Abstract Book

ESTRO 37

S601

Plan quality was evaluated by comparing the conformity index (CI), homogeneity index (HI), PTV coverage and dose to the OARs. Furthermore, scorecards are used to check if the automated plan fulfils all dose criteria. Results All automated plans offered similar PTV coverage as the original clinical plans. For 11 of the 22 automated plans, the plans were ready after Auto-Planning and an extra warm restart had been done. For the remaining 11 plans, the scorecard showed that an extra warm restart with adaption of an objective weight or value for some OAR had to be done before the plan was clinical acceptable. A typical example of the dose distribution for the original clinical (upper left panel) and automated plan (upper right panel) of a patient plan is shown in Figure 1. Plan quality of all plans were compared and the results are shown in Figure 1. The PTV coverage and CI were comparable for manual and automated plans, the homogeneity index was significantly improved. For the OARs the max dose to the spinal cord, the volume of the oesophagus V35Gy/V50Gy and V20Gy of the lung and the mean dose to heart and lung were significantly improved.

Conclusion A VMAT only technique for locoregional breast SIB irradiation was developed, which can be used with or without respiratory control and which creates very conformal and homogeneous treatment plans, with sufficient PTV coverage and a low dose to the OARs. PO-1070 Automated volumetric modulated arc therapy treatment planning for stage III NSCLC M. Kusters 1 , I. Creemers 1 , P. Van Kollenburg 1 , L. Bouwmans 1 , D. Schinagl 1 , J. Bussink 1 1 Radboud university medical center, Academic Department of Radiation Oncology, Nijmegen, The Netherlands Purpose or Objective To develop an automated volumetric modulated arc therapy (VMAT) treatment planning for stage III non-small cell lung cancer (NSCLC) patients. In this study the plan quality of 22 NSCLC patients were compared between the original manually optimized and automated VMAT plans. Material and Methods Our current protocol describes a prescription dose of 66 Gy in 33 fractions of 2 Gy at the planning target volume (PTV). Dose criteria for the organs at risk (OARs) are adapted from the QUANTEC literature. A treatment planning technique (see Table 1) has been developed that will be used clinically for NSCLC treatment planning with the Auto-Planning module in Pinnacle 9.10 (Philips Healthcare, Fitchburg, WI, USA). For the automated plans the number of beams for setup of the plans has been doubled, which gives the Auto-Planning module more room to fulfil the dose criteria.

Figure 1: Upper panels show an example of the dose distribution for the original clinical (upper left panel) and automated plan (upper right panel). In the lower panels, the plan quality is evaluated for all plans comparing the manual (light blue) with the automated plans (dark blue). In the lower left panel, the plan quality criteria for PTV are plotted and scaled (if necessary) for visualisation: V95% (divided by 100), HI (multiplied with factor 10) and CI. In the lower right panel, the dose to the OARs are shown. Abbreviations: HI = (D2% - D98%) / D50%, CI= V PTV95% 2 / (V PTV* V 95% ) Dosimetry QA for the automated plans are all within the gamma-criteria 3%/3mm. Conclusion The plan quality has been improved for the automated plans compared to the original manual optimized VMAT plans. Actual hands on time to make the plans can be reduced from 2 hours to 30 minutes. This automated planning technique can be safely introduced in the clinic. PO-1071 Dosimetric quality and delivery time of Dynamic Jaw Mode in TomoTherapy® for Breast Cancer Patients S.T. Chiu 1 , P.M. Wu 2 , K.F. Cheng 1 , P.H. Fok 1 , G. Chiu 1 1 Hong Kong Sanatorium & Hospital, Department of Radiotherapy, Happy Valley, Hong Kong SAR China 2 Hong Kong Sanatorium & Hospital, Medical Physics & Research Department, Happy Valley, Hong Kong SAR China

Table 1. Settings for the developed automated planning technique.