Abstract
IntroductionDue to its spherical surface, scalp angiosarcoma requires careful consideration for radiation therapy planning and dose delivery. Herein, we investigated whether volumetric modulated arc therapy (VMAT) is superior to intensity modulated radiation therapy (IMRT) in terms of the plan quality and delivery time.MethodsThree different coplanar treatment plans were created for four patients, comprising a two‐arc VMAT plan as well as 5‐field and 9‐field IMRT plans with 6 MV beams. The X‐ray Voxel Monte Carlo algorithm was employed for dose calculation. A radiation therapy dose of 60 Gy was prescribed to the planning target volume (PTV) in 30 fractions. The homogeneity indexes (HIs) and conformity indexes (CIs) of the PTV, organs at risk (OARs) doses and delivery times were calculated and compared.ResultsFor the VMAT, 5‐field and 9‐field IMRT plans, the mean HIs were 0.14, 0.16 and 0.15; CIs100% were 0.63, 0.61 and 0.64; CIs98% were 0.72, 0.66 and 0.70 and CIs95% were 0.74, 0.67 and 0.71 respectively. All mean dose parameters of the VMAT and 9‐field IMRT plans for the brain were equal to or lower than those of the 5‐field IMRT plan. For the 5‐field IMRT plan, the dose constraints for the left lens were not satisfied in two patients. The mean delivery times were 3.3, 11.1 and 14.7 min for the VMAT, 5‐field and 9‐field IMRT plans respectively.ConclusionThe VMAT plan quality is comparable to that of 9‐field IMRT, with a reduced delivery time. Therefore, VMAT represents a valuable, sophisticated irradiation technique for treating scalp angiosarcoma.
Highlights
Due to its spherical surface, scalp angiosarcoma requires careful consideration for radiation therapy planning and dose delivery
The lateral photon–electron (LPE) technique was performed for the treatment of scalp angiosarcoma especially if lesions are located over the whole scalp
The purpose of this study was to validate the advantages of volumetric modulated arc therapy (VMAT) over intensity modulated radiation therapy (IMRT) for the treatment of scalp angiosarcoma in terms of plan quality, delivery time and monitor units (MUs) by employing the X-ray Voxel Monte Carlo (XVMC) algorithm in four patients with varying sites and target volumes
Summary
Due to its spherical surface, scalp angiosarcoma requires careful consideration for radiation therapy planning and dose delivery. The mean delivery times were 3.3, 11.1 and 14.7 min for the VMAT, 5-field and 9-field IMRT plans respectively. Radiation therapy is commonly performed as an alternative treatment modality in such cases.[1,2] The goal of irradiation for scalp angiosarcoma is to deliver a high, uniform dose to the target while sparing organs at risk (OARs) such as the brain and optical structures. The irregular shape of the target on the spherical scalp surface requires careful consideration for radiation therapy planning and dose delivery.[3].
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