Initial Experience of a High Resolution SOLID-State Detector Array for Lattice Radiotherapy Treatments In Guatemala
Abstract
Purpose
Show the Gamma Index passing rates (GPR) for selected groups of patients treated with Lattice Radiotherapy using a high resolution solid-state detector. This study evaluates the accuracy of dose distribution for high gradient dose points in Lattice Treatments, comparing the performance of AAA and Acuros XB algorithms.
Methods
For the seven patients selected with large tumors treated with Lattice, following the recommendations from Washington University protocol, a PSQA was performed using the high resolution solid-state detector. For each patient, a measurement was simulated by placing the detector correctly. The measured planes were compared against a selected plane from the TPS calculated with AAA and AXB. Gamma Index passing rate was analyzed using global 5%/1mm, global 3%/1mm, and local 3%/1mm criteria, all with a 10% threshold.
Results
Plans characterized by extreme dose peaks and valleys showed better agreement when calculated with XB. For 6 patients, the median for plans calculated with AAA were 95.2%±1.9% (global 5/1), 91.7%±3.6% (global 3/1) and 77.0%±4.5% (local 3/1). For AXB, the results were 96.2%±3.5% (global 5/1), 95.5%±4.6% (global 3/1) and 83.2%±6.6% (local 3/1). One additional patient was removed from the dataset because of low GPR due to extreme plan modulation. All treatment plans were optimized with the Eclipse v18 planning system and all dose deliveries were performed on a Halcyon 6MV FFF LINAC. For the dosimetric verification, myQA-SRS was utilized, this detector has a resolution of 0.4mm and 105,000 pixels with an active area of 12x14 cm2.
Conclusion
Our results indicate that the high-resolution detector is an excellent option for PSQA of complex Lattice plans, giving results consistent with all the clinical requirements. The AXB showed higher agreement in high dose gradient regions compared with AAA.