Clinical implementation of Dosimetry Check™ for TomoTherapy^® delivery quality assurance

Abstract

PurposeThe delivery quality assurance (DQA) of intensity‐modulated radiotherapy (IMRT) plans is a prerequisite for ensuring patient treatments. This work investigated the clinical usefulness of a new DQA system, Dosimetry Check™(DC), on TomoTherapy®‐based helical IMRT plans.MethodsThe DQA was performed for 15 different TomoTherapy®‐based clinical treatment plans. In Tomotherapy® machines, the couch position was set to a height of 400 mm and the treatment plans were delivered using QA‐Treatment mode. For each treatment plan, the plan data and measured beam fluence were transferred to a DC‐installed computer. Then, DC reconstructed the three‐dimensional (3D) dose distribution to the CT images of the patient. The reconstructed dose distribution was compared with that of the original plan in terms of absolute dose, two‐dimensional (2D) planes and 3D volume. The DQA results were compared with those performed by a conventional method using the cheese phantom with ion chamber and radiochromic film.ResultsFor 14 out of the 15 treatment plans, the absolute dose difference between the measurement and calculation was less than 3% and the gamma pass rate with the 3%/3 mm gamma evaluation criteria was greater than 95% for both DQA methods. The P‐value calculated using Wilcoxon signed‐rank test was 0.256, which implies no statistically significance in determining the absolute dose difference between the two methods. For one treatment plan generated using the 5.0 cm field width, the absolute dose difference was greater than 3% and the gamma pass rate was less than 95% with DC, while the DQA result with the cheese phantom method passed our TomoTherapy® DQA tolerance.ConclusionWe have clinically implemented DC for the DQA of TomoTherapy®‐based helical IMRT treatment plans. DC carried out the accurate DQA results as performed with the conventional cheese phantom method. This new DQA system provided more information in verifying the dose delivery to patients, while simplifying the DQA process.

Evaluation of Delivery Analysis to Detect Intrafractional Motion during Tomotherapy

“…This in-treatment assessment confirms the variation from the first reference sinogram. Additionally, a system is also being developed to calculate and evaluate the dose distribution in the body using in vivo calculated images that have been generated [24]. In this software, the sinogram is deconvoluted by a kernel specifically adapted to the MVCT detector to obtain the corresponding primary treatment fluence map.…”

Leaf open time sinogram (LOTS): a novel approach for patient specific quality assurance of total marrow irradiation

“…The feasibility of using MVCT measured LOTS to reconstruct 3D dose distribution on to patient CT datasets have been reported by several authors either by using in-build or independent dose reconstruction algorithm in routine clinical cases [13][14][15][16][17][18][19]21]. The excellent agreement both in absolute dose (< ± 1.8%), 2Dγ (> 97%), 3Dγ (> 96%) and 2Dγ vs 3Dγ variation (≤ 2.5%) between reconstructed dose from LOTS as compared to planned, ion chamber and ArcCHECK measurement, in all ten non-TMI patients validated the accuracy and reliability of LOTS reconstructed method in Delivery Analysis against the standard methods.…”

“…The unique design of megavoltage cone beam computed tomography (MVCT) detectors in HT allows measurement of delivered sinogram (dose fluence) prior to or during treatment. Several studies have reported the feasibility of using measured sinogram to reconstruct 3D dose distribution on to the patient CT datasets using in-build or independent dose reconstruction algorithm in routine clinical cases [13][14][15][16][17][18][19]. To the best of our knowledge, no study has been conducted to provide an accurate and yet efficient PSQA of TBI/TMI/ TMLI patients treated on HT.…”

Leaf Open Time Sinogram (LOTS): A novel approach for Patient specific quality assurance of Total marrow irradiation

“…The unique design of megavoltage cone beam computed tomography (MVCT) detectors in HT allows measurement of delivered sinogram (dose uence) prior to or during treatment. Several studies have reported the feasibility of using measured sinogram to reconstruct 3D dose distribution on to the patient CT datasets using in-build or independent dose reconstruction algorithm in routine clinical cases [13][14][15][16][17][18][19]. To the best of our knowledge, no study has been conducted to provide an accurate and yet e cient PSQA of TBI/TMI/TMLI patients treated on HT.…”