ESTRO 2022 - Abstract Book

S797

Abstract book

ESTRO 2022

Results Concerning image quality, the SNR of the phantom only setup was 248 and decreased to 106 under the influence of the device. Yet, this shows a drastic improvement over the previous generation of this device, which had an SNR of 15 due to the requirement of off-center phantom placement. Regarding heating ability, temperature increase in the target ROI was on average 6°C in 10 minutes. Temperature standard deviation was 0.32°C, showing the heating stability of the MR- compatible device. Comparison of all central target measurements yielded a median gamma index of 95%, for a criterion of 5%/5mm. Conclusion This study showed that image quality with the new device increased by a factor of seven compared to the older generation. Ability of heating in terms of temperature increase followed quality assurance guidelines. Since no specific commissioning tests are defined in the literature, these tests and results may be used as a first assessment to standardize the commissioning of MR-compatible devices.

Poster Discussion: 22: Gynaecological

PD-0903 Coverage probability planning is safe for simultaneously integrated boost of lymph nodes in c.vulva

S. Mohamed 1 , M.S. Assenholt 2 , L. Fokdal 3 , J. Kallehauge 4 , J.C. Lindegaard 3 , K. Tanderup 5

1 Cairo University, NCI, Department of Radiation Oncology, Cairo, Egypt; 2 Aarhus University Hospital, Department of Medical Physics, Aarhus, Denmark; 3 Aarhus University Hospital, Department of Oncology, Aarhus, Denmark; 4 Danish Centre of particle therapy, Medical physics, Aarhus, Denmark; 5 Aarhus University, Institute of Clinical Medicine, Aarhus, Denmark Purpose or Objective Pathological inguinal lymph nodes (PILN) are found in >50% of patients with vulvar cancer referred for radiotherapy (RT). Strategies for minimizing irradiation of organs at risk (OAR) from PILN boosting are needed to minimize the risk of morbidity arising in the groin such as lymphedema. Coverage probability (CovP) is a new planning strategy for simultaneous integrated boost (SIB). CovP mirrors the probabilities of nodal movement and regression during irradiation with a slight overdose in