Dosimetric study of the plan quality and dose to organs at risk on tangential breast treatments using the Halcyon linac

Abstract

Purpose To investigate the plan quality and doses to the heart, contralateral breast (CB), ipsilateral lung (IL), and contralateral lung (CL) in tangential breast treatments using the Halcyon linac with megavoltage setup fields. Methods Radiotherapy treatment plans with tangential beams from 25 breast cancer patients previously treated on a C‐arm linac were replanned for Halcyon. Thirteen corresponded to right‐sided breasts and 12 to left‐sided breasts, all with a dose prescription of 50 Gy in 25 fractions. Plans were created with the following setup imaging techniques: low‐dose (LD) MVCBCT, high‐quality (HQ) MVCBCT, LD‐MV and HQ‐MV pairs and the imaging dose was included in the plans. Plan quality metric values for the lumpectomy cavity, whole‐breast and doses to the organs at risk (OARs) were measured and compared with those from the original plans. Results No significant differences in plan quality were observed between the original and Halcyon plans. An increase in the mean dose (Mean) for all the organs was observed for the Halcyon plans. For right‐sided plans, the accumulated Mean over the 25 fractions in the C‐arm plans was 0.4 ± 0.3, 0.2 ± 0.2, 5.4 ± 1.3, and 0.1 ± 0.1 Gy for the heart, CB, IL, and CL, respectively, while values in the MVCBCT‐LD Halcyon plans were 1.2 ± 0.2, 0.6 ± 0.1, 6.5 ± 1.4, and 0.4 ± 0.1 Gy, respectively. For left‐sided treatments, Mean in the original plans was 0.9 ± 0.2, 0.1 ± 0.0, 4.2 ± 1.2, and 0.0 ± 0.0 Gy, while for the MVCBCT‐LD Halcyon plans values were 1.9 ± 0.2, 0.6 ± 0.2, 5.1 ± 1.2, and 0.5 ± 0.2 Gy, respectively. Conclusions Plan quality for breast treatments using Halcyon is similar to the quality for a 6 MV, C‐arm plan. For treatments using megavoltage setup fields, the dose contribution to OARs from the imaging fields can be equal or higher than the dose from treatment fields.

Treatment Planning Comparison of Volumetric Modulated Arc Therapy With Trilogy and Halcyon for Bilateral Breast Cancer 

“…Previous studies have demonstrated that Halcyon could reduce the treatment time signi cantly compared to conventional LINACs [3][4][5][6][7]. Our study proved the same results in radiotherapy for bilateral breast cancer.…”

“…Therefore, we inferred that low-dose MV CBCT was the optimal setup-eld mode. Flores-Martinez et al [6] compared four different setup-eld plans for unilateral breast cancer, in their opinion low-dose MV CBCT was the most suitable technique for patients treated on Halcyon. The result was the same as ours.…”

“…Halcyon has many differences from conventional C-arm LINACs, such as jawless, dual-layer multi-leaf collimator (MLC), faster gantry rotation and daily image guided radiotherapy (IGRT). Comparable dose distribution and excellent delivery e ciency have been shown on Halcyon in radiotherapy for head and neck, brain, unilateral breast, and cervical cancers [3][4][5][6][7]. Trilogy is a conventional C-arm LINAC with jaw and Millennium MLC.…”

Treatment planning comparison of volumetric modulated arc therapy employing a dual-layer stacked multi-leaf collimator and helical tomotherapy for cervix uteri

“…After its clinical introduction in 2017, the performance of the new radiotherapy delivery platform Halcyon (H, Varian Medical Systems, Palo Alto, USA) was investigated for a variety of different treatment indications [10][11][12][13][14][15][16][17][18][19][20]. In general, the potential performance equivalence between H and other carm delivery systems was proven for head and neck, breast, prostate [13] and brain tumours [15].…”

Two-Level Factorial Pre-TomoBreast Pilot Study of Tomotherapy and Conventional Radiotherapy in Breast Cancer: Post Hoc Utility of a Mean Absolute Dose Deviation Penalty Score

“…Conventional RT used tangential breast/chest wall and anterior axillary supraclavicular fields. 19 , 20 Additional multileaf collimator segments were allowed to optimize the planning, using the Pinnacle3 Station, collapsed cone convolution algorithm. For tomotherapy, we used the TomoTherapy treatment planning system (Hi-Art, Accuray Inc., Sunnyvale, CA) for inverse planning (dynamically penalized likelihood method-cost function).…”