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The Photon Radiosurgery System (PRS) is indicated for radiation therapy treatments.

The PRS Spherical Applicators are indicated for use with the Photon Radiosurgery System (PRS) to deliver a prescribed dose of radiation to the treatment margin or turnor bed during intracavity or intraoperative radiotherapy treatments.

The Photoelectron Corporation Photon Radiosurgery System (PRS) is a miniature, high-dose rate, low energy X-ray source that emits X-ray radiation from the tip of a 3 mm diameter probe. The original PRS Model was cleared for marketing in the 510(k) K964947. The PRS was subsequently modified and cleared for marketing in 510(k) K980526 (PRS400). The PRS was cleared by these 510(k)s for the irradiation of intracranial tumors.

Since the currently cleared PRS400 is restricted to treatment of intracranial tumors, Photoelectron Corporation is also proposing in this 510(k) to modify the PRS indications for use to permit use of the PRS to irradiate tumors other than at intracranial locations.

This 510(k) is also being submitted to add the use of PRS Spherical Applicators to the PRS System. The Spherical Applicators will permit the PRS to be used for intracavitary or intraoperative radiation therapy. In addition, two accessories for use with the Spherical Applicators are also being added to the PRS: the Radiation Shields, which protect surrounding tissue and/or organs from radiation, and the PRS Interface Adapters, which provide a means for connecting the PRS X-ray Source (XRS), and the Spherical Applicators to various commercially available surgical support systems for non-stereotactic applications.

Here's an analysis of the provided text regarding the acceptance criteria and study for the Photon Radiosurgery System (PRS):

Overall Assessment:

The provided document (K992577) is a 510(k) premarket notification for the Photoelectron Corporation's Photon Radiosurgery System (PRS). This document seeks to expand the indications for use of an already cleared device and introduce new accessories. A 510(k) typically focuses on demonstrating substantial equivalence to a predicate device rather than presenting extensive clinical trial data or detailed performance acceptance criteria in the same way a PMA (Premarket Approval) might.

As such, the document does not describe traditional clinical acceptance criteria or a study proving the device meets those criteria in the context of an AI/ML device. Instead, it focuses on dosimetry data to demonstrate the performance of the new applicators and substantial equivalence to existing radiation therapy devices.

1. Table of Acceptance Criteria and Reported Device Performance

Based on the provided text, the acceptance criteria are implicitly tied to the dosimetry data demonstrating the performance of the Spherical Applicators. There are no explicit, quantifiable acceptance criteria (e.g., minimum accuracy, sensitivity, specificity) for a diagnostic outcome, as this is a therapeutic device.

Note: The document provides no specific numerical values or detailed results of the dosimetry data beyond this statement.

2. Sample Size Used for the Test Set and Data Provenance

• Sample Size: Not applicable in the traditional sense of a patient test set for an AI/ML diagnostic. The "test set" here refers to the physical characterization of the device through dosimetry. The document does not specify how many tests or measurements were conducted for the dosimetry data.
• Data Provenance: Not applicable. This is not patient-derived data but rather engineering and physics characterization of the device.

3. Number of Experts Used to Establish Ground Truth for the Test Set and Qualifications

Not applicable. The ground truth for dosimetry measurements is derived from physical measurement techniques, not expert consensus on medical images or clinical outcomes.

4. Adjudication Method for the Test Set

Not applicable. There is no expert adjudication needed for physical dosimetry measurements.

5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study was done

No, an MRMC comparative effectiveness study was not done. This device is a radiation therapy system, not an AI-assisted diagnostic tool that would typically involve human readers interpreting images.

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

This question is not directly applicable. The device itself is a standalone therapeutic system. The "performance" being evaluated is its ability to deliver radiation, not an algorithm's diagnostic output. The dosimetry data is a measure of the device's standalone performance in terms of radiation delivery characteristics.

7. The Type of Ground Truth Used

The ground truth used for the evaluation mentioned (dosimetry) is based on physical measurements and scientific principles related to radiation dose distribution. This is a form of objective, empirical data to characterize the device's output.

8. The Sample Size for the Training Set

Not applicable. This device is not an AI/ML system trained on a dataset.

9. How the Ground Truth for the Training Set was Established

Not applicable. This device is not an AI/ML system.

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The Photon Radiosurgery System is intended to be used for the irradiation on intracranial tumors.

