RF technology is not just about wireless communications—it is an increasingly important part of many new healthcare technologies that are making the hospitals of the future possible. For example, today’s healthcare providers are increasingly utilizing advanced medical diagnostic, imaging, and treatment systems, including computed tomography (CT), magnetic resonance imaging (MRI), and ultrasound systems, to enable earlier detection of potential health conditions. These conditions can then be more effectively treated with procedures by robots, lasers and microwave ablation equipment.
As healthcare innovations continue to advance, the underlying technology needed to support them must advance too. For example, one element these systems have in common is that RF technology is used to power many of their critical functions. Medical electronics applications depend on high performance and reliability from components such as coaxial cables and connectors.
There is a myriad of choices available, and in some cases, the right one may be the difference between optimal performance and failure. A sampling of the design challenges often faced when selecting the optimal cable assembly solution includes the need for very specific cables with high power, high flexibility and low loss; kink-free designs to help with flex/turn installations; nimble movement in tight and compact places; the flexibility to perform in environments with repeated movement; and situations where the RF needs to be low loss/signal to prevent interference.
Medical Advancements That Count on RF Performance
Ablation/ Robotic Surgery
An electrosurgical device unit (ESU) consists of a generator and a handpiece with one or more electrodes. Electrosurgical generators produce a variety of electrical waveforms. As these waveforms change, so do the corresponding tissue effects. Two minimally invasive procedures that use RF/microwave technology lead the way among this type of medical treatment.
Radio frequency ablation (RFA) and microwave ablation (MWA) use electrical and microwave energy to heat precision areas and destroy abnormal cells. The configuration of these life-saving machines requires coaxial cables in two critical places: both within the generator itself and to connect the external probes and catheters to the generator (see Figure 1).
Figure 1. Ablation system.
These require low loss cables that are easy to install in tight and compact places. Furthermore, using a cable with a kink-free design is ideal for installations with numerous flexing twists and turns. Connecting the probes and catheters to the generator requires cables that are small, flexible and nimble enough for the precise movements needed when performing procedures.
Additionally, robotics-assisted treatments are now often performed along with RFA and MWA. Cutting-edge custom coaxial cable solutions are often needed to power this, incorporating features such as low loss, high performance, precision, shielding and flexibility (see Figure 2).
Figure 2. Robotic surgery system.
MRI
MRI leverages RF pulses carried by coaxial cables. An MRI system must also be well shielded to minimize interference with a healthcare facility’s communications networks and electronic systems.
The MRI patient chamber is usually connected to signal and power sources in a separate, shielded room, interconnected by lengths of coaxial cable and connectors (see Figure 3). These cables must send consistent signals between magnetized and ordinary environments with high power demands. This can create challenging performance requirements for the coaxial interconnections.
Figure 3. MRI system.
While conventional corrugated cables meet low loss specifications, they are difficult to install in the restricted spaces often found within MRI applications. Cable assemblies must therefore handle suitable signal power levels without distortion and with performance levels equipping them for extreme conditions (similar to the requirements of military electronics systems). These cables need to exhibit low loss and other electrical characteristics to support MRI system performance, along with mechanical properties that can simplify installation of the system and the cables within, such as incorporating a tight bend radius for fitting into small spaces.
For example, a medical company was interested in creating a custom cable assembly for an MRI gurney. The cable needed to be able to withstand an enormous number of flexures with no loss in performance. The company’s design team worked with a coaxial cable industry expert to build a custom test set-up to simulate an application in which the assembly goes through two flexes every time a patient is placed in the MRI. The solution developed ultimately consisted of a high performance, flexible, low loss cable that was tested to more than 100,000 flexures with no degradation on performance. It was also designed with a hard, glossy Fluorinated Ethylene Propylene jacket so it would easily glide against the other cables in the gurney harness.
Quantum Computing
As quantum computing becomes more prevalent and will be saving years of development time and a substantial amount of money in engineering design. Quantum computing will ultimately give clinicians clearer insights into future healthcare risks and support predictive medicine. In diagnostic applications, quantum sensors may improve MRI machines to provide imaging at the molecular level, giving clinicians much more accurate images.
However, to keep quantum computers stable, they need to be exceptionally cold—typically colder than the vacuum of space. These extreme conditions include temperatures down to -460 degrees Fahrenheit. Quantum computers therefore require specialized cabling solutions such as a rugged, low loss and phase-stable coaxial assemblies. This class of semi-rigid cables was initially developed to support spaceflight missions, where the requirements of being vacuum sealed and able to withstand extremely low temperatures are key (see Figure 4). Beyond quantum computing, these cable assembly systems can also support other compute-intensive medical applications including drug development, virus research and advanced image processing.
Figure 4. Semi rigid cable.
Evolving Infrastructure and Connectivity Requirements
As the healthcare industry continues to take advantage of technical advancements, the communications technology powering them must also sufficiently advance to provide adequate bandwidth to support many simultaneous users, real-time video, large data transfers and more (see Figure 5). Unfortunately, despite their enormous potential, usage of many modern healthcare technologies is limited by a network’s capacity to handle data.
Figure 5. Internet of medical things (IoMT) networking equipment together.
This is because effectively communicating patient data requires ultra-reliable technologies to provide the seamless and secure transfer needed within and between medical facilities, and other outside locations such as a patient’s home. Slow network speeds and undependable connections could mean healthcare providers are unable to get the real-time data they need to make life-or-death healthcare decisions.
