Dr. Martins, as the head of the Cardiology Department, is in the highest-ranking position within this professional setting. Dr. Chan, being a senior cardiologist, would be positioned underneath Dr. Martins in the department's hierarchy but would be of a higher rank than residents, likely having more responsibilities and authority within the department. Dr. Sousa, as a resident, is in a more junior position and is supervised by Dr. Chan, which implies Dr. Chan has some level of oversight and mentorship responsibilities for Dr. Sousa's work.

Given this hierarchy, Dr. Sousa would not be responsible for making department-wide policy decisions. Those decisions are typically within the purview of senior department leadership, in this case, Dr. Martins, or collectively with other senior staff, which could include Dr. Chan. As a resident, Dr. Sousa is expected to follow such policies and may contribute ideas or feedback through the appropriate channels, but is not in a position to unilaterally establish or change them.
In a hospital, Dr. Martins is the head of the Cardiology Department. Dr. Sousa is a resident under the supervision of Dr. Chan, who is a senior cardiologist. What is the professional relationship between Dr. Martins, Dr. Sousa, and Dr. Chan, and can Dr. Sousa make department-wide policy decisions? Provide a brief response.