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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 DRTM 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 DR-m 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, computer, monitor, and the digital imaging software and the optional Stitching software.

The Varex 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 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 DR™ 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 flat panel detectors 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 allows the operator to generate sequential radiographic images and electronically join them to create a single electronic image (a leg from hip to foot, for example). Stitching is a post-processing feature that allows the user to merge up to four (4) DICOM images and does not alter the original images. Using a digital flat panel detector, and a non-integrated generator, the Nexus DR Digital X-ray Imaging System (with Stitching) is capable of acquiring multiple digital radiographic images, processing and then displaying them in a high quality single image format to visualize long bones or other anatomical features such as the spine. 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.

Here's an analysis of the acceptance criteria and the study proving the device meets them, based on the provided text:

1. Table of Acceptance Criteria and Reported Device Performance

The provided text does not explicitly list quantitative acceptance criteria in a dedicated table format with corresponding reported device performance for the stitching feature. Instead, the document focuses on demonstrating substantial equivalence through a comparison of technological characteristics and a subjective image comparison study.

However, based on the non-clinical and clinical test discussions, we can infer the acceptance criterion to be:

2. Sample Size Used for the Test Set and Data Provenance

• Sample Size: The document states "Previously acquired sequential radiographic images." No specific number or range of images (sample size) is provided for the test set.
• Data Provenance: The images were "Previously acquired sequential radiographic images from the Reference Predicate Device (InfiStitch for i5™ Digital X-Ray Imaging System)." This indicates the data is retrospective, as it was collected prior to the study for the subject device. The country of origin is not specified, but the predicate device's information (K101833) would likely originate from the US given the submission to the FDA.

3. Number of Experts Used to Establish Ground Truth for the Test Set and Qualifications

The document does not provide details on the number of experts or their qualifications used to establish ground truth for the test set. It only mentions an "image comparison study performed."

4. Adjudication Method for the Test Set

The adjudication method used is not specified. It only states an "image comparison study performed."

5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study Was Done

No, a Multi-Reader Multi-Case (MRMC) comparative effectiveness study was not explicitly stated or implied. The study described is an "image comparison study" to demonstrate substantial equivalence to a reference predicate device, not a comparison of human readers with and without AI assistance.

6. If a Standalone (Algorithm Only Without Human-in-the-Loop Performance) Was Done

Yes, the "image comparison study" and "bench testing results" described for the stitching feature appear to be a standalone performance evaluation of the algorithm's ability to stitch images, rather than involving human-in-the-loop performance measurement. The critical aspect is the quality and diagnostic utility of the stitched image itself, which is then compared (presumably by experts) to existing stitched images from a predicate device.

7. The Type of Ground Truth Used

The ground truth for the image comparison study was based on previously acquired sequential radiographic images from a legally marketed reference predicate device (InfiStitch for i5™ Digital X-Ray Imaging System). This implies that the accepted output of the predicate device serves as the "ground truth" or standard for comparison against the subject device's stitched images.

8. The Sample Size for the Training Set

The document does not provide any information regarding a training set or its sample size. This is a 510(k) submission for a device incorporating a known function (stitching) onto a new system, not a de novo submission for a novel AI algorithm requiring extensive training data. The stitching logic itself is likely rule-based or uses established image processing techniques rather than machine learning that necessitates a training set.

9. How the Ground Truth for the Training Set Was Established

As no training set is mentioned (see point 8), there is no information on how its ground truth was established.

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