6.3 Radiation oncology Flashcards Preview

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Flashcards in 6.3 Radiation oncology Deck (15):

What is radiation oncology

Treatment of cancer with high energy x-ray beams


What is fractionation?

giving the radiation in smaller doses rather than one go


What are the mechanisms of radiation injury?

Ionizing radiation
Single strand DNA breaks
Double strand (lethal)
Template distribution
Cell death


What kind of strands do you need to break to be lethal?

Double stranded


What is the effect of oxygen in radiation?

Cells next to blood vessels will have higher oygen content and will die first. As this happens other cells will move closer to the vessel.
Fractionation allows for more tumour cells to become oxygenated and thus resistant cells will become sensitive to radiation


What are the benefits of fractionation?

Kills more cells - improves tumour response
Allows normal tissues to survive at that dose more effectively
Allows susceptible cancer cells to cycle into radiation sensitive phase
Allows re-oxygenation of tumours rendering cells more sensitive
Allows normal tissue to repair


What are the 4 R's of radiation?

Repair of cellular injury
Repopulation of surviving viable cells
Re-distribution within the division cycle
Re-oxygenation of the tissue


Which phases of the cell cycle does radiation work on?

M and G2


What are the acute effects of radiation?

Mucosal, erythema, epilation and fatigue


What are the late effects of radiation?

Effects on bone growth, second malignancy, hormonal, neurological and skin necrosis


What determines the time of effects of radiation?

The turnover time of cells


What is the aim for radiotherapy in the future?

Deliver in a more effective and safe way in less time


What are the types of radiation?

External beam
Brachytherapy (cervical)


What is the equation to work out total body irradiation?

Energy absorbed = Mass x 4 Gy/4.18


Define ionizing radiation

Radiation with enough energy to remove tightly bound electrons from the orbit of an atom, causing the atom to become charged or ionized