ESTRO 2024 - Abstract Book

S5561

RTT - Patient care, preparation, immobilisation and IGRT verification protocols

ESTRO 2024

2. S. Brown, M. Beasley, M.C. Aznar, J. Belderbos, R. Chuter, D. Cobben, C. Faivre-Finn, K. Franks, A. Henry, L. Murray, G. Price, M. van Herk, The Impact of Intra-thoracic Anatomical Changes upon the Delivery of Lung Stereotactic Ablative Radiotherapy, Clinical Oncology, Volume 33, Issue 10,2021,Pages e413-e421, https://doi.org/10.1016/j.clon.2021.04.011

3. The Royal College of Radiologists. On Target 2: updated guidance for image-guided radiotherapy. London. The Royal College of Radiologists, 2021.

4. Korpics M, Johnson P, Patel R, et al. Metal Artifact Reduction in Cone-Beam Computed Tomography for Head and Neck Radiotherapy. Technology in Cancer Research & Treatment. 2016;15(6):NP88-NP94.

1910

Digital Poster

The tortoise or the hare? Evaluation of an accelerated CBCT imaging preset in thoracic IGRT

Lydia Dearing, Dylan Collins, Mohammad Ali, Tessa Gordon, John Rodgers, Clare Triffitt

The Christie NHS Foundation Trust, Radiotherapy, MAnchester, United Kingdom

Purpose/Objective:

Modern radiotherapy increasingly focusses on daily image guidance, scanning patients prior to treatment to verify the target and OAR position.

The authors department uses Elekta linear accelerators (Elekta, Stockholm, Sweden) and for thoracic patients uses a standard imaging preset which acquires a full 360° CBCT consisting of approximately 630 projections and taking about 130 seconds to acquire.

The standard rotation speed during a CBCT scan is around half of the speed used clinically when the gantry is delivering VMAT treatment.

Increasing rotation speed results in fewer projection images but improves acquisition time. In the authors department a preset was previously designed to image thoracic DIBH lymphoma patients in breath hold where the rotation speed was doubled and acquisition time dropped to 60 seconds.

The aim of the study was to assess whether this fast thoracic XVI preset provided clinically acceptable image quality for radical thoracic patients in free breath.

Material/Methods:

This study used 30 XVI from 10 consecutive radical thoracic patients (20-33#) acquired during September 2023. Departmental practice is to image thoracic patients daily prior to treatment. Standard Chest presets were used for all treatment fractions apart from one employing a Fast Chest preset during one fraction midway through the treatment