Variation in mantle technique: implications for establishing priorities for quality assurance in clinical trials

74 European and American radiotherapists responded to a questionnaire investigating the treatment of a patient with stage IIA non-bulky Hodgkin's disease by mantle irradiation. A consensus was present for the dose aims to involved and uninvolved lymph nodes and the acceptable incidence of late normal tissue effects. There was less agreement as to the total dose and dose per fraction required to maintain normal tissue toxicity within the agreed acceptable incidence. Variation was found in the radiation technique employed, the amount of spinal cord shielding used, the prescription point, modifications if irradiation was given after chemotherapy, and the routine recording of dose and dose per fraction to the normal tissue at risk. This descriptive survey confirms the need for well designed quality assurance programmes and indicates the areas of particular uncertainty that currently exist.