Guidance for the Submission 
of 510(k)s for 
Solid State X-ray Imaging Devices 
Guidance for Industry and Food and 
Drug Administration Staff 
 
 
 
Document issued on: September 1, 2016 
 
 
 
 
This document supersedes Guidance for the Submission of 510(k)s for 
Solid State X-ray Imaging Devices, issued August 6, 1999. 
 
For questions about this document contact the Division of Radiological Health at 301-796-
5790 and Yuan Fang (OIR) at 301-796-2676 or by e-mail at Yuan.Fang@fda.hhs.gov. 
 
 
 
 
 
 
U.S. Department of Health and Human Services 
Food and Drug Administration 
Center for Devices and Radiological Health 
Office of In Vitro Diagnostics and 
Radiological Health (OIR) 
Division of Radiological Health 
 
1  Preface 
 
 
Public Comment 
 
You may submit electronic comments and suggestions at any time for Agency consideration 
to  http://www.regulations.gov.  Submit  written  comments  to  the  Division  of  Dockets 
Management, Food and Drug Administration, 5630 Fishers Lane, Room 1061, (HFA-305), 
Rockville, MD 20852. Identify all comments with the docket number FDA-1997-N-0389. 
This guidance was originally assigned the docket number 97N-0390.  The docket number 
was changed to FDA-1997-N-0389 as a result of FDAs transition to its new docketing 
system (regulations.gov) in January 2008. Comments may not be acted upon by the Agency 
until the document is next revised or updated.  
Additional Copies 
 
Additional copies are available from the Internet.  You may also send an e-mail request to 
CDRH-Guidance@fda.hhs.gov to receive a copy of the guidance.  Please use the document 
number 644 to identify the guidance you are requesting.
 
2  1 
GUIDANCE FOR THE SUBMISSION OF 510(K)S FOR SOLID STATE X-
RAY IMAGING DEVICES 
I. Table of Contents  Page Number 
I.  Table of Contents  3 
II.  Scope  4 
III.   Purpose  4 
IV.  Description  4 
A.  Scintillator- photodetector  4 
B.  Direct conversion  4 
C.  Optically coupled CCD  5 
D.  Photostimulable phosphor  5 
V.  Regulatory Requirements  5 
VI.  Nonclinical Considerations  5 
A. Physical Characteristics  6 
B. Operational Functions  6 
C. Functional Characteristics  7 
D. Exposure Characteristics  8 
E.  Safety Features  9 
F.  Test Results  9 
VII.  Clinical Considerations  9 
A.  Concurrence study  10 
B.  Qualified Expert Evaluation  10 
VIII.  Labeling  11 
A.  Indications for use  11 
B.  Promotional materials  12 
C.  Instructions  12 
D.  Training materials  12 
E.  Documentation  12 
 
 
 
 
 
1This document is intended to provide guidance.  It represents the Agencys current thinking on SSXIs. It does not 
create or confer any rights for or on any person and does not operate to bind FDA or the public.  An alternative 
approach may be used if such approach satisfies the requirements of the applicable statute, regulations, or both. 
 
3  IX.  Quality Assurance Program  13 
A.  Parameter monitoring  13 
B.  Quality criteria  13 
C.  Manufacturers records  13 
D.  QA training materials  13 
  
  II  Scope 
 
This guidance applies to the category of medical imaging devices, Solid State X-ray Imagers 
(SSXI), that convert x-ray patterns into electrical signals.  The signals can in turn, with or 
without processing, be converted into visible images for use in medical diagnosis.  These 
devices are intended to be used in place of conventional x-ray film/screen systems, and image 
intensifier based fluoroscopic and image recording systems.  SSXIs indicated for 
mammography do not fall within the scope of this guidance. 
 
III  Purpose 
As solid state device technology continues to progress, solid state x-ray imaging devices will 
assume an ever-increasing role in medical x-ray systems.  This evolution will result in a 
significant number of premarket (510(k)) submissions for devices that utilize various forms of 
this technology. This document is intended to provide guidance on the type of data needed by 
the Center for Devices and Radiological Health (CDRH) to establish the substantial equivalence 
of an SSXI to a previously cleared conventional radiographic film/screen system, fluoroscopic 
image intensified imaging system, SSXI or similar device. 
 
