Toxicity and dosimetry of fractionated total body irradiation prior to allogeneic bone marrow transplantation using a straightforward radiotherapy technique.

Since 1989, we have used a relatively straightforward technique for giving total body irradiation (TBI), using anterior and posterior parallel opposed fields with the arms and fists acting as compensators. The dosimetry, toxicity and outcome of 48 patients (26 adults, 22 children) treated with TBI using this technique have been audited. A dose of 14.4 Gy in eight fractions over 4 days was prescribed to all patients with an unrelated donor and 12 Gy in six fractions over 3 days to those with a sibling donor. From May 1994, all children received 14.4 Gy because of a recommendation from the United Kingdom Children's Cancer Study Group. The range of lung dosimetry was -6% to +7% when the dose was specified to the lung maximum. The trunk doses were all within +/-10% of the prescribed dose. Doses to other regions of the body were less homogeneous but clinically acceptable in that the minimum doses were never less than -10% of the prescribed dose. Mucositis was the most common side effect; its treatment with opioids was more frequent after 14.4 Gy than after 12 Gy (P=0.0004) and in adults than in children (P=0.01). No cataracts have yet been seen in these patients. The radiation was not found to be a proven cause of clinical pneumonitis, although there was one death due to interstitial pneumonitis, which was likely to have been caused by cytomegalovirus infection in which radiation pneumonitis could not be excluded. There were no other suspected TBI-related deaths. In conclusion, this straightforward technique achieved acceptable dosimetry and was well tolerated.