RESEARCH WORK
Accepted: 2025-01-14
Objective Investigating the dosimetric impact of setup errors on target volumes and organs at risk in lung cancer patients undergoing intensity-modulated radiotherapy (IMRT) guided by cone-beam CT (CBCT). Methods The study involved 35 lung cancer patients who underwent IMRT at the Beijing Chest Hospital of Capital Medical University. A total of 175 cone-beam CT (CBCT) data sets were collected. The average setup errors in the X (left-right), Y (cranio-caudal), and Z (superior-inferior) directions were calculated for each patient. These average values were then used to generate simulated plans at the treatment center. The dosimetric data obtained, including target volumes and organs at risk, were compared with the original plans to investigate the impact of setup errors on the dosimetry of intensity-modulated radiotherapy for lung cancer. Results The setup errors in the X, Y, and Z directions were (-0.17±2.67) mm, (0.80±3.39) mm, and (-0.13±2.23) mm, respectively. Among these, the Y-direction setup error had the highest proportion exceeding 5 mm, reaching 17%. When comparing the original plans with the simulated plans, the PTV D98, D95, and D2 of the target area are (98.66±0.52)%, (100.29±0.43)%, and (106.71±0.71)%, respectively, compared to (89.84±1.82)%, (96.50±1.06)%, and (107.33±0.74)%, with statistically significant differences (P<0.001). For organs at risk, the spinal cord D1CC and Dmax increased compared to the original plan, with statistically significant differences (P<0.05). However, there were no statistically significant differences observed in dosimetric parameters for other organs at risk, including the heart (V30, V40, Dmean), lungs (V5, V20, Dmean), esophagus (V30, V50, Dmean), and left anterior descending coronary artery (LAD), when comparing the simulated plans with the original plans. Conclusion The use of CBCT can measure setup errors in lung cancer intensity-modulated radiotherapy. Setup errors can have a dosimetric impact on the actual radiotherapy plan. In clinical practice, adjustments can be made promptly based on the measured errors from CBCT to reduce setup errors and minimize their impact on the actual radiotherapy plan.