Introduction: With the increasing use of surface‐based, nonionizing image‐guided radiotherapy (IGRT) systems, a comprehensive set of clinical acceptance and commissioning procedures are needed to ensure correct functionality and proper clinical integration. Although TG‐147 provides a specific set of parameters, measurement methodologies have yet to be described. The aim of this study was to provide a comprehensive overview of the commissioning and acceptance analysis performed for the C‐Rad CatalystHD imaging system. Methods and Materials: Methodology for the commissioning and acceptance of the C‐Rad CatalystHD imaging system was developed using commercially available clinical equipment. Following TG‐147 guidelines, the following tests were performed: integration of peripheral equipment, system drift, static spatial reproducibility and localization accuracy, static end‐to‐end analysis, static rotational accuracy, dynamic spatial accuracy, dynamic temporal accuracy, dynamic radiation delivery and a comprehensive end‐to‐end analysis. Results: The field of view (FOV) of the CatalystHD was 105×109×83 cm3 in the lateral, longitudinal and vertical directions. For thermal equilibrium and system drift, a thermal drift of 1.0mm was noted. A 45 min warmup time is recommended if the system has been shut off an extended period of time (>24 hours) before the QA procedure to eliminate any thermal drift. Spatial reproducibility was found to be 0.05±0.03 mm using a rigid phantom. For the static localization accuracy, system agreement with couch shifts was within 0.1±0.1 mm and positioning agreement with kV‐CBCT was 0.16±0.10 mm. For static rotational accuracy, system agreement with a high precision rotational stage (0.01 deg precision) was within 0.10±0.07 deg. Dynamic spatial and temporal localization accuracy was found to be within 0.2±0.1 mm. Conclusion: A comprehensive commissioning and acceptance study was performed using commercially available phantoms and in‐house methodologies to provide a performance evaluation of the CatalystHD imaging system.
Purpose: The purpose of this project is to compare the Delta4 and Seven29/OCTAVIUS phantoms on the basis of patient Quality Assurance (QA) plans for Helical TomoTherapy. Materials and Methods: The PTW Seven29 2D‐ARRAY inserted into the OCTAVIUS octagonal phantom as well as the ScandiDos Delta4 phantom are intended for the dose validation of IMRT plans in which the dose delivery is from different angles. A total of 20 patient QA plans were delivered using Helical TomoTherapy with the Delta4 and Seven29/OCTAVIUS for comparison. Each plan was compared based on gamma percentage with both the clinical, 3% and 3mm, parameters and more stringent, 2% and 2mm. Results: Using the clinical gamma criteria, 3% and 3mm, the average gamma pass percentage was 96.03% for the Delta4 and 98.00% for the Seven29/OCTAVIUS. Using gamma criteria 2% and 2mm, the average gamma pass percentage were 83.31% and 89.54% respectively. On 14 out of 15 plans for 3% and 3mm, and 11 of 14 for 2% and 2mm, the Seven29/OCTAVIUS had a higher gamma percent than Delta4. Both the Seven29/Octavius and Delta4 had a 90% or greater gamma percent for all plans with 3mm, 3% parameters, and therefore each plan was considered clinically acceptable. Conclusions: In order to deliver the most accurate IMRT treatments to clinic patients, a QA plan must be performed and must pass the clinical standards before delivery. The Seven29/OCTAVIUS and the Delta4 phantoms are comparable in performance based on average gamma passing percents. Based on these measurements however, the Seven29/Octavius gives better results when using the clinical passing criteria of 3%, 3mm as well as the more stringent 2% and 2mm when comparing QA plans with Helical TomoTherapy. Research sponsored by PTW corporation.
Purpose: In vivo dose measurements for Total Body Irradiation using optically stimulated luminescent dosimeters Method and Materials: The institution's standard of care for total body irradiation uses a 6 MV Varian 600C linac with the gantry angle at 90 degrees and field size of 40×40 cm2. The patient's midline is at 350 cm. A 1.2 cm acrylic spoiler is place 40 cm from the surface of the patient and an acrylic tray holding lead compensators is at the head of the gantry. Phantom measurements were made to determine suitability of optically stimulated luminescence dosimeters (OSLDs) for in vivo dosimetry of patients undergoing total body irradiation (TBI). A 30×30×30 cm3 solid water phantom was placed at 350 cm SAD. A calibrated plane parallel ROOS ion chamber was placed at the center of the phantom under 1 cm of build up. OSLDs and TLDs were also place on the phantom adjacent to the ROOS chamber at 1 cm depth. A treatment plan was created to deliver 100 cGy to the midplane of the phantom for 1 field. All three dosimeters were irradiated. A similar setup was created using an anthropomorphic phantom at 350 SAD, TLDs and OSLDs at three different locations. In addition, in vivo measurements were made for three patients undergoing total body irradiation at nine different body points. Results: OSLD phantom measurements were in agreement of the ROOS chamber (2.6%) and TLDs (3.8%) when using the solid water phantom. Comparative measurements between TLDs and OSLDs differed by as much as 4.5% for the anthropomorphic phantom irradiation. In vivo dosimetry using OSLDs for the three patients agreed within (7.6%) for TLDs. Conclusions: Results for both the phantom and patient measurements confirm that OSLDs are both suitable and recommended for required in vivo dosimetry in Total Body Irradiation.
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