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510(k) Data Aggregation
(209 days)
The MRIdian Linac system, with magnetic resonance imaging capabilities, is intended to provide stereotactic radiosurgery and precision radiotherapy for lesions, tumors, and conditions anywhere radiation treatment is indicated.
The MRIdian Linac system (K162393; K170751) delivers ionizing radiation using a magnetic resonance imaging system (MRIS) unit for image guidance. This submission describes an optional change only to the treatment planning and delivery imaging workflows of the predicate MRIdian Linac system. ViewRay developed the following additional imaging modalities for use during MRIdian Linac system treatment planning and delivery workflows: 1. Introduction of a Treatment Delivery Computer Unit (TDCU) to increase treatment imaging reconstruction and display speed in excess of eight frames per second along with improved cine image resolution used for target tracking. 2. The predicate MRIdian Linac system supports the import of MR images obtained from a separate imaging system for use in treatment planning. In addition to importing additional MR images, the proposed MRIdian Linac system is also able to generate the following additional MR sequences for use during planning, positioning, and treatment delivery workflows: a. Turbo Spin Echo (TSE) pulse sequence family including Half Fourier Acquisition Single Shot Turbo Spin Echo (HASTE) and Diffusion Prepared Turbo Spin Echo (DP-TSE) which enables the following contrast protocols: i. T1-weighted (spin-lattice; magnetization in the same direction as the static magnetic field); ii. T2-weighted (spin-spin; magnetization transverse to the static magnetic field); and iii. Diffusion-Weighted Imaging (DWI) with ability to generate Apparent Diffusion Coefficient (ADC) maps to overlay and register to other images. b. True Fast Imaging (TRUFI) pulse sequence with radial sampling enabling higher speed imaging during treatment delivery. The currently marketed MRIdian Linac system integrates radiation therapy with simultaneous magnetic resonance imaging of soft tissues to provide optimal alignment, adaptation, and tracking. These proposed changes to the existing system described in this section aim to improve MR imaging speed and quality and provide additional image contrast modalities.
The provided text describes modifications to an existing MRIdian Linac System (K162393; K170751) and seeks to demonstrate substantial equivalence to the predicate device. However, it does not contain explicit acceptance criteria or a detailed study proving the device meets those criteria in the typical sense of a clinical performance study with human readers and ground truth for diagnostic accuracy.
Instead, the document focuses on technical equivalence and verification testing to ensure the new imaging modalities and hardware/software changes do not negatively impact the system's performance and meet safety and quality standards, making it substantially equivalent to the cleared predicate device.
Here's an analysis based on the information provided, highlighting what is present and what is absent:
1. A table of acceptance criteria and the reported device performance
The document provides a "Predicate Device Comparison Chart" (Table 6-1 on page 8) which compares various technical attributes of the cleared device with the device with changes. While these are not framed as "acceptance criteria" in the sense of a clinical performance study (e.g., sensitivity, specificity), they represent the technical performance metrics that were likely considered in verifying equivalence.
| Attribute | Cleared Device (K162393; K170751) | Device with Changes | Acceptance Criteria (Implied) | Reported Performance (Device with Changes) |
|---|---|---|---|---|
| Imaging Settings | 1. PLAN2. POSITION3. TREAT | Same | Maintain existing imaging settings and functionality. | Same |
| MR Physical Characteristics: Bore Diameter | 700 mm | Same | Maintain physical dimensions. | Same |
| Spherical Volume (DSV) | 500 mm | (Not specified for "Device with Changes," implied "Same") | Maintain diagnostic spherical volume. | (Implied 500 mm) |
| MRI Frequency | 14.7 MHz | (Not specified for "Device with Changes," implied "Same") | Maintain MRI frequency. | (Implied 14.7 MHz) |
| Field Strength | 0.345 T | (Not specified for "Device with Changes," implied "Same") | Maintain field strength. | (Implied 0.345 T) |
| Field of View | 500 mm | Same | Maintain field of view. | Same |
| Field Homogeneity | < 25 ppm over 450 mm DSV | (Not specified for "Device with Changes," implied "Same") | Maintain field homogeneity. | (Implied < 25 ppm over 450 mm DSV) |
| Field Stability | ≤ 0.1 ppm/hr | (Not specified for "Device with Changes," implied "Same") | Maintain field stability. | (Implied ≤ 0.1 ppm/hr) |
| 3D Imaging Volumes in cm | RL x AP x HFMin 20 x 27 x 29Max 54 x 48 x 54 | (Not specified for "Device with Changes," implied "Same") | Maintain 3D imaging volume capabilities. | (Implied Same) |
| 3D Imaging Resolution in cm | Min 0.075 x 0.075 x 0.15Max 0.3 x 0.3 x 0.3 | (Not specified for "Device with Changes," implied "Same") | Maintain 3D imaging resolution. | (Implied Same) |
| 2D Imaging Planes in cm | AP x HFMin. 27 x 27Max 45 x 350.35 x 0.35 | (Not specified for "Device with Changes," implied "Same") | Maintain 2D imaging plane capabilities. | (Implied Same) |
| 2D Imaging Resolution in cm | 5, 7, or 10 | Same | Maintain 2D imaging resolution. | Same |
| Geometric Accuracy | 2 mm over 35 cm FOV1 mm over 20 cm FOV | (Not specified for "Device with Changes," implied "Same") | Maintain geometric accuracy. | (Implied Same) |
| Signal to Noise | 30 | (Not specified for "Device with Changes," implied "Same") | Maintain signal to noise ratio. | (Implied 30) |
| Temporal Integrity | 0.01s or better | (Not specified for "Device with Changes," implied "Same") | Maintain temporal integrity. | (Implied 0.01s or better) |
