Acute Respiratory Events and Dosimetry of Total Body Irradiation Patients Using In Vivo Lung Dose Monitoring and Custom Lung Block Adaptation.

ABSTRACT

PURPOSE: Most myeloablative regimens before stem cell transplant involved total body irradiation (TBI). Pulmonary complications from TBI contribute to treatment-related mortality and toxicity. We report the rate of acute respiratory complications after TBI at our institution. In an exploratory analysis, we investigated differences in dosimetry between patients who did and did not experience respiratory complications. METHODS AND MATERIALS In this single institution retrospective study, 49 patients received TBI from 2016 to 2018 and had dosimetry data available for analysis. Patients were prescribed 1200 cGy to be delivered over 6 fractions. Lung doses were limited using custom lung blocks. Clinical lung complications (eg, coughing and shortness of breath) were reviewed for the hospitalization period during transplant, at 4 months after transplant, and at 1 year after transplant. Supplemental oxygen use during the hospitalization period was also reported. Median anterior-posterior diameter at the umbilicus, body mass index, and lung doses were compared between patients with and without respiratory complications using a Mann-Whitney U test. RESULTS: During the hospitalization period, 14% (n = 7) of patients used supplemental oxygen administered by nasal canula and 16% (n = 8) experienced respiratory symptoms. At the 4-month follow-up, 16% (n = 8) of patients had documented respiratory symptoms. Respiratory symptoms were grade 1 to 2 except for one grade 3 attributed to infection during the hospitalization period and another grade 3 due to infection during the 4-month follow-up. At 1-year post-TBI, 4% (n = 2) of patients reported grade 1 to 2 chronic cough. Patients with respiratory complications at the 4-month follow-up had a larger umbilical anterior-posterior diameter (31.5 cm vs 26.5 cm, P = .01) and body mass index (34.5 kg/m2 vs 29.7 kg/m2, P = .02) than patients without respiratory complication. Respiratory complications were not associated with higher lung doses. CONCLUSIONS: There was no respiratory-related mortality using the individualized planning technique described here. Acute and chronic respiratory complications were minor, with the most significant intervention requiring antibiotics for respiratory infection.