The Effect of Changing Technique, Dose, and PTV Margin on Therapeutic Ratio During Prostate Radiotherapy

Changing from conformal to IMRT, or from PTV10-7 to PTV3, did not produce a uniform interpatient increase in TRmodwhen the CTV contained the prostate alone. Radiobiological benefits of these two methods seem to be dependent on the particular anatomy of individual patients, supporting the use of patient-specific margin, planning, and dose prescription strategies.