(158 days)
The device is a permanently installed diagnostic x-ray system for general radiographic x-ray imaging including tomography. This device also supports digital tomosynthesis. The tomography and digital tomosynthesis features are not to be used for imaging pediatric patients.
Carestream Digital Tomosynthesis (DT) is a limited "sweep" imaging technique that generates multiple two-dimensional (2D) coronal slices (i.e. planes) from a series of low dose x-ray images of the same anatomy taken at the same exposure but at different angles. During a tomosynthesis acquisition the detector will be stationary while the tube head travels (sweeps) in a straight path (i.e. focal spot travel path). For each exposure, the tube will be angled toward the center of the detector. The Carestream Digital Tomosynthesis contains 3 options: Sweep angle option is to provide the desired slice thickness. The number of images per degree of sweep angle. The Projection Image Resolution allows for the selection of speed of capture versus image resolution.
The Carestream Digital Tomosynthesis (DT) system was evaluated through non-clinical (bench) testing and a clinical reader study to demonstrate its diagnostic image quality and equivalence to predicate devices.
1. Table of Acceptance Criteria and Reported Device Performance
| Acceptance Criteria Category | Specific Criteria | Reported Device Performance | Comments |
|---|---|---|---|
| Diagnostic Image Quality | Mean RadLex Rating (4-point scale) for scout and Digital Tomosynthesis exams. | 3.7156 | The RadLex scale ranged from 1 (non-diagnostic) to 4 (exemplary). All ratings were above non-diagnostic. |
| Equivalence to Predicate | "Equivalent or better in diagnostic quality compared to images obtained using commercially available predicate and reference devices." | Achieved | Statistical test results demonstrated equivalence or superiority. |
| Non-clinical Performance | Conformance to specifications, intended workflow, related performance, overall function, verification and validation of requirements for intended use, and reliability of system software. | Met | Predefined acceptance criteria were met, demonstrating the device is as safe, effective, and performs as well as or better than the predicate device. |
2. Sample Size and Data Provenance
- Test Set Sample Size:
- Clinical Images: 17 Digital Tomosynthesis image cases from adult human subjects (patients). Each case included a thoracic digital radiograph (PA and lateral chest exposure) and a DT exam (scout PA chest image and DT exposures).
- Phantom Images: 11 Digital Tomosynthesis phantom exams and corresponding Linear Tomography exams.
- Data Provenance: Clinical study conducted at Toronto General Hospital located in Toronto, Ontario, Canada (prospective). Phantom studies were also conducted.
3. Number of Experts and Qualifications for Ground Truth
- Number of Experts: Seven (7) board certified radiologists.
- Qualifications: "general varying reading experience." (No further specific details on years of experience were provided in the text).
4. Adjudication Method for the Test Set
The text indicates that seven radiologists performed an evaluation, but it does not specify an adjudication method (e.g., 2+1, 3+1 consensus). It only states they used a "graduated 4-point RadLex rating scale" and the mean rating was calculated from their assessments.
5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study
A clinical reader study was performed. The study involved seven radiologists evaluating images from the investigational device, a reference comparison (standard of care PA and lateral chest x-rays), and the predicate device (Linear Tomography phantom studies). The "statistical test results demonstrate the Carestream Digital Tomosynthesis delivers quality imaging performance that is equivalent or better in diagnostic quality compared to images obtained using commercially available predicate and reference devices."
- Effect Size: The document does not provide a specific quantitative effect size of how much human readers improved with AI (Digital Tomosynthesis) vs. without AI assistance. It states the DT system was found to be "equivalent or better" in diagnostic quality.
6. Standalone (Algorithm Only) Performance
The document describes the "Carestream Digital Tomosynthesis reconstruction software leverages algorithms that are the same in principle to those applied in computed tomography (CT), such as filtered back projection or iterative reconstruction etc." While it implies algorithm processing, the overall evaluation was of the imaging system producing the images for radiologist interpretation. The reader study assessed the diagnostic image quality facilitated by the DT feature. It is not explicitly stated whether a standalone algorithm-only performance assessment without human-in-the-loop was conducted. The focus was on the diagnostic utility of the images produced by the device.
7. Type of Ground Truth Used for the Test Set
The ground truth for the clinical cases was based on the diagnostic image quality ratings by board-certified radiologists using a RadLex scale. For the phantom studies, the ground truth would inherently be known from the phantom's construction and expected imaging characteristics, used for comparison with Linear Tomography.
8. Sample Size for the Training Set
The document does not provide information on the sample size used for the training set of any AI or reconstruction algorithms.
9. How Ground Truth for the Training Set Was Established
The document does not provide information on how ground truth was established for the training set. It focuses on the validation of the device performance.
§ 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.