(297 days)
Estimate bone mineral content (BMC in grams) and bone mineral density (BMD in grams/cm²) in the distal section of the forearm.
The DTX-100 candidate device is a single energy system, where the measured object, in this case the forearm, is submerged into a soft tissue equivalent water bath. The X-Ray generator is driven at 40 kV, with a current of 0.2 mAmps. The detector uses scintillating crystal and a photomultiplier tube. A highly stable X-Ray output, together with a source collimation of 1 mm, and excellent pixel resolution, yields images of very high quality. The typical time to estimate bone mineral content and bone mineral density is approximately 3.0 to 4.5 minutes. The effective patient dose is estimated to be 0.01 micro Sievert per scan.
Here's an analysis of the acceptance criteria and study information for the DTX-100 Bone Densitometer based on the provided 510(k) summary:
Given that this 510(k) is for a device declared "superseded" and the FDA's acceptance letter indicates substantial equivalence to a predicate device, the nature of the "acceptance criteria" and "study" are primarily focused on demonstrating equivalence rather than establishing new performance benchmarks. The core of the submission revolves around showing that the candidate DTX-100 device is identical or comparable to its predicate DTX-100 predecessor.
1. Table of Acceptance Criteria and Reported Device Performance
| Acceptance Criteria (Implied from 510(k) goal) | Reported Device Performance (DTX-100 Candidate) |
|---|---|
| Technological Equivalence to Predicate DTX-100: | |
| - X-ray transmission source | Identical: Candidate and predicate consist of computer, keyboard, monitor, printer, scanner system using X-ray transmission source. Both use SXA to estimate BMC and BMD. |
| - Soft-tissue equivalent material | Identical: Both use water. |
| - Calibration | Identical: Both use a line-by-line calibration system, ensuring good precision. |
| - Imaging technique, data acquisition, QC phantom | Identical. |
| - Source collimation | Identical: 1 mm diameter. |
| - Reference location | Identical: 8 mm Ulna-Radius gap. |
| - Accuracy and precision error | Comparable to predicate device. (Specific values not provided, but asserted to be comparable). |
| Clinical Performance (Reference Data Base): | |
| - Establishment of a reference data base for normal American female Caucasians (20-80 years old) to estimate BMC/BMD. | A reference data base was established based on BMD and BMC data collected from the non-dominant forearm of a representative sample of the reference population using a model DTX-100 bone densitometer. The data included at least 50 persons in ten-year age groups. |
| - Data statistically representative | The standard deviation of estimated BMC and BMD is statistically representative as required by FDA guidance (at least 50 people per 10-year age group). |
| - Reference data suitable for clinical use | The derived American reference data base is suitable for use by healthcare professionals to compare BMC/BMD with age-matched peers and against young adult mean values. |
2. Sample Size Used for the Test Set and Data Provenance
- Sample Size for Test Set: The submission mentions a "statistically valid quantity of women" participating in four clinical studies. Specifically, the reference data base was established with "at least 50 persons in ten year peer age groups" for normal American female Caucasians ranging from 20 to 80 years. This implies a minimum of 6 * 50 = 300 participants (20-29, 30-39, 40-49, 50-59, 60-69, 70-79).
- Data Provenance:
- Country of Origin: USA. The studies were conducted at:
- Helen Hayes Hospital (West Haverstraw, NY)
- New England Medical Center Hospitals (Boston, MA) (3 studies)
- Retrospective or Prospective: The provided information doesn't explicitly state whether the studies were entirely retrospective or prospective. However, the listed start and end dates for each protocol (e.g., "Conducted from May 1995 through May 1996") indicate they were
- Prospective in nature, as data were collected for specific purposes of the studies during those stated periods.
- Country of Origin: USA. The studies were conducted at:
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts
The concept of "experts" establishing ground truth in the traditional sense (e.g., radiologists for image interpretation) does not directly apply here. The "ground truth" for bone densitometers is typically established by the physical measurements performed by the device itself to estimate BMC and BMD according to established medical and scientific principles. The clinical studies were conducted to gather reference data on normal populations for these measurements. The "experts" would be the clinicians and researchers leading these studies, but their role was to conduct the measurements and analyze the statistical properties of the device's output against a defined normal population, not to interpret an output against a separate truth. The qualifications of these experts are not detailed, but they would presumably be medical professionals and clinical researchers associated with the listed hospitals.
4. Adjudication Method for the Test Set
Not applicable. The study involved collecting direct measurements (BMC and BMD) from individuals using the DTX-100, not interpreting cases that would require an adjudication process. The accuracy and precision of the device itself are inherent in its design and operation.
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. This device is a bone densitometer, not an AI-powered diagnostic imaging interpretation tool. There is no "human reader" component in the context of interpreting images or assisting with diagnoses where AI would improve performance. The device directly outputs BMC and BMD values.
6. If a Standalone (i.e. algorithm only without human-in-the-loop performance) Was Done
Yes, in a practical sense, a standalone performance was done. The DTX-100 bone densitometer is a device that directly measures and calculates BMC and BMD. The clinical studies gathered data from the device's output on a population to establish a reference database. There isn't an "algorithm" being evaluated beyond the inherent functioning of the densitometer itself. The device functions without human interpretation of raw data points to arrive at its final output (BMC and BMD).
7. The Type of Ground Truth Used
The "ground truth" here is the actual bone mineral content (BMC) and bone mineral density (BMD) of the study participants, as measured by the DTX-100 device itself, within the context of establishing normative data for a defined population. It is not an external "ground truth" like pathology for a lesion. The goal was to establish a clinical reference range for the device's measurements in a normal population, which then serves as a comparison point for patients.
8. The Sample Size for the Training Set
The concept of a "training set" as understood in machine learning is not directly applicable here. The DTX-100 is a physical measurement device whose underlying principles are physics-based, not a learned algorithm requiring a separate training set. The data from the four clinical studies were used to establish a reference database for a normal population, not to train the device's internal algorithms. This reference database included "at least 50 persons in ten year peer age groups" for normal American female Caucasians aged 20-80. This implies a minimum of 300 participants for the reference database.
9. How the Ground Truth for the Training Set Was Established
As explained above, there isn't a "training set" in the AI sense for this device. The "ground truth" for the reference database was established through direct
- physical measurements of BMC and BMD using the DTX-100 bone densitometer itself, conducted on a defined population (normal American female Caucasians). The values obtained from these measurements, after statistical analysis, formed the basis of the reference data base. The accuracy and precision of these measurements are asserted to be comparable to the predicate device.
§ 892.1170 Bone densitometer.
(a)
Identification. A bone densitometer is a device intended for medical purposes to measure bone density and mineral content by x-ray or gamma ray transmission measurements through the bone and adjacent tissues. This generic type of device may include signal analysis and display equipment, patient and equipment supports, component parts, and accessories.(b)
Classification. Class II.