[Last ICRU recommendations for the prescription, recording and reporting of external bean therapy].

Due to the evolution of radiotherapy techniques and equipment, in 1993 the ICRU decided to modify the guidelines that had been published in the ICRU report 29 (1978) in regard to photon beam therapy and to insert them in Report number 50 (1993). Changes that were introduced mainly concerned the prescription, recording and reporting of external beam therapy with photons. While awaiting for the upcoming publication of the report focusing on external beam therapy with electrons, the ICRU decided to publish a supplement to Report 50, as new insights had been gained after discussions with the Nordic Association of Clinical Physicists (NACP). This supplement includes the following: more accurate definitions of the margins allowing the planned target volume to be derived from the clinical target volume, the internal target volume, the expected volume of organs at-risk and the conformity index. All three points will be included in the report focusing on external beam therapy with electrons as well as extensive discussions relating to the implementation of these new recommendations.