ASTM F2554-22
(Practice)Standard Practice for Measurement of Positional Accuracy of Computer-Assisted Surgical Systems
Standard Practice for Measurement of Positional Accuracy of Computer-Assisted Surgical Systems
SIGNIFICANCE AND USE
5.1 The purpose of this practice is to provide data that can be used for evaluation of the accuracy of different CAS systems.
5.2 The use of surgical navigation and robotic positioning systems is becoming increasingly common. In order to make informed decisions about the suitability of such systems for a given procedure, their accuracy capability needs to be evaluated under clinical application and compared to the requirements. As the performance of a whole system is constrained by those of its subparts, a preliminary step must be to objectively characterize the accuracy of the tracking subsystem in a controlled environment under controlled conditions.
5.3 In order to make comparisons within and between systems, a standardized way of measuring and reporting accuracy is needed. Parameters such as coordinate system, units of measurement, terminology, and operational conditions must be standardized.
SCOPE
1.1 This document provides procedures for measurement and reporting of basic static performance of surgical navigation and/or robotic positioning devices under defined conditions. They can be performed on a subsystem (for example, tracking only) or a full computer-aided surgery system as would be used clinically. Testing a subsystem does not mean that the whole system has been tested. The functionality to be tested based on this practice is limited to the performance (accuracy in terms of bias and precision) of the system regarding point localization in space by means of a pointer. A point in space has no orientation; only multidimensional objects have orientation. Therefore, orientation of objects is not within the scope of this practice. However, in localizing a point the different orientations of the pointer can produce errors. These errors and the pointer orientation are within the scope of this practice. The aim is to provide a standardized measurement of performance variables by which end users can compare within a system (for example, with different reference elements or pointers) and between different systems (for example, from different manufacturers). Parameters to be evaluated include (based upon the features of the system being evaluated):
(1) Accuracy of a single point relative to a coordinate system.
(2) Sensitivity of tracking accuracy due to changes in pointer orientation.
(3) Relative point-to-point accuracy.
1.1.1 This method covers all configurations of the evaluated system as well as extreme placements across the measurement volume.
1.2 This practice defines a standardized reporting format, which includes definition of the coordinate systems to be used for reporting the measurements, and statistical measures (for example, mean, RMS, and maximum error).
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard, except for angular measurements, which may be reported in terms of radians or degrees.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
General Information
Relations
Standards Content (Sample)
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: F2554 − 22
Standard Practice for
Measurement of Positional Accuracy of Computer-Assisted
Surgical Systems
This standard is issued under the fixed designation F2554; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope standard, except for angular measurements, which may be
reported in terms of radians or degrees.
1.1 This document provides procedures for measurement
1.4 This standard does not purport to address all of the
andreportingofbasicstaticperformanceofsurgicalnavigation
safety concerns, if any, associated with its use. It is the
and/or robotic positioning devices under defined conditions.
responsibility of the user of this standard to establish appro-
They can be performed on a subsystem (for example, tracking
priate safety, health, and environmental practices and deter-
only)orafullcomputer-aidedsurgerysystemaswouldbeused
mine the applicability of regulatory limitations prior to use.
clinically. Testing a subsystem does not mean that the whole
1.5 This international standard was developed in accor-
system has been tested. The functionality to be tested based on
dance with internationally recognized principles on standard-
thispracticeislimitedtotheperformance(accuracyintermsof
ization established in the Decision on Principles for the
biasandprecision)ofthesystemregardingpointlocalizationin
Development of International Standards, Guides and Recom-
space by means of a pointer. A point in space has no
mendations issued by the World Trade Organization Technical
orientation; only multidimensional objects have orientation.
Barriers to Trade (TBT) Committee.
Therefore, orientation of objects is not within the scope of this
practice. However, in localizing a point the different orienta-
2. Referenced Documents
tions of the pointer can produce errors. These errors and the
pointer orientation are within the scope of this practice. The
2.1 ASTM Standards:
aim is to provide a standardized measurement of performance
E456 Terminology Relating to Quality and Statistics
variables by which end users can compare within a system (for
E2281 Practice for Process Capability and Performance
example, with different reference elements or pointers) and
Measurement
between different systems (for example, from different manu-
2.2 Other References:
facturers). Parameters to be evaluated include (based upon the
ISO 10360 Geometrical Product Specifications (GPS)—
features of the system being evaluated):
Acceptance and Reverification Tests for Coordinate Mea-
(1) Accuracy of a single point relative to a coordinate
suring Machines (CMM)
system.
