Over the years I have found that PSA readings and conclusions there from, do not follow a consistent pattern for all of us. So I tend to support your doctor's view regarding your PSA. Without ADT (hormones), it takes a while for radiation (of whatever type) to lower PSA. Then of course there is always the issue of PSA bounce (do some searching). So hang in there and hopefully your next PSA will be trending in the direction that you want.
Diagnosed March 2007, Age 57
Positive DRE, 12 Core Biopsy, 6 cores positive PCa,
Gleason 7 (4+3), Stage T2B
Rx 9 months LHRH ADT Lucrin, Neo Adjuvant,
Gold Seed implants 2 weeks prior to EBRT
70gy 3D Conformal EBRT
PSA: Nov 2006 = 6.0 ng/ml
May 2007 = 5.6 ng/ml * 1st Lucrin IMI
Aug 2007 = 0.85 ng/ml* 2nd Lucrin IMI
Nov 2007 = 0.45 ng/ml * 3rd Lucrin IMI
Jan 2008 = 0.29 ng/ml * 8 weeks EBRT and TURP in May
June 2008 = 0.12 ng/ml
Sept 2008 = 0.14 ng/ml
Dec 2008 = 0.1 ng/ml
* No incontinence, mild ED, which resoponds well to generic viagra.