(28 days)
The Varex Nexus DR™ Digital X-ray Imaging System is a high resolution digital imaging system intended to replace conventional film techniques, or existing digital systems, in multipurpose or dedicated applications specified below. The Nexus DR™ Digital X-ray Imaging System enables an operator to acquire, display, process, export images to portable media, send images over a network for long term storage and distribute hardcopy images with a laser printer. Image processing algorithms enable the operator to bring out diagnostic details difficult to see using conventional imaging techniques. Images can be stored locally for temporary storage. The major system components include an image receptor, computer, monitor and imaging software.
The Varex Nexus DR™ Digital X-ray Imaging System is intended for use in general radiographic examinations and applications (excluding fluoroscopy, angiography, and mammography).
The Varex Nexus DR™ Digital X-ray Imaging System is a high resolution digital imaging system designed for digital X-ray imaging through the use of an X-ray detector. The Nexus DR™ Digital X-ray Imaging System is designed to support general radiographic (excluding fluoroscopy, angiography, and mammography) procedures through a single common imaging platform.
The modified device consists of an X-ray imaging receptor, PaxScan 4343RC or PaxScan 4343Rv3, computer, monitor, and the digital imaging software.
The Varex Nexus DR™ Digital X-ray Imaging System is a configurable product platform designed to allow Varex to leverage the common components of digital X-ray imaging systems from which the following medical modalities can be served: General Radiography (excluding fluoroscopy, angiography, and mammography). The Nexus DR™ Digital X-ray Imaging System is then configured to function on a computer with modality specific components, functionality and capabilities to complete the specific product package.
Like the predicate device, the modified Nexus DRTM Digital X-ray Imaging System is in a class of devices that all use similar technology to acquire digital radiographic images. These devices convert X-rays into visible light that shines onto a TFT array, which converts the visible light into a digital electronic signal. This process is ultimately used for the same purpose as Radiographic film, to create an X-ray image.
Identical to the predicate device, the modified device is capable of interfacing with a PaxScan flat panel detector in vTrigger Mode or RAD Mode utilizing an external I/O box to interface with compatible X-ray generators, in non-integrated mode. The modified device also retains the ability to apply the grid suppression feature.
However, the modified device is capable of interfacing with the Varex PaxScan 4343RC and PaxScan 4343Rv3 detectors. The main difference between the additional detector models is mechanical; the PaxScan 4343RC is a cassette-sized portable tethered version whereas the PaxScan 4343v3 is utilized in a fixed configuration. Through the use of a digital flat panel detector, and a non-integrated generator, the Nexus DR™ Digital X-ray Imaging System (with PaxScan 4343RC and PaxScan 4343Rv3) is capable of acquiring digital radiographic images, processing and then displaying them in high quality for clinical diagnosis. The Nexus DR™ Digital X-ray Imaging System can then store the images on the local computer, archive them to CD/DVD media, transfer them to Hard Copy format via DICOM printers, or transfer them to PACS reviewing stations in DICOM format.
The provided text describes the Varex Nexus DR Digital X-ray Imaging System, which is a digital X-ray imaging system. The submission is for a modified device that interfaces with additional PaxScan detectors compared to the predicate device.
Here's an analysis of the acceptance criteria and study information based on the provided text:
1. A table of acceptance criteria and the reported device performance
The document presents a comparison chart of technological characteristics between the predicate device and the subject device. It doesn't explicitly state "acceptance criteria" in a pass/fail format but rather shows comparative performance metrics, with the implication that "Same" indicates meeting the expectation for substantial equivalence.
