Room: Exhibit Hall | Forum 5
Purpose: Image quality of cone-beam CT (CBCT) is important for its quantitative analysis in adaptive radiation therapy. However, due to severe artifacts, the current CBCT is limited to patient setup. We have developed a learning-based image quality improvement method which could provide CBCT images with comparable image quality as planning CT. In this study, we aim to investigate the dosimetric accuracy of our corrected CBCT (CCBCT) for prostate cancer radiotherapy.
Methods: We retrospectively investigated a total of 16 treatment plans from 10 patients, each of whom has CT for original treatment planning and CBCT during treatment setup. The CBCT were firstly corrected using our learning-based method. The CCBCT and original CBCT (OCBCT) were registered to planning CT for generating CCBCT-based and OCBCT-based treatment plans. The original planning CT-based plans served as ground truth. Clinically-relevant dose volume histogram (DVH) metrics were extracted from ground truth, OCBCT-based and CCBCT-based plans for comparison and evaluation. Gamma analysis was performed for comparison of dose distributions between the CT-based and CCBCT-based plans of each patient.
Results: Mean absolute dose differences on planning target volumes (PTVs) between OCBCT/CCBCT-based and CT-based plans are 0.93%/0.35%, respectively. Mean absolute dose differences between bladder, rectum and femur head range from 0.17%/0.09% to 0.75%/0.37% for all DVH metrics. There are significant improvements after our CBCT correction in the D10, D50, D95, Dmean and Dmax of the PTV, bladder and femur head, and in the Dmean of rectum (p<0.05). The average pass rate of gamma analysis after our correction is over 99%.
Conclusion: We have investigated the dosimetric accuracy of our CCBCT for prostate cancer radiotherapy. The quantitative results indicate that the CCBCT could provide comparable dose accuracy to the planning CT for prostate cancer treatment planning, which demonstrates the proposed correction method has great potential in CBCT-guided adaptive prostate cancer radiotherapy.
Not Applicable / None Entered.