The number of medical imaging systems continues to grow at a projected annual rate of 6.8 percent, and linear motion control systems have become vital to the successful development, advancement, and deployment of these essential pieces of medical equipment.
Medical imaging systems are now diagnostic and treatment mainstays in just about every area of clinical care, including cardiology, oncology, neurology, and trauma care. To meet growing demand, original equipment manufacturers (OEMs) need to leverage effective, modular linear motion solutions to control costs, streamline production, and beat the competition. This article will examine the various medical imaging systems, their motion control needs and challenges, and effective linear motion solutions for medical imaging applications.
Medical Imaging Applications that Need Motion Control
There are many types of medical imaging systems. The primary medical imaging applications that rely on linear motion control systems are:
- Computed Tomography (CT) Scanners – CT scanners are devices that produce 3D images of internal organs, bones, and tissues using an extensive series of 2D x-ray images. These images are taken using a single-axis rotating structure called a gantry is driven by lead screw assemblies.
- Magnetic Resonance Imaging (MRI) Scanners – Using powerful magnets that create a magnetic field that forces hydrogen atoms into a specific alignment within the body. This non-invasive diagnostic technology produces human physiological images. MRI devices distribute radio frequency energy throughout the body. This energy is interrupted by body tissue in different ways signaled back to the device to create an image.
- Positron Emission Tomography (PET) Scanners – Measuring radiation emissions from the body that radioactive elements consumed by the patient generates, PET scanners produce physiological images of specific organs or tissues. They are used to identify the presence and/or growth of cancer cells.
- Ultrasound Machines – These devices use sound waves to create images of what’s inside the body, such as to view a developing fetus or detect internal flaws.
- X-Ray Machines – Although x-ray technology has a long history in medicine, the immediate availability of x-ray images in digital format is revolutionizing diagnostic radiology and sparking a growing number of applications, particularly in dentistry and surgery.
Linear Motion Control Requirements
Linear motion control systems must precisely position patients and scanning heads to achieve accurate, reliable, and trustworthy imaging results. However, this high-precision performance must be completed in the face of unique challenges to the medical diagnostic environment.
Specifically, the linear motion control assemblies in medical imaging devices must operate comfortably for the patient and be suitable for medical diagnostic and treatment settings. They must run smoothly, quietly, and with as little maintenance necessary as possible.
Precision-engineered lead screws are the optimal solution for medical imaging applications. Lead screws and the linear guides on which they travel can be designed to substantially reduce noise generation while simultaneously providing smooth, problem-free operation. Lead screws made from specially engineered plastics with internal lubrication of the screw and nut can dramatically reduce maintenance, service calls, and downtime. It’s also beneficial to utilize modular motion control systems to simplify engineering, reduce costs, and facilitate assembly.
Single-Plane vs. Multi-Axis Motion Control Solutions
In engineering a medical imaging system, designers initially need to determine the kinematic motion required by the device and sometimes the algorithms necessary to achieve the specified movement. The most rudimentary linear motion control drives single-plane motion, such as moving a patient table in and out of a scanning mechanism or up and down. The movement is most commonly achieved with horizontal X-Y lead screw assemblies.
However, many of today’s medical imaging devices are much more sophisticated, requiring complex and challenging kinematics. For example, some systems utilize an imaging arc, often referred to as a C-arc gantry. These systems rotate both the imaging beam source and detector 180 degrees around the patient, requiring coordination of lead screw assemblies in X, Y, and Z planes around the patient table. As well as three-axis motion control to move the table vertically and horizontally and tilt the table from front to back and side to side.
Even more complex kinematics are involved in supporting isocentric linear motion. In devices that support this function, the imaging beam is maintained on the patient’s body at a specific point. In contrast, the imager and patient table move separately through many passes to create a 360-degree image. Because these motion control systems must drive up to nine axes of linear motion through the X, Y, and Z planes—all while keeping image resolution centered on a point that may only be millimeters wide—they require an extremely challenging loop computations. Lead screws are the preferred solution for all medical imaging positioning complexity because they are smooth, quiet, maintenance-free, and precise.
Configuring Lead Screws for Your Medical Imaging Application
Configuring lead-screw assemblies to meet your particular medical device design demands a thorough understanding of the kinematics and range of motion requirements, as well as available lead screw materials and performance characteristics. Modular lead screw assemblies optimized for your specific application can improve performance, minimize maintenance, and reduce costs.