Optimal pressure of Continuous Positive Airway Pressure (CPAP) for reduction mean heart dose in left-sided breast cancer radiotherapy

Abstract

Backgrounds: Although deep inspiration breath hold (DIBH) method is beneficial for improving left-sided breast radiotherapy, this technique has limited availability and some patients have poor compliance. Continuous positive airway pressure (CPAP) has been introduced as an alternative to DIBH for reproducing patient anatomy and managing tumor motion. This technique can increase lung volume, thereby displacing the heart from the treatment fields.

Objective: This study aimed to evaluate the relationship between CPAP positive pressure and mean heart dose (MHD) in the DIBH technique. Additionally, we investigated the optimal positive pressure of the CPAP method to reduce heart and lung doses in radiotherapy for left-sided breast cancer patients.

Materials and methods: Left-sided breast cancer patients were trained prior to CT simulation by wearing the CPAP mask and acclimatizing to positive pressure. Automated breast planning in breath hold-CT images was planned. The dosimetric data of MHD, heart V25%, mean left anterior descending artery (LAD), max LAD, CPAP pressure, and left lung volume were collected.

Results: In 23 left-sided breast cancer patients who successfully utilized the CPAP technique, the MHD decreased from 5.28 Gy (free breath, FB) to 3.46 Gy (CPAP). We found that CPAP pressure should not exceed 14 cmH₂O. For patients who were unable to tolerate a deep breath hold with high pressure, our study determined that a CPAP pressure of 12 cmH2O was sufficient to control the MHD. In addition heart V25, mean LAD, and max LAD were also decreased from 7.25% (FB) to 3.57% (CPAP), 25.27 Gy (FB) to 16.99 Gy (CPAP), and 44.84Gy (FB) to 31.69 Gy (CPAP), respectively.

Conclusion: CPAP is an effective tool for reducing MHD in DIBH patients. CPAP positive pressure values 12 to 14 cmH₂O  is a sufficient breathing pressure to use in left-sided breast radiotherapy.