[Dosimetry of lower segment irradiation in Hodgkin disease. II. Radiation burden of risk organs].

The radiation exposure of the risk organs kidneys, spinal marrow, gonads, liver, and pancreas was determined for three different photon energies (Co-60, continuous radiation with 6 MV and 10 MV) at the inverted Y field, as it is applied generally for the infradiaphragmatic segment irradiation of malignant lymphomas. For this purpose, the authors made use of the thermoluminescence dosimetry and film dosimetry in the Alderson phantom. The most important results are: More than half of the left kidney receives more than 50% of the applied focal dose, about 20% receive more than 90% of the focal dose. The participation of the right kidney is minimal. If the dose exceeds 20 Gy, the lumbar spinal marrow is sufficiently protected by a satellite in the dv field. A displacement of the ovaries in caudomedial direction behind the vesical absorber does not protect the ovarian function in a satisfactory manner; the ovaries should be displaced in craniolateral direction on the alae ossis ilii. We recommend the use of a testicular lead protection even if the inguinal lymph nodes are only irradiated with the vd field.