(2) Sensitivity of tracking accuracy due to changes in
3. Terminology
pointer orientation.
(3) Relative point-to-point accuracy.
3.1 Definitions:
1.1.1 This method covers all configurations of the evaluated 3.1.1 accuracy, n—the closeness of agreement between a
system as well as extreme placements across the measurement
measurement result and an accepted reference value. E456
volume. 3.1.1.1 Discussion—In the context of this standard, with the
definitions of bias and precision (see below), it can be
1.2 This practice defines a standardized reporting format,
considered that the accuracy of a measurement of a point will
which includes definition of the coordinate systems to be used
be subject to some bias error and some precision error.
for reporting the measurements, and statistical measures (for
3.1.2 bias, n—the difference between the expectation of the
example, mean, RMS, and maximum error).
measurement results and an accepted reference value. E456
1.3 The values stated in SI units are to be regarded as
standard. No other units of measurement are included in this
1 2
ThispracticeisunderthejurisdictionofASTMCommitteeF04onMedicaland For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Surgical Materials and Devices and is the direct responsibility of Subcommittee contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
F04.38 on Computer Assisted Orthopaedic Surgical Systems. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved Sept. 1, 2022. Published September 2022. Originally the ASTM website.
approved in 2010. Last previous edition approved in 2018 as F2554 – 18. DOI Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
10.1520/F2554-22. 4th Floor, New York, NY 10036, http://www.ansi.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F2554 − 22
3.1.2.1 Discussion—In the context of this standard, bias 3.1.18.1 Discussion—In the context of this standard, preci-
represents the systematic error in a set of measurements of a sion represents scatter of a set of measurements of a point.
target reference point making their average deviate from the
3.1.19 range, R, n—the largest observation minus the small-
actual reference point with a certain magnitude and direction.
est observation in a set of values or observations. E456, E2281
3.1.3 calibration, n—the pre- or intraoperative registration
3.1.20 reference element, n—an artificial item composed of
of an item or device to its reference element.
rigidly bound markers in a unique and asymmetrical pattern
3.1.4 computer-assisted surgery (CAS), n—the use of com- recognizable by the tracker. While being rigidly attached to a
puterstofacilitateorenhancesurgicalproceduresviatheuseof
therapeutic object, the position and orientation of the reference
three-dimensional space tracking of objects. element can be used to determine those of the therapeutic
object after its calibration.
3.1.5 coordinate measuring machine (CMM), n—measuring
system with the means to move a stylus and capability to
3.1.21 registration, n—the determination of the spatial rela-
determine spatial coordinates on a work piece surface. ISO
tionship between the referential frames of two coordinate
10360-1
systems. This may occur between two reference elements or
between the fiducials and a reference element of a therapeutic
3.1.6 degree of freedom (DOF), n—set of independent
object. The registration is rigid if it consists only of rotations
displacements that specify completely the displaced or de-
and translations (six degrees of freedom) and non-rigid if it
formed position of the body or system.
also comprises scaling and/or local or global distortions (seven
3.1.7 dynamic reference base, n—the coordinate system of a
degrees of freedom and more).
reference element used for the tracking of other therapeutic
3.1.22 repeatability, n—precision under repeatability
objects.
conditions. E456
3.1.8 fiducial, n—an artificial item (for example, a screw or
3.1.23 reproducibility, n—precision under reproducibility
a sphere) rigidly attached to a therapeutic object to facilitate its
conditions. E456
calibration.
3.1.24 robotic positioning system, n—use of an active me-
3.1.9 ground truth, n—shortnamefortheacceptedreference
chanical (mechatronic) device to position an instrument guide
value (see 3.1.1).
at a specified location in 3D space (up to six degrees of
3.1.10 marker, n—asingle3-degree-of-freedomindicatoron
freedom).
a reference element or dynamic reference base.
