(88 days)
The Twinheads® TH-101 Extracorporeal Shock Wave Lithotripter is intended to fragment urinary stones in the kidney (renal pelvis and renal calyces) and ureter (upper, middle, and lower ureter).
The Twinheads® TH-101 ESWL is a spark gap dual head shock wave lithotripter with an integrated fluoroscopy system for the fragmentation of kidney and ureteral calculi. The Twinheads® TH-101 delivers a pair of shock waves, which are separated from each other by a certain delay time, with perpendicular trajectories and overlapping focal zones. The pulse pairs or twin shocks are aligned with the calculi or stone utilizing the fluoroscopy system via two orientations. A rapid current pulse discharges through a small gap in each of the two heads. The pulse discharge creates a shock wave, which radiates outward. Two identical ellipsoid reflectors serve to reflect and focus the shock waves, which are transmitted into the patient by a water cushion through a membrane and contact gel. There are two shockwave sources and two cushions in the Twinheads® TH-101 ESWL. Also included are an accurate motorized table and U-arm movements, high resolution fluoroscopy, and efficient shock wave energy sources.
The provided document describes a 510(k) premarket notification for the Twinheads® TH-101 Extracorporeal Shock Wave Lithotripter. The acceptance criteria and the study proving the device meets them are outlined in section 7, "Clinical study."
1. Table of Acceptance Criteria and Reported Device Performance:
The document implicitly refers to the special controls guidance for ESWL devices as the acceptance criteria. The specific performance metrics assessed in human clinical trials for a new ESWL device would typically include:
| Acceptance Criteria (Implied from FDA Guidance for ESWL) | Reported Device Performance |
|---|---|
| Safety: No unanticipated adverse effects. | "...the device was able to fragment stones successfully and not pose any unanticipated adverse effects." |
| Effectiveness/Functionality: Successful stone fragmentation for indicated uses (urinary stones in kidney and ureter). | "...the device was able to fragment stones successfully..." and "The results of the study confirmed the functionality of the device and the adequacy of the proposed labeling." |
| Adequacy of Labeling: Labels accurately reflect device capabilities and safe use. | "...the adequacy of the proposed labeling." |
2. Sample Size and Data Provenance for Test Set:
- Sample Size: 20 patients.
- Data Provenance: The study was conducted at "two sites." The document does not specify the country of origin, but given the 510(k) submission to the FDA, it is highly probable the data was collected in the United States.
- Retrospective or Prospective: Prospective, as it states "20 patients were treated" indicating a clinical trial was performed.
3. Number of Experts and Qualifications for Ground Truth:
The document does not explicitly state the number of experts used to establish the ground truth or their specific qualifications (e.g., radiologist with 10 years of experience). In a clinical study for a lithotripsy device, the success of "stone fragmentation" would typically be assessed by the treating urologists or other medical specialists involved in post-procedure imaging and patient follow-up.
4. Adjudication Method for the Test Set:
The document does not specify an adjudication method (e.g., 2+1, 3+1) for assessing the outcomes of the clinical study.
5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study:
No, a Multi-Reader Multi-Case (MRMC) comparative effectiveness study was not explicitly mentioned or indicated in this summary. The study described is a confirmatory clinical study to demonstrate the device's functionality, safety, and effectiveness, not a comparison of human reader performance with and without AI assistance.
6. Standalone (Algorithm Only) Performance:
No, a standalone (algorithm only) performance study was not conducted. This device is a physical medical device (Extracorporeal Shock Wave Lithotripter), not an AI algorithm. The study described assesses the device's ability to fragment stones in patients.
7. Type of Ground Truth Used:
The ground truth used was based on clinical outcomes (successful stone fragmentation) and safety assessments (absence of unanticipated adverse effects) in treated patients. While not explicitly detailed, these assessments would involve post-treatment imaging and clinical evaluation by medical professionals.
8. Sample Size for the Training Set:
The document does not mention a "training set" in the context of an AI/ML algorithm. This device is a physical lithotripsy machine; therefore, the concept of a training set for an algorithm is not applicable here. The "clinical study" described serves as the primary evidence for its intended use, rather than a separate training and test set distinction typically associated with AI.
9. How Ground Truth for Training Set Was Established:
As there is no training set for an AI algorithm, this question is not applicable. The device's fundamental design and technological characteristics (Section 6) are based on established physics and engineering principles, and its performance is validated through the clinical study.
§ 876.5990 Extracorporeal shock wave lithotripter.
(a)
Identification. An extracorporeal shock wave lithotripter is a device that focuses ultrasonic shock waves into the body to noninvasively fragment urinary calculi within the kidney or ureter. The primary components of the device are a shock wave generator, high voltage generator, control console, imaging/localization system, and patient table. Prior to treatment, the urinary stone is targeted using either an integral or stand-alone localization/imaging system. Shock waves are typically generated using electrostatic spark discharge (spark gap), electromagnetically repelled membranes, or piezoelectric crystal arrays, and focused onto the stone with either a specially designed reflector, dish, or acoustic lens. The shock waves are created under water within the shock wave generator, and are transferred to the patient's body using an appropriate acoustic interface. After the stone has been fragmented by the focused shock waves, the fragments pass out of the body with the patient's urine.(b)
Classification. Class II (special controls) (FDA guidance document: “Guidance for the Content of Premarket Notifications (510(k)'s) for Extracorporeal Shock Wave Lithotripters Indicated for the Fragmentation of Kidney and Ureteral Calculi.”)