Technical Information

Solutions for medical technology—precise, reliableand long-lasting
Medical technology is an extremely sensitive industry, in more ways than one. People are in difficult and exceptional circumstances, since
their health—one of the most precious goods humans have—is under attack. Fears for one’s physical and financial well-being competewith the hope for healing and recuperation. In this situation patients are directly confronted with diagnostic and therapeutic high-techequipment that exactly mirrors this inner conflict. They cannot understand this technology, and in some cases they even fear it. At thesame time, all their hopes depend on the capabilities of these devices and machines. Naturally this also applies to the laboratories, even if
the patients are only indirectly aware of these high-tech facilities.
Devices and machines for medical technology must become accepted in this sensitive environment. One way of doing so is by ensuring
maximum comfort for the patients. This includes, for example, as smooth as possible a movement of the patient table or dental chair.
Another, and very effective, method is through reliable diagnoses and effective therapies, which instill trust in the patient. Highly precise
controls are necessary, for example, to exactly position the X-ray system of a CT scanner in very small steps for as many slices as possible
at high resolutions, or the linear accelerators of radiation therapy units.

In order to provide patient comfort and toensure high-precision control of the medicaltechnology, HEIDENHAIN offers acomprehensive range of linear, angle androtary encoders that optimally fulfill therequirements of medical technology, andfurthermore can be customized for specificrequirements:• High positioning accuracy• Measurement without backlash• High reliability and availability• High durability• Compact design

November 2013

HEIDENHAIN solutions for medical technology
Applications for diagnosis

Along with physical examinations anddiagnostics based on laboratory values
gleaned from blood and tissue samples,
imaging procedures in particular haveestablished themselves for diagnostic
procedures. These include X-rays,
computer tomography (CT) and magnetic
resonance imagining (MRI). They give thedoctor an insight into the patient’s bodywithout any invasive procedure. However,in these radiological diagnostic procedures
the patient is subjected to doses ofradiation. The more precisely the patient,
the source of radiation (X-ray tube), and thedetector can be positioned relative to eachother, the slighter the dose is.

Linear motions
As a rule, linear motions must bemeasured and controlled when moving thepatient table. The patient’s comfort is,naturally, a primary concern.
The height of the table can be adjusted sothat the patient may easily take place. In
modern CT and MRI scanners, the patientis brought into the scanning area whilelying on the table. Both the vertical andhorizontal motions must be smooth andwithout jerk, so that the patient feels asense of safety and security, and, ofcourse, does not come to harm.
In the scanning area of the diagnostic
equipment, the patient or the body part tobe examined must be positioned exactly
before examination can begin. Then,
depending on the diagnostic procedure,
the patient must be moved through thescanning area in a highly precise anddefined manner, so that images with thedesired slice thickness and necessary
resolution can be generated.

Linear encoders for a high degree of
patient comfort and very exact images
Absolute linear encoders from HEIDENHAIN
fulfill all requirements for use in modern
diagnostic equipment. Their fine graduations
and photoelectric scanning principle
transmit absolute, high-resolution position
values in short cycle times. This enables
highly dynamic closed-loop control of thedrive for the patient table, with very steadymotions and barely perceptible accelerationand deceleration. Also, thanks to theabsolute measurement, the position values
are always available immediately.
A high degree of self-monitoring and selfdiagnosis guarantee the functional safetyof linear encoders from HEIDENHAIN andprovides data for preventive service andmaintenance scheduling. Electronic andmechanical connection to the respective
system is possible without problems.

Rotary motions
Depending on the diagnostic device andtechnology, the sender (source) and/orreceiver (detector) move in a circle aroundthe patient. In order to achieve a highresolution and excellent image quality, adefined rotational movement at constantangular speed is necessary, possibly also
exactly coordinated with the linear motionof the patient table.

Rotary encoders and angle encoders
for perfect rotational motions
Absolute rotary encoders and angle
encoders provide the necessary position
data for controlling the rotational motion
with a high resolution and in short cycle
times. Absolute position measurement
always provides measured values
immediately. A reference run of thediagnostic mechanisms to determine areference position, i. e. a reset to the homeposition, is not required.
HEIDENHAIN angle encoders arecharacterized by high accuracy values in
the arc second range and better, down to± 0.4“. Rotary encoders from HEIDENHAIN
achieve accuracy grades as good as ± 12“.
The various designs versions, such as withmounted stator coupling or separate shaft
coupling, ensure that there are noproblems in the mechanical mounting.
Common interfaces are used for theelectronic connection.

