How important is dosimetrist experience for intensity modulated radiation therapy? A comparative analysis of a head and neck case.

Abstract

Treatment planning for IMRT is a complex process that requires additional training and expertise. The aim of this study was to compare and analyze IMRT plans generated by dosimetrists with varying levels of IMRT planning experience. The computed tomography (CT) data of a patient previously treated with IMRT for left tonsillar carcinoma were used. The patient's preexisting planning target volumes (PTVs) and all organs at risk were provided with the CT data set. Six dosimetrists with variable IMRT planning experience generated IMRT plans according to the department's protocol. Plan analysis included visual inspection and comparison of dose-volume histogram, conformity indices, treatment delivery efficiency, and dose delivery accuracy. Visual review of the dose distribution showed that the 6 plans were comparable. However, only the 2 most experienced dosimetrists were able to meet the strict PTV aims and critical structure constraints. The least experienced dosimetrist had the worst planning outcome. Comparison of delivery efficiency showed that the number of segments, total monitor units, and treatment time increased as the IMRT planning experience decreased. Dosimetrists with higher levels of IMRT planning experience produced a better quality head and neck IMRT plan. Different planning experience may need to be considered when organizing appropriate departmental resources.