Dosimetric problems associated with total body irradiation.

Total body irradiation (TBI), which is carried out with high energy photons at large source distances and with large fixed fields, involves special dosimetric requirements. The dose measurements published thus far on anthropomorphic phantoms have shown that deviations from the dose values calculated with "normal" dose functions occur as a result of completely different scatter radiation distributions. The higher the photon energy selected, the more slight these deviations become.