2 Radiation Safety

Question 1

What are the 2 types of radiation?

Answer 1

1. ionising - radiation removes electrons from atoms to form ions (carcinogenic)
2. non-ionising - radiation cannot create ions but has thermal or photochemical effects

Question 2

Application of ionising radiation?

Answer 2

IN VIVO:

Radiology (X-rays and CT(computed tomography)

Nucelar medicine

Radiotherapy

IN VITRO:

radio-labelled techniques

blood irradiation

Question 3

Applications of non-ionising radiation?

Answer 3

MRI

UV therapy

Lasers

Question 4

What is brachytherapy?

Answer 4

Using radioactive needles to direct radiation onto tumours

Question 5

What is SPECT? How does it work?

Answer 5

Single photon emission computed tomography

Select a particle that will go to a specific area you want to look at. Add a low damaging radioactive label to it. You can now study the area. eg. flow rates in the kidney

Question 6

What is PET/CT?

Answer 6

positron emission tomography and computed tomography
*high CT radiation dose

Question 7

What is the unit describing radiation dose absorbed by an organ?

Answer 7

A Gray

This is a very large unit - a human would die within 30 days with an exposure of 10 Gray

We give tumours 80-100 Gray

Question 8

What is the unit of effective dose?

Answer 8

Sievert (Sv)

Whole body acute lethal dose = 5-7 Sv

Annual background in Sydney = 2.3mSv

CT chest/abdo/pelvis = 20mSv

Question 9

Describe the process of radiation interaction with the body

Answer 9

1. energy absorption and ionisation (~instantly)
2. interaction of ions with molecules and formaiton of free radicals (~instantly)
3. free radicals interact with molecules, cell and DNA (seconds)
4. Cell death, changes in DNA (minutes to years)

Question 10

List 5 radiation protection precautions

Answer 10

1. Time - longer exposure, higher dose
2. Shielding - high density, thickness and atomic number required. includes aprons, and walls (2mm lead radiography, 25mm lead PET, 2500mm concrete for radiotherapy)
3. Distance - decreases by 25% when you twice the distance
4. Personal monitoring - we use 20% of international annual limit doses (2x natural background radiation)
5. Radiation protection bodies sets regulations

Question 11

What can go wrong with radiation?

Answer 11

Burns

Wrong patient, area, dose

Pregnancy - foetus risk is of development problems or later life cancer