HEIDENHAIN solutions for medical technology
Applications for therapy

During the diagnosis, the patient’s comfort
is of primary concern. But during therapy it
is his safety. No matter whether it isradiation therapy or a robot-assisted
operation, such procedures often affecthighly sensitive areas of the body, such asthe brain, spine, nervous system or vitalinternal organs.
Inaccuracies in the positioning or guidanceof the therapy instruments can have farreaching consequences. An incorrectly
targeted or shaped beam in radiation
therapy, a brachytherapy seed not placed
exactly, an incorrectly guided instrument ina robot-assisted operation, and the therapy
will not lead to the desired success, or,even worse, could damage the neighboringand healthy tissue.
Correspondingly important, therefore, isthe highly precise positioning of theinstruments, including continuous, realtime feedback to the doctor and equipment
operators regarding the current status.

Positioning of beam paths in radiation
therapy
In radiation therapy, cancer cells are treatedby, for example, bombarding them withhigh-energy photons. One method is to
aim the beams at the tumor from different
directions outside the body so that theyintersect exactly where treatment isnecessary. This way, a radiation dosage
sufficient for treatment is administered atthat point, while at the same time eachindividual beam poses no danger for thetissue it passes through.

In order for the intersection point of thesebeams to lie precisely within the desired
treatment area, the sources of the beams
must be aligned very exactly. First theymust be positioned on a radial path aroundthe patient, and then there focused on thepatient at just the right angle. Positioning
errors of just a few angular seconds canexponentiate themselves and then, since
the beams are all so narrow, there will be
no optimal point of intersection.
The high reliability and availability of thelinear and angle technology from HEIDENHAIN is definitive here, in particular regarding the high dosages of radiation, which
can influence or destroy electrical components.

Guidance of instruments and seeds
So while in radiation therapy the precisealignment of beam sources outside thepatient’s body, with a target inside hisbody, must be ensured, robot-assisted
operations and brachytherapy actually
move instruments, implants or medical
seeds through a patient’s body. Especiallybecause these types of therapy are
considered to be minimally invasive, theyrequire the highest degree of precision
when guiding the instruments past healthy
and possibly very sensitive tissue on theway to the actual site of the operation orimplantation. Once there, the instruments
must continue to be guided with theutmost precision in a minimum of space tothe point of actual operation, in order toavoid any unintentional damage to healthy
tissue.

The guidance and operation of theinstruments in these types of therapy
require highly precise linear and angular
technology, with the highest possible
resolution of the measurement results. The
operator must know at every point during
the operation exactly where the guided
instrument is in the body, and how it isoriented there. This includes, for example,
the alignment of a miniature camera or theposition of a microgripper or cauter inelectrocautery. The instrument must thenobey the commands of the operator
exactly. Furthermore, the operating system
must be guaranteed not to fail; the linear
and angle encoders from HEIDENHAIN
fulfill all of these requirements safely andreliably. They supply measurement data ata high resolution without backlash, andtheir interfaces ensure rapid data transfer
to the control electronics so that theoperation can be performed without delays.

HEIDENHAIN solutions for medical technology
Applications in the laboratory

Modern medical laboratories arecharacterized by highly automatedprocesses with a high degree ofrepeatability. Their task is the analysis ofvery small individual samples in large
charges within a very brief time. To thisend, for example, the cavities on microtiterplates are becoming ever smaller and evermore closely placed. In this manner, large
charges of samples can by analyzed withthe sparing use of expensive reagents.
In order for the results of the analyses tobe absolutely reliable and correct, thelaboratory equipment, such as automaticpipetters for liquid handling, must be
controlled very precisely. One faulty
transfer of liquids would lead to erroneous
results and the destruction of valuable andpossibly irreplaceable samples. The
importance of modern laboratory
technology is also shown by the fact thatmany devices are equipped with redundantmeasuring technology that continuously
monitors the position.

Absolute positioning accuracy
Linear and angle encoders from
HEIDENHAIN ensure a high degree of
positioning accuracy at high traverse
speeds. Thanks to the absolute position
measurement, exact information about theposition is available at all times, such as forthe pipettes in the automatic pipetters. The
high resolution of the encoders and therapid data transfer to and from the control
permit very precise positioning, but at thesame time ensure a very steady and evencontrol response for movement of thesamples without jerk.
For rotatory systems there are absolute
angle encoders with a measuring accuracy
as good as ± 0.4“. For linear systems
HEIDENHAIN offers linear encoders withan accuracy grade of ± 3 µm up to ameasuring length of 28 m. This makes
high-precision monitoring and controlling oflong measuring and control paths in linked
laboratory chains possible.

