ESTRO 38 Abstract book

S872 ESTRO 38

This analysis reports our initial experience with amplitude-gated DIBH technique for SBRT in patients with oligometastases treated on an institutional review board approved prospective protocol. Material and Methods Between 2016 and 2018, 21 consecutive patients with oligometastatic disease to lung and liver were treated with SBRT utilizing amplitude-gated DIBH technique and were included in this analysis. After being coached for 3- 4 days to achieve a reproducible breath hold in terms of amplitude and duration, simulation CT scans and orthogonal fluoroscopy images were acquired in free breathing and DIBH phases. The gated amplitude was set at +/- 2mm from the recorded baseline DIBH pattern. Target delineation and plan evaluation was performed in accordance with the ongoing RTOG BR001 protocol. Treatment planning was performed with co-planar 6MV FFF 2-3 Arc VMAT technique on Eclipse v13.5. The dose was escalated in consecutive patients from BED 10 of 75 Gy 10 up to 132 Gy 10 . Patient-specific pre-treatment QA was performed for all patients. Pre- and intra-treatment positioning verification was performed with DIBH CBCT for all patients for each treatment fraction and corrected on a 6D treatment couch. The primary endpoints of the analysis were local control (LC) and time to local progression (TTLP). Results Results: A total of 21 metastatic sites were treated, with 90.6% sites being located in lung and liver. 1 year LC rate was 88.9% (± 2 SD = 0.148) and mean TTLP was 16.8 months (95% CI = 15.5 to 18 months). The median overall survival was 16.0 months (95% CI: 15.1 to 16.8 months). Breath- hold duration across all patients varied from 25 to 45 seconds. Maximum measured tumor motion during fluoroscopy in free breathing varied from 8-15 mm (Mean, 95% CI = 10.5 mm, 9.3 to 11.8 mm) and in DIBH it reduced to 1-2 mm (Mean, 95% CI = 1.7 mm, 1.6 to 2 mm), which permitted a reduction in PTV margins from 5mm to 3mm. DIBH CBCT acquisition was time-consuming, as it required two consecutive breath-holds within a short duration. We noted a significant degradation in image quality with three consecutive breath-holds or two breath-holds with a long gap in between. The Dose Gradient Index for all DIBH SBRT plans varied from 0.73 to 1.49 cm (Mean, 95% CI = 0.998, 0.883 to 1.112 mm). Total MU’s varied from 1794 to 4765 (Mean, 95% CI = 3168 MU, 2651 to 3685 MU), with beam-on time varying from 120 to 537 seconds (Mean, 95% CI = 334 sec, 263 to 407 sec). Implementation time for the first treatment session (including imaging and verification) varied from 693 to 2488 seconds (Mean, 95% CI = 1464 sec, 1184 to 1744 sec). Conclusion Conclusions: Amplitude-gated DIBH technique for SBRT in oligometastatic disease yielded equivalent results to reports previously published in the literature. Reduced target motion with DIBH resulted in reduction of PTV margins. The main limitation of this technique is long patient-on-table time, which is directly dependent on the patient’s breath-hold duration. EP-1619 SBRT and the treatment of adrenal gland metastasis D. Georgiev 1 , N. Gesheva-Atanasova 1 , S. Lalova 1 , A. Balabanova 1 , I. Mihaylova 1 , B. Antonov 1 , K. Ormankova 1 1 National Oncological Center Hospital, Radiotherapy, Sofia, Bulgaria Purpose or Objective The purpose of the study is to evaluate our experience in the use of stereotactic body radiation therapy (SBRT) for treatment of adrenal glands metastasis and in particular the dosimetry planning, clinical outcomes and toxicity. Material and Methods From 6/2016 to 6/2018, 8 patients were treated with 10 lesions of the adrenal gland - 7 of the lesions were located

Purpose or Objective To evaluate the results of palliative radiotherapy for lung cancer with prospective assessment of quality of life (QoL). Material and Methods The study group comprises 162 patients with lung cancer undergoing palliative radiotherapy in 2014-2016. The mean patients’ age was 66 years (46-89 years). There were 43 female (27%) and 27 male (73%) patients. A total of 115 patients (71%) were in a good performance status ZUBROD 0-1, whereas the rest was in a poor general condition: 36 (22%) ZUBROD-2 and 11 patients (7%) ZUBROD-3. Stage IIIA was diagnosed in 27 patients (17%), Stage IIIB in 17 (10%) and stage IV in 40 patients (73%). Radiotherapy was performed with 6 or 20 MV photons, using 2D technique and two opposed AP-PA fields in 131 patients (81%), whereas 3DCRT technique with 3- or 4- fields was utilized in remaining patients. The radiation schedules were as follows: 20 Gy with 4 Gy per fraction- 96 patients (59%), 20-30 Gy with 2 Gy per fraction- 34 patients (21%), 30 Gy with 3 Gy per fraction- 27 patients (17%) and 5 patients did not completed the planned RT. The prospective evaluation was based on QLQC30, RSCL and Pain questionnaires filled by each patient before, at the completion of radiotherapy and 3-4 months post- treatment. In this study the evaluation of changes of pain intensity (NRS scale 0-10), global QoL (scored 0-100) and dyspnea was performed. With NRS scale- the higher point means more pronounced pain. With general QoL scale the higher point means better QoL. The intensity of dyspnea is scored on a 4-point scale (never, sometimes, often, very often), with higher score meaning more pronounced symptom. The comparison was performed with non-parametric Wilcoxon test. Results The mean intensity of pain before treatment was 3.3 points. At the completion of radiotherapy it was 5.7 points. At the last measurement 3-4 months post- treatment it was 2.8 points. The differences with respect to the pre-treatment value were significant (p=0.0002 and p=0.009). The mean global QoL was scored 56 points before treatment. At the completion of radiotherapy it was 35 points, at the last measurement 3-4 months post- treatment it was 62 points. The differences as compared to the pre-treatment value were significant (p=0.000 and p=0.000). The mean dyspnea score before radiotherapy was 2.4 points. At the completion of radiotherapy it was 3.3 points, at the last measurement 3-4 months post- treatment it was 2.3 points. The difference between pre- treatment and post-treatment value was significant, and there was a trend to improvement between pre-treatment and 3-4 month post-treatment value (p=0.000 and p=0.06). Conclusion Shortly after palliative radiotherapy for lung cancer a decrease in general status and increase in existing symptoms may be expected. At longer follow-up an improvement as compared to the pre-treatment status is reported. Patients with expected survival of at least 3-4 months seem to benefit from palliative radiotherapy. EP-1618 Early clinical results and feasibility of amplitude-gated DIBH for SBRT: A multi-centre experience K. Chufal 1 , I. Ahmed 1 , C.P. Bhatt 2 , R. Chowdhary 1 , R. Singh 1 , A. Pahuja 1 1 Rajiv Gandhi Cancer Institute & Research Centre, Radiation Oncology, Delhi, India ; 2 Sarvodaya Hospital & Research Centre, Department of Radiation Oncology, Faridabad, India

Purpose or Objective