Effect Of A Single Dose Of Radiotherapy

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Radiation is energy emitted from a source. It has the property to ionise when it has such a high energy, that at the moment it interacts with an atom, it can remove tightly bound electrons from its orbit, causing the atom to become charged (ionized).
The ionising effect of X-rays allows them to damage the DNA in cells and divide cells in the body. This property is used it the cancer treatment.
When a person has cancer, their cells divide uncontrollably because of changes in their DNA, forming tumours: these are group of abnormal cells that form growths. Rapidly dividing cells are particularly vulnerable to the effect of ionising radiation. By directing high energy X-rays at the tumours, the cancerous cells get deeply damaged.This cancer treatment is called radiotherapy.
The effect of a single dose of radiotherapy can lead the damaged cells to repair themselves, repair incorrectly or die. Healthy cells subject to a dose may recover if given time. Radiotherapy is therefore given in short bursts over a long period of time.
There are many subsets of radiotherapy including: the Superficial System: treats skin surface tumours with energies of 50-150kV
MV systems for deep tumours (photons) and superficial skin/thyroid tumours (e’s) at 22Mev
Linear Accelerators (Linacs) are used to deliver X-rays to a patient. They are designed to deliver multiple beams at once. The combined beam needs to focus on tumours and avoid healthy tissue.
Wedges (door stop shaped shields) progressively
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