TD34-Prescribing, Recording, and Reporting Photon Beam Therapy:

A Review of ICRU-50 & ICRU-62

Zuofeng Li, D.Sc.

Department of Radiation Oncology

Washington University

St. Louis, MO 63110

The prescription, recording and reporting of radiation therapy dosage is critical in the accurate delivery of radiation treatment to cancer patients.  Various, sometimes ambiguous methods have been used in the prescription and reporting of radiation dosage.  Such methods include, among others, prescription of dose to isocenter or a similar point within the target in the low dose gradient region, or as a percentage of local or global maximum doses.  Several issues needs to be carefully considered before consistent and unambiguous methods of dose prescription and reporting can be devised and implemented, prominent among them are the clear definition of target tissue to be treated.  With the introduction of advanced radiotherapy delivery techniques such as Intensity Modulated Radiation Therapy (IMRT), the methodology of dose prescription and reporting can become an integral part of dose optimization, placing an even more important role on how the prescription dose is specified.  This session reviews the recommendations of the ICRU reports number 50 and 62, augmented by practical examples of how the targets are defined for specific treatment sites.  A literature review is provided that contains data on margins of target volumes for typical disease sites.