This study evaluates the accuracy of dose distributions in Tomotherapy using two platforms: the Hi-Art and Radixact X9 systems. Dose verification was conducted using Delivery QA (DQA) to establish machine-specific tolerance limits (TLs) and action limits (ALs) based on AAPM TG-218 recommendations.

A total of 150 intensity-modulated radiation therapy (IMRT) Helical Tomotherapy plans were analyzed across three treatment regions: Head and Neck (HN), Chest, and Pelvis. Measurements were performed using ArcCHECK™ with gamma criteria of 3%/3 mm and 3%/2 mm, applying a 10% dose threshold.

Under the 3%/2 mm criteria, the TLs for the Hi-Art system were 95.41% (HN), 94.72% (Chest), and 98.42% (Pelvis), while ALs were 94.94%, 93.60%, and 97.70%, respectively. In the Radixact X9 system, TLs were 95.45% (HN), 93.61% (Chest), and 90.10% (Pelvis), with corresponding ALs of 95.06%, 91.05%, and 88.50%.

For both systems, TLs exceeded 95% and 90% for the 3%/3 mm and 3%/2 mm criteria, respectively. While Radixact X9 demonstrated slightly higher TLs and ALs than Hi-Art in the HN region, it showed lower TLs and ALs in the Chest and Pelvis regions. These findings provide valuable machine-specific benchmarks for dose verification in Tomotherapy, contributing to improved quality assurance in clinical practice.