Monaco-Serial Biological Function K-value Index Constraint for Cardiac Dose

A Retrospective Study on the Monaco-Serial Biological Function K-value Index Constraint for Cardiac Dose

Breast cancer is the most common malignant tumor in women globally, with radiotherapy being a crucial adjunctive treatment . However, due to the proximity of the breast radiotherapy target to the heart, there is a dose-effect relationship between radiation dose and the risk of radiation-induced heart disease, leading to a significantly increased risk of cardiac complications in patients undergoing left-sided breast cancer radiotherapy . Modern radiotherapy planning systems, utilizing inverse intensity-modulated radiotherapy (IMRT) dose optimization algorithms, effectively limit radiation exposure to organs at risk while ensuring target dose conformity, and have been widely adopted in clinical practice . To further reduce heart dose, the deep inspiration breath-hold (DIBH) technique has become an essential method in recent breast cancer radiotherapy. DIBH increases lung volume, thereby expanding the distance between the target and the heart, enhancing dose attenuation in the target area and minimizing radiation exposure to the heart. The combination of DIBH with IMRT dose optimization algorithms effectively minimizes radiation to the heart and its substructures, reducing the risk of radiation-induced heart disease.

The Monaco radiotherapy planning system is one of the most widely used systems, employing the Monte Carlo dose calculation algorithm, which offers high accuracy and provides dose optimization results that are closer to actual radiation-induced damage. The Serial function within the system is one of the key biological optimization tools, particularly effective in dose constraints for the heart and its substructures. In Monaco-Serial, when the Power Law Exponent value, or K value, is set to 1, it is more sensitive to average dose constraints, and is commonly used for average dose constraints to the heart and its substructures in left breast cancer free-breathing IMRT (FB-IMRT) radiotherapy . However, in deep inspiration breath-hold IMRT (DIBH-IMRT), due to significant changes in the spatial relationship between the heart and the target, previous parameter settings may no longer provide the optimal solution, and there is currently no relevant research or To maximize the dose constraints for the heart and its substructures and reduce the risk of radiation-induced damage, this study conducted a retrospective analysis of 51 patients who had previously undergone left-sided breast cancer DIBH-IMRT. Radiotherapy plans were designed with different Monaco-Serial K values, followed by dosimetric comparisons. Additionally, the correlation between dose-volume changes of organs at risk (OARs) after K value adjustments and anatomical changes post-DIBH was analyzed. The aim is to identify the optimal K value setting for the Monaco-Serial biological optimization function in left-sided breast cancer DIBH-IMRT, providing data support for the clinical application of the Monaco system in designing DIBH-IMRT radiotherapy plans for left breast cancer.

The study included 51 left-sided breast cancer patients who underwent breast-conserving surgery followed by whole-breast radiotherapy, with an average age of 43.3 years (range: 29-72 years). All patients had good compliance and completed the entire DIBH treatment process. The workflow which includes CT simulation and positioning under both FB and DIBH, Monaco radiotherapy plan design, radiotherapy plan evaluation, and the correlation analysis of anatomical changes and dose reduction rates after DIBH.

Study Overview

• Status: Not yet recruiting
• Conditions: Breast Cancer Radiotherapy Planning
• Intervention / Treatment: Other: radiotherapy planning

• Study Type: Observational
• Enrollment (Estimated): 51

Contacts and Locations

• Study Contact: Name: Jianjun Lai; Phone Number: +8615924193343; Email: 385806945@qq.com

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Child; Adult; Older Adult
• Accepts Healthy Volunteers: No

• Sampling Method: Non-Probability Sample

Study Population

The patients who have successfully completed left-sided breast cancer DIBH-IMRT radiotherapy.

Description

Inclusion Criteria:

• The patients who have successfully completed left-sided breast cancer DIBH-IMRT radiotherapy.

Exclusion Criteria:

• The patients who have not completed left-sided breast cancer DIBH-IMRT radiotherapy.

Study Plan

How is the study designed?

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
In the Monaco radiotherapy planning system, the dose-volume metrics for organs at risk and the metrics for changes in anatomical structures are extracted.	In the radiotherapy planning system, the radiation dose-volume data for the patient's heart and lungs is extracted, specifically including the mean dose and maximum dose to the heart, the maximum dose and mean dose to the LAD (left anterior descending artery), and the V5, V20, V30, and mean dose to the affected lung tissue (units: Gy). Additionally, anatomical indicators following DIBH (Deep Inspiration Breath Hold) are observed in the radiotherapy planning system, including the volume increase of the affected lung (units: cm³ or %), the distance between the heart and the breast (units: cm), and the volume ratio between the heart and the affected lung (units: % or ratio).	2025.3.1

Collaborators and Investigators

• Sponsor: Jianjun Lai

Study record dates

Study Major Dates

• Study Start (Estimated): January 25, 2025
• Primary Completion (Estimated): March 1, 2025
• Study Completion (Estimated): March 1, 2025

Study Registration Dates

• First Submitted: January 19, 2025
• First Submitted That Met QC Criteria: January 26, 2025
• First Posted (Actual): March 25, 2025

Study Record Updates

• Last Update Posted (Actual): March 25, 2025
• Last Update Submitted That Met QC Criteria: January 26, 2025
• Last Verified: January 1, 2025

More Information

Terms related to this study

• Other Study ID Numbers: PDIBT002

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No