| Imaging Pulse Sequences: T1, T2, DWI | Can be imported from an alternative imaging device. | Can be acquired by the proposed MRIdian Linac system or imported from an alternative imaging device. | The new system should be able to acquire these sequences directly in addition to importing them. | Device with changes can acquire these sequences. This is an enhancement, exceeding the predicate's capability in this specific aspect. |
| Imaging During Radiation Therapy Delivery | Single plane: 4 frames/secThree planes: 2 frames/secIn-plane resolution: 2.5 x 2.5 mm or less | Single plane: 8 frames/secThree planes: 2 frames/secIn-plane resolution: 2.5 x 2.5 mm or less | The new system should meet or exceed the predicate's imaging speed for critical functions. | Device with changes exceeds predicate with 8 frames/sec for single-plane imaging. |
| Localization/Positioning | 3D volume, max 540x540x480 mm FOV, 3.0x3.0 mm or less in-plane resolution, <60s acquisition. | Same | Maintain localization/positioning capabilities. | Same |
| Planning Volumes | 540x465x430 mm FOV, 1.5x1.5 mm or less in-plane resolution. | Same | Maintain planning volume capabilities. | Same |
| Multi-Channel RF System | Body coil SNR ≥ 12, Uniformity ≥ 60%12 Channel Torso Coil SNR ≥ 30 (Sagittal, Transversal), SNR ≥ 25 (Coronal), Uniformity ≥ 50%10 Channel Head/Neck Coil SNR ≥ 30 (Sagittal, Transversal), SNR ≥ 25 (Coronal), Uniformity ≥ 50% | Same with the addition of:4 Channel Head Coil SNR ≥ 30 (Sagittal, Transversal), SNR ≥ 25 (Coronal), Uniformity ≥ 50% | Maintain or enhance RF system performance. | Same, plus added 4 Channel Head Coil capability, enhancing coverage. |
2. Sample size used for the test set and the data provenance (e.g. country of origin of the data, retrospective or prospective)
The document primarily describes design verification testing and conformance to standards (e.g., IEC 60601-1, IEC 60601-2-33, IEC 62304). This implies testing was performed on:
- The hardware and software components of the MRIdian Linac System with the proposed changes.
- The testing would involve engineering tests, phantom studies, and possibly data from internal development/testing, rather than a "test set" of patient data in the context of diagnostic performance.
- No information is provided on a "test set" of patient data, its sample size, or provenance. This is because the submission focuses on asserting technical equivalence and safety rather than a new clinical claim requiring a performance study on patient data.
3. Number of experts used to establish the ground truth for the test set and the qualifications of those experts (e.g. radiologist with 10 years of experience)
Not applicable/Not provided. Since this is a technical verification of an upgraded system rather than a new diagnostic algorithm, the concept of "experts establishing ground truth" for patient cases, as in an AI-driven image interpretation study, does not apply. The verification would involve engineers validating system specifications and output against known physical or simulated inputs.
4. Adjudication method (e.g. 2+1, 3+1, none) for the test set
Not applicable/Not provided. Adjudication methods are relevant for studies where multiple human readers are evaluating cases and their interpretations need to be reconciled to establish a consensus ground truth. This type of study was not 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
No MRMC comparative effectiveness study was mentioned or performed. This submission is not about evaluating a new AI assistant for human readers. It's about modifying an existing medical device's technical specifications and demonstrating that these modifications do not compromise safety or essential performance and maintain substantial equivalence to the predicate.
6. If a standalone (i.e. algorithm only without human-in-the-loop performance) was done
The document does not describe the evaluation of a standalone algorithm for diagnostic or therapeutic tasks. The MRIdian Linac System is an integrated system where imaging capabilities are part of the therapy delivery workflow, not a separate diagnostic algorithm. The changes enhance the imaging capabilities within this system.
7. The type of ground truth used (expert consensus, pathology, outcomes data, etc)
Not explicitly described in terms of clinical ground truth. The "ground truth" for the verification testing would be the engineering specifications, performance standards (e.g., frame rate, resolution, field homogeneity), and safety requirements that the device's enhanced features were tested against. For example, a physics phantom might be used to verify image resolution or geometric accuracy.
8. The sample size for the training set
Not applicable/Not provided. This submission does not describe the development or training of a new AI algorithm that would require a "training set" of data.
9. How the ground truth for the training set was established
Not applicable/Not provided. As there is no described training set for an AI algorithm, this information is not relevant to the document.
In summary:
This 510(k) submission (K181989) is primarily a technical modification submission for an existing medical device. Its purpose is to demonstrate that changes made to the MRIdian Linac System (specifically, enhanced imaging modalities, increased image reconstruction speed, and a condensed equipment footprint) maintain substantial equivalence to the predicate device (K162393; K170751) and comply with relevant safety and performance standards. The "acceptance criteria" are largely implied by the need to meet or exceed the predicate's technical specifications and adhere to recognized international standards for medical electrical equipment. No clinical performance study involving patient data, human readers, or AI algorithm evaluation is described.
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