COMPARISON OF DIAGNOSTIC AND RADIOTHERAPY PLANNING PROTOCOLS IN LUNG CANCER TREATMENT

Abstract

Purpose: The purpose of the study was to compare a standard diagnostic protocol for computed tomography imaging on a positron emission tomography scanner at the Department of Nuclear Medicine, and a radiotherapy imaging protocol for pre-planning needs in radiotherapy for lung cancer treatment, to determine the differences between these two protocols and to propose possible improvements in the dose optimisation for computed tomography imaging in a radiotherapy protocol. Methods: In this retrospective study, data were collected via the SyngoVia program and statistically analysed according to the patient dose load in computed tomography imaging in standard and radiotherapy protocols. The analysis encompassed data on a total of 56 patients in the period from 1 January 2017 to 1 December 2018. We compared data on patient dose load in computed tomography imaging in a standard protocol before and after the introduction of the improved sinogram-affirmed iterative reconstruction method (SAFIRE). Results and discussion: It was established that there are statistically significant differences in dose per patient (p<) in computed tomography imaging in standard and radiotherapy protocols. Statistically significant differences were also established in computed tomography imaging in the standard protocol before and after the introduction of the improved iterative reconstruction method (p=0,001). Dose load on the lung in computed tomography imaging was 67.5% lower in the standard protocol with the iterative reconstruction in image space (IRIS) method than in the radiotherapy protocol. The introduction of the improved SAFIRE method additionally lowered the dose per patient by 34.2% compared to the IRIS method. Conclusion: In the future, the introduction of the improved iterative reconstruction method is possible for the reconstruction of tomographic images, including for radiotherapy imaging protocol that takes into account the impact of the indirect reduction in the dose on the accuracy of the identification of tumour target volumes when planning radiation treatment for the patient. Key words: positron emission tomography with computed tomography, iterative reconstruction, dose optimization, lung cancer, radiation treatment planning