Fig. 1 Varian Medical Systems, Inc.
Thanks to exceptionally accurate linear and rotary encoders from HEIDENHAIN, modern CT and MRI machines ensure a high level of patient comfort and exceptional image quality.

Comfortable Medical Devices Possible with Reliable Position Encoders

Medical equipment often requires reliable, highly accurate measurement solutions for applications such as patient positioning or position measurement in automated laboratories. HEIDENHAIN examines how encoders can be used for precision medical equipment.

At first glance, patient positioning and laboratory automation appear to be two completely different fields within the vast medical technology sector. Yet, when it comes to positioning, they share many commonalities: Both of these applications require encoders featuring high position accuracy, absolute measurement without backlash, high reliability, failure safety, ruggedness, and a compact design.

Exceptional Comfort, High-Accuracy Imaging

When the examination table of a modern CT or MRI machine is moved for positioning, motion must be measured and controlled in a variety of directions. For example, something as simple as the patient reaching and getting on the table requires adjustment of the table’s height. Once the patient is lying on the table, it is moved into the scanning area. In both of these operations, patient comfort is paramount. Smooth, gentle motions make the patient feel safe and prevent causing pain.

The transfer of samples without losses in highly automated laboratory equipment, such as in automated pipettors, is made possible through exact positioning and smooth control behavior for jerk-free traversing movements.

Once in the scanning area of the diagnostic machine, the patient—or rather, the part of the body to be examined—must be brought into exact position before the examination can begin. In addition to longitudinal and transverse positioning, the inclination is adjusted as well. Then, depending on the diagnostic procedure, the patient must be moved through the scanning area in a controlled manner with exceptional precision so that images with the desired slice thickness and required resolution can be generated.

In these cases, high accuracy exposed linear and rotary encoders are extremely well suited for these applications. By directly measuring the absolute position at all times without a reference run and by transmitting high-resolution position values, these encoders permit highly dynamic closed-loop control of the drives. Acceleration and deceleration are, in turn, barely perceptible, resulting in very smooth and comfortable movements for the patient. At the same time, positioning is also highly accurate.

HEIDENHAIN’s LIC 2100 exposed linear encoder with absolute position measurement ensures smooth motion, providing comfort to patients during positioning as well as advantages for liquid handling in the lab.

Encoders equipped with functional safety also will provide a high degree of self-monitoring and self-diagnostics. They deliver data for the preventive management of servicing and maintenance intervals. Moreover, an EnDat 2.2 interface permits online diagnostics of the encoders’ operating status to enable high availability of the expensive diagnostic imaging equipment. A mechanical fault exclusion feature aids in this as well.

Error-Free Transfer of Samples

Modern medical laboratories are characterized by heavily automated processes with high repeatability. These labs are tasked with analyzing tiny individual samples in large batches within a very short amount of time. This is why, for example, the wells on microtiter plates are becoming ever smaller and more closely spaced. By this means, large sample batches can be analyzed with only a tiny amount of expensive reagents.

HEIDENHAIN’s ECN 1123 and EQN 1135 rotary encoder versions with functional safety ensure high availability for medical technology equipment.

In order for the analysis results to be absolutely reliable and correct, laboratory equipment, such as automated pipettors for liquid handling, must be controlled with great precision. One faulty transfer of liquids could lead to erroneous results and the destruction of valuable and possibly irreplaceable samples. The fact that many devices are equipped with redundant measuring technology that continuously monitors the position shows just how important accuracy is in modern laboratory technology.

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