Purpose: To present the technique of total body irradiation (TBI), applied for the first time in Romania, at the Institute of Oncology Bucharest, as part of stem cell transplantation for hematological malignancies.
Patients and methods: The total dose administered was 12 Gy at the reference point, 2 Gy/fraction, one fraction per day, 6 consecutive days, with a total dose of 8 - 11.4 Gy delivered to the lung, using Mevatron Primus linear accelerator (6 MV & 15 MV, 200-300 cGy/min in isocenter), in vivo dosimetry detectors and equipment for the reference dosimetry, personalized blocks for lung shielding sustained by polymethylmethaacrylate (PPMA) plate, Simulix HP simulator, and computer tomographic (CT) scans. Techniques used were: a) two parallel opposed anteroposterior / posteroanterior (AP/PA) fields with the patient in prone and supine position; b) two parallel opposed lateral fields with the patient placed on a lateral table, at 320 cm from the source. The percentage depth dose, tissue maximum ratio (TMR), off axis ratio (OAR) and the reference dose rate were measured for every patient's geometrical characteristics, with an uncertainty of +/- 2.2% and were used to calculate monitor units and to evaluate the dose in organs at risk (lungs, gonads, eyes etc).
Results: 5 patients (3 with the AP/PA technique and 2 with the lateral technique) were irradiated. All patients completed their irradiation in good clinical condition. The acute side effects were minimal (WHO grade 1: nausea/ vomiting--all patients; diarrhea--1 patient; headache--2 patients; photophobia and diplopia--1 patient; head and neck skin erythema--all patients). Because of the short follow-up period no safe evaluation of late side effects can be done. However, during this period one patient developed a non-aggressive form of chronic liver graft vs. host disease (GVHD) and one patient died due to acute GVHD.
Conclusion: TBI as part of stem cell transplantation for hematological malignancies was successfully realized at our Institute, with favorable clinical results. This technique is easy to carry out and reproducible.