A method of determining the prescription isodose line for stereotactic radiotherapy VMAT plan / 中华放射医学与防护杂志
Chinese Journal of Radiological Medicine and Protection
;
(12): 477-480, 2020.
Artigo
em Chinês
| WPRIM
| ID: wpr-868459
ABSTRACT
Objective:
To establish a method of determining the prescription isodose line for steretactic radiotherapy (SRT) volumetric modulated arc radiotherapy (VMAT) plan.Methods:
Eight patients with brain metastases treated with SRT were enrolled. The volume of planning target volume (PTV) ranged from 3.5 to 11.7 cm 3 (median 6.1 cm 3). Reference VMAT plans were designed for each patient with identical prescription dose. Then, the original PTV was contracted by a few millimeters to form a new target for optimization to get plans with different IDLs. The minimum margin which was needed to be contracted to achieve optimal IDL range for each PTV was also studied.Results:
To achieve the optimal IDL range, 4 or 5 mm PTV contraction was needed for all patients, and the average IDL was (66.05±0.02)%. Compared with reference plans, the average gradient index (GI) of optimal IDL plans decreased by 20% from 4.05±0.39 to 3.37±0.24 ( Z=-2.521, P<0.05). The V40, V30, V5 and mean dose in normal brain tissue decreased by 11.5% ( Z=-1.973, P<0.05), 7.2% ( Z=-2.105, P<0.05), 12.8% ( Z=-2.521, P<0.05) and 8.1%, respectively ( Z=-2.382, P<0.05), and there was no statistically significant difference with V20, V10 and conformity index ( P>0.05).Conclusions:
The optimization of IDL for SRT-VMAT plan can be achieved with the method of contracting PTV to form new target for planning. 4 or 5 mm is needed to be contracted to achieve the optimal IDL range, and to get lower GI and protect the normal brain tissue.
Texto completo:
DisponíveL
Índice:
WPRIM (Pacífico Ocidental)
Idioma:
Chinês
Revista:
Chinese Journal of Radiological Medicine and Protection
Ano de publicação:
2020
Tipo de documento:
Artigo
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