- 作者：Vijayalakshmi Kuppusamy<sup> ; sup><sup>viji_medphy@yahoo.co.in" class="auth_mail" title="E-mail the corresponding authorsup><sup> ; sup><sup>viji.medicalphysicist85@gmail.com" class="auth_mail" title="E-mail the corresponding authorsup> ; Vivekanandan Nagarajan ; Lavanya Murugan
- 关键词：Diamond SCS ; VMAT ; Heterogeneity corrections
- 刊名：Reports of Practical Oncology & Radiotherapy
- 出版年：2016
- 出版时间：September-October 2016
- 年：2016
- 卷：21
- 期：5
- 页码：473-479
- 全文大小：1174 K
sSec_2">Background
spar0010">The secondary independent monitor unit or dose calculation verifications have led to a significant increase in the workflow associated with QA treatments. Modelling, validation and commissioning are necessary steps thereby making it a useful tool for QA.
sSec_3">Materials and methods
spar0015">PTW Diamond SCS is capable of calculating VMAT fields, based on modified Clarkson integration, accounting for multi-leaf collimators (MLC) transmission and measured collimator scatter factors. Validation for heterogeneity corrections is made using circular phantom with inserts of various density materials. 150 VMAT plans were compared using (i) plans calculated in homogeneous cylindrical phantom and (ii) VMAT plans calculated with heterogeneity corrections using electron density values for each organ.
sSec_4">Results
spar0020">Diamond SCS calculated dose for homogeneous cylindrical phantom resulted in average deviation of (0.1 ± 2.14%) with Eclipse TPS calculated dose and (−2.0 ± 1.66%) with absolute measured dose. PTW's OCTAVIUS-4D phantom with 729 ion chamber detector array measurements agreed well with Eclipse TPS calculated dose showing an average deviation of (−1.69 ± 1.56%). Diamond SCS dose calculations were performed with heterogeneity corrections for 124 VMAT plans with isocentre at a region above −350 HU. The overall MU variations between Diamond SCS and TPS Acuros-XB algorithms were within ±5%.
sSec_5">Conclusion
spar0025">Hence, the Diamond SCS can be used as an additional tool along with phantom measurements for patient specific quality assurance of VMAT plans with heterogeneity corrections having isocentre at a region above −350 HU.