All procedures have some risks. The risks of a Meckel scan are minimal and may include a small amount of bleeding where the I.V. was inserted.
A Meckel scan does use radiation. But it uses only a tiny dose, about the same as a chest X-ray. In high doses, radiation is dangerous and raises the risk for cancer. The amount of radiation from a single Meckel scan is so small that it likely does not really increase your child's risk for cancer.
Your child's doctor will advise a Meckel scan only if the risks of not getting a scan are greater than any possible risks from radiation. Talk with your doctor if you have any concerns.