Comparison and calculation of absorbed dose rate in the bone marrow by the Mammosite and Contura applicators in breast cancer brachytherapy with MCNP

Introduction: Breast cancer is the most common cancer among women. With the increasing prevalence of this disease, the focus has been on new methods. Brachytherapy is one of the ways to treat breast cancer. This is a type of radiation therapy that is performed by providing a dose using radioactive sources located at the treatment site, therefore it is a good way to treat tumors.Materials and methods: MCNP Code: The MCNPX code is one of the most powerful computational codes based on the Monte Carlo method. ORNL-MIRD Phantom: To calculate the dose, a model of the human body is required as a phantom. The analytical model of the human body is described by ORNL-MIRD publications. Mammosite applicator: Which is a tool for high-dose rate brachytherapy (HDR) and includes a duct for transmitting radioactive source, an elastic balloon, and a radioactive source. Mammosite-ML or Contura applicator: is almost identical to Mammosite, The difference is that the Mammosite has a central duct but the Mammosite-ML model has 3, 4 or 5 additional ducts around the central duct.Result: Absorption dose rate of body organs by Mammosite applicator with target volume in the right breast: Target Volume: 7/01 × 10-1 , Left breast: 6/89 × 10-3, Right breast: 7/26× 10-1 ,Red bone marrow: 2/30 × 10-3 . Absorption dose rate of body organs by MammoSite applicator with target volume in the left breast: Target Volume: 7/02 × 10-1, Left breast: 7/26 × 10-1, Right breast: 6/88× 10-3, Red bone marrow: 2/27 × 10-3. Absorption dose rate of body organs by Contura applicator with target volume in the right breast: Target Volume: 9/77 × 10-1, Left breast: 1/04 × 10-2, Right breast: 6/8× 10-1, Red bone marrow: 2/06 × 10-3. Absorption dose rate of body organs by Contura applicator with target volume in the left breast: Target Volume: 9/74 × 10-1, Left breast: 6/6 × 10-1, Right breast: 1/06× 10-2, Red bone marrow: 2/03 ×10-3.Conclusion: The absorbed dose by the bone marrow in the Contura applicator is reduced compared to the Mammosite applicator. This is due to the asymmetric dose distribution by the Contura applicator and the increase in the number of lateral ducts around the central duct

Keywords:

Brachytherapy , Mammosite , Mammosite-ML or Contura applicator , Breast , Red Bone Marrow