EVALUATION OF JO-IMRT TREATMENT PLANNING TECHNIQUE IN NASOPHARYNGEAL CANCER

Purpose/Objectives: The purpose of this study was to evaluate, compare three dimensional conformal radiation therapy (3D-CRT) and Jaw only intensity modulated radiation therapy (JO-IMRT) treatment planning techniques for the treatment of nasopharyngeal cancer. The efficacy in meeting multiple normal tissue constraints while maximizing tumor coverage was evaluated.

Materials/Methods: For each patient, eight plans were generated using Prowess Panther 5.1 software, including a conventional three dimensional conformal plan (3D plan) and seven inverse DAO IMRT plans using conventional jaw-only (JO plan). The purpose of this study is to evaluate JO-IMRT plans for nasopharyngeal cancer patients who didn’t have access to the linear accelerator equipped with MLC (multi-leaf collimator).

Results: All plans were evaluated by the radiation oncologist for adequate dose coverage to the gross tumor volume (GTV). Each plan was evaluated based on the dose delivered to the organs at risk (OR). The dose to high neck nodes, spinal cord, parotid glands and tumor volume were compared between the two treatment techniques. Quality of the plan meets the goals of the radiotherapy plan. The tumor received the full dose that the doctor had prescribed before and the dose delivered to the tumor did not exceed 107% of the prescription dose. The volume of region that received highest radiation dose did not exceed the volume of the tumor. According to this case study, JO-IMRT planning technique illustrated a preferable minimal dose to OR while maximizing tumor coverage for throat lesion. The dose distribution to the tumor of JO-IMRT radiotherapy was much better than that of 3D-CRT radiotherapy. At the same time, with JO-IMRT plan, the doses delivered to the parotid glands were significantly reduced compared to 3D-CRT plan. From the evaluation index of COIN and HI, we can confirm that the quality of JO-IMRT plan is much better than 3D-CRT plan. In addition, the IMRT radiotherapy doesn’t create electrons, photons, so that skin burns for patients will be reduced.