ESTRO 2024 - Abstract Book

S1182

Clinical - Head & neck

ESTRO 2024

68

Digital Poster

Dosimetric Comparison of Three Radiotherapy Techniques for Graves' ophthalmopathy

Xiaopeng Zhu, Zhe Zhang, Feng Peng, Yajie Liu

Peking University Shenzhen Hospital, Department of Radiation Oncology, Shenzhen, China

Purpose/Objective:

To evaluate the dosimetric parameters of three different radiotherapy plannings: HyperArc (HA), Volumetric modulated arc therapy (VMAT) and Intensity-modulated radiation therapy (IMRT) for patients with Graves' Ophthalmopathy (GO), providing a reference for the clinical selection of radiotherapy techniques for GO.

Material/Methods:

8 patients diagnosed with GO were recruited in this study. HyperArc plan, VMAT plan and IMRT plan were designed for each patient. Dosimetric parameters of the targets and organs at risk (OARs) originated from the three kinds of plans were compared and analyzed.

Results:

Compared with VMAT and IMRT plans, the PTV in the HyperArc plan has a higher CI index (HA VS VMAT, p=0.036; HA VS IMRT, p=0.009) and HI index (HA VS VMAT, p=0.027; HA VS IMRT, p=0.001), a lower GI index (HA VS VMAT, p=0.030; HA VS IMRT, p=0.000), and reduced doses to the optic chiasm (HA VS VMAT, p=0.000; HA VS IMRT, p=0.000) and maximum dose to the brainstem (HA VS VMAT, p=0.003; HA VS IMRT, p=0.002). The doses to the lens and brain are comparable to those in VMAT and IMRT (p>0.05). The dose to the eyeball is slightly increased (Left eye: HA VS VMAT, p=0.106; HA VS IMRT, p=0.008. Right eye: HA VS VMAT, p=0.005; HA VS IMRT, p=0.000).

Conclusion:

For radiotherapy of GO, HA, VMAT, and IMRT are all feasible radiotherapy techniques. Compared with VMAT and IMRT, HA has better target distribution and conformity, uniformity and dose gradient, and better protection of the optic chiasm and brainstem. HA can be used as a preferred technology for GO radiotherapy.

Keywords: Graves' Ophthalmopathy; Radiotherapy; HyperArc