Radiation hygiene requirements for highly conformal radiation therapy

Over the last years, several methods of radiation application have been developed which increasingly allow the high-dose volume to be adapted to the target volume of a radiation therapy. Nevertheless, neither the dose-effect relations in the case of inhomogeneous exposure of normal tissue nor the biological effects of low radiation doses at a distance from the high-dose volume are clear. Research projects have to be conducted on these questions to improve knowledge about the risks of late deterministic and stochastic effects of highly conformal radiation therapy. It is also necessary to collect corresponding clinical data and results in the course of a patient follow-up of sufficient scope and duration.

The Commission on Radiological Protection comes to the following conclusions:

• The application of highly conformal radiation therapy requires a justifying indication in each individual case.
• The application of highly conformal radiation techniques is only permitted in centres which are adequately equipped and prepared and only with the participation of qualified physicians and medical physics experts.
• The necessary knowledge and capabilities must be taught during the training of physicians and medical physics experts.
• The specific requirements are to be taken into account in the planning and application of radiation therapy and in quality assurance.
• The application of new techniques must be accompanied by detailed documentation and thorough follow-up care.
• Especially in the case of children and young patients with a good prognosis, the justifying indication has to be weighed up against the secondary tumour risk; this process needs to be documented.
• There is a need for research projects on the toxicity in normal tissue in the case of inhomogeneous dose distribution, including late (deterministic and stochastic) effects of a modified dose distribution. It is also necessary to conduct research in order to determine the biological effectiveness of scattered radiation as a function of the distance between the target volume and different end points.