Mapcheck for dose verification of intensity-modulated radiotherapy in the treatment of nasopharyngeal carcinoma

Objective:To investigate the feasibility of using Mapcheck instead of film in dose verification of intensity-modulated radiotherapy(IMRT) in the treatment of nasopharyngeal carcinoma.Methods:From August 2007 to March 2008,18 patients with nasopharyngeal carcinoma confirmed by pathological examination received 9 fields of IMRT after each IMRT plan of those patients passed the single point verification,This study made the calculation at 0 degree for each field one by one,carried out 6 MV X ray plan,performed linear accelerator irradiation for each field,and made Mapcheck verification to get relative dose distributions for comparison with the γ irradiation.After all the fields of the IMRT plan passed(coincidence rate over 90%),the planar dose film verification was performed and the passing rate was calculated.Results:The mean coincidence rate of the 18 IMRT plans was(95.5±2.07)% verified by Mapcheck after passing the single point verification.The mean coincidence rate was(97.8±1.0)% by planar dose film verification.The passing rates of both plans were 100% in this study.Conclusion:The study showed that it was feasible to use Mapcheck instead of film in dose verification of IMRT plan in the treatment of nasopharyngeal carcinoma.