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To assess the effect of respiratory movement on dose distribution via intensity-modulated radiotherapy (IMRT) in patients with lung cancer based on real respiratory movement parameters. Twenty-seven patients with lung cancer who underwent four-dimensional computed tomography (4DCT) and received IMRT were analyzed retrospectively to determine the three-dimensional tumor motion amplitude and respiratory period. Based on the above movement parameters, the dose distribution of the tumor on the respiratory movement platform in the head-foot and left-right directions was measured. The difference in IMRT dose distribution between the respiratory motion and static states was compared using the two-dimensional gamma analysis method, and the effect of respiratory motion on dose verification was analyzed. The mean respiratory motion period of patients was 3.3 s, and the mean tumor motion amplitude in the head-foot direction (5.6 mm) was greater than that in the left-right direction (2.1 mm) and the anterior-posterior direction (2.3 mm), with the maximum at 18 mm. The γ-passage rate tended to decrease gradually with the increase intumor motion amplitude. When the tumor motion amplitude was greater than 3 mm, the γ passage rate was less than 95% in most beams. The differences of γ-passage rates grouped by the median respiratory period were statistically significant in the left-right directional motion state. IMRT dose validation in lung canceris affected by the amplitude of tumor motion and the respiratory motion cycle. Respiratory motion management techniques are recommended for patients with a large respiratory motion amplitude to improve the accuracy of dose delivery to the target.

Purpose: This study aims to assess the dosimetry and treatment efficiency of TaiChiB-based Stereotactic Body Radiotherapy (SBRT) plans applying to treat two-lung lesions with one overlapping organs at risk. Methods: For four retrospective patients diagnosed with two-lung lesions each patient, four treatment plans were designed including Plan Edge, TaiChiB linac-based, RGS-based, and a linac-RGS hybrid (Plan TCLinac, Plan TCRGS, and Plan TCHybrid). Dosimetric metrics and beam-on time were employed to evaluate and compare the TaiChiB-based plans against Plan Edge. Results: For Conformity Index (CI), Plan TCRGS outperformed all other plans with an average CI of 1.06, as opposed to Plan Edge′s 1.33. Similarly, for R50 %, Plan TCRGS was superior with an average R50 % of 3.79, better than Plan Edge′s 4.28. In terms of D2cm, Plan TCRGS also led with an average of 48.48%, compared to Plan Edge′s 56.25%. For organ at risk (OAR) sparing, Plan TCRGS often displayed the lowest dosimetric values, notably for the spinal cord (Dmax 5.92 Gy) and lungs (D1500cc 1.00 Gy, D1000cc 2.61 Gy, V10Gy 15.14%). However, its high Dmax values for the heart and great vessels sometimes exceeded safety thresholds. Plan TCHybrid presented a balanced approach, showing doses comparable to or better than Plan Edge without crossing safety limits. In terms of beam-on time, Plan TCLinac emerged as the most efficient treatment option in three out of four cases, followed closely by Plan Edge in one case. Plan TCRGS, despite its dosimetric advantages, was the least efficient, recording notably longer beam-on times, with a peak at 33.28 minutes in Case 2. Conclusion: For patients with two-lung lesions treated by SBRT whose one lesion overlaps with OARs, the Plan TCHybrid delivered by TaiChiB digital radiotherapy system can be recommended as a clinical option. [ABSTRACT FROM AUTHOR]