The PRS400 Photon Radiosurgery System is a modification of the Photoelectron Corporation PRS Model 3. Modifications have been made to increase radiation safety, improve the user interface with the system, and improve manufacturability of the PRS components. None of the changes affect the function, intended use, or overall design of the PRS. Both devices are complete systems for highly focused treatment of intracranial tumors. The heart of the system is a miniature, high dose rate, low energy X-ray source equipped with a 3.175 mm diameter, 10 cm long interstitial probe. The X-ray source is designed so that the tip of the probe can be positioned precisely into the tumor and a prescribed therapeutic radiation dose delivered in a single fraction. X-rays are emitted from the tip of the PRS' probe in a spherically symmetric pattern and the tumor is destroyed from the inside out. A sterile sheath is placed over the probe prior to insertion into the turnor. The voltage, current, and exposure time of the X-rays are set via the PRS400 Control Console. A complete set of accessories is provided to assist in placement of the interstitial probe and to perform quality control of the X-ray source in the clinical setting. Additional laboratory-based components of the PRS include an automated dosimetry water tank for calibration and a CCD-camera based radio chromic film reader for dose verification.

The provided document is a 510(k) summary for the Photoelectron Corporation PRS400 PHOTON RADIOSURGERY SYSTEM. This submission is for a medical device that delivers radiation therapy, not an AI/ML powered device. As such, the standard acceptance criteria for AI/ML devices (e.g., sensitivity, specificity, AUC) and associated study methodologies (e.g., MRMC, standalone performance) are not applicable.

The document describes non-clinical tests performed to demonstrate substantial equivalence to a predicate device, the PRS Model 3.

Here's an analysis based on the document's content:

1. Table of Acceptance Criteria and Reported Device Performance:

Since this is not an AI/ML device, the acceptance criteria are based on demonstrating comparable performance and safety to a predicate device, specifically regarding its radiative properties.

• Low photon energy
• Steep fall-off in dose with distance from the probe
• Nearly spherical dose distribution around the probe | In vitro laboratory studies demonstrate that the PRS400 and the Model 3 produce the "same output" characterized by:
• Low photon energy
• Steep fall-off in dose with distance from the probe
• Nearly spherical dose distribution around the probe. |
  | Function, Intended Use, Overall Design Equivalence | No changes affecting these aspects compared to the predicate device. | "None of the changes affect the function, intended use, or overall design of the PRS."
  "The technological and functional characteristics of the PRS400 are essentially identical to the PRS Model 3." |
  | Radiation Source Equivalence | Radiation source in PRS400 is "essentially the same" as PRS Model 3 and produces "nearly identical radiative output." | "The radiation source used in both models is essentially the same and produces nearly identical radiative output." |

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

• Sample Size: The document does not specify a "sample size" in the context of a statistical study with a defined test set. The non-clinical tests described are "In vitro Laboratory Studies" comparing the radiative properties of the two devices. It implies multiple measurements were taken to characterize the output, but the exact number of instances or measurements is not provided.
• Data Provenance: The studies were "In vitro Laboratory Studies." The country of origin is implicitly the United States, given the submitter's address and the FDA submission. The studies are prospective in the sense that they were conducted specifically for this submission to characterize the new device.

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

• This question is not applicable to this type of device submission. Ground truth, in the context of AI/ML, refers to a definitively correct answer established by human experts or other objective means. For a radiation delivery device, the "ground truth" is measured physical properties like dose distribution, photon energy, and fall-off rates, which are determined by physical dosimetry and equipment, not human expert consensus.

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

• Not applicable. Adjudication methods are typically used to resolve discrepancies in expert-assigned ground truth in subjective assessments for AI/ML models. The PRS400's performance is objectively measured.

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. The PRS400 is a radiation delivery system, not an AI-assisted diagnostic or treatment planning tool. There are no "human readers" in the context of interpreting the device's output to make a diagnosis or directly interact with the device's primary function in this manner.

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

• Not applicable. The PRS400 is hardware with embedded control systems, not a standalone AI algorithm. Its performance is inherent in its physical and electrical design. The "In vitro Laboratory Studies" essentially measure the standalone physical performance of the device without patient interaction, but this is a characterization study, not an algorithm performance study.