5G
5G wireless networks are now being rolled out to provide this much-needed bandwidth, at higher millimeter-wave frequency bands. For example, telemedicine requires a network that can support real-time high-quality video, which has traditionally required wired networks. With 5G however, healthcare systems can enable mobile networks to handle telemedicine visits, which has the potential to greatly increase reach. This technology can also enable patients to get treatment sooner and have access to a wider variety of specialists.
Wearables, which are commonly used in remote health-monitoring applications, increase patient engagement and decrease hospital costs. 5G technology, which has lower latency and higher capacity, can increase remote monitoring offerings for healthcare systems. Providers can be confident they will receive the data needed, in real-time, to help provide excellent patient care.
Ultimately, by enabling these technologies through advanced communications networks, healthcare systems can improve the quality of care and patient experience, reduce costs and more. But 5G demands a high level of interconnectivity – the frequencies can span from 24 GHz to 100 GHz, which is much higher than traditional wireless networks. As a result, RF performance and reliability are critical to support 5G. Optimal coaxial cables for this environment require higher frequency, broad bandwidth, proven reliability and low latency. Cable construction should also focus on high flexibility, low insertion loss and superior shielding.
Distributed Antenna Systems
Seamless communications among the facility, provider and patient is also critical in the healthcare environment. Therefore, indoor wireless communications solutions should be designed to cover the full area of a healthcare facility and surrounding buildings—but achieving full wireless coverage can be difficult. This is due to factors such as structural layout, building materials, types of electronic systems within the facility, number of users and more. For example, “blind spots” may occur because different building materials can act as shields blocking radio signals from reaching a mobile device user.
To eliminate these factors and achieve effective wireless communications coverage throughout the healthcare facility, many install distributed antenna system (DAS) technology. DAS solutions support licensed cellular communications frequency bands, such as 4G LTE and 5G, as well as unlicensed wireless bands such as Bluetooth, Wi-Fi, and wireless local area network (WLAN) frequencies. The DAS should be designed to handle peak loads based on bandwidth requirements for maximum use of Internet of Medical Things (IoMT) devices, medical diagnostic equipment and even a waiting room full of visitors on mobile devices.
While a DAS solution can greatly fortify wireless communications, it typically relies on high performance coaxial cables for connection to the public cellular network. The feed signal for a DAS from a cellular communications service provider may come from a base transceiver station, small cell, repeater or another source. Small cells, such as femtocells or picocells, are often used to provide cellular communications service inside buildings and DAS equipment ensures the signal levels and coverage within the buildings are adequate.
Coaxial cables with millimeter-wave capabilities will provide the performance needed for DAS links from 5G small cells and other cellular network sources. They should provide frequency range from DC to 50 GHz with better than 90 dB shielding or extend that frequency range to 70 GHz with a small-diameter cable capable if fitting into tight spots.
DAS equipment is also available in passive and active forms, with runs of coaxial cables helping to distribute cellular signals throughout a facility. PIM stability and UL plenum are required for indoors and ruggedness is needed for outdoor solutions. These coaxial cable assemblies need to be ultra-flexible while maintaining low PIM and be able to withstand flexure.
Why Passive Intermodulation Effects Are a Critical Consideration
5G and other modern mobile communication systems have wide transmitted signals. These signals can mix with themselves to generate intermodulation signals centered at the same frequencies and predicted by the intermodulation equations. These patterns can overlap with other intermodulation signals created from the other intermodulation orders.
These passive intermodulation (PIM) effects become an issue when two or more frequencies exist on the same cable at high power and interact with non-linear junctions along the RF path such as ferrous materials, solder air voids, loose fittings, loose conductive material, etc. This situation can result in the formation of new frequencies that are harmonics of the two original frequencies. These new frequencies may interfere with the lower power receive band and impact system efficiency.
PIM is an important factor in outdoor distributed antenna systems (oDAS) where multiple high power transmit signals are involved. Wireless carriers may also specify PIM performance in some applications such as lower power indoor distributed antenna systems (iDAS), as it is often viewed as a measurement of system quality.
The cable flexibility needed in these environments and PIM performance do not typically go hand-in-hand. Many products (corrugated cables, solder dipped cables and RG cables) do not have all the features needed for top PIM performance and/or ruggedness. It is important to find a manufacturer that can create ultra-flexible cables with ruggedness and performance along with bend movement and flexure. Furthermore, they should find additional ways to improve the cable assembly’s performance such as optimizing the induction soldering process to eliminate air voids, as well as thoroughly testing assemblies for both static and dynamic PIM.
Conclusion
RF is the backbone of many of today’s healthcare advancements, including MRI, medical telemetry, RF/microwave ablation, surgical robotic systems and a variety of IoMT technologies. As healthcare innovations continue to advance, so do the RF products needed to support them.
The ability to communicate medical data generated by these advanced diagnostic and treatment systems and devices to healthcare providers, patients and others is equally important as the device itself. Communications networking may be the difference between life and death in a healthcare facility—and developers of this critical infrastructure should choose the optimum mix of high-frequency RF/microwave coaxial cables and connectors to provide the essential interconnections required.
There are myriad choices available, and in some cases, the right one may be the difference between a system’s performance or failure. It is advantageous to work with a partner with dedicated expertise in RF/coaxial cable technologies to help create the optimal solution for your specific medical application. Healthcare developers should also seek a partner with a wide breadth of products created from experience in performance-critical industries such as military electronics, aerospace, space and other rugged environments, as well as the ability to create custom solutions designed for any specific need.