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U.S. Department of Health and Human Services

Radiation-Emitting Products

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Information for Industry: X-ray Imaging Devices

Laboratory Image Quality and Dose Assessment, Tests and Standards

Compliance testing for required performance characteristics is specified in 21 CFR 1020.30-1020.33 ("Diagnostic x-ray systems and their major components;" "Radiographic equipment;" "Fluoroscopic equipment;" and "Computed tomography (CT) equipment"). Recognized standards specify additional methods for assessment of image quality and dose.

The following table lists common laboratory tests for evaluation of general-use x-ray imaging devices and the applicable standard for each modality; it is provided for reference and is not intended to be exhaustive. The tests listed focus on ensuring the imaging device is capable of producing diagnostic quality images at a reasonable dose. Posting of this list does not imply that every applicable test and associated standard has been listed. For additional standards applicable to specific devices, please refer to the Recognized Consensus Standards Database. The guidance entitled "Recognition and Use of Consensus Standards" describes how the agency will use information on conformance with recognized standards.

Corresponding tests and standards for mammography systems are included in section 8 of the guidance entitled "Class II Special Controls Guidance Document: Full-Field Digital Mammography System."

Table 1. Physical Laboratory Tests and Applicable Standards

Test and brief description

Modality

Relevant standard or more detailed instructions

Sensitometric Response: The output digital signal value versus the radiation exposure curve provides the sensitometric response of the image acquisition system.

General radiography (excludes dynamic imaging/fluoroscopy and CT)

IEC 62220-1 ed1.0 (2003-10) Medical electrical equipment- Characteristics of digital x-ray imaging devices- Part 1: Determination of the detective quantum efficiency

Dynamic imaging x-ray devices (i.e. fluoroscopic or cardiac imaging)

IEC 62220-1-3 ed1.0 (2008-06) Medical electrical equipment - Characteristics of digital X-ray imaging devices - Part 1-3: Determination of the detective quantum efficiency - Detectors used in dynamic imaging

Modulation Transfer Function (MTF): Provides a quantitative measure of the spatial resolution properties of the image acquisition system.

CT

IEC 61223-3-5 ed1.0 (2004-08) Evaluation and routine testing in medical imaging departments–Part 3-5: Acceptance tests–Imaging performance of computed tomography X-ray equipment; Corrigendum 1 (2006-03)

and

IEC 61223-2-6 ed2.0 (2006-11) Evaluation and routine testing in
medical imaging departments – Part 2-6: Constancy tests –
Imaging performance of computed
tomography X-ray equipment

General radiography (excludes dynamic imaging/fluoroscopy and CT)

IEC 62220-1 ed1.0 (2003-10) Medical electrical equipment- Characteristics of digital x-ray imaging devices- Part 1: Determination of the detective quantum efficiency

Dynamic imaging x-ray devices (i.e. fluoroscopic or cardiac imaging)

IEC 62220-1-3 ed1.0 (2008-06) Medical electrical equipment - Characteristics of digital X-ray imaging devices - Part 1-3: Determination of the detective quantum efficiency - Detectors used in dynamic imaging

Noise Power Spectrum (NPS): As a function of spatial frequency and exposure level, this test provides a quantitative measure of the noise properties of the image acquisition system.

General radiography (excludes dynamic imaging/fluoroscopy and CT)

IEC 62220-1 ed1.0 (2003-10) Medical electrical equipment- Characteristics of digital x-ray imaging devices- Part 1: Determination of the detective quantum efficiency

Dynamic imaging x-ray devices (i.e. fluoroscopic or cardiac imaging)

IEC 62220-1-3 ed1.0 (2008-06) Medical electrical equipment - Characteristics of digital X-ray imaging devices - Part 1-3: Determination of the detective quantum efficiency - Detectors used in dynamic imaging

Detective Quantum Efficiency (DQE): This test provides a quantitative measure of the efficiency of signal -to-noise ratio (SNR) transfer of the image acquisition system. This measure is obtained by calculating the detective quantum efficiency (DQE) as a function of spatial frequency. SNR analysis should be performed using exposure levels covering the range normally encountered using your system to provide the dynamic range of the system.

General radiography (excludes dynamic imaging/fluoroscopy and CT)

IEC 62220-1 ed1.0 (2003-10) Medical electrical equipment- Characteristics of digital x-ray imaging devices- Part 1: Determination of the detective quantum efficiency

Dynamic imaging x-ray devices (i.e. fluoroscopic or cardiac imaging)

IEC 62220-1-3 ed1.0 (2008-06) Medical electrical equipment - Characteristics of digital X-ray imaging devices - Part 1-3: Determination of the detective quantum efficiency - Detectors used in dynamic imaging

Image Erasure and Fading: For systems using a delayed readout of image data, such as a photostimulable phosphor, tests should include image decay as a function of time and temperature and signal retention as a function of the number of erasures and exposures.

General radiography, fluoroscopy

For testing recommendations also appropriate for radiographic and fluoroscopic systems, please see section 8 of the guidance entitled "Class II Special Controls Guidance Document: Full-Field Digital Mammography System."

