from Practical Essentials of Intensity Modulated Radiation Therapy, second edition, ed K.S. Clifford Chao

Target Volume Delineation

• CTV1 (low risk) = prostate +/- proximal seminal vesicles (74Gy)
• CTV1 (intermediate risk) = prostate + proximal seminal vesicles (76-78Gy) / CTV2 = distal seminal vesicles (56Gy)
• CTV1 (high risk) = prostate, gross extracapsular disease and proximal seminal vesicles (76-78Gy) CTV2 = distal sem ves and periprostatic nodes (56Gy)
• PTV (if daily imaging) 5mm posterior and 8 mm all other (if less rigorous imaging then 1.1 cm) (PTV should get 95% of prescription dose)

• Rectum: V65 less than or equal to 17% and V40 no more than 35%
• Bladder: V65 at 25% and V40 at 35%
• Femoral Heads v50 below 10%
• on axial cuts the full rectum less than 50% IDL and less than half the 90% IDL