This is a prospective, controlled observational trial of patients undergoing clinically indicated cardiothoracic computed tomography (CT), including pulmonary or aortic angiography and coronary CT angiography (CCTA).

The development of a novel CT scanner capable of sequential or fast-pitch spiral techniques in most patients (Siemens Definition Flash) represents a potentially crucial technical innovation at a particularly critical juncture. National healthcare systems are under pressure to deliver accurate and cost-effective diagnosis of an increasing number of patients and CT angiography in various settings is a proven, highly accurate technique that has been shown to improve diagnostic efficiency and reduce the cost of care.

However, there has been increasing concern about the lifetime attributable risk of cancer from radiation related to diagnostic procedures. Such concern extends to other radiation-based procedures that contribute to the cumulative lifetime radiation exposure of patients. The Flash scanner holds the promise of substantially reducing exposure resulting from a variety of examinations.

The CT DOSE multicenter trial is therefore designed to validate the extent of dose reduction attendant to the use of the Flash scanner in cardiothoracic scanning, and to determine whether image quality is preserved in spite of significant dose reduction.

Inclusion Criteria:

• Scans from patients undergoing clinically indicated pulmonary angiography, aortography and/or CCTA.
• Age greater than or equal to 18 years.

Exclusion Criteria:

• No exclusions

Patients undergoing clinically indicated cardiothoracic computed tomography (CT), including pulmonary or aortic angiography and coronary CT angiography (CCTA)at 10 sites. Patient selection will be based on a site consecutive CT scan log.