The Cardius 3 X-ACT Imaging System is a gamma camera for Single Photon Emission Computed Tomography (SPECT) integrated with an attenuation device consisting of an x-ray generator. The Cardius 3 X-ACT Imaging System is intended for use in the generation of cardiac studies, including planar and SPBCT studies, in nuclear medicine applications. Cardius 3 X-ACT produces non-attenuation corrected SPECT Images and attenuation corrected SPECT images with x-ray transmission data that may also be corrected for scatter.

Device Description

The Cardius® 3 X-ACT Imaging system is a gamma camera for the acquisition and processing of Single Photon Emission Computed Tomography (SPECT) as well as correcting attenuation artifacts associated with these Emission studies. The device consists of an x-ray generator integrated with the previously cleared Cardius 3 XPO triple head SPECT system to provide attenuation correction functionality. The attenuation correction functionality will be included with the Cardius 3 X-ACT imaging system, or offered as an accessory for previously purchased Cardius 3 XPO systems that are configured to accept the attenuation correction functionality.

The Cardius 3 X-ACT Imaging system is designed to provide extended imaging functionality relative to the current Cardius XPO series imagers. A typical patient study comprises an emission (SPECT) study followed by a transmission study. The SPECT study is acquired using the similar system hardware and software technology as a Cardius-3 XPO imaging system. For the transmission study, the low dose x-ray generator is used to produce an attenuation map that is used for attenuation correction (AC) of the emission data. An iterative reconstruction technique then uses the attenuation map and the SPECT data as input, and the AC and non-AC reconstructed volumes are saved in the database for physician review. The attenuation correction data provided is additional information that may be reviewed by the interpreter. The original SPECT data remains available to the interpreter.

AI/ML Overview

The provided text describes the Digirad Cardius 3 X-ACT Imaging System, a gamma camera for SPECT imaging with integrated X-ray-based attenuation correction. The document focuses on its substantial equivalence to predicate devices and does not contain a detailed study with specific acceptance criteria, reported performance metrics, or information on ground truth establishment and expert adjudication typical for a clinical study comparing AI performance against established criteria.

Therefore, many of the requested fields cannot be directly extracted from the provided text. The device received 510(k) clearance based on demonstrating substantial equivalence to existing predicate devices, rather than meeting specific quantitative performance acceptance criteria in a clinical study that would involve expert readers assessing AI output.

Here's a breakdown of what can and cannot be answered based on the provided input:

1. A table of acceptance criteria and the reported device performance

Acceptance Criteria	Reported Device Performance
(Not explicitly stated as quantitative acceptance criteria in the provided text)	The testing shows Cardius 3 X-ACT meets the design specifications, which are similar to the predicate device functional specifications. Digirad internal testing and clinical images obtained with the Cardius 3 X-ACT imaging system have demonstrated equivalent efficacy to the predicate devices, and did not raise new questions regarding safety and effectiveness.
Demonstrates substantial equivalence to predicate devices based on intended use and technology	The FDA issued a substantial equivalence determination.
Functions as per its specifications (bench testing)	All tests passed with the actual results substantially matching the expected results.

2. Sample size used for the test set and the data provenance

Sample Size: Not specified. The document mentions "clinical images obtained with the Cardius 3 X-ACT imaging system" but does not quantify the number of images or patients.
Data Provenance: Not specified (e.g., country of origin, retrospective or prospective).

3. Number of experts used to establish the ground truth for the test set and the qualifications of those experts

Number of Experts: Not specified.
Qualifications of Experts: Not specified. The document mentions "physician review" but no details on expert qualifications for establishing ground truth are provided.

4. Adjudication method (e.g., 2+1, 3+1, none) for the test set

Adjudication Method: Not specified. Given that the clearance is based on substantial equivalence and "equivalent efficacy," a formal adjudication process for a test set is not explicitly described.

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

MRMC Study Done: No. The device itself is an imaging system providing attenuation corrected images, not an AI assistance tool for human readers.
Effect Size of Human Readers Improvement with AI: Not applicable, as this is not an AI-assisted diagnostic device. The attenuation correction data is described as "additional information that may be reviewed by the interpreter."

6. If a standalone (i.e. algorithm only without human-in-the loop performance) was done

Standalone Performance: Not explicitly evaluated in the context of an "algorithm only" performance against a ground truth in the way modern AI devices are. The device "produces non-attenuation corrected SPECT Images and attenuation corrected SPECT images with x-ray transmission data," implying the output is for physician review. The device's performance is implicit in its ability to produce these corrected images and its "equivalent efficacy" to predicate devices.

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

Type of Ground Truth: Not specified. The basis for "equivalent efficacy" is not detailed, but it would likely be based on expert interpretation of images for relevant clinical findings (e.g., myocardial perfusion defects) compared to predicate devices. It is not stated if this involved pathology or outcomes data.

