4D CT Scan Versus 3D CT Scan Concerning Cardiac Dosimetry Assesment for Left Sided Breast Cancers Radiotherapy (RD3D4)

4D CT Scan Versus 3D CT Scan Concerning Cardiac Dosimetry Assesment for Left Sided Breast Cancers Radiotherapy

4D CT Scan With Respiratory Gating Versus 3D CT Scan Concerning Cardiac Dosimetry Assesment for Left Sided Breast Cancers Radiotherapy

To establish if the cardiac radiation dose assesment is well aproximated with routine 3D CT scan compared to 4D CT experimental scan with respiratory gating (breath motion monitoring). The study population relates to left side breast cancers female patients that require a radiation therapy treatment.

As a standard of care, the postoperative breast cancers radiation therapy is generally based on a 3 dimensions CT scan that does not incorporate the breathing motion by definition. Meanwhile, the patients must commonly receive the treatment in free motion breathing condition. More of that, the Cardiac dose, especially the LAD (left anterior descending artery) dose has been established as the main cause of radiation induced ischemic heart disease (RIHD) and should be consider in the first place. In more concrete terms, the higher the LAD dose is, the greater the RIHD relates: arise the LAD dose by 1 Gy means a 7.4% higher risk to cause a RIHD during the next 5 years. That being said, to determine if the cardiac dosimetry and the dose-volume histograms (specifically for the left side breast cancer treatments including or not the internal mammary artery) obtained from a 3D CT scan reflect well or not the reality (which is widely subject to the breathing motion). Finally, because it has been established that a 4D CT scan can monitor the breathing motion, it seems definitely interesting to compare it with the average 3D CT scan to address this concern.

Breast Cancer, Radiation-Induced Vascular Disease, Left Anterior Descending Coronary Artery Stenosis, Radiotherapy Side Effect, Cardiac Ischemia, Left Sided Breast Cancer, LAD (Left Anterior Descending) Coronary Artery Stenosis

Assesment of an usual cardiac dosimetry based on 3D CT scan. Only this dosimetry will be used to treat the patients. Because of the crossover model, patients are included in both arms.

Assesment of an experimental cardiac dosimetry based on 4D CT scan. Not used to treat the patients. Because of the crossover model, patients are included in both arms.

10 minutes breathing motion monitoring during an additional CT scan to establish a more accurate cardiac and LAD dosimetry compared to reality

To determine if the mean LAD (left anterior descending artery) dose significantly changes statistically between an usual 3D CT scan versus a 4D CT with breathing motion monitoring (10 breathing phases are monitored). Based on stastical test with 95% confidence intervals, to evaluate if there is a significant difference between 4D CT LAD mean dose and 3D CT LAD mean dose.

Inclusion Criteria: Age ≥ 18 yo Sex=female Patients diagnoses with a left side breast cancer for which a radiation therapy is indicated and confirmed in a multidisciplinary consultation meeting. Be able to understand and give her personal free consent, no judicial protection measure. Written or oral consent, in compliance with the clinical investigation rules and regulation. Patient affiliated with social security system Treatment expected to be realized in Saint Quentin Hospital Exclusion Criteria: Patient < 18 yo Pregnant women. Breastfeeding women. Consent not given Claustrophobia Incapacited subject or judicial protection measure Other research with exclusion period time ongoing All the inclusion criteria not met

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Delineation of target volumes and organs at risk in adjuvant radiotherapy of early breast cancer: national guidelines and contouring atlas by the Danish Breast Cancer Cooperative Group" Acta Oncologica 2013, Nielsen et al

Tangential Field Radiotherapy for Breast Cancer-The Dose to the Heart and Heart Subvolumes: What Structures Must Be Contoured in Future Clinical Trials? Front Oncol 2017, Duma et al.