Hi, Thanks for writing in. Cancer is a difficult condition to treat and complete staging is required before starting treatment. This is because the treatment for each stage of cancer differs and for better recovery and cure a detailed test is required. Prostate cancer is known to spread to the bones of the skeleton. As you are aware, your father also had the same problem and his prostate cancer had affected his bones. Sodium chloride scan is a technique by which radioactive chemical will be injected in to the system and images acquired after a short duration. This scan will tell any cancer areas in the bones and this is recommended to know if your brother has a prostate cancer that has involved the bones. In the conventional scan, it take time to visualize cancer in the bones. In the sodium chloride scan the bone involvement is visible many months before it can be seen in the conventional scan. Therefore the doctor has taken the right decision in recommending a sodium chloride scan for your brother who has prostate cancer. This is to provide accurate staging of disease and give the required treatment. Please do not worry.