Improving the reproducibility and accuracy of DIBH with a laser distance sensor self-monitoring system in left breast cancer patients

When adjuvant radiation therapy (RT) is employed following breast-conserving surgery (BCS), it is imperative to exercise caution regarding the risk of radiation exposure to the heart in patients diagnosed with left-sided breast cancer. Deep-inspiration breath-hold (DIBH) is a technique that regulates the patient’s breathing and expands the chest wall to increase the distance between the treatment area and surrounding organs, thereby providing protection for the heart. The self-monitoring system with a laser distance sensor (LDS) is not attached to the patient’s body and allows for the monitoring of respiration, thereby ensuring the reproducibility of DIBH. The experiment was conducted on 11 clinical left-sided breast cancer patients per group with or without self-monitoring. When self-monitoring was not performed, patients demonstrated a tendency to breathe regardless of the DIBH baseline, and there was no evidence of any tendency to correct errors. The mean distance error between the first and second DIBH was 3.78 mm and 3.95 mm, respectively, with an overall tendency for the average distance error to increase. When self-monitoring was performed, there was a tendency to correct errors according to the DIBH baseline. The average distance error between the first DIBH and the second DIBH was 2.02 mm and 1.98 mm, respectively, which was relatively small. The self-monitoring system with LDS helps to maintain the DIBH throughout the treatment period, thereby ensuring that treatment effects are consistent with the prescribed treatment plan can be expected. Furthermore, LDS, which can measure absolute distance, enhances the accuracy of patient positioning for DIBH.