8. The sample size for the training set

Sample Size for Training Set: Not applicable. The device uses "Digirad's internally developed proprietary algorithms" (for reconstruction and attenuation correction) but does not describe these as "trained" in the typical machine learning sense with a distinct training set. The algorithms are part of the system's design and function.

9. How the ground truth for the training set was established

Ground Truth for Training Set Establishment: Not applicable for the reasons stated above.

Summary of what the document provides for regulatory clearance:

The device received 510(k) clearance by demonstrating substantial equivalence to existing predicate devices (Philips Medical Systems BrightView VCT Imaging System and Digirad's Cardius 3 XPO Imaging System). The equivalence was based on:

Similar intended use: Gamma camera for SPECT imaging, generating cardiac studies, and providing attenuation-corrected images.
Similar technology: Gamma camera for SPECT imaging and X-ray based attenuation correction.
Design Specifications: Bench testing confirmed the device met its design specifications, which were similar to the predicate device's functional specifications.
Equivalent Efficacy: Internal testing and clinical images demonstrated "equivalent efficacy" and did not raise new safety or effectiveness concerns compared to predicate devices.

The document does not detail a clinical study with quantitative performance metrics for the device against specific acceptance criteria, nor does it describe a ground truth process involving expert readers in the context of an AI device. Instead, it focuses on the engineering and functional demonstration of equivalence.

Summary

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K083649

9 2009 MAR

Appendix 2: 510(k) Summary

A. Sponsor

Digirad Corporation 13950 Stowe Drive Poway, California 92064 Contact Person: Joel Tuckey Tel: (858) 726-1527 Fax: (858) 726-1700

B. Date Prepared: December 8, 2008

C. Device Name

Trade Name:	Cardius 3 X-ACT Imaging System
Common Name:	Gamma Camera System
Classification Name:	System, Emission Tomography
Device Class:	21CFR 892.1200, Class II
Product Code:	KPS

D. Cleared/Predicate Devices

The Cardius 3 X-ACT Imaging System is substantially equivalent to the following cleared devices:

BrightView VCT Imaging System cleared April 11, 2008 under K080927 for Philips (1) Medical Systems

Cardius 3 XPO Imaging System cleared March 23, 2007 under K070542, and (2) September 12, 2008 under K082368 for Digirad Corporation.

E. Device Description

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AC and non-AC reconstructed volumes are saved in the database for physician review. The attenuation correction data provided is additional information that may be reviewed by the interpreter. The original SPECT data remains available to the interpreter.

F. Intended Use

The intended use is the same as the predicate devices. The Cardius 3 X-ACT Imaging System is a gamma camera for Single Photon Emission Computed Tomography (SPECT) integrated with an attenuation device consisting of an x-ray generator. Cardius 3 X-ACT produces non-attenuation corrected SPECT Images and attenuation corrected SPECT images with x-ray transmission data that may also be corrected for scatter.

ে Technology

The Philips Medical Systems BrightView VCT imaging system (K080927) and Digirad's Cardius 3 XPO (K070542 and K082368) predicate devices have similar technology (gamma camera for SPECT imaging and x-ray based attenuation correction), and the same intended use as the Cardius 3 X-ACT imaging system. In Cardius 3 X-ACT, Digirad's internally developed proprietary algorithms are implemented using software technology. A low-dose xray generator is used for attenuation correction. Digirad's solid state detectors are used to acquire both emission (SPECT) and transmission scans. The transmission and emission scans share the same imaging plane. The patient sits upright in a chair that rotates to acquire both emission and transmission scans.

H. Testing

Verification and Validation tests were conducted to demonstrate the Cardius 3 X-ACT functioned as per its specifications. Bench testing was done per guidelines for radiation measurements. All tests passed with the actual results substantially matching the expected results. The testing shows Cardius 3 X-ACT meets the design specifications, which are similar to the predicate device functional specifications. Digirad internal testing and clinical images obtained with the Cardius 3 X-ACT imaging system have demonstrated equivalent efficacy to the predicate devices, and did not raise new questions regarding safety and effectiveness.

I. Conclusion

Testing results demonstrate that the Cardius 3 XPO Imaging System meets the specifications and is substantially equivalent to the predicate devices, based on comparisons of intended use and technology, and overall system performance.

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DEPARTMENT OF HEALTH & HUMAN SERVICES

Image /page/2/Picture/1 description: The image shows the logo for the U.S. Department of Health & Human Services. The logo consists of a circular seal with the text "DEPARTMENT OF HEALTH & HUMAN SERVICES (USA)" arranged around the perimeter. Inside the circle is a stylized graphic of an eagle or bird-like figure with three horizontal lines extending from its body, representing the department's mission to protect the health of all Americans and provide essential human services.

