A Method For Estimating Delivered Dose To Head-And-Neck Cancer Patients Treated With IMRT
E Wolf*, N Kumar, B Huth, M Lamba, H Elson, Barrett Cancer Center, Cincinnati, OhioSU-E-J-192 Sunday 3:00PM - 6:00PM Room: Exhibit Hall
Purpose: To evaluate one method for estimating the delivered dose to H&N IMRT patients through the analysis of weekly CBCT data.
Methods: The planning CT (pCT) and weekly kv-CBCT images were imported into the treatment planning system from the oncology information system . The treatment plan was applied incorporating the shifts resulting from the CBCT and the dose was calculated for each data set. The CT images with dose information were exported to the image fusion and analysis software. Using deformable registration, each weekly CBCT image and accompanying dose was deformed to the pCT. A dose accumulation of the weekly CBCT dose was used to obtain the "delivered" dose to the patient. The "delivered" dose was compared to the "planned" dose through DVH analysis of target volumes and OARs. Data was analyzed for 5 H&N cancer patients treated with IMRT using a simultaneous-integrated-boost (SIB) technique.
Results: For the PTV70, the D95 decreased by an average of 1.3%. For OARs, the dose to the parotids, spinal cord, brainstem, and larynx were considered. The maximum doses to the spinal cord did not exceed 107% of the planned dose. The mean dose to the brainstem was within 2 Gy of the planned dose and the larynx was within 5 Gy of the planned dose. The mean dose to the parotid (spared) was 25.3 Gy compared with the planned mean dose of 24.3 Gy.
Conclusion: When assuming that the weekly CBCT data is representative of daily alignment for this cohort of head-and-neck patients, the PTV70 dose agreed within 1.3% and the OAR within 11% of the planned dose.