Abstract Book

S190

ESTRO 37

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 individuals. Seed loss was defined as the number of seeds on CT being lower than the number of seeds on the X-ray. Results Seed loss was scored in 7 patients (2,2%) with a total of 8 seeds (0.04%) lost between X-ray and CT (see figure 1) • In 2 patients one seed was lost. In both cases the seed was not found by survey of the treatment room, the ward, or an extra survey scan of the lungs of the patient. It was concluded that the seeds migrated out of the prostate, but were still within the patient.

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

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In 1 patient, 2 seeds were found in the urine prior to discharge. These seeds were recovered. In 3 patients, 1 seed was lost according to the CT. However, in these 3 cases the lost seed was found upon reconstruction in the TPS. 1 seed was embedded within an implantation needle. This seed was overlooked on the X-ray. On CT the seed loss was detected and the seed was recovered from the implantation needle. An incident report was written and after this event each X-ray is double checked by two RTT’s (previously one). For the following 132 patients, only one seed in one patient seemed lost on CT, however this seed was found upon reconstruction in the TPS.

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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

fig 1.

Conclusion Only 8 out of 20462 implanted seeds were lost at the day of implant. In 2 cases it was concluded that seeds had migrated in the body, 6 seeds were recovered. In only one case CT contributed to seed recovery. Therefore, it was concluded that the CT scan is no longer necessary for seed counting or seed recovery and that X- ray just after implantation and careful survey before discharge of the patient are sufficient.