X-ray Safety Training

Texas A&M Health Science CenterEnvironmental Health and Safety

Rev. 03-2015

Agenda

• Introduction– Regulatory structure– Rad safety program

• What is radiation?– Types of radiation– Biological effects of

radiation– Background radiation– Radiation detection

• HSC Procedures– Safety (PPE, storage, etc)– Survey Procedure

REGULATORY OVERSIGHT

Line of Authorization from the State

• US NRC– Delegates responsibilities

to TDSHS

• TDSHS– Issues licenses and

ensures compliance within the state

• HSC– Radiation Safety Officer

(RSO) and Radiation Committee (RSC) oversee institutional compliance

Line of Authorization at the HSC

• HSC– Holds a “Registration” for use of X-ray generating

devices our campuses– RSO and RSC• Create, review, and approve the institutional radiation

safety manual• Create review and approve new principal investigators

(PIs) to become radiation generating device permittees

EHS website

http://www.tamhsc.edu/ehs/

HSC X-ray Permit

X-RAY PRODUCTION AND BASICS

X-ray production (X-ray tube)

X-ray production - Bremsstrahlung

• Bremsstrahlung X-rays• Charged particles radiate

electromagnetic energy whenever they experience a change in velocity (either in speed or direction)

• These x-rays are emitted when high-speed charged particles undergo rapid acceleration

X-ray production – electron ejection

• Incoming electron can impart enough energy to result in an ejection of the K shell electron

• An Electron will drop into the K shell to balance energy results in the characteristic x-ray

X-ray production - characteristics

• Electron “holes” can be filled with either an L-shell or M-shell electron

• N, O, and higher shell electrons create characteristic x-rays that are lost in the noise

• Al or Be filters are used to block the x-rays of lower energy than the characteristic to “harden” the beam

X-ray basics – ionizing radiation

• Ionizing• Alpha• Beta• Gamma• X-ray

• Non-Ionizing – Microwaves – Sunlight – Infrared waves – Radio waves – Lasers

X-ray basics - shielding

• X-rays will pass through many materials

• Most often, they require lead or concrete as a shield

Radiation Penetration

UNITS & DEFINITIONS USED IN RADIATION

Units & Definitions - Exposure

Roentgen R the unit of exposure to Ionizing Radiation. The amount of γ or x-ray radiation required to produce 1.0 electrostatic unit of charge in 1.0 cubic centimeter of dry air.

Use the abbreviation “R/hr” or “mR/hr” when measuring an x-ray, gamma, or beta dose.

Units & Definitions – Absorbed Dose

RAD (radiation absorbed dose) is a unit of measurement used to describe the amount of energy transferred from a source of ionizing radiation to any material, including human tissue.

• As a unit of exposure, 1 rad means that each gram of air at 0° C and 1 atmosphere has absorbed 100 ergs of energy.

• As a unit of dose, 1 rad means that each gram of exposed tissue has abosorbed 100 ergs of energy.

• Note: The SI unit for absorbed dose is the Gray (Gy). 100 rad = 1 Gy

Units & Definitions – Dose + Risk

Different types of ionizing radiation cause differing degrees of biological effects even when the same amount of energy is transferred.

To create a universal measurement, the “rad” is multiplied by the specific quality factor for a type of ionizing radiation to determine the dose equivalent.

The rate at which an individual is exposed (i.e. an hour verses a lifetime) also influences the level of biological harm.

Use a dosimeter to measure a dose equivalent.

Units & Definitions – Quality Factor

• Used to relate the absorbed dose of various kinds of radiation to the biological damage caused to the exposed tissue

• Necessary because the same amounts absorbed of different kinds of radiation cause different degrees of damage

• Converts the absorbed dose to a unit of dose equivalence to compare damage caused by any kind of radiation

Radiation Type Quality Factor (QF)

X-rays, Gamma rays, Beta particles

1

Protons 10

Alpha particles 20

Units & Definitions – Dose Equivalent

Dose Equivalent Rem (Roentgen Equivalent Man) is the dose equivalent for tissue, and takes into account the varying amount of damage to tissue based on the energy and radiation type, and accounts for tissue sensitivity or the risk of malignancy from the radiation induced injury.