Perfect radial runout
Numerous laboratory processes require
devices that can perform defined rotational
cycles with the utmost radial runout precision, even at changing rotational speeds:
Absolute angle encoders with shaft speeds
up to 1500 min-1 and rotary encoders withshaft speeds up to 12 000 min-1 are ideallysuited for this exact rotational control. In
this application as well the high resolutionof HEIDENHAIN encoders and their rapid
data transmission ensure very precise radial runout, gentle acceleration and deceleration, and a quick response to the control
commands.

Encoders from HEIDENHAIN
Competency in measuring and control technology

HEIDENHAIN is one of the worldwide
technological leaders for linear, angle, androtary encoders, as well as for digital
readouts for machines and facilities.
HEIDENHAIN achieves this success by
combining the continuous drive to provide
technically superior products with reliability,
closeness to the customer, and a practiceoriented frame of mind. Part of this is thecontinual dialog with science and researchon the one hand and with users andcustomers on the other.
Competence in the area of linear andangular metrology is reflected by a large
number of customized solutions for users.
These include the measuring and test
equipment developed and built for many of
the world’s standards laboratories and theangle encoders for various telescopes andsatellite receiving antennas. HEIDENHAIN
naturally applies the know-how gained
from these experiences to all products,
ranging from customized solutions for
specific industries to series production.

Measuring standard and absolutemeasuring principle
HEIDENHAIN encoders with opticalscanning incorporate measuring standardsof periodic structures known as
graduations. They have grating periods asfine as 2 µm or even better, combined withhigh edge definition and good homogeneityof the graduation. Together with the photo­
electric scanning method, this finegraduation is a precondition for the highquality of the output signals of HEIDEN­
HAIN’s linear, angle and rotary encoders
and digital readouts. With the absolutemeasuring principle the position value isavailable immediately after the encoder has
been switched on. The absolute position
information is read from the graduatedmeasuring standard, which is formed froma serial code structure, and from a separate
incremental track that is interpolated forthe position value.

Advantages for medical technology
Devices for medical technology must
perform many different linear and rotary
movements without any positioning errors.
Linear, angle and rotary encoders, as well
as digital readouts from HEIDENHAIN
perfectly fulfill this requirement. After all,the advantages of the fine measuring
standard and the absolute measuring
procedure are of particular interest for
applications in medical technology. Theyoffer:• High-precision positioning• Safe position capture even when notunder power• High system accuracy• High resolution of the control steps
The compact and fully-integrated design ofthe digital readouts and linear, angle androtary encoders from HEIDENHAIN permit
their installation even where space islimited. At the same time they operate
absolutely reliably and with a high degreeof availability.

Encoders from HEIDENHAIN
Further information

Catalog
Length Gauges

Catalog
General Catalog

Lieferübersicht
Längenmessgeräte

Messtaster

Längenmessgerätefürgesteuerte
MesstasterWerkzeugmaschinen
Winkelmessgeräte
DrehgeberBahnsteuerungenTastsystemePositionsanzeigen

SeptemberAugust20122013

November 2007

CatalogAngle Encoders with Integral Bearing

Catalog
Exposed Linear Encoders

OffeneLängenmessgeräte

März 2012

Contents:
Absolute Linear Encoders
LIC
Incremental Linear Encoders
LIP, PP, LIF, LIDA

Winkelmessgeräte
mit Eigenlagerung

August 2013

Contents:
Absolute Angle Encoders
RCN, ECN
Incremental Angle Encoders
RON, RPN, ROD

Catalog
Angle Encoders without Integral Bearing

Catalog
Rotary Encoders
Contents:
Absolute Rotary Encoders
ECN, EQN, ROC, ROQ
Incremental Rotary Encoders
ERN, ROD

Contents:
HEIDENHAIN-ACANTOHEIDENHAIN-SPECTOHEIDENHAIN-METROHEIDENHAIN-CERTO

Winkelmessgeräteohne Eigenlagerung

Contents:
Incremental Angle Encoders
ERA, ERO, ERP

September 2011

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