Biological improvements allow radiotherapy to kill the tumour cells but leave the normal cells unharmed. Radiation needs to be given in small amounts over time in order to deliver an excellent cosmetic and functional outcome. This is called fractionation. Fractionation describes how the total radiation dose is given in smaller partial doses, often daily. Fractionation allows normal tissue to survive radiation while the tumour cells in the same volume die. This is because normal cells have good radiation repair mechanisms while tumour cells do not. After a small dose of radiation the normal cells can repair while the tumour cells cannot. The tumour cells die. Most repair happens in the first 6 hours following radiation treatment. We are actively researching new biological ways to decrease the number of fractions and therefore decrease the number of visits to the radiotherapy department, to make the treatment experience easier on patients. One of them in mainstream practice now is the Adaptive split course radiotherapy (ASCRT) (Fogarty GB, Br J Dermatol. 2018)
Physical improvements include increased conformity of radiation. Better conformity means that the dose to cancer can be increased while the dose to normal tissue is decreased. Better conformity gives better functional and cosmetic outcomes in normal tissues after treatment. The new technologies deliver enough dose to the skin to cure skin cancer and its precursors, and yet leave the normal skin and organs underneath unharmed.
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