Powering cutting-edge medical equipment

In this article, Chris Maidment, Marketing Director, TDK-Lambda UK examines why high reliability power supplies are essential.

TDK-Lambda’s products are used in a variety of medical devices and systems, such as magnetic resonance imaging (MRI) scanners, computerised tomography (CT) scanners, positron emission tomography (PET) scanners, X-ray systems, haematology analysers, DNA equipment, patient monitors, ultrasound scanners, robotic surgical systems, and dialysis equipment.

Alternating current is supplied by the electrical grid (AC). This AC power must be converted to direct current (DC) for medical equipment using an AC-DC power supply. Since patient care demands frequently need 24/7 operation of critical equipment, manufacturers have high expectations of the power supply – it must be incredibly reliable. What makes these power supplies so reliable? Let’s examine this in more detail using actual medical devices and equipment.

Computerised tomography (CT ) scanners

The first piece of medical equipment is the CT scanner, which is rapidly evolving. This specialised imaging and testing equipment is used by many medical facilities. It uses X-rays and a computer to take cross-sectional images of the body. While emitting X-rays for imaging, the tube producing the X-rays inside the gantry of the CT scanner revolves 360° around the patient’s bed.

Figure 1: An X-ray emitting gantry (tube and detector), a bed for the patient, and a console – the computer’s control panel – make up a CT scanner. 

Power supplies supply energy to the image processing and other controllers during CT scanning, supporting the fundamentals of such evolution. Therefore, it is crucial that these products have high dependability and efficiency. Given that these CT scanners can be expensive, with some systems costing hundreds of thousands of euros, a long service life for extended use is essential.

The development of the multi-slice CT scanner, which can produce sharp 3D images at speeds of several seconds to many tens of seconds, occurred in recent years. The heart and brain may now be seen clearly thanks to recent advancements in 4D CT technology. Additionally, the accuracy of diagnostic imaging results is improving with the use of artificial intelligence (AI).

Hospital equipment now has more advanced features and higher levels of precision; therefore, taking steps to lessen the effects of noise is more important than ever. TDK-Lambda also provides power line electromagnetic compatibility (EMC) filters as a remedy for this.

Patient comfort is important during any procedure. Audible noise from the power supply’s cooling fan can be irritating and tiring for both the patient and the technician. TDK-Lambda has addressed this with two of their latest multiple output modular power supplies.

The QM series offers power levels from 550W to 2,000W and up to 18 outputs. Its efficiency of up to 91% reduces internal losses allowing the use of low speed, low audible noise fans for cooling.

Figure 2: New from TDK-Lambda – the MU4 series modular medical power supply is just 1U high

The MU4 series can deliver up to 800W and uses an intelligent fan control. It’s microcontroller algorithm monitors the temperature of the primary converter and each output module, allowing the fan speed to be adjusted for optimum cooling. The MU4 fan rotation speed is therefore reduced, producing an audible noise profile as low as 36dBA.

Patient monitors

Next is the patient monitor, which has often been featured in recent news, films, and TV programmes. It is a medical device for monitoring a patient’s vital signs, such as electrocardiogram data and blood pressure. They are widely used in intensive care units (ICUs), critical care units (CCUs) and operating theatres to monitor patients over time and alert clinicians if there is a sudden change in their condition.

Figure 3: Patient monitors for checking vital signs

Here, power supplies must be extremely stable in order to be used year-round, around-the-clock in settings where system failures must never, ever occur. Compact power supplies are particularly in great demand because of the recent increase in the number of major devices used in operating theatres, such as ventilators and artificial heart-lung machines. Some of the smallest power supplies in the market are available from TDK-Lambda at 2 x 3 inches (AC/DC 60W class), and they have a low height profile that makes them ideal for integration into flat-screen monitors.

Figure 4: TDK-Lambda’s CUS-M series and PFE1000FA series are used in medical devices such as CT scanners and patient monitors

TDK-Lambda power supplies comply with various medical standards, such as the latest version of medical standard IEC60601-1 (Edition 3.1). The company already complies with ISO13485, an international standard for quality management systems for medical devices, at its development and design/production bases in Japan, United Kingdom, United States, China, and Malaysia.