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The XCT 2000 L performs a Quantitative Computed Tomography (QCT) scan at various user selectable skeletal sites and measures volumetric bone density (mg/cm3). It provides separate values for the inner core of the bone (trabecular region), the outer ring of the bone (cortical region), and the entire bone (Total). It also provides Axial SSI and Polar SSI values as an aid to physicians in evaluating fracture risk and bone strength. These bone density estimates can also be used as an aid to physicians in determining fracture risk.

The XCT 2000 L performs a Computed Tomography (CT) scan at various user selectable skeletal sites and measures volumetric bone density in mg/cm3. It provides separate values for the inner core of the bone (trabecular region), the outer ring of the bone (cortical region), and the entire bone (Total). It also provides Axial SSI and Polar SSI values as an aid to physicians in evaluating fracture risk and bone strength. These values are calculated from the raw data taken during the CT scan and do not require additional scan time or patient dose. The XCT 2000 L has a 140 mm measurement diameter, a selectable resolution range of 0.2 to 0.8 mm, a typical scan time of 80 seconds, and a typical dose of 40 mRems. It can do multiple scans at selectable spacing. The XCT 2000 L measures a wide variety of skeletal sites, including the Heel (os calcis), Forearm, Knee, and Tibia. The XCT 2000 L has an in vivo precision of < 3 mg/cm3 for the trabecular region and < 9 mg/cm3 for the cortical region. It is calibrated to the COMAC phantom with an accuracy of 2 % The XCT 2000 L also includes Fracture Risk assessment based on the World Health Organization (WHO) criteria.

Here's a breakdown of the acceptance criteria and study information for the Norland XCT 2000 L pQCT Bone Densitometer, based on the provided 510(k) summary:

Acceptance Criteria and Device Performance

Study Information

The 510(k) summary for the Norland XCT 2000 L pQCT Bone Densitometer describes the device and its performance but does not detail a specific clinical study with sample sizes, expert involvement, or comparative effectiveness. Instead, it focuses on demonstrating substantial equivalence to predicate devices (Norland XCT 960 pQCT bone densitometer K922286 and Fracture Risk Assessment for Norland bone densitometers K980569).

The performance metrics provided (in vivo precision and accuracy) are likely derived from internal testing and validation rather than a large-scale clinical trial described in detail in this summary.

Here's what can be inferred or explicitly stated based on the provided document, addressing your specific points where possible:

1. Sample size used for the test set and the data provenance:

   • Test Set Size: Not explicitly stated. The document focuses on performance metrics like "in vivo precision" and "accuracy," which imply testing, but the sample size of subjects or phantoms used for these evaluations is not provided.
   • Data Provenance: Not explicitly stated. The nature of "in vivo precision" suggests human subjects, but details on location or retrospective/prospective nature are absent.

2. Number of experts used to establish the ground truth for the test set and the qualifications of those experts: Not explicitly stated. The summary does not describe a process for establishing ground truth via expert review for the performance metrics. The "accuracy" is mentioned in relation to the COMAC phantom, implying a physical standard rather than expert interpretation of images.

3. Adjudication method (e.g. 2+1, 3+1, none) for the test set: Not applicable based on the information provided. Expert adjudication is not mentioned, as the device primarily measures physical bone density values.

4. 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. This document describes a bone densitometer, not an AI-assisted diagnostic tool requiring human reader improvement studies. The device measures physical parameters and provides calculated values.

5. If a standalone (i.e. algorithm only without human-in-the-loop performance) was done: The device itself is a "standalone" system in terms of its measurement capabilities. It performs the CT scan and calculates bone density values, SSI, and T-scores. While physicians interpret the results, the core function of measurement is algorithmic. The precision and accuracy metrics are for this standalone measurement capability.

6. The type of ground truth used (expert consensus, pathology, outcomes data, etc):

   • For precision, the ground truth is the consistency of repeated measurements on the same subject/phantom.
   • For accuracy, the ground truth is the known values of the COMAC phantom.
   • The "fracture risk assessment" component uses WHO criteria (T-Scores), which are established clinical guidelines rather than a specific ground truth derived from a study for this device.

7. The sample size for the training set: Not applicable. This is a medical device for measurement, not a machine learning algorithm that requires a "training set" in the conventional sense. Its "training" would involve calibration to known physical standards, such as the COMAC phantom.

8. How the ground truth for the training set was established:

   • The device is "calibrated to the COMAC phantom." The ground truth for this calibration would be the known physical density values of the COMAC phantom.
   • The WHO criteria for fracture risk assessment are established clinical guidelines, not a ground truth derived from a training set for this specific device.

In summary, the 510(k) provided focuses on defining the device's measurement capabilities and demonstrating substantial equivalence to existing devices based on its physical performance characteristics (precision and accuracy) rather than presenting a clinical study with detailed statistical analysis of human reader performance or AI algorithm training.

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