Image Guided and Intensity Modulated Radiotherapy
Image guided radiotherapy (IGRT) and intensity modulated radiotherapy (IMRT) are two new techniques that allow the radiotherapy beams to best target the prostate and spare the surrounding normal tissues. IMRT and IGRT provide cure rates considered equivalent to those of surgery and brachytherapy, with very low risks of complications. IMRT and IGRT suit both younger and older men.
IMRT uses dozens of mini-beams of radiation in order to ensure the prostate is completely covered with high doses of radiation whilst minimizing the doses to surrounding normal tissues. IGRT allows the treatment machines (linear accelerators or “linacs”) to target the prostate more accurately. IGRT usually requires insertion of gold seeds (or “fiducial markers”) as a one-off procedure prior to the course of IMRT. The prostate is a mobile organ, with its motion dependant on how full the bladder and bowel are. The fiducial markers allow the linacs to see where the prostate is, and the machine is moved before each treatment to ensure the prostate is targeted and normal tissues are avoided.
IMRT and IGRT are able to give high doses of radiotherapy, called dose-escalation. Dose-escalation with IMRT and IGRT can deliver doses similar to those given with brachytherapy, yet also spare surrounding normal tissues.
From a patient’s perspective, the advantages of IMRT and IGRT are that they provide cure rates equivalent to surgery and brachytherapy, without patients having to undergo significant invasive procedures. IMRT and IGRT offer very low rates of complications again similar to the low rates seen with surgery and brachytherapy. The main disadvantage of IMRT and IGRT is that the treatment goes over an 8 week period, compared to high-dose rate brachytherapy which typically takes 6-7 weeks. The types of side-effects are similar to those seen with EBRT, but the risks are much lower. The risks of significant complications are around 1-2%.
After treatment you will have further PSA tests to monitor developments. Your PSA should gradually reduce over about 12 months to between 0 and 2. If the PSA rises again, it is often 10 years or longer before problems arise. There are several treatment options available if the PSA rises (“salvage treatments”). Salvage treatments after IMRT and IGRT are the same as for EBRT, and include radical prostatectomy, cryotherapy, high-frequency ultrasound (HI-FU), hormone therapy and chemotherapy.