ESTRO 36 Abstract Book

S970 ESTRO 36 _______________________________________________________________________________________________

Datta 6 , S. Sinha 7 , S. Chatterjee 2 1 Tata medical center, Radiotherapy, Kolkata, India 2 Tata medical center, Radiation Oncology, Kolkata, India 3 Tata medical center, Oncopathology, Kolkata, India 4 Tata medical center, Breast Surgery, Kolkata, India 5 Tata medical center, Nuclear Medicine, Kolkata, India 6 Tata medical center, Psycho-Oncology, Kolkata, India 7 Tata medical center, Statistics, Kolkata, India Purpose or Objective There are no standard palliative breast radiotherapy regimens for local control but many use the dose equivalent as in the adjuvant setting (40Gy/15 fractions). Within HYPORT study we are exploring a dose of 35 Gy in 10 fractions over 2 weeks prescribed to the breast and supraclavicular fossa (SCF) to palliate advanced incurable breast cancers Material and Methods A gafchromic RTQA2 film based matching of the junction of tangents and Supraclavicular (SCF) fields (JF) is being carried out to assess the geographical overlap or separation during first 3 fractions. Similarly during the first 3 fractions, in-vivo thermo luminescent dosimetry (TLD) is being performed to confirm received dose by placing a TLD over isocenter of the tangential fields and another at JF. Primary objective for the study has been set to assess the acute toxicity using CTCAE version 4 in 30 total patients Results Of the required 30 patients, 19 have been recruited. Median dose planned to receive by 95% volume of the breast PTV was 96.3% (range=95.2-98.9%). The median dose max planned to the breast PTV was 106.4% (range=105.4-106.9%). Breast PTV receiving ≥105% of the prescribed dose was planned to be 1.75% (median) with no point dose ≥107%. Organ at risks (OAR) dose constraints were met for all patients. The junction movement range using gafchromic RTQA2 film was between -2mm to +3mm. TLD measured dose (median) and percentage variation of tangential field isocenter dose and field junction dose for first three fractions is summarized in table 1. Median percentage variation for tangential field isocenter dose as measured using TLD was 3 % (Range = -9.7 to 9.4%) and similarly median percentage dose variation for JF as measured with TLD was 1.2 %( Range= -8.5 to 8.9%). At a median follow up of 5 months only 1patient reported grade 2 acute skin toxicity (others had grade 1). None of the patients complained of dysphagia or acute brachial plexopthy Conclusion QA measures in the HYPORT study confirm the delivery of the prescribed two week dose schedule with no significant over dosage at the JF. A dose of 35Gy is well tolerated EP-1764 Implementation of a patient specific QA in- vivo dosimetry protocol using the PerFRACTION 3D system F. Vinagre 1 , P. Rachinhas 1 , P. Simões 1 , A. Cavaco 1 , F. Balau 1 , M. Borrego 1 1 Centro Hospitalar e Universitário de Coimbra, Department of Radiotherapy, Coimbra, Portugal Purpose or Objective The goal of this presentation is to share the experience in implementing an EPID-based in-vivo dosimetry system PerFRACTION™ 3D (PF) from Sun Nuclear Corporation in our center. The results for approximately 50 patients treated with VMAT and IMRT plans in a Truebeam 2.5, Varian Medical Systems, included in a in-vivo dosimetry protocol in clinical routine, are presented and discussed. Material and Methods About fifty patients treated with a VMAT/IMRT technique were included in this study. In the first 3 fractions of

demand). MR acquisition was also designed to allow for collection of data needed for CT+MR as well MR-only (or synthetic CT) workflows. This is expected to facilitate access to the in-house adaptive RT implementation in RayStation (RaySearch, Stockholm, Sweden). All MR image data was validated for RT use by means of comprehensive testing for global image quality and correction of spatial distortions. In particular for liver, the management of motion was adapted for the MR environment in the case of potential subjects undergoing either breathhold or abdominal compression (AC). Breathhold was evaluated using Medspira (Minneapolis, MN) whereas AC was implemented using pneumatic pressure belts. Staff requirements and safety for in-room operations was evaluated via simulations and dry runs. Conclusion Workflows for MR guidance in prostate and liver were designed and preliminary tested. The next step is to enable imaging-only clinical trials in patients. Based on feedback the workflows will be refined to allow for the full implementation of MR-guidance studies. EP-1762 A Comparative Study of 4D and 3D CTSimulation in Esophageal Carcinoma J. Li 1 , G. Lai 1 1 Fujian Cancer Hospital, radiation oncology, Fuzhou- Fujian, China Purpose or Objective To compare the internal gross target volume (IGTV) and its displacement of primary esophageal carcinoma (EPC) on the base offour-dimensionaland three-dimensional computed tomography (4D-CT and 3D-CT) simulation technology. Material and Methods Twenty-two esophageal cancerpatients with pathological proved diagnosiswererecruited in this prospectively study. Every patient sequentially received contrast enhancement free-breathing 3D-CT and respiration-synchronized4D-CT simulationchest.Then the target volume and the displacement on three orthogonal directionsof three different IGTV planningmethods (including IGTV 4D, IGTV 4D' and IGTV 3D . The dice similarity coefficient (DSC) and overlap index (OI) between IGTV 4D and IGTV 4D' , between IGTV 4D and IGTV 3D for different segments of esophagus were calculated. Statistical analysis included theFriedman test, analysis of variance on the base of repeated measurement data and paired-samples student t test and the P <0.05 was set as statistically significant. Results There were statistical significance of displacement at left- right, anterior-posterior, and superior-inferior directions of primary esophageal tumor GTV of the ten phases originated from medium-thoractic segments and medium- lower-thoractic segments ( P = 0.005 and P = 0.001). There presented a significant differences of primary tumor volume where appeared IGTV 3D > IGTV 4D > IGTV 4D' ( P <0.05).In other words, the implementation of GTV by means of extending position error from based of 3D-CT wouldlead to unnecessary radiation of the surrounding normal tissues (about 9~24%); However, the application of GTV only by means of integrating end-inhalation and end-exhalation phases would result in uncover target area (about 10~34%). Conclusion 4D-CT simulation technology is superior to 3D-CT simulation technologyfor IMRT in esophageal cancer. EP-1763 Acute toxicity and in-vivo dosimetry of a two week hypofractionated schedule within the HYPORT study A. Saha 1 , G. Goswami 2 , S. Mandal 2 , A. Mahata 2 , D. Midha 3 , R. Ahmed 4 , S. Agarwal 4 , S. Ray 5 , J. Das 5 , S.S.