SU-F-T-411: A Quantitative Parameter for Treatment Plan Quality.

PURPOSE: To create an IMRT treatment plan quantitative score using QUANTEC dose/volume parameters to assess plan quality.

METHODS: 132 IMRT patient plans of various treatment sites were evaluated. The optimized plan's dose volume histogram (DVH) was exported to Velocity for evaluation. The proposed scoring was based on calculating the shortest distance from the QUANTEC objective to the DVH line of each organ. Each plan was normalized against the "perfect" plan where the organs at risk (OAR) received no dose and hence the distance between the QUANTEC objective and the DVH line was maximized. The normalized scores allowed comparing the quality of plans across the treatment sites, dosimetrists, and physicians. The scores were plotted and statistically analyzed to serve as basis for future plans.

RESULTS: The score for each site was evaluated and the average percentage score resulted in the abdomen having an average percent score of 1.68 ± 1.49, 34.61 ± 35.19, 11.00 ± 15.39, 28.44 ± 25.13, 1.99 ± 5.83 for abdomen, brain, chest, head/neck, and pelvis. Differences in scores between the treatment sites are largely attributed to OAR segmentation and proximity of the OAR to the PTV. Small score differences between dosimetrist were attributed to the number of plans they have completed per site. A larger sample of treatment plans is being evaluated to investigate the effect of dosimetrist's experience on plan quality.

CONCLUSION: This approach allows comparison of patient treatments which will help improve patient care and treatment outcomes with a quantitative score. A larger number of patient plans is being evaluated for improved statistics.