Final answer:
MUGA scans are performed to monitor cardiac function in patients receiving doxorubicin due to the risk of cardiotoxicity. The timing of these scans can vary, usually after early treatment cycles, and should follow the specific protocol recommended by the oncologist.
Step-by-step explanation:
The question pertains to monitoring cardiac function using multiple gated acquisition (MUGA) scans in patients receiving the chemotherapy drug doxorubicin. This drug is known to potentially cause cardiotoxicity, which is why MUGA scans are used to assess left ventricular ejection fraction (EF) at baseline and during treatment. The specific timing for MUGA scans after the initiation of doxorubicin can vary depending on the treatment protocol, but is often performed after the first few cycles to monitor cardiac function. While the question does not provide the exact treatment protocol, generally speaking, a patient with a normal EF at baseline might undergo their first MUGA scan after the first cycle of doxorubicin, but subsequent scans could be after the second or third cycles respectively. It is essential to follow the oncologist's recommendations and the specific protocol in place for MUGA scan timing.