Radiation therapy suggestion

My dad is at the point where he needs/wants to make the decision for the next step. Surgery and Seeds are not an option, so which one of the well know radiation therapies would you recommend - proton, IGRT, IMRT or .....? We have not discussed this with a radiation oncologist yet, probably in the next few weeks.

Age 69 y.
Intermediate grade t1c - located in the prostate - not spread outside
6/11/14 biopsy - Gleason score 3+3=6 - 5%; 3+4=7 - 20%; 3+3=6 - 1%; 3+3=6 - 10%; 3+4=7 - 30%; 3+4=7 - 40%; and 3+4=7 - 20%
PSA:
3/15/13-7.71, 4/1/13-7.22, 3/11/14-8.89, 3/18/14-10.52
After diagnosed, started hormonal therapy (Lupron 3 months). First PSA Nov.'14 was 4.2

Thanks in advance!

Why aren't seeds an option? (I'm not hinting it might be I just don't know).

I had HDR brachytherapy a month ago. The procedure seems rather moderate and my first PSA was 1.7 - a drop from 4.6. They expect a steady drop over the next couple of years and a cure for me. I'm feeling good, and except for moderate fatigue for a week and some urgency urinating I don't have any issues.

Seeds might not be an option if you have a history of urinary retention, urination difficulties (reduced flow, trouble starting), enlarged prostate, etc. One of the reasons I opted for proton therapy was that I had a history of urinary flow problems (difficulty starting, weak stream, frequency) and none of my physicians thought BT to be a viable option. Thus I chose proton, have had a good result so far and no regrets. BT is a great way to go for some people, but it isn't necessarily the best choice for everyone.