Public Health Service

Food and Drug Administration 9200 Corporate Boulevard Rockville MD 20850

9 2009 MAR

Mr. Joel Tuckey Vice President Quality Digirad® Corporation 13950 Stowe Drive POWAY CA 92064-8803

Re: K083649

Trade/Device Name: Cardius 3 X-ACT Imaging System Regulation Number: 21 CFR §892.1200 Regulation Name: Emission computed tomography system Regulatory Class: II Product Code: KPS Dated: March 3, 2009 Received: March 4, 2009

Dear Mr. Tuckey:

We have reviewed your Section 510(k) premarket notification of intent to market the device referenced above and have determined the device is substantially equivalent (for the indications for use stated in the enclosure) to legally marketed predicate devices marketed in interstate commerce prior to May 28, 1976, the enactment date of the Medical Device Amendments, or to devices that have been reclassified in accordance with the provisions of the Federal Food, Drug, and Cosmetic act (Act) that do not require approval of a premarket approval application (PMA). You may, therefore, market the device, subject to the general controls provisions of the Act. The general controls provisions of the Act include requirements for annual registration, listing of devices, good manufacturing practice, labeling, and prohibitions against misbranding and adulteration.

If your device is classified (see above) into either class II (Special Controls) or class III (PMA), it may be subject to such additional controls. Existing major regulations affecting your device can be found in the Code of Federal Regulations, Title 21, Parts 800 to 898. In addition, FDA may publish further announcements concerning your device in the Federal Register.

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Please be advised that FDA's issuance of a substantial equivalence determination does not mean that FDA has made a determination that your device complies with other requirements of the Act or any Federal statutes and regulations administered by other Federal agencies. You must comply with all the Act's requirements, including but not limited to: registration and listing (21 CFR Part 807); labeling (21 CFR Part 801; good manufacturing practice requirements as set forth in the quality systems (QS) regulation (21 CFR Part 820); and if applicable, the electronic product radiation control provisions (Sections 531-542 of the Act); 21 CFR 1000-1050.

This letter will allow you to begin marketing your device as described in your Section 510(k) premarket notification. The FDA finding os substantial equivalence of your device to a legally marketed predicate device results in a classification for your device and thus, permits your device to proceed to the market.

If you desire specific advice for your device on our labeling regulation (21 CFR Part 801), please contact the Office of Compliance at one of the following numbers, based on the regulation number at the top of this letter.

21 CFR 876.xxx	(Gastroenterology/Renal/Urology)	(240) 276-0115
21 CFR 884.xxx	(Obstetrics/Gynecology)	(240) 276-0115
21 CFR 892.xxx	(Radiology)	(240) 276-0120
Other		(240) 276-0100

Also, please note the regulation entitled, "Misbranding by reference to premarket notification" (21 CFR Part 807.97). For questions regarding postmarket surveillance, please contact CDRH's Office of Surveillance and Biometrics' (OSB's) Division of Postmarket Surveillance at 240-276-3474. For questions regarding the reporting of device adverse events (Medical Device Reporting (MDR)), please contact the Division of Surveillance Systems at 240-276-3464. You may obtain other general information on your responsibilities under the Act from the Division of Small Manufactures, International and Consumer Assistance at its toll-free number (800) 638-2041 or (240) 276-3150 or at its Internet address http://www.fda.gov/cdrb/industry.suppor/index.html.

Sincerely yours,

Janine M. Morris

Acting Director, Division of Reproductive, Abdominal, and Radiological Devices Office of Device Evaluation Center for Devices and Radiological Health

Enclosure

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Indications for Use 510(k) Number (if known): K083649 Device Name: Cardius 3 X-ACT Imaging System

Indications for Use:

Prescription Use X (Part 21 CFR 801 Subpart D) AND/OR Over-The-Counter Use (21 CFR 801 Subpart C)

(PLEASE DO NOT WRITE BELOW THIS LINE-CONTINUE ON ANOTHER PAGE OF NEEDED)

Concurrence of CDRH, Office of Device Evaluation (ODE)

Aonchhang

(Division Sign-Off) (Division Sign-On)
Division of Reproductive, Abdominal, and Radiological Device 510(k) Number _

Regulation Number and Section

§ 892.1200 Emission computed tomography system.

(a)
Identification. An emission computed tomography system is a device intended to detect the location and distribution of gamma ray- and positron-emitting radionuclides in the body and produce cross-sectional images through computer reconstruction of the data. This generic type of device may include signal analysis and display equipment, patient and equipment supports, radionuclide anatomical markers, component parts, and accessories.(b)
Classification. Class II.