Radiation Dose From Computed Tomography Before and After Implementation of a High Pitch Dual Spiral Technique

Computed tomography has emerged as the "gold standard" for the diagnosis of a broad range of
medical diagnoses. For cardiac imaging alone, the installation of CT scanners in US
cardiology practices alone has tripled over the past 2 years. Patients who undergo cardiac
CTA (computed tomography angiography) may be subjected to relatively high doses of ionizing
radiation (ie. 4 times annual background radiation) during the diagnosis and management of
coronary artery disease. Current radiation doses for cardiac CT examinations are comparable
to the effective doses for patients undergoing nuclear stress tests or cardiac
catheterization (ie. approx 10-15 milliSieverts). In addition, non cardiac CT protocols,
such as chest CT examinations for the evaluation of pulmonary arteries, thoracic and
abdominal aorta, and lung nodules, are associated with significant radiation exposure. Many
patients undergo repeated CT examinations over several years for such pathology. There is a
growing public concern regarding the cancer risk associated with such radiation.

Recent major technological advances have been made with the advent of newer generation CT
scanners which allow significant radiation dose reduction. One such scanner, the dual
source CT, is a new high pitch dual source spiral technique that offers the ability to
image a patient's chest with ECG gated imaging protocols within a single second. These
technological advances allow significant radiation dose savings, often resulting in
effective radiation doses of less than one millisievert (mSv).

Inclusion Criteria:

- All patients who undergo chest CT examinations (including cardiac CTA, and non
cardiac CT examinations including pulmonary embolism, lung nodule and aortic
pathology protocols)