This study is about finding the best way to give a cancer medicine called carboplatin. We use a special dye called iohexol to help doctors figure out the right dose. Carboplatin is used in chemotherapy, which is a type of treatment that stops cancer cells from growing. The study looks at how well different ways of measuring kidney function work for planning carboplatin doses. It also checks how carboplatin affects patients and if other tests can better predict kidney function.

• The study requires 7-8 blood samples and lasts 3-4 weeks.
• Only men aged 18 and older can join, and they need to have good overall health.
• Those with allergies to certain dyes or foods, or specific health conditions, can't participate.

Participants will get iohexol and carboplatin through an IV (a needle in the vein) and will be checked on for a few weeks. This study is for men who will receive carboplatin as part of their cancer treatment, and it's important they can follow the study rules and finish all parts of the study.