(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. PLAN |
- POSITION
- 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 |
§ 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.