One should not opt for imaging studies unless it is a must; they are not safe and can cause cancers in long run.
A UK analysis published in the Journal Lancet in 2004 had shown that fluoroscopic X Ray radiation exposure during catheter-based coronary angiography can cause up to 280 cases of cancer per million examinations performed.
The mean duration of fluoroscopy in electro physiologic cardiac interventional procedures ranges from 15 to 67 minutes. The radiation dose from one hour of fluoroscopy during electro physiologic ablation procedures can result in 0.7 to 1.4 excess fatal malignancies per 1000 women and 1.0 to 2.6 per 1000 men as per two studies published in American Journal of Cardiology (1998) and Circulation (2004)
At doses used in diagnostic and interventional procedures, ionizing radiation releases free radicals that may cause DNA damage. This radiation-induced cancers may develop decades after exposure, and include myeloma, blood cancers, lung cancer, thyroid cancer, breast cancer, bone cancer, and skin cancer.
Effective dose of radiation is measured in sieverts (Sv) or millisieverts (mSv). A whole body radiation dose of 1 Sv is associated with a 4 to 5 percent increased relative risk of fatal cancer. (1 Sv = 1000 mSv).
Mild exposure is called when the exposure is < 3 mSv, Moderate >3 to 20 mSv, High 20 to 50 mSv and very high exposure means >50 mSv.
The effective dose related to any radiologic procedure can be considered in the context of the annual effective dose to individuals from natural background radiation sources, including radon, cosmic rays, terrestrial, and internal sources. This background effective dose, approximately 3 mSv, does not pose a significant risk of future cancer to individuals.
A typical X ray procedure results in a total effective dose of 8.3 mSv per hour of fluoroscopy. The mean cardiac fluoroscopy time in managing paroxysmal atrial fibrillation is 57 minutes, atrial flutter is 20 minutes, ablation is 22 minutes and Pulmonary Vein isolation is 39 minutes.
Multiple medical tests involving radiation exposure lead to high cumulative doses of radiation. In one study in 20 year period a heart patient may end up with 15 procedures involving radiation exposure. Of these four may be high dose procedures (≥3 mSv). The cumulative estimated effective dose from all medical sources exceeds 100 mSv in 31.4 percent of patients.
Use of CT may account for 1.5 to 2 percent of all future cancers in the United States.
The 2006 Biological Effects of Ionizing Radiation VII lifetime attributable cancer risk model predicts that 1 in 1000 persons exposed to 10 mSv (single diagnostic CT scan of the neck, chest, abdomen, or pelvis) will develop cancer due to that single exposure.
The lifetime attributable cancer mortality risk attributable to a single radiation exposure in a one year-old child is 1 in 550 following an abdominal CT and 1 in 1500 following a brain CT.
It has been estimated that 29,000 future cancers could be attributed to CT scans performed in the US in 2007 alone.
1 in 500 women and 1 in 660 men will develop cancer from their abdominal CT scan if the procedure is performed at the age of 20.
A 45 year-old adult undergoing one single full-body CT procedure would accrue an additional lifetime attributable cancer mortality risk of 0.08 percent from a single scan.
The lifetime attributable cancer mortality risk is 1.9 percent lifetime for thirty years of annual scans.
All patients should be given a general idea about the magnitude of the proposed radiation dose. The exposure should be compared with an estimated effective dose to a single chest x-ray (0.02 mSv), a transcontinental airplane flight (0.02 mSv), or annual individual radiation dose from the natural background (3.0 mSv).
The dose from a single abdominal CT scan is comparable to the collective dose of 400 chest x-rays or natural background radiation for three years. 
