Abstract

The Dual Source Technology

posted by DSCT.com editors | May 13, 2009

A dual-source CT (DSCT)* is equipped with two x-ray tubes and two corresponding detectors that are oriented in the gantry with an angular offset of 90 degrees. As a result, it is possible to double the temporal resolution to 83 ms compared to that of single-source CT, double the speed of the acquisition, and offer twice the power, while cutting the radiation dose in half.

Areas of Application

The main areas of application for DSCT are in cardiac and emergency/acute care, as well as Dual Energy imaging.

Cardiac CT

Challenge: With single-source CT, the heart rate is recommended to be lower than 65 or 60 beats per minutes to obtain diagnostic image quality. This is accomplished with heart rate-lowering medication (i.e. beta-blockers). To overcome this limitation, single-source technology often relies on multi-segment reconstruction, where data from different heartbeats are added to each other. The problem is the motion of the coronary arteries between the cardiac cycles causes motion artifacts, resulting in reduced image quality. In addition, imaging different positions of the heart multiple times requires a higher dose of radiation.

How DSCT overcomes this challenge: DSCT is characterized by a heart rate-independent acquisition of data without the use of heart rate-lowering medication. Studies show that DSCT is feasible in patients with high heart rates and arrhythmias (including atrial fibrillation) without compromising image quality and subjecting the patient to excess radiation. Because the acquisition time is less than 50 % compared to that of single-source CT, the DSCT can lower the radiation dose with different ECG-controlled modulation techniques.

Emergency/Acute Care

Challenge: Current single-source CT systems are limited in handling obese patients – the power, bore sizes, and table weight limits can pose a challenge. In addition, scan quality with single-source CT is compromised by heart rate.

How DSCT overcomes this challenge: A DSCT system has the ability to quickly scan patients in an acute care setting regardless of size, condition, or heart rate. This includes obese patients, trauma patients, acute chest pain patients, and stroke patients.

Obesity – Obese patients can be routinely scanned with combined power of 160 kW, bore opening of 78 cm, and table weight capacity of 300 kg.
Chest pain – DSCT can be used to quickly rule out the major causes of chest pain (i.e. pulmonary embolism, aortic dissection, myocardial infarction) without using heart-rate lowering medication. That means patients can be triaged within 10 minutes after presenting at the ER.
Stroke – With a dynamic range of 20 cm and perfusion coverage of 11 cm, DSCT allows visualization of the entire extension of the infarcted brain tissue.
Whole body – Using a scan range of 2 meters, coverage of 87 mm/second with 0.33 mm spatial resolution allows visualization of the complete peripheral artery tree.

Dual Energy

A dual-source CT (DSCT) system simultaneously uses two x-ray sources at different energy levels. This makes it possible to differentiate between fat, soft tissue and contrast material (iodine) on the basis of their unique energy-dependent attenuation profiles.