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Masters Thesis | Medical Science | India | Volume 13 Issue 8, August 2024 | Rating: 7.1 / 10

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Comparison of Gamma Analysis using Two Different Commercially available 2D Array Detectors for Pre-treatment Verification of Volumetric Modulated Arc Therapy

Nkurunziza Rodgers, Avin Kumar, Ashwini K, Kavya, Nisha

Abstract: Volumetric modulated Arc therapy (VMAT) represents a significant advancement in radiation therapy, offering benefits in treatment efficacy, patient experience, and reduction in side effects. However, due to the complexity of the treatment delivery, precise delivery is required to ensure that the intended dose is accurately administered to the tumor while sparing surrounding healthy tissues. Using two array detectors, the study uses the gamma analysis method to validate patient-specific quality assurance (QA) accuracy and reliability in volumetric modulated arc therapy (VMAT). This study used an Elekta synergy platform electron linear accelerator operated in the range of photon energies,4MV, 6MV, 6MV FFF, and 15MV. The 30 selected esophageal cancer patients were planned in TPS (Monaco V6.1.4) and recalculated on PTWseven29 and MapCHECK3, the 2D dosimetric devices for planar dose distribution. To compare the two dosimetric devices, the gamma analysis method was used with five gamma criteria of dose difference/distance to agreement of 3%/3mm, 3%/2mm, 3%/1mm, 2%/2mm, and 2%/1mm for the threshold values of 0.1%, 5%, and 10% at a tolerance level of 95%. All the gamma criteria used had average gamma pass rates greater than 95%. MapCHECK3 presented higher average gamma pass rates than PTWseven29 at gamma criteria of 3%/1mm and 2%/1m. Therefore, the choice between these two dosimeters should depend on specific clinical needs, such as the complexity of the treatment plan to be verified and the required level of precision.

Keywords: VMAT, Gamma analysis, dosimetric comparison, 2D array detectors, Patient specific QA

Edition: Volume 13 Issue 8, August 2024

Pages: 1427 - 1430