 The estimated average radiation dose for the entire cardiac computed protocol is 10.55 mSv and shall not exceed 15mSv. Beta-blockers will be used to control the heart rate and thus maintain the radiation dose as low as reasonably achievable. The total contrast dose will not exceed 140 ml. Depending on patient size, 50-70 ml of iodinated contrast will be used for each of rest and stress scans. 