Purpose: To evaluate the dosimetric impact of four different radiotherapy techniques for a case of left-sided breast cancer with Internal Mammary lymph Nodes (IMN) involvement. Materials and methods: To identify the best radiotherapy technique for this patient. four methods were compared: 3D Conformal Radiotherapy (3D-CRT). Volumetric Modulated Arc Therapy (VMAT). https://www.solarvillagehomes.com/product-category/cassette/