CT Technology Offers 50% Lower Dose for Highly Sensitive Patient Groups

A new computed tomography (CT) system offers early detection exams and functional diagnoses with up to 50% lower radiation dose, which can help make treatment decisions easier. The technology also minimizes artifacts in cardiac and thoracic examinations.

Siemens Healthcare (Erlangen, Germany) had its first public presentation worldwide November 2013 at the University Medical Center Mannheim (Heidelberg, Germany). In its first few weeks of clinical use at Mannheim’s Institute for Clinical Radiology and Nuclear Medicine, the third-generation of dual- source CT scanners (each with two radiation tubes and detectors) enabled considerably more rapid and more precise diagnoses at reduced doses.

In addition, the high-end CT now offers customized diagnoses for challenging patients, e.g., for very young patients or renal insufficiency patients, the very ill, and obese patients. “In a general population with a very complex age and disease structure, this new CT scanner can solve the problems presented by every radiological situation for virtually every patient,” said institute director Prof. Stefan Schönberg.

Patients suffering from renal insufficiency will benefit from the substantial reduction in contrast medium. Early detection examinations and functional four-dimensional (4D) imaging can be conducted using up to 50% lower radiation dose. This means that this procedure can now be used on a routine basis and physicians can make faster and more well founded decisions as to which tumor therapy to use for the individual in question.

“Somatom Force negates many aspects of computed tomography that up to now have limited its application. For example, the administration of contrast medium that proves problematic for many patients can be greatly lowered,” said Walter Märzendorfer, CEO of CT and radiation oncology at Siemens Healthcare.

Up to 20% of patients suffer from renal insufficiency. Contrast medium containing iodine can place extra burden on the kidneys of older patients and especially those with chronic illnesses. Initial examinations in Mannheim revealed that the average quantity of contrast medium administered in thoracic examinations could be lowered from between 90–110 mL to between 25–35 mL. This is made possible by the two Vectron X-ray tubes in Somatom Force, which enable routine examinations at very low tube voltages of 70–100 kilovolts.

As the contrast-to-noise ratio rises, the amount of contrast medium can be lowered accordingly. The CT system can also deliver considerable added benefits in treatment control. 4D imaging, which shows the function of organs and vessels next to their morphology, is particularly important here because it allows additional information to be gathered about primary tumors and metastases. A disadvantage of this dynamic perfusion was that, up to now, high dose values of more than 50 millisievert (mSv) in specific cases were required, e.g., for liver imaging. This dose can now be more than halved with the Somatom Force system. In one of the Mannheim cases, just 14.7 mSv was required.

Such values enable the procedure to be used on a regular basis, thereby enabling faster and more careful decisions to be made about which treatment is most suitable for an individual patient. In the case of novel but also very expensive antiangiogenesis therapies, which suppress blood vessel formation in the tumor through the administration of medication, Somatom Force can be used to determine specifically at a much earlier stage whether the treatment is working. It can also help to ensure that medication costing several thousand euros per month is deployed more efficiently and so to reduce the overall cost of the treatment.

Typically, long-term CT monitoring is used to identify the correct time to potentially switch treatments. The significantly reduced the cumulated radiation dose with this technology is a great advantage. “This CT system means that medical imaging is no longer restricted to traditional diagnostics,” explained Prof. Schönberg. “As radiologists, we can now work toward the ultimate goal of all medical intervention: The patient’s recovery.”

Early cancer detection at up to 50% lower dose The US National Lung Screening Trial (NLST) screening study conducted in the United States has encouraged a shift of priorities in cancer prevention: The study showed that mortality rates can be reduced by 20% if early lung cancer detection is performed with low-dose CT instead of traditional chest X-rays. Somatom Force is particularly suitable for such early detection examinations due to its previously unattained low dose values. Up to 50% lower than that of earlier high-end CT models, this radiation dose can be attributed to the Turbo Flash mode of Somatom Force and the use of two special spectral filters—selective photon shields, which optimize the X-ray spectrum and thus significantly improve the air/soft-tissue contrast.

Examinations performed at the University Medical Centre Mannheim revealed that dose values of 0.1 mSv for a lung scan could be achieved with the CT system, even in routine clinical situations. “With Somatom Force, there are almost no more contraindications for computed tomography,” said PD Dr. Thomas Henzler, head of cardiothoracic imaging at the University Medical Centre Mannheim.

Another advantage in pulmonary diagnostics is the enlarged field of view (50 cm) of the Turbo Flash Mode on Somatom Force, which covers the entire organ. This extremely quick scan mode with an acquisition rate of nearly 400 mm per second allows the entire thorax to be visualized in approximately one second.

Due to an extremely fast acquisition rate (737 mm/s), if a larger body region is to be scanned, the entire thoracic-abdominal exams can even be performed in just one second. This means that patients may not need to hold their breath. With the Somatom Force, even high heart rates do not lead to disruptive motion artifacts in clinical images, a fact indicated by images taken of a female patient with 90 heartbeats per minute and no medicinal measures to lower her heart rate.

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