Application of auto-planning in radiotherapy for breast cancer after breast-conserving surgery

To evaluate the quality of planning target volume (PTV) and organs at risk (OAR) generated by the manual Pinnacle planning (manP) and Auto-Planning (AP) modules and discuss the feasibility of AP in the application of radiotherapy for patients with breast cancer. Thirty patients who underwent breast-conserving therapy were randomly selected. The Philips Pinnacle 9.10 treatment planning system was used to design the manP and AP modules for PTV and OAR distribution on the same computed tomography. A physician compared the plans in terms of dosimetric parameters and monitor units (MUs) using blind qualitative scoring. Statistical differences were evaluated using paired two-sided Wilcoxon's signed-rank test. On comparing the plans of AP and manP modules, the conformal index (P < 0.01) and D₅₀ (P = 0.04) of PTV in the AP group was lower than those in the manP group, while D₁ was higher (P = 0.03). In terms of dosimetry of OAR, ipsilateral lung V_{20 Gy} (P < 0.01), V_{10 Gy} (P < 0.01), V_{5 Gy} (P < 0.05), and D_mean (P < 0.01) of the AP group were better than those of the manP group. Heart V_{40 Gy} and D_mean of all patients with breast cancer in the AP group were lower than those in the manP group (P < 0.01). Moreover, 12 patients with left breast cancer had the same results (P < 0.01). The MU value of the intensity-modulated radiation therapy module designed using two different methods was higher in the AP group than in the manP group (P = 0.32), although there was no statistical significance. The AP module almost had an equal quality of PTV and dose distribution as the manP module, and its OAR was less irradiated.