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

• The "ground truth" for the non-clinical tests was the physical measurement and characterization of the radiation output of the PRS400, compared against the known and accepted physical properties of the predicate PRS Model 3. This involved dosimetry (measuring dose distribution) and characterization of photon energy.

8. The sample size for the training set:

• Not applicable. This is not an AI/ML device that requires a training set.

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

• Not applicable. This is not an AI/ML device that requires a training set.

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The Photon Radiosurgery System is intended to be used for the irradiation of intracranial tumors.

The Photon Radiosurgery System (PRS) is a complete system for highly focused treatment of intracranial tumors. The PRS includes an X-ray Source and Control Box, along with accessories for clinical treatment, quality assurance, laboratory calibration and dose verification. The miniature X-ray source incorporates a 3.175 mm diameter. 10 cm long interstitial probe and is designed to be mounted on a stereotactic frame so that the probe tip, covered with a sterile sheath, can be positioned precisely into the tumor. High dose rate, low energy X-rays are emitted from the probe tip in a spherical pattern and a prescribed therapeutic radiation dose delivered in a single fraction destroys the tumor from the inside out. Voltage, beam current, and treatment time or photon count are set on the Control Box which is powered by a rechargeable battery. Accessories are provided to assist in placement of the interstitial probe and to perform quality control of the X-ray source in the clinical setting. Additional laboratory-based components of the PRS include an automated dosimetry water tank for calibration and a CCD-camera based radiochromic film reader for dose verification.

Here's a breakdown of the acceptance criteria and study information for the Photoelectron Corporation PHOTON RADIOSURGERY SYSTEM (K964947), based on the provided text:

Acceptance Criteria and Reported Device Performance

The provided 510(k) summary does not explicitly list quantitative acceptance criteria in a table format with corresponding reported performance metrics. Instead, it focuses on demonstrating substantial equivalence to predicate devices in terms of intended use, technological/functional features, construction, materials, safety, and effectiveness.

The "acceptance criteria" can be inferred from the claims made regarding the device's performance and similarity to predicate devices, particularly that it is "as safe and effective as legally marketed predicate devices for the irradiation of intracranial tumors."

Here's an attempt to structure the information based on the available text:

Detailed Study Information:

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

   • Sample Size (Clinical Test Set): "eligible subjects diagnosed with primary or metastatic intracranial tumors which were either solitary or multiple in number." No specific number is provided in the summary, but it implies a cohort of human patients.
   • Data Provenance: "at multiple clinical sites" (implies prospective human clinical data). "Autopsy data was also obtained" (retrospective on deceased subjects).

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

   • The document does not specify the number of experts or their qualifications for establishing ground truth in the clinical studies. It mentions "clinical, radiological, functional and quality of life measures," which would typically involve expert interpretation (e.g., radiologists for imaging, neurologists for functional assessments, etc.), but this is not detailed.

3. Adjudication method for the test set:

   • The document does not specify an adjudication method (e.g., 2+1, 3+1, none) for the clinical test set data.

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:

   • No, an MRMC study was not done. This device is an X-ray radiation therapy system, not an AI-powered diagnostic imaging tool. Therefore, the concept of "human readers improve with AI vs without AI assistance" does not apply.

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

   • Yes, a standalone performance was done in the sense of the device performing its intended function without direct human "in-the-loop" assistance for radiation delivery. The device delivers radiation based on pre-programmed parameters. Preclinical in vitro laboratory studies and animal studies would represent standalone performance of the system against biological tissues.

6. The type of ground truth used:

   • Preclinical: "Highly demarcated areas of tissue destruction" observed in animal studies.
   • Clinical: "Autopsy data" (direct objective evidence of tissue effects), "clinical, radiological, functional and quality of life measures." This implies a combination of direct pathological evidence and various clinical/imaging outcomes.

7. The sample size for the training set:

   • The document does not specify a separate "training set" sample size. The description of clinical studies refers to the overall evaluation of safety and effectiveness, implying a single study phase for reporting to the FDA rather than a distinct training/test split in the modern machine learning sense. The device itself is not described as an AI/ML algorithm that requires a "training set" in that context.

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

   • As there's no mention of a "training set" in the context of an AI/ML device, this question is not directly applicable. For the overall studies, ground truth was established through a combination of animal tissue analysis, human autopsy data, and various clinical and radiological assessments as outlined above.

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