Repeated Exposure test for ghosting: Tests for quantitatively assessing residual images/ghosts are described in IEC standards as "lag effect" tests.

General radiography

IEC 62220-1 ed1.0 (2003-10) Medical electrical equipment- Characteristics of digital x-ray imaging devices- Part 1: Determination of the detective quantum efficiency

Dynamic imaging x-ray devices (i.e. fluoroscopic or cardiac imaging)

IEC 62220-1-3 ed1.0 (2008-06) Medical electrical equipment - Characteristics of digital X-ray imaging devices - Part 1-3: Determination of the detective quantum efficiency - Detectors used in dynamic imaging

Tube current modulation (or automatic exposure control) performance: A demonstration of the degree of control intended with respect to tube-current modulation on non-uniform phantoms or with respect to temporal gating should be performed for a range of exam conditions (phantom sizes or time sequences).

CT: Specifies that CT scanners provide an AEC feature, but does not specify any test of AEC performance.

IEC 60601-2-44 ed3.0 (2009-02) Medical electrical equipment – Part 2-44: Particular requirements for the basic safety and essential performance of X-ray equipment for computed tomography; Corrigendum 1 (2010-05)

Radiography and fluoroscopy

The following standard also applies to interventional fluoroscopy (with exceptions and additions noted in IEC 60601-2- 43):
IEC 60601-2-54 ed1.0 (2009-06) Medical electrical equipment - Part 2-54: Particular requirements for the basic safety and essential performance of X-ray equipment for radiography and radioscopy

Dose or exposure index measurement, display, automatic reporting of values, and documentation

CT: Dose indices based on Computed Tomography Dose Index 100 (CTDI100) and requirements for radiation dose structured reporting

IEC 60601-2-44 ed3.0 (2009-02) Medical electrical equipment – Part 2-44: Particular requirements for the basic safety and essential performance of X-ray equipment for computed tomography; Corrigendum 1 (2010-05)

Radiography and fluoroscopy: defines reference air kerma and reference air kerma rate

IEC 60601-2-54 ed1.0 (2009-06) Medical electrical equipment - Part 2-54: Particular requirements for the basic safety and essential performance of X-ray equipment for radiography and radioscopy

Interventional fluoroscopy: defines reference air kerma, reference air kerma rate, dose-area product; specifies range of operating conditions for dose measurements; defines skin dose as air kerma for display purposes

IEC 60601-2-43 ed2.0 (2010-03) Medical electrical equipment - Part 2-43: Particular requirements for the basic safety and essential performance of X-ray equipment for interventional procedures

Exposure index standard for general radiography tube current modulation systems

IEC 62494-1 ed1.0 (2008-08) Medical electrical equipment - Exposure index of digital X-ray imaging systems - Part 1: Definitions and requirements for general radiography

Radiation dose structured reporting for radiography and fluoroscopy

IEC/PAS 61910-1 ed1.0 (2007-07) Medical electrical equipment - Radiation dose documentation - Part 1: Equipment for radiography and radioscopy

Reproducibility of radiation output for dental x-ray devices

IEC 61223-3-4 ed1.0 (2000-03) Evaluation and routine testing in medical imaging departments - Part 3-4: Acceptance tests - Imaging performance of dental X-ray equipment

Modality-specific tests not specified in above categories (examples included for reference; not exhaustive)

Dental x-ray imaging:
Line pair resolution; Low contrast resolution; Image homogeneity

IEC 61223-3-4 ed1.0 (2000-03) Evaluation and routine testing in medical imaging departments - Part 3-4: Acceptance tests - Imaging performance of dental X-ray equipment

CT:
Sensitivity Profile; Patient-Support Positioning and Accuracy; Tomographic Section Thickness; Noise; Uniformity; Mean CT Numbers

IEC 61223-3-5 ed1.0 (2004-08) Evaluation and routine testing in medical imaging departments–Part 3-5: Acceptance tests–Imaging performance of computed tomography X-ray equipment; Corrigendum 1 (2006-03)

and

IEC 61223-2-6 ed2.0 (2006-11) Evaluation and routine testing in
medical imaging departments – Part 2-6: Constancy tests –
Imaging performance of computed
tomography X-ray equipment

and

IEC 60601-2-44 ed3.0 (2009-02) Medical electrical equipment – Part 2-44: Particular requirements for the basic safety and essential performance of X-ray equipment for computed tomography; Corrigendum 1 (2010-05)

Fluoroscopy and radiography:
Additional tests are specified in the standards on the right (some of these tests are also included in the FDA performance standards).

IEC 60601-2-54 ed1.0 (2009-06) Medical electrical equipment - Part 2-54: Particular requirements for the basic safety and essential performance of X-ray equipment for radiography and radioscopy

and

IEC 60601-2-43 ed2.0 (2010-03) Medical electrical equipment - Part 2-43: Particular requirements for the basic safety and essential performance of X-ray equipment for interventional procedures