ESTRO 37 Abstract book

S187

ESTRO 37

Purpose or Objective The dosimetric benefits and inferred improvement in quality of life associated with deep inspiration breath hold (DIBH) when treating breast cancer patients are documented in the literature. However there is little published about the resource requirements of DIBH in everyday practice. This project aimed to document the current practices of DIBH in Europe; how technology and protocols impact treatment duration. Filling this knowledge gap could encourage the implementation of DIBH increasing its availability to patients. Material and Methods An online survey was developed and issued to all radiation therapy centers on the continent of Europe. Technology, local practice, and protocols were analysed. Appointment duration for DIBH and non DIBH were compared to quantify resource implications. Thematic analysis was used on the patient criteria responses. Results 172 responses from 26 countries met the criteria, 129 used DIBH when treating left breast cancer. Due to heterogeneity and small sample size quantitative statistics were not possible. Patients ability to breath hold for 20 seconds was the most common patient selection criteria reported. Infrared cameras, specifically Real time Position Management™ (RPM) (Varian Medical Systems Inc., USA) was the most frequently reported method or technology used to deliver DIBH. [fig 1] Literature shows RPM can be used with a variety of planning systems, CT’s and linear accelerators; as such the decision of technology used to deliver DIBH does not appear to be limited by the respondents existing equipment. The majority of respondents reported using one CT appointment for planning, either taking DIBH only scans or both DIBH and non DIBH scan at the same appointment. Nearly half of respondents reported using audio coaching, utilising the existing intercom in the control room rather than installing additional equipment. The mean treatment appointment duration was 19 minutes 37 seconds. Stratified by technology, its impact on appointment duration was quantified. [table1] Using infrared cameras reported the shortest appointment time at 19 minutes, where additional technology was not required to deliver DIBH e.g. VM/VDIBH a similar appointment duration and standard deviation was reported. The mean duration of DIBH appointments and non DIBH appointment duration were also compared by technology type. The difference between them quantified the increase in resource requirements more clearly than comparing technology alone. [table1] Fig.1 Technology used to deliver DIBH

Conclusion There are trends in DIBH left breast cancer delivery methods across the continent of Europe. The technology chosen to deliver DIBH appears to impact the overall duration of treatment appointments irrespective of local protocols. DIBH can be clinically delivered without additional hardware and software with similar appointment duration. PV-0371 Analysis of seed loss at day of implant for I- 125 prostate brachytherapy. Can we skip the CT scan? R. Schokker 1 , W.A. Bazen 1 , J.R.N. Van der Voort van Zijp 1 , M.A. Moerland 1 1 UMC Utrecht, Department of Radiation Oncology, Utrecht, The Netherlands Purpose or Objective Iodine-125 prostate brachytherapy at our center is performed on an outpatient basis. After implantation of seeds, an intra-operative X-ray is taken to verify that all planned seeds have been inserted into the patient's prostate. Also, the used equipment is checked with a radiation survey meter to account for potential I-125 seeds that may not have been implanted into the prostate. Finally, several hours after removing the Foley catheter and before discharge of the patient a CT scan (CT) is made to assess the number of seeds within the patient’s prostate. With a CT, a patient is exposed to radiation. The ALARA principle implies critical investigation of existing procedures and strives to minimize radiation exposure to the patient. Furthermore, the current procedure is an extra workload for RTT’s as the patient has to be transferred between the ward and the CT. The purpose of this study is to analyze if the CT is necessary to account for any lost seeds prior to patient discharge. Material and Methods We assessed the data of 319 patients that were treated between January 2014 and September 2017. In total 20462 seeds were implanted. The number of seeds on X-ray should be equivalent to the number of seeds in the TPS. This was scored for each patient. Also, the number of seeds detected on the CT was scored for each patient. Differences between the number of implanted seeds on the X-ray and CT were recorded for the involved

Table.1 Mean DIBH & Non DIBH appointment durations by technology