Feasibility of lattice radiotherapy using proton and carbon-ion pencil beam for sinonasal malignancy

Dong Yang; Weiwei Wang; Jiyi Hu; Weixu Hu; Xiyu Zhang; Xiaodong Wu; Jiade J Lu; Lin Kong

doi:10.21037/atm-21-6631

Feasibility of lattice radiotherapy using proton and carbon-ion pencil beam for sinonasal malignancy

Ann Transl Med. 2022 Apr;10(8):467. doi: 10.21037/atm-21-6631.

Authors

Dong Yang^{1

2

3}, Weiwei Wang^{1

2

3}, Jiyi Hu^{2

3

4}, Weixu Hu^{2

3

4}, Xiyu Zhang^{1

2

3}, Xiaodong Wu^{1

2

3}, Jiade J Lu^{2

3

4}, Lin Kong^{2

3

4}

Affiliations

¹ Department of Medical Physics, Shanghai Proton and Heavy Ion Center, Fudan University Cancer Hospital, Shanghai, China.
² Shanghai Key Laboratory of Radiation Oncology (20dz2261000), Shanghai, China.
³ Shanghai Engineering Research Center of Proton and Heavy Ion Radiation Therapy, Shanghai, China.
⁴ Department of Radiation Oncology, Shanghai Proton and Heavy Ion Center, Fudan University Cancer Hospital, Shanghai, China.

Abstract

Background: Sinonasal malignancies are a treatment challenge because of their complex anatomy and close proximity to organs at risk (OARs). We aimed to investigate the feasibility of lattice radiotherapy (LRT) using pencil beam scanning (PBS) proton or carbon-ion beams in the treatment of sinonasal malignancies.

Methods: A total of 10 patients with nonoperative and bulky sinonasal adenoid cystic carcinomas (ACC) were enrolled. Spherical vertices with a 1 cm diameter and average center-to-center (c-t-c) distance of 3.51 cm were delineated within the gross tumor volumes (GTVs). The prescription doses were 15 Gy[relative biologic effectiveness (RBE)] to the vertices and 3 to 3.5 Gy(RBE) to the periphery, delivered as clinical target volume boosts (CTVboosts) in 1 fraction. Photon, proton, and carbon-ion LRT plans were generated. Peak-to-valley dose ratios (PVDRs) and the doses delivered to the vertices, the CTVboost, and OARs were compared among the 3 plans.

Results: The mean PVDR_min values for the photon, proton, and carbon-ion LRT plans were 4.78 (range, 4.34 to 5.36), 4.82 (range, 4.15 to 5.37), and 4.69 (range, 4.31 to 5.28), respectively. The mean PVDR_mean values for the same plans were 3.42 (range, 3.15 to 3.79), 2.93 (range, 2.19 to 3.74), and 3.58 (range, 3.09 to 4.68), respectively. There were no significant differences between the PVDR_min and PVDR_mean values across the 3 LRT plans. Most critical organs were better protected in the proton and carbon-ion LRT plans than in the photon LRT plans. The photon LRT plans showed the highest maximum degree (D_max) of vertices. Furthermore, these plans did not introduce more doses to the OARs compared to the 1-fraction clinical boost plan.

Conclusions: Despite minimal differences in PVDR, proton and carbon-ion LRT plans can better protect OARs than photon LRT plans.

Keywords: Lattice radiotherapy (LRT); carbon-ion; pencil beam scanning (PBS); proton; sinonasal malignancy.