We aimed to report the dosimetric effects of integrating the deep inspiration breath-hold technique (DIBH) into tangential-based volumetric modulated arc therapy (TVMAT) in left breast cancer patients who underwent breast-conserving surgery (BCS).
METHODS
Sixty-one patients who underwent BCS were included in the study. Patients were divided into two groups
according to whether irradiation was applied only to the breast or to the breast + regional lymph nodes
(RLN). DIBH-TVMAT and free-breath (FB)-TVMAT plans were generated using a mono-isocentric
technique with two partial arc rotations for each patient. The same gantry angles were used for both FBTVMAT
and DIBH-TVMAT plans. DIBH-TVMAT and FB-TVMAT plans were evaluated, and dosimetric
parameters were compared.
RESULTS
The mean cardiac dose in the FB-TVMAT and DIBH-TVMAT plans was 8.8 Gy and 5 Gy, respectively,
indicating a 42% dose reduction in patients receiving only breast radiotherapy (RT) (p=0.000).
Left lung volumes that received 5 Gy and 20 Gy were also significantly in favor of DIBH-TVMAT
(p=0.001; p=0.003). A 23% reduction was encountered in the maximum dose applied to the left anterior
descending coronary artery (LADCA) after the DIBH-TVMAT plan in patients who received
RT to the breast and RLN (p=0.000). The addition of supraclavicular lymph nodes to the treatment
field revealed an increase in the heart volume that received 5 Gy and the ipsilateral lung volumes that
received 5, 10, and 20 Gy.
CONCLUSION
The technique integrating DIBH with TVMAT provides a significant dose reduction not only to the
heart and LADCA but also to the bilateral lungs and contralateral breast without sacrificing target volume
dose coverage.