| Feature/Item | Acceptance Criteria (Predicate Device K171138) | Reported Device Performance (Subject Device - Nexus DR with PaxScan 4343RC, 4343Rv3) |
|---|---|---|
| Flat Panel Detector | Varex PaxScan 4336Wv4 | Varex PaxScan 4343RC / PaxScan 4343Rv3 |
| Detector Material | a-Si sensor array with CsI or Gd2O2S:TB scintillator | Same |
| Detector Dimensions | 17" x 14" | 17" x 17" |
| Pixel Size | 139 x 139 microns | Same |
| Detector Element Matrix | 3072 x 2560 | 3072 x 3072 |
| Dynamic Range | 16 bits | Same |
| QVAL (Uniformity) | 14.1 +/- 3.8 | 17.3 +/- 4.2 |
| Spatial Resolution | 3.2 lp/mm | Same |
| Modulation Transfer Function | 0.9 @ 1 cycle/mm, 0.25 @ 2 cycles/mm, 0.17 @ 3 cycles/mm | 0.55 @ 1 cycle/mm, 0.27 @ 2 cycles/mm, 0.14 @ 3 cycles/mm |
| Detective Quantum Efficiency | 0.58 @ 1 cycle/mm, 0.43 @ 2 cycles/mm, 0.26 @ 3 cycles/mm | 0.55 @ 1 cycle/mm, 0.43 @ 2 cycles/mm, 0.30 @ 3 cycles/mm |
| External Connectivity | DICOM 3.0 Compatible | Same |
| Operator Console | Graphical User Interface | Same |
| Image Processor | Intel CPU Based PC | Same |
| Image Storage | Hard Drive | Same |
| Operating System | Windows 10 | Same |
| Image Acquisition Cycle Time | 12 seconds | 9 seconds |
| Power Requirements | 110/120V, 230/240V, 50/60 Hz | Same |
| Grid Suppression | Yes | Same |
| Panel Acquisition Mode | vTrigger or RAD Mode | Same |
| Generator Interface Criteria | Digital signals for Select, Prep, Request; relay outputs for Expose | Same (Applicable generators listed) |
2. Sample size used for the test set and the data provenance (e.g. country of origin of the data, retrospective or prospective)
The document explicitly states: "Clinical images were not necessary to establish substantial equivalence based on the modifications to the device (the PaxScan 4343RC and PaxScan 4343Rv3 Flat Panel Detectors use identical technology as the predicate device image detector), and bench testing results provide enough evidence that the subject device works as intended."
This indicates that no clinical test set using patient data was employed for this particular submission. The evaluation was based on non-clinical (bench) testing. Therefore, information on sample size, country of origin, or retrospective/prospective nature of a clinical test set is not applicable.
3. Number of experts used to establish the ground truth for the test set and the qualifications of those experts (e.g. radiologist with 10 years of experience)
Since no clinical test set was used, there were no experts involved in establishing ground truth for a clinical test set. The evaluation primarily relied on engineering and performance metrics from bench testing.
4. Adjudication method (e.g. 2+1, 3+1, none) for the test set
Not applicable, as no clinical test set was utilized.
5. If a multi reader multi case (MRMC) comparative effectiveness study was done, If so, what was the effect size of how much human readers improve with AI vs without AI assistance
Not applicable. The device is an X-ray imaging system, not an AI-based diagnostic tool for interpretation assistance, and no MRMC study was conducted.
6. If a standalone (i.e. algorithm only without human-in-the loop performance) was done
Not applicable. The device is a digital X-ray imaging system; it is not an algorithm for standalone diagnostic performance.
7. The type of ground truth used (expert consensus, pathology, outcomes data, etc)
For the non-clinical tests, the ground truth was based on engineering specifications, physical measurements, and industry standards (e.g., lp/mm for spatial resolution, QVAL for uniformity, DQE values).
8. The sample size for the training set
Not applicable. The device is a medical imaging hardware system with associated software, not a machine learning algorithm that requires a training set of images in the typical sense. The software aspects would have undergone verification and validation testing, but not "training" with a dataset as an AI algorithm would.
9. How the ground truth for the training set was established
Not applicable, as there was no training set for a machine learning model.
§ 892.1680 Stationary x-ray system.
(a)
Identification. A stationary x-ray system is a permanently installed diagnostic system intended to generate and control x-rays for examination of various anatomical regions. This generic type of device may include signal analysis and display equipment, patient and equipment supports, component parts, and accessories.(b)
Classification. Class II (special controls). A radiographic contrast tray or radiology diagnostic kit intended for use with a stationary x-ray system only is exempt from the premarket notification procedures in subpart E of part 807 of this chapter subject to the limitations in § 892.9.