(81 days)
THE CAPINTEC 292 ELECTROMETER IS INTENDED TO BE USED BY TRAINED MEDICAL PHYSICISTS OR QUALIFIED RADIATION THERAPY TECHNOLOGISTS TO PERFORM QUALITY ASSURANCE CHECKS AND MEASUREMENTS ON THE OUTPUT FROM THERAPEUTIC X-RAY MACHINES OR TELETHERAPY UNITS. WITH THE ADDITION OF AN OPTIONAL CAPINTEC CRC DOSE CALIBRATOR CHAMBER, THE 292 MAY ALSO BE USED BY TRAINED MEDICAL PAYSICISTS OR QUALIFIED TECHNOLOGISTS TO MEASURE RADIOACTIVE SOURCES USED FOR THERAPEUTIC OR DIAGNOSTIC TREATMENT.
The 292 is a precise and accurate software controlled low impedance electrometer with four measurement ranges, adjustable + bias voltage which can act as a dose or dose rate meter.
Here's an analysis of the provided text, focusing on acceptance criteria and the study proving device performance:
Acceptance Criteria and Device Performance Study for Capintec Model 292 Electrometer
1. Table of Acceptance Criteria and Reported Device Performance
| Acceptance Criteria | Reported Device Performance |
|---|---|
| 100% success in function and intended use | Excellent agreement between 292 and 192 electrometers when measuring x-ray machines (to the limits of reproducibility of individual x-ray machines). |
| 100% agreement between software algorithms and manual calculations. | |
| Agreed to within 1% between 292 (with CRC dose calibrator chamber) and CRC 15R dose calibrator when measuring NIST radioactive sources. | |
| Evaluation of suggestions for improvement in software/hardware from "beta test sites" | Suggestions were received and would be evaluated, tested, and incorporated if appropriate. |
| Correction of any problems discovered during beta testing | Problems would be corrected prior to release to production. |
2. Sample Size Used for the Test Set and Data Provenance
The document does not explicitly state a numerical "sample size" in terms of number of devices or number of measurements for the primary comparison. Instead, it describes:
- Test Set Description: "The same NIST calibrated ionization chamber was used with both the 192 and 292 electrometers, and measurements were made under a variety of accelerator and orthovoltage machine settings."
- Data Provenance: The measurements were likely conducted internally by Capintec or in collaboration with a National Institute of Standards and Technology (NIST) certified facility, given the use of "NIST calibrated ionization chamber" and "NIST radioactive sources." The "beta test sites," which contributed to identifying issues and suggestions, were described as "selected radiation oncology facilities." The data is likely prospective as it involves new testing of the 292 electrometer.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts
The document does not specify a distinct set of "experts" to establish a ground truth for the test set. Instead, the ground truth is established by:
- Reference Devices: The predicate devices (Capintec Model 192 electrometer and CRC 15R dose calibrator) served as the de-facto "ground truth" for comparison. These are established, pre-amendment devices or existing devices with proven performance.
- NIST Calibration: The use of "NIST calibrated ionization chamber" and "NIST radioactive sources" implies that the accuracy of the measurements and the reference values are traceable to national standards, which can be considered the highest form of metrological "ground truth."
- Implicit Expertise: While not explicitly stated as "experts," the "trained medical physicists or qualified radiation therapy technologists" who performed the measurements using the 192, 292, and CRC 15R would have the necessary qualifications to conduct these tests and interpret the results.
4. Adjudication Method for the Test Set
No explicit adjudication method (e.g., 2+1, 3+1) is described. The comparison relies on:
- Direct Measurement Comparison: Results from the 292 were directly compared to those from the predicate 192 electrometer and the CRC 15R dose calibrator.
- Software Verification: Software algorithms were verified against "manual calculations," suggesting a direct comparison without a complex multi-person adjudication process.
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 done. This type of study is typically used for diagnostic imaging devices where different human readers interpret cases with and without AI assistance. The Capintec Model 292 Electrometer is a measurement device, not an interpretive diagnostic tool, so such a study would not be applicable.
6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) Study Was Done
Yes, a standalone performance evaluation of the algorithm (software) was explicitly done: "In addition, the software algorithms were verified against manual calculations and agreement was 100%." This verifies the internal logic and calculations performed by the device's software without direct human interpretation being part of the performance metric.
7. The Type of Ground Truth Used
The ground truth used was a combination of:
- Reference Device Performance: The established, pre-amendment Capintec Model 192 electrometer and the CRC 15R dose calibrator served as the primary reference for performance comparison.
- NIST Traceability: The use of "NIST calibrated ionization chamber" and "NIST radioactive sources" indicates that the ground truth for the physical measurements is traceable to national metrological standards.
- Manual Calculation Verification: For the software, "manual calculations" served as the ground truth.
8. The Sample Size for the Training Set
The document does not specify a sample size for a "training set." The 292 electrometer is a microprocessor-based measurement device, not an AI/machine learning model that typically requires a distinct training set. The development process would involve traditional engineering, calibration, and testing, rather than machine learning training.
9. How the Ground Truth for the Training Set Was Established
As there is no explicit mention of a "training set" in the context of machine learning, the question of how its ground truth was established is not directly applicable. The device's functionality is based on established physics principles and precision measurement, with performance verified against existing, validated devices and NIST standards.
§ 892.5050 Medical charged-particle radiation therapy system.
(a)
Identification. A medical charged-particle radiation therapy system is a device that produces by acceleration high energy charged particles (e.g., electrons and protons) intended for use in radiation therapy. This generic type of device may include signal analysis and display equipment, patient and equipment supports, treatment planning computer programs, component parts, and accessories.(b)
Classification. Class II. When intended for use as a quality control system, the film dosimetry system (film scanning system) included as an accessory to the device described in paragraph (a) of this section, is exempt from the premarket notification procedures in subpart E of part 807 of this chapter subject to the limitations in § 892.9.