Despite applying an IMRT dose of 81 Gy to prostate cancer, a substantial fraction of men with intermediate - high risk prostate cancer may go on to develop local failure. There is a known dose - response relationship for prostate cancer radiation. We sought to determine if it was feasible to increase the dosage within the general peripheral zone region of the prostate gland, where prostate tumors preferentially reside, without increasing the dose to surrounding normal structures. Five consecutive prostate cancer patients were chosen, who had already undergone treatment with tomotherapy. A peripheral zone simultaneous integrated boost (SIB) volume was added to each case. This was done by making the SIB equal the prostate (CTV) contour, and then coming 5 mm off of the bladder, rectum, penile bulb, and the “anterior stripe”. The anterior stripe was drawn on each prostate slice as a 0.8cm spot in the mid gland that was then extended 3cm anteriorly. The SIB did not extend outside the prostate gland and was adjusted if necessary. PTV was based on standard expansion of the prostate (CTV) contour by 5 - 6mm, 3mm posteriorly. Contouring was solely CT based, and all patients had fiducial markers. Plan was rerun with the tomotherapy Treatment Planning System (TPS), administering 1.8 Gy x 45# = 81 Gy to the PTV, and the SIB was prescribed 2.0 Gy x 45# = 90 Gy. These plans were not used for treatment, but were compared with the patients' actual treatment plans. The average treatment volumes were 28.0 cc for the SIB, 60.3 cc for the CTV, and 114.8 cc for the PTV. The mean dose to the prostate (CTV) was 82.97 Gy in the standard plan, and 89.80 Gy in the dose painting plan (p < 0.00001), for an 8.2% increase. This resulted in a BED that was 11.6% increased, based on an alpha-beta value of 3.0. However, the rectal median dose was only increased by 2.4%, and the bladder median dose was only increased by 3.6%. Rectal V70 dropped from 9.4% to 8.1% with the dose painting plan, and the bladder V70 dropped from 13.9% to 13.4%. Penile bulb median dose was identical at 44 Gy. All these changes in normal tissue dose were statistically non-significant. Treatment delivery times were identical at 217 seconds. Dose painting a generic peripheral zone was very straightforward, allowing a simultaneous integrated boost to be prescribed. This resulted in a significantly higher BED to be administered to the prostate gland overall, yet the rectal and bladder dosages were not significantly increased. This may improve the therapeutic ratio. We plan to test this strategy for intermediate - high risk cases and also incorporate 3T MRI fusion to help improve demarcation of prostate contour, peripheral zone, urethra, and tumor nodule(s).