Dosimetry intercomparisons for evaluation of late effects of ionizing radiation.

In 1971, 1973 and 1976 intercomparisons of absorbed dose and dose distribution over a mouse phantom for roentgen irradiation were performed as part of the program of the European Late Effects Project Group (EULEP). Sixteen institutes from 8 countries participated in the sessions of the third intercomparison. In general, progress has been made concerning accuracy and precision of the dosimetry; in 2 cases, discrepancies could be resolved after additional measurements. With regard to the dose distribution over a mouse phantom, the results are not satisfactory; 4 out of 15 participants are still unable to perform uniform irradiations. The necessity of repeated intercomparisons is clearly demonstrated to allow a comparison of biologic results obtained in cooperative research programs.