The dose equivalent can be determined by applying a tissue weighting factor (risk factor) to the absorbed dose (rad).

Use the abbreviation “Rem/hr” or “mRem/hr” when measuring an x-ray, gamma, or beta dose.

Note: The SI unit for dose is the Sievert (Sv). 100 Rem = 1 Sv

BIOLOGICAL EFFECTS OFIONIZING RADIATION

Excitation and Ionization

Excitation Ionization

Ionizing Water

Radiation Induced Decomposition of Water within a cell• H2O can form the following:

– H2O+

– H2

– H+

– H0

– OH-

– OH0

– HO2

– H2O2

– e-

• Free radicals within the cell can result in indirect effects

Harderian Wasp Eggs

Effects of ionizing radiation (DNA)

• DNA damage can result from radiation– Single and double strand breaks– Most often repaired successfully by the cell

Potential Outcomes of Radiation Damage to Parent Cells

Radiosensitivity

Law of Bergonie & Tribondeau (1906)Determinants of Radiosensitivity

Law states that radiosensitivity varies:1. Directly with rate of cell division

(more metabolically active = more radiosensitive)

2. Directly with number of future divisions a cell will undergo

(younger cells are more radiosensitive)

3. Inversely with the degree of cellular differentiation

(stems cells are the most radiosensitive)

Radiosensitive tissues

Radio-sensitive Cells Radio-resistant Cells

Reproductive Cells Bone, Cartilage, Muscle

Blood forming tissues Liver

Epithelium of skin Kidney

Epithelium of gastrointestinal tract Nerve tissue

Biological Effect Parameters:

The radiogenic biological effect depends on:

1. Radiation Type

2. Rate of Exposure / Absorption

3. Area Exposed (Variation in Cell Sensitivity)

4. Variation in Species and Individual Sensitivity

Biological Effects Sumary

• In summary, radiation may:– Interact within the body– Deposit energy in the body– Create ionizations in the body– Cause DNA damage

• All of which may lead to biological damage, but:– Damage may be repaired– Damage may be benign– Damage may be neutralized through apoptosis

RADIATION PROTECTION

ALARA

Philosophy• Radiation doses are

kept as low as possible• Stems from Linear-Non-

Threshold dose model• ALARA program

required by Federal and State regulations

Keys to ALARA

• Time• Distance• Shielding• Housekeeping

Radiation Protection Basics

The INDIVIDUAL working with radiation generating devices

MUST

assume the RESPONSIBILITY for their own safety

AND

must ensure that their actions do not result in a hazard to others.

Natural Background – Radon

Natural Background - Cosmic

Natural Background – Terrestrial

Natural Background – Dose Map

Natural Background – Internal

Natural Background – Medical

Natural Background - Consumer

Natural Background - Other

Natural Background – Total

Risk versus Dose models

Radiation Risk in Perspective

Health Physics Society Position Statement (March 1996):

• Radiogenic health effects (primarily cancer) are observed in humans only at high doses.

• Below this dose, estimation of adverse health effects is speculative since risk of health effects are either too small to be observed or are non-existent.

• Epidemiological studies have not demonstrated adverse health effects in individuals exposed to small doses (less than 10 rem) delivered in a period of many years

Regulatory Limits

Maximum Permissible Dose Limits

Whole Body 5 Rem / yearLens of eye 15 Rem / yearSkin

50 Rem / year

Minor (under 18 y/o) 0.5 Rem / year

Unborn Child of Worker 0.5 Rem over entire

gestation period of DPW

Members of the General Public 0.1 Rem / year

Dose Limit Comparison

• 100,000 rad -Molecular destruction

• 1,000 rad – 100% of people die: CNS syndrome

• 450 rad – LD50 (50% of people die)

