NCT07498855

Robustness Evaluation of Deep Inspiration Breath-Hold (DIBH) Plans in Internal Mammary Irradiation

Robustness Evaluation of Deep Inspiration Breath-Hold (DIBH) Radiotherapy Plans for Internal Mammary Irradiation in Postoperative Breast Cancer

• Status: Recruiting
• Phase: —
• Study type: Observational
• Enrollment: 25 (estimated)
• Sponsor: Ruijin Hospital · Academic / Other
• Sex: Female
• Age: 18 Years
• Healthy volunteers: Not accepted

Summary

This study is an investigator-initiated, single-arm, single-center, prospective, observational study. The hypothesis is that during the implementation of deep inspiration breath-hold (DIBH) radiotherapy plans in postoperative breast cancer patients receiving internal mammary irradiation, the actual target dose coverage and organ-at-risk (OARs) dose parameters remain within clinically acceptable ranges.

Detailed description

For patients with left-sided breast cancer, postoperative radiotherapy can expose the heart to excessive radiation, increasing the risk of cardiac toxicity. DIBH displaces the heart away from the chest wall by expanding the thoracic cavity during breath-holding to reduce cardiac radiation doses. Although DIBH has demonstrated efficacy in reducing cardiac exposure in left-sided breast cancer, its application in internal mammary and regional lymph node irradiation remains uncertain due to potential issues related to dose robustness associated with larger target volumes near the heart. The success of DIBH depends on maintaining a stable respiratory gating window; however, individual variations in breath-holding capacity and fatigue may lead to intrafractional and interfractional positional errors, which can compromise target coverage and increase doses to OARs. Surface-guided systems monitor respiratory motion but may not accurately represent the positions of deep-seated targets and OARs, raising concerns about dose coverage, particularly for the internal mammary target. State-of-the art radiotherapy techniques such as Intensity-Modulated Radiation Therapy (IMRT) and Volumetric Modulated Arc Therapy (VMAT) provide improved dose conformality and reduce high-dose cardiac exposure. However, the integration of these techniques with DIBH and the impact of positional errors on dose robustness remain inadequately studied. Proton therapy, due to its steep dose fall-off, minimizes cardiac and pulmonary exposure but is highly sensitive to positional changes. This sensitivity may amplify uncertainties during DIBH, particularly in the context of internal mammary irradiation. This study aims to evaluate the dose robustness of DIBH in left-sided breast cancer patients undergoing internal mammary irradiation, with a specific focus on the impact of respiratory motion amplitude during breath-holding on dose distribution, as well as intrafractional and interfractional positional errors. Using offline CT and Cone-Beam CT (CBCT) data, it will assess positional deviations and compare the performance of IMRT, VMAT, and Intensity-Modulated Proton Therapy (IMPT) during DIBH. The findings will provide critical evidence to optimize DIBH for internal mammary and regional lymph node irradiation, improving clinical outcomes while minimizing cardiac toxicity.

Conditions

• Breast Cancer

Interventions

Type	Name	Description
RADIATION	DIBH with 3mm Gating Window	The patient will receive moderately hypofractionated radiotherapy targeting the ipsilateral breast, supraclavicular and internal mammary nodes, and high-risk axillary region, with a prescribed dose of 40 Gy (RBE) /15Fx. IMRT, VMAT, or proton therapy will be chosen based on the radiation oncologist's judgment and patient preference. Respiratory gating tolerance is set at ±1.5 mm (3 mm total). Three simulated CT scans during DIBH will assess gating window positions: CT1: Breath-hold at the center of the gating window. CT2: Breath-hold at the upper edge, simulating maximum thoracic expansion. CT3: Breath-hold at the lower edge, simulating minimum thoracic expansion. Setup errors (intrafraction and interfraction) and respiratory waveforms monitored via Surface Guided Radiation Therapy（SGRT）systems will be recorded for analysis.
RADIATION	DIBH with 2 mm Gating Window	The patient will receive moderately hypofractionated radiotherapy targeting the ipsilateral breast, supraclavicular and internal mammary nodes, and high-risk axillary region, with a prescribed dose of 40 Gy (RBE) /15Fx. IMRT, VMAT, or proton therapy will be chosen based on the radiation oncologist's judgment and patient preference. Respiratory gating tolerance is set at ±1 mm (2 mm total). Three simulated CT scans during DIBH will assess gating window positions: CT1: Breath-hold at the center of the gating window. CT2: Breath-hold at the upper edge, simulating maximum thoracic expansion. CT3: Breath-hold at the lower edge, simulating minimum thoracic expansion. Setup errors (intrafraction and interfraction) and respiratory waveforms monitored via SGRT systems will be recorded for analysis.
RADIATION	DIBH with 1.5 mm Gating Window	The patient will receive moderately hypofractionated radiotherapy targeting the ipsilateral breast, supraclavicular and internal mammary nodes, and high-risk axillary region, with a prescribed dose of 40 Gy (RBE) /15Fx. IMRT, VMAT, or proton therapy will be chosen based on the radiation oncologist's judgment and patient preference. Respiratory gating tolerance is set at ± 0.75 mm (1.5 mm total). Three simulated CT scans during DIBH will assess gating window positions: CT1: Breath-hold at the center of the gating window. CT2: Breath-hold at the upper edge, simulating maximum thoracic expansion. CT3: Breath-hold at the lower edge, simulating minimum thoracic expansion. Setup errors (intrafraction and interfraction) and respiratory waveforms monitored via SGRT systems will be recorded for analysis.

Timeline

• Start date: 2025-10-01
• Primary completion: 2026-12-31
• Completion: 2027-05-31
• First posted: 2026-03-27
• Last updated: 2026-03-27

Locations

1 site across 1 country: China