IV  Description 
The devices covered by this guidance are solid state transducers  (typically flat rectangular 
panels) that intercept x-ray photons, and through one of several processes convert the photon 
energy into an electrical signal that is subsequently used to create a visible image.  Some of the 
basic types currently available to perform the x-ray conversion are: 
 
A.  Scintillator - photodetector devices.  A scintillator such as cesium iodide absorbs the input 
x-ray photons.  The scintillator in turn emits visible spectrum photons that illuminate an 
array of photodetectors that create an electrical charge representation of the x-ray input.  
A matrix scan of the array converts the integrated charges into a modulated electrical 
signal. 
B.  Direct conversion devices.  The input x-ray photons are absorbed in an x-ray sensitive 
material (e.g. photoconductor) that creates an electrical charge representation of the x-ray 
input. The charge is read-out by a matrix scan of the array (e.g. through switching 
transistors) that converts the charges into a modulated electrical signal. 
 
4  C.  Optically coupled CCD. A scintillator such as cesium iodide absorbs the input x-ray 
photons.  The scintillator in turn emits visible spectrum photons that are optically coupled 
(via lens(es) or fiber- optics) to one or more charged coupled detectors (CCD).  The CCD 
in turn converts the visible image into an electrical signal in the same manner as in a TV 
camera. 
D.  Photostimulable phosphor. The input x-ray photons are absorbed by a phosphor plate such 
as barium-fluoro-bromo-iodide creating trapped electrons just below the conduction band. 
Subsequent scanning of the plate with red or near-infrared laser light releases the electrons, 
a process that results in the emission of green, blue or UV light in proportion to the input x-
ray exposure.  The light is collected by a photomultiplier that converts it into a modulated 
electrical signal. 
After the electrical signal is generated it is converted to a digital value and often processed to 
enhance the visibility of the viewed image.  The resultant output signal can be transmitted to 
remote viewing sites, and/or it can be stored electronically for later viewing.  The signals can 
also be input to a hard- copy device (e.g. laser scanner) to make paper or film copies of the 
images. 
 
V  Regulatory Requirements 
Prior to marketing, new x-ray imaging devices must conform to the Radiation Control for 
Health and Safety Act of 1968 (RCHSA) and the Medical Device Amendments (MDA) to the 
Federal Food, Drug, and Cosmetic Act of 1976. 
Under RCHSA the devices must conform to the Performance Standards for Ionizing Radiation 
Emitting Products.  Specifically they must meet applicable sections of 21CFR1020.30 
Diagnostic x-ray systems and their major components, 1020.31 Radiographic equipment, or 
1020.32 Fluoroscopic equipment. 
Under MDA, a device may be cleared for marketing via a 510(k) premarket notification.  To 
do so, the device must be shown to be substantially equivalent to a legally marketed predicate 
device.  Predicate devices for SSXIs are preamendment or cleared devices that have the same 
or similar intended use(s) as the device being submitted for clearance.  The fact that such a 
predicate may itself be exempt from 
510(k) requirements does not exempt the SSXIs from this requirement (ref. 21 CFR 892.9 
(b)). SSXIs operate using a different fundamental scientific technology than film or image 
intensifiers and, therefore, are not exempt from the requirements of 510(k). 
Product Code 90 MQB has been established for SSXIs and they are currently classified in 
Class II. 
 
 
VI  Nonclinical Considerations 
In addition to the General Information required for all medical devices submitted for 510(k) 
 
5  clearance (Ref.: 21 CFR 807.87) the following nonclinical information specific to SSXIs 
should also be included. This information will assist in determining the equivalence to the 
predicate device(s) identified by the sponsor. 
Unless stated otherwise herein or by the manufacturer, all characteristics and measurements 
reported are assumed to be taken while the device is functioning at room temperature.  For 
quantitative measurements that are reported, the degree of uncertainty should be included (e.g. 
error bars). 
A. Physical Characteristics 
1.  Provide the overall dimensions including length, width, thickness and 
any shape characteristics that are unique to the device. 
2.  Provide the sensor element dimensions and spacings including the fill factor, the 
fraction of the exposed area of the device that is sensitive to incident x-rays.  Also 
describe any features added to compensate for input photon loss resulting from 
inactive interelement spacing. Include total horizontal and vertical element count if 
applicable. 
3.  Provide the structure cross section showing schematically the elements of the device 
so that its means of x-ray conversion and signal generation are explained. 
4.  Describe the interconnections of the elements, and any active or passive elements 
that are used to store, switch or otherwise process the electrical signals in the 
detector itself. 
5.  Provide a schematic diagram of the elemental signal storage scheme and the 
overall scanning and readout mechanism.  This may be included as part of 
A.3. above. 
6.  Provide the input electrical power requirements with tolerance limits and effects of 
power noise on the operation of the device. 
B. Operational  Functions 
1.  Provide the method(s) of exposure, and for fluoroscopy, rates of response (frames 
per second).  Describe a typical exposure sequence from turn-on of the device to 
presentation of the image to the user. 
2.  Provide the x-ray absorber(s), material description. Describe the primary x-ray 
detection material and its x-ray detection properties as a function of photon 
energy (keV) or wavelength (mm); including any nonlinear response 
characteristics. 
3.  Provide a description of the energy conversion mechanisms utilized (e.g. x-ray to 
 