• 50 rem/yr – extremity regulatory limit

• 15 rem/yr – lens of the eye regulatory limit

• 10 rem/yr – “whole body” exposure causes measurable blood changes when acute

• 5 rem/yr – whole body regulatory limit for trained radiation workers

• 4.167 rem/qtr – HSC extremity administrative dose limit

• 1.25 rem/qtr – HSC lens of the eye administrative dose limit

• 0.417 rem/qtr – HSC whole body administrative dose limit

RADIATION DETECTION

Detecting Radiation

• Not detectable by any of our natural five sense

• Requires specialized equipment

• Varying types of equipment for different types of radiation and the type of measurements desired

• Knowledge of the technology is key to making sure that you know which detector to choose to which situation

Gas Filled Detectors

Geiger-Mueller

• Geiger-Mueller detectors can be used to survey for a variety of different radioisotopes. Pancake probe GM detectors (shown on the bottom right) are the most efficient type of GM detectors and should be used when available.

Gas Ionization Curves

Scintillators

Photomultiplier tube Sodium Iodide Probe

PROCEDURES

Safety Procedures

1. External Exposure Protection Methods2. Laboratory Procedures3. Emergency Response

Radiation Safety

• External exposure sources– Mitigated by:

• Time• Distance• Shielding• Housekeeping (efficient processes/procedure design)

Dosimetry

• Primary dosimeter is either a OSL or TLD badge

• Sensitive to gamma and hard beta radiations

• Provides RSO with dose information on a quarterly basis

• Does not provide information during a real time exposure to radiation

Dosimetry - Badge

• Dosimeter badges should be worn on either the lapel or waist– Whichever is closest to

the source of radiation

Dosimetry - Ring

• Your ring badge will come with your name on it. Wear the badge with the name plate facing the source of radiation

• Be sure to wear the ring badge under your gloves to capture actual dose to your skin

Safe Practices and Procedures

• Consult HSC eduSafe or Emergency Flipchart and Manuals

• If injuries occur, they take first priority– Call 911– Provide first aid– Monitor individual for

contamination

Detector Use – Device Overview

Detector Use – First Steps

1. Turn meter on

2. Battery check

Detector Use – Device Use Tips

3. Audio on

4. Fast/Slow response

5. Sensitivity setting

Incident Reporting

• Report the following to EHS– Actual OR suspected overexposure incidents– Leakage test failure (shielding is inadequate)– Exposure to the general public– Loss of device

Special Rules (Pregnancy)

– A woman is only pregnant when she submits the paperwork.

– Tighter dose restrictions are applied to protect the baby (no more than 0.5 rem over the course of the pregnancy – 10CFR20)

– A woman has the right to declare and undeclare at any time.

Declared Pregnancy

Security

– Do not be afraid to challenge ANYONE you do not recognize in your lab or lab area.

• Unauthorized personnel should not be in your lab. Asking for identification is appropriate in all circumstances.

– No one other than authorized users should have access to radiation producing devices.

Summary

• What is radiation?– Types of radiation– Biological effects of radiation– Background radiation– Radiation detection

• HSC Procedures– Safety (PPE, storage, etc)– Survey Procedure

Contact Information

• Radiation Safety Officer– Erich Fruchtnicht– fruchtnicht@tamhsc.edu– 979-436-0551

• Bryan EHS Officer– Marc Goldsmith– goldsmith@tamhsc.edu– 979-436-0559

• Temple EHS Officer– Cristina Bazan– bazan@tamhsc.edu– 254-742-7024

• Houston EHS Officer– Stephanie Colman– colman@tamhsc.edu– 713-677-7953

• Dallas EHS Officer– Hiram Patterson– hpatterson@bcd.tamhsc.edu– 214-828-8301

• Kingsville EHS Officer– Call the RSO for radiation

questions

Test

• Go to: http://www.tamhsc.edu/ehs/radiation-safety.html• Click on “X-ray Safety Test”• Take test• Click submit