Rad Safety and Bio exam 1 Mizzou

R

- measures exposure in air by ionization

- only applies to x-rays and gamma rays and does not account for biological effects

rad

- measures how much energy is absorbed in tissue

- shows absorbed dose, not biological effect

rem

- measures does equivalent (biological effects)

-takes the type of radiation into account

Gy

- SI unit for absorbed dose (same as rad)

Sv

- SI unit for equivalent/effective dose (same as rem)

Film badge dosimeter

- use photographic film that darkens when exposed to radiation

- Inexpensive, permanent records, detects radiation types and energies, easily accessible

- cant be reused, sensitive to heat, limited accuracy for low doses, and must be processed

OSL dosimeter

- uses aluminum oxide crystals that store energy when exposed to radiation, laser light stimulates the crystal to release the stored energy as light, light is measured.

- very sensitive, can be reread, not effected by environmental factors (heat), wide range of doses can be read, fast.

- more expensive, requires a special reader, cannot distinguish different types of radiation

TLD dosimeter

- uses crystalline materials that store energy when exposed to radiation, crystal is heated and energy is released as light, light is measured.

- accurate, wide dose range, can be reused, small

- more expensive, can be effected by heat, cant be re read

Pocket ion chamber

- pen-shaped device that has a small ion chamber, radiation ionizes the air inside

- immediate reading, reusable, does not need to be processed

- expensive, no permanent records, less accurate

Controlled area

- area where radiation exposure is possible and access may be limited by the licensee

- limit is 5,000 mrem/year whole body

Restricted area

- area where access is limited by the licensee to protect individuals against unnecessary risk of exposure to radiation and radioactive materials.

- limits include exposure >2mR/hr in the area or it contains radioactive material exceeding 10 times the quantity specified per isotope.

Radiation area

- area in which radiation levels could result in a dose greater than 0.005 rem in 1 hour at 30 cm from the source, or greater than 100 mrem over 5 days.

High radiation area

- area where radiation levels can exceed 0.1 rem in 1 hour at 30 cm from the source.

Unrestricted area

- area where access is not limited or controlled by the licensee.

- may not exceed 2mR/hr and radioactive materials may not be used or stored in this area

Steps to operate a geiger counter

1. check and confirm calibration date is recent

2. turn the meter to battery check setting to test battery

3. set the meter to the most sensitive setting

4. check the calibrated source, measure to ensure the activity matches the recorded value

5. survey appropriate areas and record values

Area surveys

- Daily: areas where radiopharmaceuticals are eluted, prepared, or administered

- Weekly: radiopharmaceutical storage and waste areas

- Monthly: laboratories where small quantities are used (<200uCi)

- Quarterly: where sealed sources or brachytherapy sources are stored

Removable contamination

- Daily: not done

- Weekly: areas where radiopharmaceuticals are eluted, prepared, or administered and radiopharmaceutical storage and waste areas

- Monthly: laboratories where small quantities are used (<200uCi)

- Quarterly: where sealed sources or brachytherapy sources are stored

Dose limits- Occupational workers

5 rem/year (5,000 mrem)

Dose limits- General public

0.1 rem/year

Dose limits- Fetal

0.05 rem/year

Dose limits- Lens of eye

15 rem

Dose limits- Bone marrow, breast, lungs, gonads, skin, hand, forearm

50 rem

Where is a dosimeter worn

worn between chest and waist, lead apron = at collar level, ring worn on index finger of dominant hand

How often are dosimeters swapped out?

- film badge; monthly

- OSL: 1-3 months

- TLD: 1-3 months

- pocket: daily

Occupational lifetime limit

- 1 rem x age

- absolute, corrective action required by limiting dose to 1 rem/ year until CLEDE is less than CLDEL

Occupational yearly prospective limit

- 5 rem/year

- can be averaged over time, action not required but strongly recommended if exceeded

Occupational quarter retrospective limit

- 3 rem/quarter (plant workers)

- action recommended to meet prospective limits if exceeded

Cosmic radiation

- 30 mR/ year, comes from space (the sun), naturally occurring

Terrestrial radiation

- 30 mR/ year, comes from minerals in the ground, naturally occurring

Radon gas

- 100-200 mR/ year, comes from decaying uranium from the ground seeping from the ground into homes, naturally occurring

Internal radiation

- 40 mR/year, comes from radioisotopes stored in our bodies, naturally occurring

Man made radiation

- mostly for medical purposes

Safety precautions- x-ray

- Fixed barriers (lead walls/windows)

- Lead protective gear (aprons, glasses, gloves, thyroid shields)

- Collimation

- Distance

- Dosimetry monitoring devices

- Deadman switch, AEC, pulsed fluoroscopy

- rotating staff and keeping non-essential personnel out of the room

Safety precautions- Nuc med

- lead lined containers

- syringe shields

- lead L block shields (in hot lab)

- using tongs or forceps to handle materials

- wipe tests and gloving

- dosimetry monitoring devices

ALARA

- As Low As Reasonably Achievable

- achieve with time, distance, and shielding

Image gently

- for pediatric imaging, focus on reducing exposure while maintaining high quality diagnostic images

- achieved by tailoring exposures/doses to patient size and needs.

Image wisely

- for adult imaging, focus on reducing exposure while maintaining high quality diagnostic images

- achieved by tailoring exposures/doses to patient size and needs.

Inspecting an x-ray department

- radiation output and equipment performance

- shielding and room design

- scatter and leakage of radiation

- image quality and dose optimization

- protective devices/ PPE

- radiation safety practices

- personnel monitoring and record

- regulatory compliance

Declaring pregnancies

- encouraged to report at the earliest possible time in writing

- 2nd dosimetry device assigned for fetus and worn at appropriate level

- worker does not have to be limited unless the dosimetry reading is close to or exceeded (0.5 rem throughout the pregnancy)

- document instruction on DEL and ALARA guidelines/practices

Dosimetry reports

- include workers information, monitoring period, badge type, radiation dose values at DDE, SDE, LDE.

- values shown in mrem or mSv

- used to determine how much the worker was exposed to in a given period, can suggest corrective actions in exposure levels are high.

When should an employee be assigned a dosimetry badge?

1/10 of the recommended dose limit

White I label

<0.5 mR/hr at surface

Yellow II label

<50 mR/hr at surface, <1 mR/hr at 1 meter

Yellow III label

<200 mR/hr at surface, <10 mR/hr at 1 meter

Package label contents

- name of contents

- activity in Becquerels (Bq)

- transport index

transport index

the activity of package contents at 1 meter from the package in mR/hr

safely receiving a package

1. wear PPE

2. visually inspect for damages

3. check at surface and 1 meter with Geiger counter (readings must match label)

4. swipe test container on all sides covering at least 300 cm^2

5. open and check contents for leaks

Radium girls

- 4,000 women who painted watch faces and refine radium ore

- used their mouths to maintain points of paintbrushes

- developed anemia, bone fractures, necrosis of the jaw, eventually cancers

- led us to discover and study harmful impacts of radiation exposures