3.1.25 root mean square (RMS), n—means of estimation of
3.1.11 maximum error, n—the largest distance between any
the scatter of a set of values, which consists of the square root
measured point and its ground truth for any trial during a
of the average of the squared values.
testing procedure.
3.1.26 therapeutic object, n—a surgical item or a part of the
3.1.12 mean, n—of a population, u, average or expected
patient.
value of a characteristic in a population; of a sample, x, sum of
3.1.27 tracker, n—a device that detects and locates fiducials
the observed values in the sample divided by the sample size.
and markers in its measurement volume. This can be achieved
E456
by mechanical linkage or by analyzing signals of various types
3.1.13 measurement range, n—the interval of allowed val-
(visible or infrared light, electromagnetic field, or ultrasound).
ues for a specific degree of freedom while performing the
practice.
4. Summary of Practice
3.1.14 measurement volume, n—measuring range of a
4.1 This practice provides recommendations for the
tracker, stated as simultaneous limits on all spatial coordinates
collection, analysis, and presentation of data regarding the
measured by the tracker. ISO 10360-1
positional accuracy (in terms of bias and precision) of surgical
3.1.15 navigation system, n—a set of devices consisting of a
navigation and robotic positioning systems under repeatable
computer, its associated software, and a tracker capturing the
conditions.
reference elements within the measurement volume. This
4.2 Data to be reported consists of all measurements, their
system provides real-time feedback of the state of the surgical
corresponding errors if applicable, their statistical analysis, the
scene under operation.
test conditions, and the system conditions.
3.1.16 phantom, n—standardized measurement object. See
5. Significance and Use
Appendix X1 for details regarding the design of the phantom
used in this practice.
5.1 The purpose of this practice is to provide data that can
be used for evaluation of the accuracy of different CAS
3.1.17 pointer, n—the device offered by the evaluated sys-
systems.
tem to point and locate a position on any object including
anatomical landmarks.The pointer is the whole device, includ-
5.2 The use of surgical navigation and robotic positioning
ing the stylus-like tip all the way to any reference element used
systems is becoming increasingly common. In order to make
to track it in space.
informed decisions about the suitability of such systems for a
3.1.18 precision, n—the closeness of agreement between given procedure, their accuracy capability needs to be evalu-
independent measurement results obtained under stipulated ated under clinical application and compared to the require-
conditions. E456 ments.As the performance of a whole system is constrained by
F2554 − 22
those of its subparts, a preliminary step must be to objectively 8.3 System Conditions—The system is composed of various
characterize the accuracy of the tracking subsystem in a parts and all their references and configuration shall be
controlled environment under controlled conditions.
provided, including firmware and software versions. Any
changes to the system beyond what is provided and configured
5.3 In order to make comparisons within and between
by the manufacturer are to be reported and justified (for
systems, a standardized way of measuring and reporting
example, using third-party markers or pointer). Specific details
accuracy is needed. Parameters such as coordinate system,
of the phantom are also to be reported (for example, the divot
units of measurement, terminology, and operational conditions
dimensions). The measured points are to be acquired only
must be standardized.
through the firmware and software provided by the manufac-
6. Apparatus
turer.
6.1 The system under test is considered to have at least
8.4 Phantom Placement and Registration—In the first series
some tracking functionality, a pointer and associated hardware,
of tests, place the system tracker nominally at the recom-
and software. If the system is provided by the manufacturer
mended distance from the phantom. At this location, a regis-
with various combinations of parts, the evaluation must be
tration of the phantom to the dynamic reference base may be
performed at least with the combination known to present the
required for most systems.Any registration shall be performed
worst-case scenario in terms of accuracy. For example, the
as described by the manufacturer, simulating registration of a
tester may use the longest pointer with the smallest reference
patient’s anatomy in the clinical environment. Registration can
elements.
only be done once to cover the sequence of steps 8.6 – 8.9, but
6.2 This practice relies on a phantom. See Appendix X1 for
may be repeated in between.
