(99 days)
MRCAT imaging is intended to provide the operator with information of tissue properties for radiation attenuation estimation purposes in photon external beam radiotherapy treatment planning.
Indication for use:
MRCAT Head and Neck is indicated for radiotherapy treatment planning for patients with soft tissue tumors in the Head and Neck region.
MRCAT Head & Neck is a software application to Ingenia, Ingenia Ambition, and Ingenia Elition MR systems. MRCAT Head & Neck is available to the customer as an option to Ingenia MR-RT package, which is a set of accessories for Ingenia systems.
Automated generation of MRCAT images takes place at the MR console of Ingenia. The embedded image post-processing runs in the background parallel to image acquisition. MRCAT algorithm enables automatic tissue characterization: Bones are segmented from mDixon in-phase and water images using machine learning based segmentation. Body outline is segmented using in-phase and water images. Tissues are then assigned a continuum of HU values depending on the fat and water intensities of the voxels. The HU assignment provides MRCAT images with CT-like density information.
The Philips Oy MRCAT Head & Neck device, a software application for MR systems intended to provide tissue property information for radiation attenuation estimation in photon external beam radiotherapy treatment planning for soft tissue tumors in the Head and Neck region, underwent testing to demonstrate substantial equivalence to its predicate device, MRCAT Brain.
The primary study focused on validating the accuracy of simulated dose calculations and geometric accuracy when using MRCAT Head & Neck images compared to CT-based plans.
1. Table of Acceptance Criteria and Reported Device Performance:
| Acceptance Criteria (MRCATHN) | Reported Device Performance |
|---|---|
| Dose Accuracy: |
- Simulated dose based on MRCAT Head & Neck images shall not differ in 95% of the indicated patients (gamma analysis criterion 2%/2mm realized in 98% of voxels within the PTV or exceeding 75% of the maximum dose) when compared with CT-based plan.
- The average simulated dose based on MRCAT Head & Neck shall not deviate more than 5% or 1 Gy, whichever is greater, in 99% of the indicated patients in the volume of sensitive organs when compared with a CT-based plan. | - PTV dose differences obtained when using MRCAT in place of CT were well below 1% with a very small bias, indicating clinical insignificance.
- Results for artificial PTVs (automatically placed around the head and neck region) agreed well with clinical plan results, strengthening the conclusion of accurate dose calculations.
- The device met the dose accuracy criteria. |
| Geometric Accuracy: - ± 1 mm accuracy: 200 mm diameter sphere
- ± 2 mm accuracy: 400 mm diameter sphere (limited in the bore direction by +/- 160 mm from the z=0 mm plane)
- ± 5 mm accuracy: 500 mm diameter sphere (limited in the bore direction by +/- 160 mm from the z=0 mm plane) | - The document explicitly states: "MRCAT accuracy:
- ± 1 mm accuracy: 200 mm diameter sphere
- ± 2 mm accuracy: 400 mm diameter sphere (limited in the bore direction by +/- 160 mm from the z=0 mm plane)
- ± 5 mm accuracy: 500 mm diameter sphere (limited in the bore direction by +/- 160 mm from the z=0 mm plane)"
While the exact "reported performance" against these metrics is not detailed in the provided summary, the statement "MRCAT Head and Neck met the acceptance criteria and is adequate for this intended use" implies these geometric accuracy criteria were also met. The visibility of bone structures described as "equivalent for both products" (MRCAT Brain and MRCAT Head & Neck) also supports similar geometric performance. |
| Safety and Effectiveness: - Compliance with relevant international and FDA-recognized consensus standards (ANSI/AAMI ES60601-1, IEC 60601-1-6, IEC 60601-2-33, IEC 62304, IEC 62366-1, ISO 14971). | - The MRCAT Head and Neck complies with the aforementioned international and FDA-recognized consensus standards. Verified through non-clinical verification and validation tests. The device met the safety and effectiveness criteria. |
2. Sample Size Used for the Test Set and Data Provenance:
- Test Set Sample Size: The summary mentions "PTV dose differences obtained when using MRCAT in place of CT" and "artificial PTV analysis". It also refers to "95% of the indicated patients" and "99% of the indicated patients," suggesting a study involving patient data or simulated patient cases. However, the exact number of patients or cases in the test set is not explicitly stated in the provided document.
- Data Provenance: The document does not specify the country of origin of the data or whether the study was retrospective or prospective.
3. Number of Experts Used to Establish Ground Truth and Qualifications:
- The document does not explicitly state the number of experts used to establish ground truth for the test set or their specific qualifications.
- However, it does mention that "The HU values for the MRCAT Head and Neck are calibrated using registered CT images from several sites." This implies that the CT images, which serve as the reference for HU values, were acquired and potentially interpreted by medical professionals, though their role in "ground truth establishment" for the specific test set is not detailed.
4. Adjudication Method for the Test Set:
- The document does not describe an adjudication method (e.g., 2+1, 3+1). The "ground truth" seems to be primarily based on CT images and their associated dose calculations.
5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study:
- A MRMC comparative effectiveness study was not discussed in the provided text. The evaluation focuses on the device's performance in dose and geometric accuracy against a CT-based plan, rather than comparing human reader performance with and without AI assistance.
6. Standalone (Algorithm Only) Performance:
- Yes, the study appears to evaluate the standalone performance of the MRCAT Head & Neck algorithm. The dose accuracy and geometric accuracy criteria are stated as direct evaluations of the "simulated dose based on MRCAT Head & Neck images" and "MRCAT accuracy," respectively, implying no human intervention in the generation or initial interpretation of the MRCAT images for these assessments. The device provides "information of tissue properties for radiation attenuation estimation purposes," which is then used in treatment planning.
7. Type of Ground Truth Used:
- The ground truth primarily used for comparing dose accuracy and HU values is based on CT-based plans and registered CT images. CT is considered the gold standard for electron density information in radiotherapy planning.
8. Sample Size for the Training Set:
- The document states that the "CNN is trained using matched pairs of CT and MRCAT source images" and "The HU values for the MRCAT Head and Neck are calibrated using registered CT images from several sites." However, the exact sample size of the training set (number of images/patients) is not specified.
9. How the Ground Truth for the Training Set Was Established:
- The ground truth for the training set was established using "matched pairs of CT and MRCAT source images." This means that for each MR image used for training the CNN, a corresponding CT image was available. These CT images, presumably acquired as part of standard clinical practice, provided the reference Hounsfield Unit (HU) values for tissue characterization and density information that the MRCAT algorithm aims to replicate. The calibration of HU values also used "registered CT images from several sites," reinforcing the reliance on CT as the ground truth.
§ 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.