Systematic and comprehensive analysis of the dose-response characteristics of a morning quality check of a linear accelerator and an important application of accelerator performance prediction

Abstract

Background: This paper aimed to analyze the output constancy of a medical linear accelerator using PTW QUICKCHECK webline and studied the sensitivity of the PTW QUICKCHECK webline . Materials and Methods: The paper statistically analyzed the output doses of 6 MV and 10 MV of photons and 6 MeV, 9 MeV, and 12 MeV of electrons from a medical linear accelerator measured before the daily treatment to assess the output stability of a medical linear accelerator. Some modifications were introduced by artificially altering the external irradiation conditions, and the percent variations from baseline values were noted. The gantry angle was changed and some deviations were established in the vertical, longitudinal and lateral directions to study the sensitivity of the PTW QUICKCHECK webline . The beam flatness, symmetry, radiation quality and output energy of 6 MV of photon energy were statistically analyzed. Results: Among the measurements, no parameters exceeded the tolerance of ±3%. QUICKCHECK webline was capable of detecting the variations in the central axis dose, flatness, symmetry and radiation quality under the testing conditions. Similar to the photon energy, electron energy measurements also confirmed that the detector was sensitive to a small variation in output introduced by the testing conditions. An important application of accelerator performance prediction in this study confirms the irreplaceable and important function of morning quality checks of a linear accelerator. Conclusions: The output dose measured before daily treatment using PTW QUICKCHECK webline to analyze the linear accelerator output constancy helps to decrease the system error, effectively reduces the errors of the accelerator system, and avoids serious mistakes.

Monitoring Linear Accelerator Output Constancy and Overall Performance Using the PTW Quickcheckwebline

“…An established daily output dose monitoring mechanism and an effective routine (daily/ weekly/ monthly) measurement system should be an essential part of radiation therapy linear accelerator system quality assurance [1,2]. Similar study have been performed elsewhere [9,10,12,14,19,20] where various dosimetric parameters of the linear accelerator were studied with the help of different daily QA equipment. Nicewonger D et.…”

“…al [12] and Jiang D. et. al [20] performed the evaluations with PTW QCw for the Varian linear accelerator while our study is performed on a Elekta Synergy linear accelerator. Even though the orientation of some of the graphs were different than that of the referenced studies [12,20], the final results expected from the daily QA equipment is in agreement with the previous studies.…”

Using KMeans Clustering to Evaluate and Alert for Deviations of Linac Photon Beam Parameters

“…Nicewonger et al, (2019) [ 9 ] found the PTW Quick check device to be a suitable tool for daily testing quantitatively and efficient solution qualitatively. D.Jiang et al, (2020) [ 3 ] observed that PTW Quick check device produced fitting linearity and reproducibility when compared with Farmer chamber. Dhoju et al, (2023) [ 10 ] concluded Beam monitorization following quality assurance protocol improves quality of the exposed beam during treatment procedure of patients.…”

“…As Binny et al, (2016) [ 2 ] correctly stated, every linac require verification to account for uncertainties in linac’s mechanical positions, focal spot position etc, in this study we can see how two beam matched units show varying parameters for the daily QA. D.Jiang et al, (2020) [ 3 ] could observe the drift in the absolute output for all energies but unable to conclude that the issue was with the monitor chamber until after 200 days of measurements and after intense analysis. A tool is hence required to not only measure the daily QA parameters but also to evaluate them and help to identify the issue if the measurement shows marked deviation.…”