Objective To explore the dosimetric characteristics of TomoHelical (TH) and TomoDirect (TD) with simultaneous integrated boost for silver clip marked tumor bed after breast-conserving surgery of left breast cancer.
Methods Totally 20 patients with breast-conserving surgery of left breast cancer were selected, and TOMO therapeutic planning system was used to design TH plan and TD plan. The dosimetry parameters of the two plans were analyzed.
Results In the comparison of planning gross tumor volume (PGTV) between the two plans, the radiation dose to 2% of the target volume (D2), the radiation dose to 98% of the target volume (D98), the radiation dose to 50% of the target volume (D50) and the conformal index (CI) of the TH plan were higher than those of the TD plan, and the significant difference was observed in CI between two plans (P < 0.05). In the comparison of planning tumor volume (PTV) between the two plans, theD98 and CI of the TH plan were significantly higher than those of the TD plan, D50 was significantly lower than that of the TD plan, but D2 of the TD plan was significantly better than that of the TH plan (P < 0.05). The volume of left lung exposed to 5 Gy radiation dose (V5), 10 Gy radiation dose (V10) and 20 Gy radiation dose (V20), V5 and mean radiation dose (Dmean) of right lung, Dmean of right breast, D2 of spinal cord and Dmean of heart in the TD plan were significantly lower than those in the TH plan (P < 0.05).
Conclusion Both TH and TD can meet the clinical dosimetry requirements of simultaneous integrated boost for patients with silver clip marked tumor bed after breast-conserving surgery of left breast cancer, and TD is obviously better than TH in the protection of organs at risk. Therefore, it is suggested that TD technology should be the priority choice for patients with cardiopulmonary disease after breast-conserving surgery and heart injury after chemotherapy.
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