129; Radiology

Question 1

What is Radical radiotherapy?

Answer 1

Radiotherapy treatment with the intent to Cure

Question 2

What is Adjuvant radiotherapy?

Answer 2

2^o treatment, after the ‘main event’ ee surgery

Question 3

What is Palliative radiotherapy?

Answer 3

Radiotherapy to control treatment.

Will only be used if treatment is ‘worth’ the side effects

Question 4

What is Radiotherapy?

Answer 4

The use of

• Ionising photons (Xrays)
• Electrons
• (other charged particles)

to treat diease

(Radiation is Carcinogenic)

Question 5

How does Radiotherapy work?

(simply)

Answer 5

• Ionising radiation produces reactive oxygen species within cells that damage the DNA
• Radiation can also damage DNA directly, ‘direct strike’

DNA damage can be reparable, but a single DNA break is probably lethal:

Can cause apoptosis or death of daughter cells

Question 6

What cells does radiotherapy damage?

Answer 6

• All cells but dividing cells don’t repair as effectively (ee cancer cells)
  
  • Rapidly dividing normal tissue is thus worse affected also (ee gut epithelium)
• Radiation has the potential to kill all cells
• Some cells normal & cancerous are affected differently

Question 7

What is the major dose-limiting factor in most radiotherapy treatments?

Answer 7

Normal tissue tolerance

Challenge is to deliver lethal does to tumour whilst sparing normal surrounding tissue

Question 8

What is the ‘therapeutic window’?

Answer 8

The dose which is effective against the cancer w/o being too damaging to normal tissue

Question 9

What are the units of measurement for therapeutic radiation?

Answer 9

Gray (Gy)

1 Gy = 1joule/kg

Question 10

What determines the depth of penetration of the radiation?

Answer 10

The Energy & Type of radiation

ee

• Low energy (kV) shallow

Skin cancers; max dose at skin, rapidly absorbed by deeper structures.

• High energy (mV) deeper

Breast cancer; penetrating; builds up at depth, spares skin.

Question 11

What is the difference between the dose delivered by Protons and Photons?

Answer 11

Protons deliver a targeted dose

Photons deliver dose to collateral areas

Question 12

Why is radiotherapy delivered in fractions?

Answer 12

fraction= individual RT treatment

• Delivers sub-lethal damage to tissues
• Allows normal tissue DNA to repair

Question 13

What is IMRT (intensity modulated radio therapy)?

Answer 13

Method for directing higher doses to specified areas; conventional treatment delivers high doses to collateral areas

• Can conform radiation dose in a concave pattern
• Able to ‘squeeze’ RT dose into tight corners

Question 14

List some side effects of radiotherapy

Answer 14

• Fatigue
• Sore skin
• Mucositis
• Cough
• Hair loss
• Nausea
• Anaemia

Question 15

What is Brachytherapy?

Answer 15

Radiotherapy treatment where radioactive source is placed in or next to the tumour

Question 16

What are the advantages of Brachytherapy?

Answer 16

A vary high dose can be delivered directly to the tumour

And the dose of the RT falls off quickly