Peter Semester 1 year 2

Question 1

RADIATION definition

Answer 1

The emission or transmission of energy in the form of waves or particles through space or through a material medium.

BUT Radiation may also refer to the energy, waves, or particles being radiated.

Question 2

Examples of EM radiation

Answer 2

radio waves, visible light, x-rays and gamma rays

Question 3

Particle radiation

Answer 3

alpha, beta, and neutron radiation. Radioactive fission, fusion and decay

Question 4

Acoustic radiation

Answer 4

sound and ultrasound

Question 5

seismic waves

Answer 5

earthquakes

Question 6

Which type of radiation is a major concern and why?

Answer 6

Ionising radiation because it knocks electrons off atoms, disrupting molecular bonds. This cause mutation, cancer, radiation sickness and death.

Question 7

What are 2 sources of radiation

Answer 7

Background and Artificial

Question 8

In 2006 what was the average per capita dose in USA

Answer 8

6.2 milliseverts

Question 9

What was the greatest source of ionising radiation in USA?

Answer 9

Radon and Thoron and CT

Question 10

How does radon and thoron occur

Answer 10

It is the decaying by product of Uranium as it decays to lead. These gases seep into poorly ventilated houses.

Question 11

What are the various types of background radiation?

Answer 11

Radon and Thoron, internal, terrestrial, cosmic

Question 12

What are the various type of artificial radiation?

Answer 12

Medical exposure, consumer products (air travel, building materials and smoking) (0.1 mSv),

Question 13

Why is there a jump in dose/exposure in USA from 1980 to 2006?

Answer 13

The use of CT and nuclear medicine produced most of the radiation dose in 2006.

Question 14

What are the 4 types of radiation quantities and units?

Answer 14

Exposure (X) (C/kg), Absorbed (D) (Gray), Equivalent (H) (Sv), Effective (E) (Sv)

Question 15

What is KERMA?

Answer 15

Kinetic energy released in matter. It is the amount of energy transferred from the X-ray beam to the charged particles per unit mass in the medium of interest.

For low energy/diagnostic Xrays this is roughly the same as absorbed dose.

Question 16

Exposure (X)(C/kg)

Answer 16

Measure of the quantity of radiation produced in air.
X= charge/mass air
(The amount of electric charge produced by ionising radiation per unit mass of air.)

Useful quantity in instrumentation.
It isn’t useful as a dose because it only applies to air but with calculation it can be changed to radiation dose.

Question 17

Absorbed dose (D) (Gray)

Answer 17

D= Energy/ mass matter

Energy transferred per unit mass of matter. The greater the mass the lesser the absorbed dose relative to the person.

Question 18

Equivalent dose

Answer 18

Takes into account the ability of different radiations to produce different amounts of damage to living tissue.

To get the Equivalent Dose (H) multiply the Absorbed Dose (D)by the radiation weighting factor wr and add up the
contributions from each type of radiation.
Xrays - 1
Neutrons - 5-20
Protons - 2
Alpha particles - 20

Question 19

Effective dose

Answer 19

Different tissues have different sensitivities to radiation. Used to work out risk to individual and offspring.

To get Effective Dose (E) multiply the Equivalent Dose (H) by the contributions to each tissue

Important when thinking about risks of radiation dose

Question 20

DAP

Answer 20

Xray field area x radiation dose to air.
mGy.cm^2.

DAP values can be changed by altering technique factors and size of the exposed field.