design requirements. The phantom size and points have been
designed to approximate a typical surgical site on the human 8.5 Point Acquisition—In each trial, the tester locates the
body. All divots of the phantom shall be measured by a CMM individual labeled points on the phantom and acquires its
(or another measurement system of similar performance trace-
position using the pointer following the system manufacturer’s
able to NIST, FDA, EU, and ISO standards). These phantom instructions for obtaining point data. This includes pointer
measurements will constitute the ground truth used for the
orientation except for the rotation tests in 8.7.
accuracy assessment. Therefore, the accuracy of the CMM
8.6 Test 1: Single Point Accuracy—Treating the phantom as
must be better than that of the system being evaluated.
if it was part of the patient’s anatomy, this test requires the
6.3 If the evaluated system relies on a dynamic reference
measurement of a designated point of the phantom multiple
base for its measurements, a reference element is attached to
times, to compare the positions measured versus the actual
the phantom. This reference element and its attachment shall
position on the phantom relative to its local coordinate system.
replicate as close as possible those used in a surgical setting.
Thesinglepointmeasurementisthenindependentlyperformed
6.4 If dedicated additional software functionality is used for
20 times on the central divot (#20 in Fig. X1.1). Bias is
assistance in performing the tasks outlined in this practice, or
estimated by the difference between the average of the mea-
for statistical analysis of the measurements, this addition must
sured points and the central divot. The result is a small error
not alter the way the measurements are made by the system to
vector emanating from the target reference point. Calculate the
be used clinically.
average of all the error vectors by vectorial summation then
dividing the length of the resulting vector by the number of
7. Hazards
vectors. Report the average error vector and the length of the
7.1 None.
longesterrorvector.Forthedeterminationofprecision,startby
calculating the average point of all measurements, which
8. Procedure
represents the system’s best estimate for the locati
...
This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: F2554 − 18 F2554 − 22
Standard Practice for
Measurement of Positional Accuracy of Computer Assisted
Computer-Assisted Surgical Systems
This standard is issued under the fixed designation F2554; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This practice addresses the techniques of document provides procedures for measurement and reporting of basic static
performance (accuracy, repeatability, and so forth) of surgical navigation and/or robotic positioning devices under defined
conditions. The scope covers the tracking subsystem, testing only in this practice the accuracy and repeatabilityThey can be
performed on a subsystem (for example, tracking only) or a full computer-aided surgery system as would be used clinically. Testing
a subsystem does not mean that the whole system has been tested. The functionality to be tested based on this practice is limited
to the performance (accuracy in terms of bias and precision) of the system to locate individual points in space. regarding point
localization in space by means of a pointer. A point in space has no orientation; only multi-dimensionalmultidimensional objects
have orientation. Therefore, orientation of objects is not within the scope of this practice. However, in localizing a point the
different orientations of the localization tool pointer can produce errors. These errors and the orientation of the localization tool
pointer orientation are within the scope of this practice. The aim is to provide a standardized measurement of performance variables
by which end-users end users can compare within a system (for example, with different fixed reference frameselements or stylus
tools) pointers) and between different systems (for example, different manufacturers) different systems. from different
manufacturers). Parameters to be evaluated include (based upon the features of the system being evaluated):
(1) LocationAccuracy of a single point relative to a coordinate system.
(2) Relative point to point accuracy (linear).Sensitivity of tracking accuracy due to changes in pointer orientation.
(3) Repeatability of coordinates of a single point.Relative point-to-point accuracy.
(4) For an optically based system, the range of visible orientations of the reference frames or tools.
(5) This method covers all configurations of tool arrays in the system.
1.1.1 This method covers all configurations of the evaluated system as well as extreme placements across the measurement
volume.
1.2 The system as defined in this practice includes only the tracking subsystem (optical, magnetic, mechanical, and so forth) stylus,
computer, and necessary hardware and software. As such, this practice incorporates tests that can be applied to a prescribed
phantom model in a laboratory or controlled setting.
1.2 This practice defines a standardized reporting format, which includes definition of the coordinate systems to be used for
reporting the measurements, and statistical measures (for example, mean, standard deviation,RMS, and maximum error).
1.4 This practice will serve as the basis for subsequent standards for specific tasks (cutting, drilling, milling, reaming, biopsy
needle placement, and so forth) and surgical applications.
