantaneously dose analysis.
How are pocket dosimeters read?
Pocket dosimeters are read by pointing one end at a light source and observing the other end close to the eye.
Pocket dosimeters have limitations:
Type of Radiation that can be read: 20 keV to 2 MeV x-rays and gammas
Sample dose range 0 to 200 mR , 0 to 600 R

22. Dosimeters: Electronic
Electronic dosimeter are also issued less frequently than OSL and TLD badges, normally during emergencies.
How are Electronic Badges read?
Electronic badges can be set to give a dose rate, sound a dose rate alarm, and provide instantaneous dose analysis.
Electronic badges have limitations:
Can give you total dose and total dose alarm
Sample measurement range 0.1 mrem to 999 rem
Sample energy range of 60 keV photos to 6 MeV

23. Proper Dosimetry Badge Wear
For Whole Body Badges:
Worn on the part of the body between your neck and waist
Wear it so name tag faces radiation source
If lead apron is worn, wear the badge at collar level on the outside of apron
For Dual Badges:
One badge on the collar, outside lead apron
One badge on the waist, under lead apron

24. Proper Dosimetry Badge Wear
Wear your ring badge with the white label on the same side as the palm of your hand.
Remember, your palm is closest to the radioactive materials you are working with, so the badge should also be closest to the materials.
If you are wearing a glove, wear your ring underneath the glove.

25. Responsibilities of Those Wearing Dosimeters
Store your dosimetry badge in a non-radiation location when not in use
Exchange your badge when requested by the Departmental Badge Coordinator
Keep your badge at work. Don’t take it home
Wear your dosimetry badge:
whenever using radiation-producing machines or radioactive materials that present an external hazard
for the current monitoring period
in the correct location on the body
If you are pregnant and wish to begin fetal monitoring, it is your responsibility to declare your pregnancy in writing to the RSP
Never share your dosimetry badge or wear someone else’s
Do not intentionally expose dosimeters to radiation
Do not wear your dosimetry badge for non-occupational exposures
Do not use your badge at an institution other than UCLA
Don’ts
Do’s

26. Badge Exchange Reporting……
Badges are exchanged on a monthly or quarterly basis for radiation exposure processing. Here’s how it works:
EH&S automatically sends replacement badges to Department Badge Coordinators during the last few days of the month.
Department Badge Coordinators exchange your badge by collecting the used one and providing you with a new one. (Late badges will incur a $5-$11 fee.)
Dosimeters are returned to EH&S (by the Department Badge Coordinators) for processing.
EH&S mails all Dosimeters to an outside company for processing, and provides follow-up exposure reports to Department Badge Coordinators.
EH&S Radiation Safety maintains all exposure records indefinitely. Here are the important facts about reports:
Contact your Department badge coordinator or the Radiation Safety Program to view your dose report.
Your radiation exposure history will be provided to you or your subsequent employers on request. 
If dose of “M” is reported, the total dose received was below the minimal detectable level.

27. Scenario 3: What do you think?
If a radiation worker becomes pregnant what should she do?
Declare her pregnancy in writing to the Radiation Safety Program if she wishes to begin fetal monitoring.
Immediately stop working with radiation.
Continue working, since she already has a radiation badge.
Click here to see the correct answer…

28. Scenario 3: What do you think?
If a radiation worker becomes pregnant what should she do?
Declare her pregnancy in writing to the Radiation Safety Program if she wishes to begin fetal monitoring.
Immediately stop working with radiation.
Continue working, since she already has a radiation badge.
Correct! There are safe levels of working with radiation under the guidance of the Radiation Protection Program. A separate fetal badge is issued to keep track of the more stringent fetal dose limits.

29. Recording Your Completion Annual Refresher Training
Now that you have read through this annual refresher training module, be sure to record it on your laboratory’s Principal Radiation Worker Training Record Form. Beside your name, mark the “OL” box for online, date, and initial the form.

30. For more information
Questions about the annual refresher training or need a copy of your lab group’s training form? Contact the your responsible health physicist or the Radiation Safety Training Manager at ext or
Questions about topics discussed in this module? Contact the Dosimetry Program Manager at ext