0506 - Radiation Oncology Flashcards

1
Q

What is fractionation?

A

Providing a radiation dose in multiple parts to maximise effect but minimise unwanted cell death.
Allows you to hit cells when they are working (multiple hits instead of one), maximising damage to the tumour.
So improves tumour response and allows regeneration of healthy cells between disease.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the 4 R’s of radiobiology

A

Repair of cellular injury (healthy cells repair better than tumour)
Repopulation of surviving viable cells (basal layer repopulates to counter radiation)
Redistribution within the cell division cycle (Don’t want to give it in S phase - G2 or M best)
Re-oxygenation of the tumour (making more vulnerable)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are the mechanisms of radiation injury?

A

Photons of ionising radiation ionise the DNA (either directly or via H2O), causing DNA strand breaks.
Single strand DNA breaks are repairable, double strand breaks induce apoptosis as the template is disrupted.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are some common side effects of radiation therapy (acute and late)?

A

Acute - generally epithelial - dry mucosa, erythema, epilation, all localised, and fatigue.
Late effects are a mix of multiple factors rather than just single cell/local area issues (remembering that all cells are damaged, but may not die until they divide, so can come much later). All generally vascular/fibrosis or second malignancy is the point.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly