Abstract book - ESTRO meets Asia

S12 ESTRO meets Asia 2018

displayed for Linac-3DCRT, TomoHelical, TomoDirect- 3DCRT and TomoDirect-IMRT plans.

the mean heart dose with FB was, 1.89 Gy; range (0.74 and 2.94 Gy). Mean heart dose variation is 40.74%. Average Ipsilateral Lung mean dose with DIBH was, 7.69 Gy; range, (6.20 to 10.40 Gy). The average value of the Ipsilateral Lung dose with FB was , 8.09 Gy; range (6.55 to 10.35 Gy). Mean ipsilateral lung dose variation is 4.94%.

Conclusion Dose deviations caused by the interplay effects of respiratory motion during FB have significant impact. DIBH significantly reduced cardiac and ipsilateral lung dose. Hence such techniques should be increasingly used in clinical practice in order to get improved clinical outcomes and a decrease in treatment-related morbidity for left-sided breast cancer patients. PV-029 Analysis of 6MV FB versus 6MV UF photon beam treatment planning and delivery by IMRT technique T. Suresh 1 , S. Madeswaran 2 , Y. Girigesh 1 , S. Kothanda Raman 1 , G. Munish 1 , D. Abhinav 1 1 Rajiv Gandhi Cancer Institute & Research Centre, Radiotherapy, Delhi, India 2 VIT University, Physics, Vellore, India Purpose or Objective Evaluation of potential benefit of 6MV photon unflattened beam (UFB) over conventional 6MV flattened beam (FB) in fixed field intensity-modulated radiation therapy (IMRT) in different anatomic sites. Material and Methods Retrospectively 40 patients were selected, for each diagnosis 10 cases were selected. The cases were ca.supraglootic larynx, ca. upper thoracic oesophagus, ca. left breast and ca. cervix. All patients were immobilized in supine position. Thermoplastic sheet was used for immobilization. CT slices were taken at 3-mm slice intervals. Target volumes (TV) and OAR’s were delineated respective slices. All the patient planning were performed on Varian Eclipse External planning system, dose calculation was performed on anisotropic analytical algorithm, and the equipment selected was True beam Linear Accelerator inbuilt with high definition 120 multileaf-collimator. Doses were prescribed to achieve 95% target volumes (TV) to 100% prescription dose. 6MV FB and 6MV UFB IMRT plans were generated for all patients. From the cumulative dose volume histogram, TV coverage, homogeneity index, conformity indexes, OAR dose were computed. Treatment monitor units, Beam On time , mean body non-tumour tissues integral dose and low dose volume of 1Gy, 2Gy, 3Gy, 4Gy and 5Gy on normal tissue were noted. Results The outcome results from our study shown that 6MV UF beam also generate plan almost similar to 6MV FB in IMRT modality in terms of target coverage, homogeneity index, conformity index, and dose to OAR’s. Statistically significant p value (<0.05) were found in treatment MU, Beam ON time (BOT), mean body NTID and non-tumor tissue low dose volumes. All the cases the delivered MU per fraction was found to be less in 6MV FB IMRT plan and Abstract withdrawn

Figure 2 . Average D mean

(Gy) for organs-at-risk. Average

D mean for 2 female patients is shown for breasts, ovaries, for 3 male patients is shown for testes. For other organs, average from 5 patients is shown. Conclusion TomoDirect treatments have the potential to better spare laterally-situated OARs, lower NTID and shorten long treatment times of TomoHelical radiotherapy. It effectively reduces PTV inhomogeneity, increases conformity, and better spares all OARs compared with Linac-3DCRT. Therefore, TomoDirect radiotherapy may be considered as a CSI treatment alternative to TomoHelical radiotherapy and in place of Linac-3DCRT. PV-028 Free Breathing versus Deep Inspiration Breath-Hold OAR Doses in Breast Cancer P. Gamre 1 , K. Chauhan 2 , U. Gaikwad 1 , R. Phurailatpam 2 , T. Wadasadawala 1 , R. Sarin 1 1 Advanced Centre for Treatment- Research and Educatio n in Cancer- Mumbai, Radiation Oncology, Mumbai, India 2 Advanced Centre for Treatment- Research and Educatio n in Cancer- Mumbai, Medical Physics, Mumbai, India Purpose or Objective Aim: To quantify benefit of deep inspiration breath-hold (DIBH) in terms of Organ at risk (OAR) sparing as compared to free-breathing (FB) in women receiving adjuvant radiotherapy (RT) for breast cancer. Materials and Methods: Ten patients with left-sided breast cancer previously treated with DIBH technique were included in this dosimetric study. These comprised of six women with conserved breast and four women with mastectomy. All women underwent training for breath hold exercises at least one week prior to RT simulation. Consistency of breath hold and adequate breath hold time was ensured. Computed tomography scans for RT planning were acquired in supine position on an inclined board with both arms above head. Both FB and DIBH scans were acquired using Varian RPM system (version 1.7.5). Both the series were transferred to the Eclipse treatment planning system (ARIA version 13.5) for generation of plans on FB as well as DIBH scans. Six women were treated with Mono isocentric technique (MIT) and four with dual isocentric technique (DIT). Breast/chest wall was treated with bitangential technique and supraclavicualr fossa with single anterior portal. The prescription was 40 Gy at 2.66 Gy per fraction in 15 fractions. Results Dosimetric differences between DIBH and FB scans were considerable. Average heart mean dose with DIBH was, 1.12 Gy; range, (0.65 to 1.65 Gy). The average value of and uterus. Average D mean