Intensity Modulated (IMRT) and Image Guided Radiotherapy (IGRT) For Prostate Cancer
External beam radiotherapy uses high-energy X-rays to kill cancer cells in the prostate to eradicate the disease.
A special shielding device in the radiotherapy machine carefully shapes X-ray beams to the size and shape of the prostate to target the cancer cells and minimise damage to healthy cells and nearby organs such as the bladder and bowels. This technique is known as conformal radiotherapy.
Intensity Modulated Radiotherapy (IMRT)
The aim of this approach is to increase the dose of radiation to the prostate while sparing normal tissue. A device called a multi-leaf collimator in the radiotherapy machine adjusts the size and shape of the radiation beams. There are 80 tiny shielding “leaves” on each side of the beam that are moved in and out of the radiation field while the beam is on, to vary the beam intensity and precisely distribute the radiation dose.
Recent studies have demonstrated that full coverage of the intended treatment target can be achieved while reducing doses to surrounding tissues with IMRT. It allows the oncologist to treat prostate cancer with higher doses of radiation, which is proven to improve the outcome while minimising the side-effects.
Image-Guided Radiotherapy (IGRT)
IGRT is the ideal complement to IMRT. Newer radiotherapy machines enable the radiographers to take a scan immediately before treating the patient in the treatment room. The aim is to detect any changes in the position of the prostate gland that can be caused by variations in internal anatomy, such as the filling of the bladder or gas in the rectum. Using this information, the radiation beams can be adjusted in order to precisely target the treatment to the cancer and, just as importantly, prevent too much dose to surrounding tissues. IGRT is performed before every treatment session.