They take a CT scan of the area; this identifes the prostate and prostate bed. Then the scan is sent to a phyisist who develops a dose plan. The plan is sent back to the radiologist and input. The plan can follow the contour of the bed to whatever margin is set. It can also avoid or give a lower dose to the bladder neck and other areas. If a tumor is identified they can target the individual tumor or lymphnode. If they can't identify one, the suspected area is radiated. For suspected lymphnode the entire pelvic area is steralized.
IMRT rotates around you and puts out thousands of beams from all directions all coming together at an exact point. That point gets all the radation energy, and because it is comming from thousands of different directions the normal tissues it goes through only get a mere fraction of the total energy.
It is like focusing a thousand magnifying glasses on one point; no one beam would have the energy to light a fire, but when all beams hit that one point a great amount of heat is generated at that point.
The reason that SRT has a poor success rate is that agressive PC, G8 and above have a greater chance of getting into the bloodstream and causiing micomets. Billions of pc cells roaming through your body looking for a place to set up, which is usually the lymphnodes. Once the pc escapes the prostate bed and gets into the blood stream SRT is of no use. SRT will kill all the PC cells that are localized in the prostate area, but if cells are already in the bloodstream or lymphatic system only HT can stop them from growing.
64 years old.
PSA rising for 10 years to 40, free psa 10-15. Had 5 urologists, 12 biopsies and MRIS all neg. Doctors DXed BPH and continue to get biopsies yearly. 13th biopsy positive in 10-08, 2 cores of 25, G6 less than 5%. Scheduled for surgery as recommended by Urological Oncologist.
2nd Opinion from Dr Sholtz, a Prostate Oncologist, said DX wrong, pathology shows indolant cancer, but psa history indicates large cancer or metastasis. Futher tests and Color Doppler confirmed large transition zone tumor that 13 biopsies and MRIS missed. G7, 4+3, approx 16mmX18mm.
Combidex MRI in Holland eliminated lymphnode mets. Casodex and Proscar reduced psa to 0.6 and prostate from 60mm to 32mm. Changed diet, no meat and dairy. All staging tests indicate that tumor is local and non agressive. (PAP, PCA3, MRIS, Color Doppler, Combidex, tumor reaction to diet and Casodex, and tumor location in transition zone). Surgery a poor option because tumor is located next to the urethea and positive margin is very likely; permanent incontenance is also high probability with surgery.
Seed implants on 5-19-09, 3 hours door to door, no pain, minor side affects are frequency and urgency; very controlable with Flowmax and lasted 4 weeks. Daily activities resumed day after implants with no restrictions. Gold markers implanted with seeds to guide IMRT.
25 treatments of IMRT 6 weeks after seed implants. No side affects at all.
PSA at end of treatment 0.02 mostly the result of Casodex. When I stop Casodex next week expect PSA to rise. Next PSA in November. Treatments and side affects have greatly exceeded my expectations. Glad to have this 11 year journey finally conclude.