Radiobiology

Question 1

Describe the events of Hiroshima and Nagasaki and the radiation effects

Answer 1

USA dropped 2 bombs on Japan
80,000 deaths in Hiroshima, 35,000 in Nagasaki
Effects:
Many developed fatal cancers
Of surviving population, 46% more likely to develop cancer

Question 2

Describe the experience of Sadako Sasaki in reference to Hiroshima and Nagasaki

Answer 2

Was 2 at time of explosion
By aged 12 she had thyroid and skin cancer, and developed leukaemia (stochastic effects)

Question 3

Describe the events of Chernobyl and the effects of the radiation

Answer 3

Explosion of nuclear power plant.
Those living close received 3.96Gy dose (37,000 chest xrays)
Effects:
31 deaths on the day (4.5-25Gy)
Hundreds of thousands of “liquidators”
Projected 4,000 still die due to cancers

Question 4

Describe the events of Fukishima

Answer 4

An earthquake triggered a tsunami, caused nuclear reactor to breach
Only 1 death attributed to this event

Question 5

What are the 2 different types of effects on the body

Answer 5

Direct or Indirect

Question 6

Describe direct effects to the body

Answer 6

Beams of charged particles strike living tissue
Charged particles: alpha, beta, proton, electron

Question 7

Describe indirect effects to the body

Answer 7

Gamma rays strike living tissue
Secondary charged particles - ejected electrons
Electrons can then cause ionisation in DNA

Question 8

Describe free radicals

Answer 8

Atom, molecule or ion with at least 1 unpaired electron
Created when electrons removed from atom
Radicals want to stabilise by taking electrons, will damage any molecule in contact

Question 9

Describe Linear Energy Transfer (LET)

Answer 9

Rate at which energy is deposited by charged particles

Question 10

How do you calculate LET

Answer 10

Average value
Divide energy deposited (keV) by distance travelled (10^-6m)

Question 11

Describe low LET

Answer 11

X-rays and gamma rays
Secondary electrons produced in ionisation so can travel further

Question 12

Describe high LET

Answer 12

Proton and alpha particles
Larger mass than electrons, deposit energy over smaller distances

Question 13

What are deterministic effects?

Answer 13

No ‘safe’ dose
Radiographer must identify dangers

Question 14

What are stochastic effects?

Answer 14

No threshold dose, patient at risk any point over 0
Effects: leukaemia, bone/lung/thyroid cancer, genetic damage

Question 15

What are the 3 types of doses?

Answer 15

Absorbed, equivalent, effective

Question 16

Describe absorbed doses

Answer 16

Measurement of energy deposited in medium by ionising radiation (unit-Gy)

Question 17

Describe equivalent doses

Answer 17

Calculated by considering type of radiation used (unit-Sv)

Question 18

Describe effective doses

Answer 18

Calculated by multiplying equivalent dose by tissue weighting factor for each body part and adding them up