6  light to electrical signal).  Describe all the processes in the device that involve 
energy conversion (e.g. x-ray to visible). 
4.  Describe the readout mechanisms, and techniques used to commutate detector   
elements.  Describe the means used to sequentially read-out the signal from 
successive elements. Include maximum and minimum rates, and for fluoroscopic 
devices the means provided for establishing synchronization with display or 
recording devices. 
5.  Provide a description of the output data, and any direct access to output signals.  
Indicate what communications standard (e.g. DICOM) is used to format the data for 
downloading and analysis. 
C. Functional Characteristics 
1.   For fluoroscopic devices, provide the output format of the video signal, sample 
waveform and standards applied.  Provide a sketch or photograph of horizontal 
scan line and vertical field signals noting the key elements of signal. 
2.  Provide an estimate of Detective Quantum Efficiency  (DQE) at low spatial and 
temporal frequency.  Describe the method used to make the estimate, and the level 
of uncertainty due to propagation of error. 
3.  For quantum limited performance [i.e. The noise added by the SSXI does not 
exceed the x- ray quantum noise when operated in the normal range of exposures or 
frame rates.] provide data showing that the device operates in a quantum limited 
mode at the frame rates or exposure levels specified for its use.  If not quantum 
limited, provide the range of exposures (for fluoroscopy: frame rates) where 
quantum limited operation is not achieved.  It is expected that all predicate devices 
exhibit quantum limited behavior over their normal operating ranges. 
4.  Provide a plot of the modulation or contrast transfer function of the device.  
Indicate the device settings and input dose level required to obtain the 
measurement.  If the transfer characteristic varies with any other function 
indicate how and provide the maximum and minimum transfer functions that the 
device provides when used with typical clinical exposures. 
5.  Quantify the effects aliasing has on the DQE and Modulation Transfer Function 
(MTF) of the device.  If aliasing is evidenced from the pre-sampled MTF, 
quantitatively describe how it affects the resulting image.  If there are no aliasing 
effects from the device explain why. 
6.  Provide a plot of the output signal level as a function of input dose level for a 
specified x-ray spectrum.  The spectrum may be defined in terms of kVp and beam 
filtration.  Plot so that any nonlinearities are clearly shown.  Other methods of 
 
7  showing the dynamic range capabilities of the device may also be used. 
7.  Lag or residual signal level from prior exposures, short term and long term: Describe, 
quantitatively where possible, any device characteristics (often due to electron or 
hole trapping) that cause the device to include in the output, signal components 
attributable to one or more prior exposures.  Indicate the relative amplitude and 
decay characteristics of such signals. 
8.  Means provided to expose and/or readout subsections (partial areas) of the full 
SSXI: Describe, if this is a characteristic of the device, how it can be under-
scanned so that only a portion of the total detector matrix is utilized. 
9.  Describe how x-ray beam alignment and collimation to the active area of the 
device will be achieved to meet the requirements of 21CFR1020.31 or .32. What 
signal(s) will the device provide to indicate the size and position of the active area?  
If no under-scanning capability is provided, so indicate. 
10. Describe the allowable types and quantity of defects, and any methods of 
compensation or blanking that are utilized to compensate for allowable maximum 
output, minimum output or otherwise inoperative pixel elements. 
11. Provide data or a plot of any change in detection sensitivity as a function of time 
after the device is ready (e.g. biased, erased, etc.) for the next exposure.  Also 
indicate any other changes such as reduction in dynamic range that take place after 
the device is ready. 
12. Provide a plot of the latent image decay characteristic as a function of time and 
temperature.  Also describe any impact on signal retention as a function of the number 
of erasures and/or exposures the device has experienced. 
13. Recovery  Time  for  radiographic  devices:  Indicate  the  time  after  readout  is  
complete (including any preparation function) until the device is able to accept the 
next exposure. 
 
D. Exposure Characteristics 
1.  Dose Requirements and reciprocity changes: Provide quantitative measurements of the 
input dose required to generate an image or video frame equivalent to that provided 
by a predicate device.  Also indicate any changes in this characteristic that will 
occur with time and/or cumulative radiation exposure. 
2.  Stability  of  device  characteristics  with  time  (total  integrated  exposure):  In  
addition  to exposure requirement changes, indicate any other characteristics of the 
device that change with time and/or total integrated exposure. 
 
