ESTRO 2021 Abstract Book

S1243

ESTRO 2021

each adrenal and pancreas. In 100 accrued brain mets patients with 167 brain lesions, 42 % had lung primary, 32% breast and 9% RCC. One, 3 & 5 fraction SRS was done in 61%, 15% and 24%.SRS dose was 12 Gy in 4%,13- 18Gy in 19%, 20-24Gy in 42% and 25-30Gy in 35%. Solitary mets was in 59%, up to 3 in 32% and >3 in only 9% patients. At mean follow up 58.8 wks (4-164 wk), 86 had follow up evaluation (39 patients were alive, 47 expired). Among 32 patients had recurrent brain mets, 20 underwent treatment (12 received re-SRS, 5 WBRT, 3 had surgery). In 22 patients with lung oligomets, 3 had synchronous and 19 had metachronous lung mets. Primary site was colorectal in 9, thyroid in 3, kidney 4, head neck in 2, liver in 1, endometrium in 1, pancreas in 1, sarcoma 1. Mean PTV was 21cc (range: 2.8 – 78 cc). 18–24 Gy/1fr, 45-54Gy/3fr, 35-50Gy/1fr & 48Gy/8fr in 6, 8, 5 and 1 patient respectively. Among 17 evaluable patients CR was in 76% (13/17) and PR 12% (2/17). 2 (12%) papillary carcinoma thyroid patients had progressive disease. At mean Follow up of 11 months, 7 (32%) were alive with controlled disease, 8 (36%) were alive with disease progression. 2 (9%) had local and distant failure and 10 (45%) had systemic progression. 2/3 (66%) of choroidal metastasis had CR. In liver metastasis, 8/11 (72%) had CR. In bone metastasis 10/15 (66%) had excellent symptomatic relief with radiological response. 1 Faculty of medecine University of Sfax, Radiotherapy Department CHU Habib Bourguiba Sfax Tunisia, Sfax, Tunisia; 2 Faculty of medecine University of Tunis, Radiotherapy Department CHU Habib Bourguiba Sfax Tunisia, Sfax, Tunisia Purpose or Objective The aim of our study was to evaluate the impact of COVID-19 pandemic on oncology radiotherapy residents' training. Materials and Methods An online survey with 14 questions was sent to all radiation oncology residents (ROR) (total of 25 ROR). The participants were invited to anonymously answer questions regarding 1) demographic date 2) reorganization of activity in their respective departments during the COVID-19 pandemic (from Mars to June 2020) 3) evaluation of their training before (BP) and after (AP) the pandemic declaration. The following items were evaluated with a 5-point satisfaction scale (1 = (poor training) to 5 (excellent training)): staff, multidisciplinary meeting (MM), bibliographies, courses, supervision by mentors during consultations, contouring and in scientific studies. The involvement of residents in training was self-rated on a scale of 1 to 5 (1 = lack of motivation and 5 = highly motivated). Wilcoxon test was used to compare satisfaction BP vs AP. Value of p<0.05 was considered statistically significant. Results The participation rate was 87% (20 residents). The median age was 28.65 years [27-32] with a sex-ratio of 0.25. All training levels were represented. Following the reorganization of work, 55% of ROR worked 1 day/2 and 30% 1 week/2. The staff, MM, bibliography and courses were canceled in 20%, 75 %, 70% and 95% of cases, respectively. In the other cases, these activities were reduced or realized with videoconference. Medical consultations and dosimetry scans were reduced in 65% and 75% of cases, respectively. Satisfaction with the training was significantly reduced following the pandemic for: staff (average of 3.4 BP vs. 2.3 AP; p = 0.001), MM (average of 3 AP vs. 1.25 PP ; p <0.0001), bibliography staff (average of 3.45 BP vs 1.5 AP; p = 0.001) and courses (average of 2.25 BP vs 1 AP; p = 0.003) . There was no significant difference for the supervision of mentors during consultations (2.35 BP vs. 2.15 AP), contouring (2.6 BP vs. 2.25 AP) and for carrying out scientific studies (2.15 BP vs 2 AP). About half of the residents had no motivation during the period of the epidemic for educational activities. Conclusion The initial period of the Covid-19 pandemic had a negative impact on training activities of residents in radiotherapy. The reduction observed was multifactorial: reduction in overall clinical and educational activities, lack of supervision and reduced motivation of ROR. PO-1518 Effect of bladder filling protocols on bladder volume variation in the age of adaptive radiotherapy B. Sanderson 1 , N. Joseph 2 , T. Elumalai 1 , A. Cree 3 , M. van Herk 4 , P. Hoskin 4 , A. McWilliam 4 , Y.P. Song 1 , A. Choudhury 4 1 The Christie NHS Foundation Trust, Department of Clinical Oncology, Manchester, United Kingdom; 2 Ministry of Health, Department of Clinical Oncology, Chilaw, Sri Lanka; 3 The Clatterbridge Cancer Centre NHS Foundation Trust, Department of Clinical Oncology, Birkenhead, United Kingdom; 4 The University of Manchester, Division of Cancer Sciences, Manchester, United Kingdom Purpose or Objective Drinking protocols are increasingly used in pelvic radiotherapy to optimise bladder volume reproducibility. However, there is no data to show their efficacy. This study assesses the effect of a standardised bladder filling protocol on bladder volumes during each fraction and across the radiotherapy schedule. Materials and Methods Twenty patients undergoing radiotherapy for cancers of the cervix or bladder at a tertiary centre were included. All patients were instructed to void prior to drinking 300mls of water. They were imaged using 1.5T Siemens Aera MRI scanner after 30min. Two T2 sequences were taken 20min apart. This process was repeated weekly throughout treatment. Bladders were contoured at both time points on Raystation 7R by a single oncologist. Two patients were excluded due to poor image quality. Factors affecting bladder filling were Conclusion SBRT with CK is feasible in Indian patients with small volume oligo-metastasis. PO-1517 Which impact of the COVID-19 pandemic on residents training in radiotherapy? N. Fourati 1 , D. Aissaoui 2 , F. Dhouib 1 , W. Siala 1 , W. Mnejja 1 , J. Daoud 1