ESTRO 2022 - Abstract Book

S1639

Abstract book

ESTRO 2022

Purpose or Objective The surface-guided radiotherapy (SGRT) VisionRT® system uses a combination of real-time optical and laser- based imaging to accurately position patients receiving radiotherapy. The aim of this study is to analyse the implementation efficiency of SGRT in four Genesis Care radiotherapy centers in Spain and to collect the RTT impressions regarding this system. Materials and Methods The system was implemented at GenesisCare facilities in Madrid, Barcelona, Alicante, and Málaga starting on August 15, 2020. Prior to this implementation, the centers were trained in a training program consisting of: A) An online course; B) A didactic weekend course; and C) Go live supervision during the first treatments for three days. The course was delivered by an expert VisionRT® trainer and a qualified radiotherapy technician. After two months of implementation, we collected the diagnostic and staging information of patients treated with the VisionRT system between the go live and October 16,2020. To evaluate the efficacy, we considered a goal of patients with SGRT in the practice: > 75% High, 75%- 50%: moderate, < 50%: low. Tattoo base method set up was allow for head and neck immobilization, skin cancer or clinician discretion. A questionnaire was carried out to the RTT working in these centers. The questionnaire contained a 1-5 satisfaction scale asking about the SGRT system: 1. very poor; 2. poor; 3. fair; 4. good; or 5. very good regarding six points. These were safety (patient ID recognition), set up (precision increase, time reduction), management (no covid contact), confidence (technique), improvement (daily practice), and patient satisfaction (RTT point of view). Results 93.4 % of the patients in these four centers were positioned under SGRT conditions, and 6.6 % were positioned with a tattoo-based method. OF the total of 295 patients with SGRT, 212 of them were positioned without tattoos. The evaluated patients have breast cancer (43.0%), prostate cancer (18.6%), metastatic cancer (8.1 %) or lung cancer (5.4%). 21 RTT responded to the questionnaire. Results are as follows: 1. Safety: 61.9% very good and 38.1% good; 2. Set-up: 61.9% very good, 28.6% good, and 9.5% moderate; 3. Accuracy increase: 42.8% very good, 19% good, 28.6% fair, 4.8% poo,r and 4.8% very poor; 4. Management (contactless COVID): 47.6% very good, 14.3% good, 23.8% fair, and 14.3% poor; 5. Confidence (real time): 9.6% very good, 47.6% good, 33.2% fair, and 9.6% poor; 5. Improvement: 52.4% very good, 23.8% good, 23.8% fair; 6. Patient satisfaction with tattoo less from the technician point of view: 90.4% very good, 4.8% good, and 4.8% moderate. Conclusion The implementation of SGRT was carried out with high efficiency considering that 93,4% of care were delivered with this technique. RTT consider this technique very good for safety, accuracy, confidence, and improvement in the daily practice. Purpose or Objective The main objective of this study was to compare two patient immobilisation devices in lung Stereotactic Body Radiation Therapy (SBRT): one based on a patient-customized body cushion and dedicated to SBRT and the other based on a simple arm support. Materials and Methods Twenty patients treated for early-stage lung cancer with SBRT were included in the study. Ten patients were installed in supine position with arms above their head in a Vacuum Cushion (VC) dedicated to SBRT (Bluebag, Elekta). Ten other patients were positioned with a simple support device consisting in an arm support (AS) (Posirest®, CIVCO). For each fraction, all patients had a pre-treatment 4-dimensional cone-beam computed tomography (4D-CBCT) and a post-treatment 3D-CBCT to compare positioning accuracy and immobilisation quality. For both CBCT, a first rigid registration with the planning CT was performed on the spine at the level of the target. Translations and rotations were reported. Treatment time, age, Performance Status (PS) and Body Mass Index (BMI) were also reported. Results The median number of fractions per treatment was 5 (range 3-10). Position deviations (translations and rotations) from 112 4D-CBCT pre-treatment and 111 3D CBCT post-treatment were estimated. Mean inter fraction errors were similar between both installations: in vertical and lateral direction, deviations were less than 1.2mm and inferior or equal to 1.1° in rotation. For longitudinal translations, mean inter-fraction errors were 1mm with VC and -4.0mm with AS For the patients installed with VC, mean vertical, longitudinal and lateral intra-fraction errors, were 0.0mm, -0.2mm and -0.3mm respectively (SD 1.0, 1.5 and 1.8mm respectively). For the arm with AS, mean vertical, longitudinal and lateral intra-fraction errors were -0.2mm, -0.8mm and 0.1mm respectively (SD 2.3mm, 2.7mm and 2mm respectively). The time between the pre-treatment 4D-CBCT and the post-treatment 3D-CBCT was 14.3min and 15min for VC and AS installation respectively. No correlation between age, PS or BMI and immobilisation accuracy was found. Conclusion Our results were consistent with the literature. The use of a simple arm support allowed a intra fraction positioning error < 1 mm compatible with lung SBRT considering a GTV to PTV margin of 5mm. PO-1847 Comparative study of two patient immobilisation devices for lung stereotactic body radiation therapy S. Boisbouvier 1 , I. Martel Lafay 1 , M. Zahra Ayadi 1 1 Centre Léon Bérard, Radiotherapy, Lyon, France