This practice is under the jurisdiction of ASTM Committee F04 on Medical and Surgical Materials and Devices and is the direct responsibility of Subcommittee F04.38
on Computer Assisted Orthopaedic Surgical Systems.
Current edition approved Nov. 1, 2018Sept. 1, 2022. Published December 2018September 2022. Originally approved in 2010. Last previous edition approved in 20102018
as F2554F2554 – 18.–10. DOI 10.1520/F2554–18.10.1520/F2554-22.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F2554 − 22
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this
standard.standard, except for angular measurements, which may be reported in terms of radians or degrees.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of
regulatory limitations prior to use.
1.5 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
E456 Terminology Relating to Quality and Statistics
E2281 Practice for Process Capability and Performance Measurement
2.2 Other References:
ISO 10360 Geometrical Product Specifications (GPS)—Acceptance and Reverification Tests for Coordinate Measuring
Machines (CMM)
3. Terminology
3.1 Definition of Terms Specific to Accuracy Reporting:
3.1.1 accuracy, n—the closeness of agreement between a measurement result and an accepted reference value. E456
3.1.1.1 Discussion—
The term accuracy, when applied to a set of measurement results, involves a combination of a random component and of a common
systematic error or bias component.
3.1.2 bias, n—the difference between the expectation of the measurement results and an accepted reference value. E456
3.1.2.1 Discussion—
Bias is the total systematic error as contrasted to random error. There may be one or more systematic error components contributing
to the bias. A larger systematic difference from the accepted reference value is reflected by a larger bias value.
3.1.3 maximum error, n—the largest distance between any measured point and its corresponding reference position (for example,
as measured by CMM) for any trial during a testing procedure.
3.1.4 mean, n—the arithmetic mean (or simply the mean) of a list of numbers is the sum of all the members of the list divided
by the number of items in the list. If one particular number occurs more times than others in the list, it is called a mode. The
arithmetic mean is what students are taught very early to call the “average”. If the list is a statistical population, then the mean
of that population is called a population mean. If the list is a statistical sample, we call the resulting statistic a sample mean.
3.1.5 measurement range, n—see measurement volume.
3.1.6 precision, n—the closeness of agreement between independent measurement results obtained under stipulated conditions.
E456
3.1.6.1 Discussion—
Precision depends on random errors and does not relate to the true value or the specified value. The measure of precision usually
is expressed in terms of imprecision and computed as a standard deviation of the test results. The standard deviation is expressed
as:
N
¯
~X 2 X!
( i
i51
S 5
!
N 2 1
Less precision is reflected by a larger standard deviation. “Independent test results” means results obtained in a manner not
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http://www.ansi.org.
F2554 − 22
influenced by any previous result on the same or similar test object. Quantitative measure of precision depends critically on
the stipulated conditions. Repeatability and reproducibility conditions are particular sets of extreme stipulated conditions.
3.1.7 range, R, n—the largest observation minus the smallest observation in a set of values or observations. E456, E2281
3.1.8 repeatability, n—precision under repeatability conditions. E456
3.1.8.1 Discussion—
Repeatability is one of the concepts or categories of the precision of a test method. Measures of repeatability defined in this
compilation are repeatability, standard deviation, and repeatability limit.
3.1.9 reproducibility, n—precision under reproducibility conditions. E456
3.1.9.1 Discussion—
Ability of a test or experiment to be accurately reproduced, or replicated.
3.1.10 resolution, n—of a device/sensor, the smallest change the device or sensor can detect in the quantity that it is measuring.
The resolution is related to the precision with which the measurement is made.
3.1.11 standard deviation, n—the most usual measure of the dispersion of observed values or results expressed as the positive
square root of the variance. E456
3.1.12 variance, n—of a random variable, measure of its statistical dispersion, indicating how its possible values are spread around
the expected value. Where the expected value shows the location of the distribution, the variance indicates the scale of the values.
A more understandable measure is the square root of the variance, called the standard deviation.
