ESTRO 2024 - Abstract Book

S5562

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

ESTRO 2024

course. This image and two standard XVIs acquired on treatment fractions directly before and after the fraction where the Fast Chest preset was acquired were used in the study.

5 RTTs competent in IGRT and of varying experience (4-18 years) participated in the study. All study images were assessed offline. The observers were request to assess eight structures provided by the clinical Lung team (see figure 1 in results) using a visual grading assessment (VGA) analysis. Structures for each image were graded either ‘Very Clear’ and ‘Clear’, deemed clinically acceptable, or ‘Unclear’ and ‘Not Visible’, considered clinically unacceptable. The images were graded by observers according to the perceived ability to identify them on each image.

Resultant data was analysed using descriptive statistics.

Results:

8 structures from 30 XVIs were assessed by 5 RTTs. Longitudinal field of view limitations on two XVIs led to the omission of 4 structures within these XVIs from assessment. This resulted in a total of 1,140 individual structures being analysed via VGA. (760 standard Chest, 380 Fast Chest). Figure 1 shows results from the analysis where grading from both standard departmental Chest XVI presets were combined. The Fast Chest XVI achieved a greater percentage of clinically acceptable structures (85.2%) that either cohort of the standard XVI preset (80.6% and 83.8% respectively), and higher than their combined percentage (82.2%). In addition, the Fast Chest XVI scored higher than the combined standard Chest XVI preset for all individual structures in terms of clinical acceptability, although the standard Chest XVIs received a higher percentage grading very clear for primary tumour visualisation.

Figure 2 provides comparison of standard and Fast Chest XVI images side by side for illustrative purposes. A small increase in radial streak artefacts may be noted on the Fast Chest images.