8  3.  Uniformity of device characteristics (large and small area): Describe any 
nonuniformity characteristics of the device that may cause large or small area changes 
such as shading. 
4.  Frame-Rate for fluoroscopic devices: Indicate the maximum number of images that 
can be generated per unit time and any characteristics that change as a function of 
frame rate.  For any characteristics that do change, indicate how they change.  If the 
frame rate limit is a function of another characteristic(s) [outside the SSXI] indicate 
which one(s) and indicate how that characteristic(s) impacts the frame rate. 
5.  Reuse Rate for radiographic devices: Indicate the maximum number of images 
that can be generated per unit time. If limited by other than the device itself, 
describe. 
E. Safety Features 
1.   Indicate what means [e.g. ready signal] that are provided to indicate the SSXI is 
prepared to accept and process an x-ray input. 
F. Test Results 
1.  Provide samples of test pattern images (SSXI and predicate) that show the 
ability of the device to provide images equivalent to those of a predicate 
device(s).  Each image should have with it the x-ray factors used and the set-up 
parameters of the device.  The test patterns must be clearly identified and all 
characteristics indicated (e.g. lp/mm for each bar group). The geometry of the test 
set-up must be indicated as well as the focal spot size of the x-ray source.  The 
images may be on film recorded from the output, or VHS videotape in the case of 
fluoroscopy devices.  Any signal processing used should be described. 
2.  Provide sample measurements of the characteristics described in C and D above; 
include the tolerance or level of uncertainty associated with each measurement. 
VII  Clinical Considerations 
Nonclinical information may be sufficient to support the substantial equivalence of a subject to a 
predicate device for many types of modifications without the need to provide additional clinical 
data. For example, clinical information may not be necessary for the following types of 
modifications:   
1. Overall change in the dimensions of the image receptor with otherwise identical materials 
2. Change in the pixel size and resolution with the same x-ray detection material 
3. Change in the image receptors wireless functionality 
Manufacturers may contact FDA and consider a pre-submission to seek feedback on whether 
clinical images may be necessary based on the results of the bench testing or type of 
modifications. 
 
9  In addition to the nonclinical information described above, one of the following two options for 
providing clinical information should also be included if the nonclinical information alone would 
not be sufficient. Investigations involving clinical subjects must comply with 21 CFR Parts 50 
and 56. 
A.  Concurrence study 
1. Conduct and report the results of a concurrence study of 30 or more clinical image 
pairs (from the same or equivalent patients) that show the ability of the device to 
provide images  of  equivalent  diagnostic  capability  to  those  of  a  cleared  
predicate  device(s).     For fluoroscopic devices, the study may be done live (as 
viewed by the user/evaluator) or from sequences on VHS videotape or film produced 
from the video signal.  Each image should be supported by the x-ray factors and set-up 
used as well as the operating parameters of the device and any signal processing 
performed. 
2. Sample images: Representative pairs of sample images (from those taken for VII.A. 
above) should be submitted for each anatomical region (and/or study) that is indicated 
for the device. 
3. Other findings: Provide any other clinically significant findings that are discovered in the 
process of using the device. 
B.  Qualified Expert Evaluation 
1. Clinical images from only the subject device may be submitted if they are accompanied 
by an evaluation of the images by a qualified expert. For purposes of this guidance:  
a. A qualified expert is a U.S. board certified (or equivalent) radiologist or a U.S. 
board certified (or equivalent) subspecialty physician or dentist experienced in 
imaging related to the device's intended use. We recommend that the physician 
have at least five years of experience following residency and fellowship. 
Fellowship training in the device-targeted clinical area is desirable. We 
recognize, however, that a relevant fellowship may not always exist. We also 
recommend that at least 50% of the readers practice should be in the modality 
or sub-specialty related to the device's intended use. 
b. For non-US board-certified clinicians, equivalence to US board certification is 
assumed if the reading clinician graduated from a training program accredited by 
the Accreditation Council for Graduate Medical Education International 
(ACGME-I), or from programs approved by the American Board of Radiology 
(ABR) International Medical Graduate Alternate Pathway or by the Educational 
Commission for Foreign Medical Graduates (ECFMG). Board equivalence will 
be assessed by the FDA on a case-by-case basis. 
 
