Is the radiation exposure from a CT scan safe?

Patient: I had a small amount (cells) of blood in my urine. My blood work was normal. My doctor has ordered a CT scan. Is there any reason why I could not have ultrasound instead? I am concerned about radiation.

Symptoms: none

Doctor: Thank you for your question. We are not certain as to why you were not prescribed to take an ultrasound, and what your past medical history is to warrant ordering a CT scan of your abdomen. Computed Tomography uses x ray radiation to provide diagnostic imaging of a specified area of the body. A CT scan of the abdomen/pelvis exposes the patient to about 10mSv of radiation and is considered a low risk exposure. Please consult your doctor as to what are the clinical indications for the CT scan are as we cannot ascertain this from your description.Thank you for choosing