Application of ArcCHECK system in the verification of tomotherapy plan for esophageal cancer

Objective To explore the application of ArcCheck system in the validation of Helical and Direct tomotherapy plans for esophageal cancer and summarize relevant experience. Methods The Helical and Direct tomotherapy verification plans were established for 32 patients with esophageal cancer at different positions according to the doctor′s instructions, which were verified by the ArcCHECK system to compare the passing rate of the results.The correlation between the volume of the target area and the passing rate of the planned verification was analyzed. The therapeutic verification plan with a small target volume was made. The target area was placed at the center of ArcCHECK phantom and the area of detectors to statistically compare the verification passing rates. Results Helical plan showed a significantly higher passing rate than the Direct plan (P 0.05). Conclusions The passing rate of the Helical plan is generally higher than that of the Direct plan, which may be related to the angular response of the ArcCHECK detector and the fact that more reference points are not included for calculation due to low-dose radiation. In addition, it may also be related to the higher requirements of Direct plan for tomotherapy dose control system. In the Helical verification plan, when the 3%/3mm criterion is adopted, the larger the target volume, the higher the possibility of lower passing rate, whereas the correlation coefficient between them is relatively low. The high-dose area can be verified by the plans at the center of the phantom or the detection point. With the comprehensive consideration, we suggest putting it at the center of the phantom. Key words: Esophageal neoplasm/helical tomotherapy; ArcCHECK system; Plan verification; Quality assurance