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most patients given external beam are treated using IMRT (of IGRT) techniques, the recommended doses and the safe doses to normal structures are constantly being revised, some current representative guidelines are noted below
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
