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The DexaCare® G4 is a cost effective, table top bone densitometer. The DexaCare® G4 is a modification of the predicate Osteometer MediTech DTX-200 device listed in 510(k) K964562. The DexaCare® G4 candidate device is a dual energy system, where the measured object, in this case the forearm, by the software, is divided into two compartments, bone and soft-tissue. Having two energies, and two compartments (unknowns) it is possible to establish and solve two formulae with two unknowns. The X-ray generator is driven at 55kV, with a current of 300pAmps. The beam is filtered with Tin (Sn), using the K-Edge of this material to enhance the separation of the low and the high energy. The average energy peaks are approximately 29 keV, and 46 keV respectively. A highly stable X-ray output, together with a source collimation of 1 mm and a pixel resolution of 0.4mm X 0.4mm, yields images of very high quality. The detector is a sandwich construction, using solid state photodiodes consisting of two diodes with scintillation material. The two energies are separated by the sandwich construction. The X-ray beam meets the first scintillator, where predominantly the low energy is detected, and then it meets the second scintillator, where the rest of the energy is detected. The typical time to estimate bone mineral content and bone mineral density is approximately four minutes. The effective patient dose is estimated to be 0.1 micro Sievert per scan.

AI/ML Overview

Here's a breakdown of the acceptance criteria and study details for the DexaCare® G4 device, based on the provided text:

1. Table of Acceptance Criteria and Reported Device Performance

The submission primarily focuses on demonstrating substantial equivalence to a predicate device rather than setting explicit numerical acceptance criteria for independent performance. The "acceptance criteria" can be inferred as showing comparable performance to the predicate device, specifically regarding the correlation and lack of significant difference in BMC and BMD measurements.

Acceptance Criterion (Inferred from study goal)	Reported Device Performance (DexaCare® G4 vs. DTX-200)
Correlation of BMC and BMD measurements between the DexaCare® G4 and the predicate DTX-200 should be similar to the correlation between two DTX-200 devices.	"The correlation observed between the DexaCare® G4 and the DTX-200 was similar to that observed between the two DTX-200 devices."
Differences in BMC and BMD measurements between the DexaCare® G4 and the predicate DTX-200 should be small and not clinically significant.	"The differences observed in BMC and BMD between the DexaCare® G4 and DTX-200 were small and not clinically signficant."
Clinical performance of the DexaCare® G4 should be similar to that of the predicate DTX-200.	"The clinical performance of the DexaCare® G4 is similar to that of the DTX-200."

2. Sample Size and Data Provenance

Test Set Sample Size: 16 subjects.
Data Provenance: Retrospective for the purpose of demonstrating equivalence, and conducted in-house at Osteometer MediTech, Inc. in Hawthorne, CA, USA. This indicates the data was collected specifically for this validation study, not from a broad population in multiple countries.

3. Number of Experts / Qualifications for Ground Truth

Not applicable. This study does not involve expert readers establishing ground truth for diagnostic accuracy, but rather compares quantitative measurements from two devices.

4. Adjudication Method

Not applicable. The study involves direct measurements of BMC and BMD, followed by statistical comparison (paired t-test, linear regression), not interpretation needing adjudication.

5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study

No, an MRMC comparative effectiveness study was not performed. The device is a bone densitometer producing quantitative measurements, not a system that assists human readers in interpretation.

6. Standalone Performance Study

Yes, a standalone study was performed. The study compared the measurements of the DexaCare® G4 directly against measurements from the predicate DTX-200 devices without human-in-the-loop interpretation being evaluated. The algorithm's output (BMC and BMD) was directly compared.

7. Type of Ground Truth Used

The "ground truth" in this context is the quantitative measurements (Bone Mineral Content and Bone Mineral Density) obtained from the predicate DTX-200 device. The study aims to show that the new device's measurements are essentially the same as those from the established predicate device.

8. Sample Size for Training Set

No information is provided regarding a separate training set. The study describes a clinical validation study on 16 subjects. Given the nature of a bone densitometer (a measurement device as opposed to an AI diagnostic assistant that requires extensive image-based training), it's highly probable that traditional calibration procedures were used rather than a "training set" in the machine learning sense. The document states: "The DexaCare® G4 uses a line-by-line calibration system to ensure good precision."

9. How Ground Truth for Training Set Was Established

Not applicable, as no training set in the AI sense is specifically mentioned. Calibration for the device would typically be established using phantoms with known bone mineral content/density values, following industry standards for bone densitometry. However, the document does not detail the specific methods for establishing the accuracy of the calibration system itself.

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