Dosimetric advantages of a “butterfly” technique for intensity-modulated radiation therapy for young female patients with mediastinal Hodgkin’s lymphoma

Abstract

PurposeHigh cure rates for Hodgkin’s lymphoma must be balanced with long-term treatment-related toxicity. Here we report an intensity-modulated radiation therapy (IMRT) technique that achieves adequate target coverage for mediastinal disease while minimizing high- and low-dose exposure of critical organs.Methods and materialsTreatment plans for IMRT and conventional anteroposterior-posteroanterior (AP-PA) techniques, with comparable coverage of the planning target volume (PTV), were generated for 9 female patients with mediastinal Hodgkin’s lymphoma assuming use of inclined positioning, daily breath-hold, and CT-on-rails verification. Our “butterfly” IMRT beam arrangement involved anterior beams of 300°−30° and posterior beams of 160°−210°. Percentages of normal structures receiving 30 Gy (V30), 20 Gy (V20), and 5 Gy (V5) were tabulated for the right and left breasts, total lung, heart, left and right ventricles, left anterior descending coronary artery (LAD), and spinal cord. Differences in each variable, conformity index, homogeneity index, and V107% between the two techniques were calculated (IMRT minus conventional).ResultsUse of IMRT generally reduced the V30 and V20 to critical structures: −1.4% and +0.1% to the right breast, −1.7% and −0.9% to the left breast, −14.6% and −7.7% to the total lung, −12.2% and −10.5% to the heart, −2.4% and −14.2% to the left ventricle, −16.4% and −8.4% to the right ventricle, −7.0% and −14.2% to the LAD, and −52.2% and −13.4% to the spinal cord. Differences in V5 were +6.2% for right breast, +2.8% for left breast, +12.9% for total lung, −3.5% for heart, −8.2% for left ventricle, −1.5% for right ventricle, +0.1% for LAD, and −0.1% for spinal cord. Use of IMRT significantly reduced the volume of tissue receiving 107% of the dose (mean 754 cm3 reduction).ConclusionsThis butterfly technique for IMRT avoids excess exposure of heart, breast, lung, and spinal cord to doses of 30 or 20 Gy; mildly increases V5 to the breasts; and decreases the V107%.

Long-term risk of second malignancy and cardiovascular disease after Hodgkin lymphoma treatment

“…37 Additional advanced techniques such as deepinspiration breath-hold and intensity modulated RT with butterfly techniques further significantly reduce doses to the heart and cardiac substructures. 60,61 The risk of anthracycline-related HF, however, likely increases because of the increased use of anthracyclines. A recent report showed that cumulative incidence curves of CVD were similar for HL patients treated from 1965 to 1974, 1975 to 1984, and 1985 to 1995, implying that a large population of survivors remains at increased CVD risk for many years to come.…”

Slant board immobilisation of head-and-neck radiotherapy patients who cannot tolerate a flat position

“…Both met our department's dosimetric standards. Voong et al 10 recently demonstrated that use of 'butterfly' IMRT beam arrangements, in conjunction with immobilisation on an inclined board with breath-hold during radiation treatment, reduced high doses to nearby critical organs and kept the low integral dose at acceptable levels in comparison with anterior-posterior techniques. In our study, meaningful differences between the two IMRT plans in the flat and tilted positions were not identified.…”

Contemporary Radiation Therapy in Combined Modality Therapy for Hodgkin Lymphoma

“…The potential for IMRT to decrease the dose to the heart and lungs in the setting of mediastinal RT has been demonstrated and is illustrated in Figure 2. [24][25][26] Nevertheless, use of IMRT should be individualized to the specific patient. As also shown in Figure 2, IMRT plans can sometimes expose a larger volume of normal tissue to low doses of radiation compared with conventional treatment plans because of the use of multiple beams with IMRT, an issue that could impact the long-term risk of secondary malignancies.…”