Changing the Shape of CT Scanners in Response to Patient’s Expanding Waistlines

As computed tomography (CT) imaging systems continue to grow in size, weight capacity and ability to adapt for the growing waistline of patient population is essential.

A recent evaluation, performed by Siemens Healthcare (Erlangen, Germany), of the historic and current statistics of CT imaging systems, has revealed a substantial increase in the design and capacity of computed tomography (CT) scanners provided to the United Kingdom’s NHS [National Health Service] and private hospitals over the past 15 years to accommodate the rise in obesity. This is comparable to recent figures published by Public Health England citing that 64% of people in the United Kingdom are now overweight or obese.


When an individual labeled as “obese” is referred to hospital for a scan, key considerations for clinicians include if the system will hold the person’s weight, if they can fit in the bore, and if there is enough power to penetrate the patient. The internal assessment, looking at a range of CT scanners over the past 20 years, has revealed that the weight allowance of imaging tables has increased by 88%. Furthermore, X-ray generator power, which contributes to scanners providing a good quality image in spite the patient’s size, has risen by 380%, the bore size, where the patient lies, has increased by a total of 10 cm.

“The number of bariatric patients being referred for CT scans has more than doubled in the last 25 years and this is predicted to continue rising,” states Russell Lodge, CT business manager at Siemens Healthcare. “We have witnessed a growing need and demand for obesity provision from hospital imaging departments across the country to ensure patients of all sizes can gain access to the treatment they need. It is essential that manufacturers respond from a design and innovation perspective to ensure that systems hold more weight, include a bigger bore and penetrate larger body mass.”

Being able to hold a person’s weight without causing damage to the scanner or risking injury to the patient is an increasingly important consideration for clinicians. Table weight allowances have nearly doubled from 160 kg in earlier scanners on the market approximately 10 years ago up to the availability of 300 kg allowances in current systems.

The X-ray generator power rating of a CT scanner is a significant factor in ensuring good image quality; therefore if there is not enough power when it comes to larger patients, a diagnostic image may not be captured. Power has increased substantially from around 50 kW 10 years ago, with the most advanced CT scanners now up to 2 x 120 kW, making it suitable for rapid volume coverage with obese patients.

In earlier generation diagnostic systems, the bore, where the patient enters the imaging system, would typically be 70 cm. Recently, this has expanded up to 80 cm. This is good news in response to a rising waist size in United Kingdom adults, which sees an average of 40% of adults with a raised waistline in 2012 compared to an average of 24% in 1993.

The older CT imaging systems had a 160 kg table weight allowance, 50 kW power capability, and a 70-cm bore. The CT imaging systems of today have up to 300 kg table weight allowance, 2 x 120 kW power, and an 80-cm bore.

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