ICRU Issues Report on Stereotactic Treatments with Small Photon Beams

The International Commission on Radiation Units and Measurements (ICRU) has released Report 91, which provides comprehensive recommendations on stereotactic treatments with small photon beams.

The ICRM, which aims to develop internally acceptable recommendations regarding quantities and units of radiation and activities, published, “Prescribing, Recording and Reporting of Stereotactic Treatments with Small Photon Beams,” which recommends a strict definition of target volumes [gross tumor volume (GTV clinical target volume (CTV)] by reviewing imaging modalities used in clinical practice.

Rapid developments in imaging and radiation-delivery technology have fueled the application of small photon beams in stereotactic radiation therapy (SRT). Historically, stereotaxy referred to the use of a three-dimensional coordinate system to localize intracranial targets and has been more recently extensively developed in extracranial clinical situations.

SRT involves stereotactic localization techniques combined with the delivery of multiple small photon fields in a few high-dose fractions. In SRT, the therapeutic ratio is optimized through delivery of highly conformal dose distributions with steep dose fall-off ensuring optimal dose in the target volume combined with minimal normal-tissue irradiation.

This report also covers fundamentals of small-field dosimetry, treatment-planning algorithms, commissioning and quality assurance for the existing delivery systems, as well as the role of image guidance during delivery. It also recommends a framework for prescribing, recording and reporting stereotactic radiotherapy, and covers most of the pathologies eligible for stereotactic delivery (malignant and non-malignant).

The report is consistent with previous ICRU reports: 50 (1993), 62 (1999) and 83 (2010).

For more information, contact David A. Schauer, ScD, CHP, at icru@icru.org, 301-657-2652 (x31) or 301-907-8768 (fax).

Web Extras

  • The ICRU Report 91, “Prescribing, Recording and Reporting of Sterotactic Treatments with Small Photon Beams,” is available from Oxford University Press in soft- and hard-copy formats at http://jicru.oxfordjournals.org