10  2. The purpose of this evaluation is to determine if the radiographic images are of 
acceptable quality for clinical use by a qualified expert. The set of images should be 
representative of the range of clinical procedures and anatomical regions identified by 
the devices intended use. A full set of 30 images may not be necessary if the set of 
images can sufficiently demonstrate the range of capability of the system for the 
intended anatomical region(s).  
For example, for general purpose radiographic indications, FDA recommends evaluating 
one clinical image for the following anatomical regions (and/or studies):  
a. Chest LAT 
b. Chest PA 
c. Pelvic 
d. Abdomen 
e. C-Spine AP, lateral, odontoid view. Obliques may be included. 
f. L-Spine, AP and lateral 
g. Shoulder, AP, internal and external rotation 
h. Extremities (hand, wrist, elbow, foot, ankle, knee, etc.) AP, lateral, oblique or a 
complete series. 
3. The qualified expert should evaluate the images for each case and provide an overall 
assessment of whether these image sets collectively are clinically adequate.  
4. Any issue with image evaluation or image quality should be fully explained.  
5. Each clinical image should be accompanied by its acquisition parameters, including x-ray 
exposure conditions (anode, filter, kVp, mAs, exposure, half-value layer), and estimated 
dose (e.g. dose-area product).  
6. These clinical images should be included in the submission in pdf and DICOM format.   
If the nonclinical information or clinical image evaluation raise any specific concerns regarding 
the device and its predicate, you should contact the Division of Radiological Health, Office of 
In Vitro Diagnostics and Radiological Health (OIR), to discuss the necessity and content of 
clinical data prior to submitting your 510(k). 
VIII  Labeling 
A premarket submission for an SSXI device should contain information on device 
labeling.  The information provided should include: 
 
A.  Indication(s) for Use: A general description of the disease(s) or condition(s) that the 
device will be used to help diagnose and the patient population for which the device is 
intended. 
 
11  Examples:  
The ________ is indicated for use in generating real time fluoroscopic images in 
patients where medically indicated. 
The ________ is indicated for use in generating radiographic images of human 
anatomy.   It is intended  to replace a radiographic film/screen system in all general 
purpose diagnostic procedures. 
B.  Promotional Materials: All brochures and advertising copy that have been prepared to 
promote the use and sale of the device. 
 
C.  Instructions for Installation, Check-Out and Use: 
 
1.  Users Manual: A description of the methods for selection of the x-ray technique 
factors, image processing algorithms, and display settings (e.g. window width, 
window position, gray  scale  transfer  characteristic,  etc.)  for  the  generation  of  
the  displayed  image.    All cautions, warnings, and contraindications associated 
with the use of the device.  State the fill factor achieved by the device and indicate 
over what exposure range (and frame rates for fluoroscopic devices), if any, the 
devices operation is not quantum limited. 
2.  Ancillary Requirements: This information should include instructions on which 
particular display device(s) is appropriate and the method of using such display 
device(s) to achieve the  intended  use(s).    A  description,  if  applicable,  of  any  
instructions  needed  to  obtain optimum images from either hard-copy (laser camera) 
or soft-copy (CRT) device(s) that will display the SSXI generated image. 
D.  Training Materials: To address the issue of how to account for the learning curve 
effect in the clinical utilization of an SSXI device, an approach to moving up the 
learning curve may be demonstrated by the use of a set of comprehensive training 
materials. A description of all training materials to be used by the manufacturer should be 
provided as part of the submission. 
 
E.  Documentation: In considering the total content of the labeling for this category of device, 
users should be provided with objective documentation of imaging performance from the 
manufacturers. Users can then employ this information in their evaluation of the 
importance of any tradeoffs between different characteristics of imaging performance.  The 
documentation should include the data described in response to the Clinical and 
Nonclinical Considerations sections of this guidance encompassing: sensitometric 
response characteristics, spatial resolution properties, DQE, dynamic range and the 
display means utilized, the results of image tests, and typical patient doses.  These data 
should also show the level of uncertainty associated with each measurement. 
 
12   
IX  Quality Assurance Program 
A submission should contain a complete description of the quality assurance program 
recommended to the user for maintaining the continued proper functioning of the SSXI device 
including its control hardware, software, and power supplies.  The description should include the 
following information: 
A.  Parameter  monitoring:  A  list  of  the  parameters  to  be  monitored  and  the  procedures  
for  and frequency of monitoring. 
B. Quality criteria: A description of the standards, quality criteria, or limits of acceptance 
that are in place for each of the monitored parameters. 
C. Manufacturers records: A list of the records, with sample forms (if applicable) that the 
manufacturer will maintain for the QA program. 
D. Q.A. training materials: A description of all training materials to be provided for 
performing, recording, and monitoring QA tests. 
 
13