3.1 Definition of Terms Specific to Surgical Navigation and Robotic Positioning Systems: Definitions:
3.1.1 data integrity, accuracy, n—condition in which data is identically maintained during any operation, such as transfer, storage,
and retrieval.the closeness of agreement between a measurement result and an accepted reference value. E456
3.1.1.1 Discussion—
In the context of this standard, with the definitions of bias and precision (see below), it can be considered that the accuracy of a
measurement of a point will be subject to some bias error and some precision error.
3.1.2 bias, n—the difference between the expectation of the measurement results and an accepted reference value. E456
3.1.2.1 Discussion—
In the context of this standard, bias represents the systematic error in a set of measurements of a target reference point making their
average deviate from the actual reference point with a certain magnitude and direction.
3.1.3 calibration, n—the pre- or intraoperative registration of an item or device to its reference element.
3.1.4 computer-assisted surgery (CAS), n—the use of computers to facilitate or enhance surgical procedures via the use of
three-dimensional space tracking of objects.
3.1.5 coordinate measuring machine (CMM), n—measuring system with the means to move a stylus and capability to determine
spatial coordinates on a work piece surface. ISO 10360-1
3.1.6 degree of freedom (DOF), n—set of independent displacements that specify completely the displaced or deformed position
of the body or system.
3.1.7 dynamic reference base, n—the coordinate system of a reference element that is intraoperatively attached to a therapeutic
object and allows tracking that object. It defines the local coordinate system of the therapeutic object.used for the tracking of other
therapeutic objects.
3.1.8 fiducial, n—an artificial objectitem (for example, a screw or sphere) that is implanted into, or a feature created on, a
therapeutic object prior to virtual object acquisition to facilitate registration.a sphere) rigidly attached to a therapeutic object to
facilitate its calibration.
F2554 − 22
3.1.9 ground truth, n—short name for the accepted reference value (see 3.1.1).
3.1.10 marker, n—a single 3-degree-of-freedom indicator on a reference element or dynamic reference base.
3.1.11 maximum error, n—the largest distance between any measured point and its ground truth for any trial during a testing
procedure.
3.1.12 mean, n—of a population, u, average or expected value of a characteristic in a population; of a sample, x, sum of the
observed values in the sample divided by the sample size. E456
3.1.13 measurement range, n—the interval of allowed values for a specific degree of freedom while performing the practice.
3.1.14 measurement volume, n—measuring range of a tracker, stated as simultaneous limits on all spatial coordinates measured
by the tracker. ISO 10360-1
3.1.15 navigation system, n—a device set of devices consisting of a computer withcomputer, its associated software, and a
localizer that tracks reference elements attached to surgical instruments or implants as well as one or more dynamic reference bases
attached to the therapeutic object. It tracker capturing the reference elements within the measurement volume. This system provides
real-time feedback of the performed action by visualizing it within the virtual environment.state of the surgical scene under
operation.
3.1.16 phantom, n—standardized measurement object. See Appendix X1 for details regarding the design of the phantom used in
this practice.
3.1.17 pointer, n—the device offered by the evaluated system to point and locate a position on any object including anatomical
landmarks. The pointer is the whole device, including the stylus-like tip all the way to any reference element used to track it in
space.
3.1.18 precision, n—the closeness of agreement between independent measurement results obtained under stipulated conditions.
E456
3.1.18.1 Discussion—
In the context of this standard, precision represents scatter of a set of measurements of a point.
3.1.19 range, R, n—the largest observation minus the smallest observation in a set of values or observations. E456, E2281
3.1.20 reference element, n—a device attached to surgical instruments and implants and other devices that enables determination
of an artificial item composed of rigidly bound markers in a unique and asymmetrical pattern recognizable by the tracker. While
being rigidly attached to a therapeutic object, the position and orientation in 3d space (up to 6 degrees of freedom) of these by
means of a tracker. It defines the local coordinate system of this instrument or implant.of the reference element can be used to
determine those of the therapeutic object after its calibration.
3.2.9 referencing, n—tracking of a therapeutic object by means of a dynamic reference base.
3.1.21 registration, n—the determination of the transformation spatial relationship between the coordinate spaces of the
therapeutic and virtual objects referential frames of two coordinate systems. This may occur between two reference elements or
between the co
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