(229 days)
The Stereotactic Radiosurgery system is to be used to create a treatment plan for any patient with single or multiple lesions of the brain and for whom radiation therapy has been prescribed.
The system will calculate and display, both on-screen and in hard-copy, either two- or three-dimensional radiation dose distributions within a patient for a given treatment plan set-up.
The FOCUS Radiation Treatment Planning System accepts a) patient diagnostic imaging data from CT or MR scans or from films and b) "source" dosimetry data, typically from a linear accelerator. The system then permits the user to define a target volume to be treated based on these diagnostic images. Based on the prescribed dose, the user, typically a Dosimetrist or Medical Physicist, can then create multiple treatment scenarios involving the number, position(s) and energy of radiation beams and the use of treatment aids between the source of radiation and the patient (wedges, blocks, ports, etc.). The FOCUS System then produces a display of radiation dose distribution within the patient, indicating not only dose to the target volume but to surrounding tissue and structures. The "best" plan satisfying the prescription is then selected. one which maximizes dose to the target volume while minimizing dose to surrounding healthy volume. The parameters of the plan are output in hard-copy format for later reference and for placement in the patient file.
The software addition to add stereotactic radiosurgery treatment planning capability to FOCUS was developed at the Mallinckrodt Institute of Radiology of the Washington University School of Medicine in St. Louis, Missouri. The addition of Stereotactic Radiosurgery Therapy Planning capability to the system is a logical extension of the original intended use of the system. Stereotactic Radiosurgery is actually a sub-set of standard treatment planning in that it accepts the same inputs in the same formats as that for general planning. One significant, simplifying difference is that, in Stereotactic Radiosurgery Therapy, there are no treatment aids between the source and the patient. All therapy is performed using what are referred to as "open fields". A second difference is the introduction of "headframes" which, as the name implies, attach to the patients head and provide a unique patient coordinate system. The significant issue introduced here is one of coordinate transformation between the headframe and the patient diagnostic imaging data from the CT or MR machine. The system has been validated and marketed to support only the BRW headframe for CT or MR scans.
The FOCUS Stereotactic Radiosurgery Treatment Planning System underwent several non-clinical tests to establish its safety and effectiveness.
Here's a breakdown of the requested information:
1. Table of Acceptance Criteria and Reported Device Performance
The provided text describes categories of tests and states that "All testing provided results which met the criteria set." However, it does not explicitly list specific numerical acceptance criteria for each test category. It only broadly states that the results "met the criteria set."
| Acceptance Criteria Category | Reported Device Performance |
|---|---|
| Transfer of CT and MR Images | Results met the criteria set. |
| Verification of Coordinate Transformation Algorithm | Results met the criteria set. Verified against a current marketed device. |
| Fiducial Marker Localization Verification | Results met the criteria set. |
| Verification of Accuracy of Linear and Spherical Rulers and Checking of Image Pixel Size Detection | Results met the criteria set. |
| Verification of Target Points In Different Software Modules of the System | Results met the criteria set. |
| Verify Alignment of Isodoses with Image Anatomy | Results met the criteria set. |
| Verification of Accuracy of the Dose Calculation Algorithm | Results met the criteria set. Verified against calculated and measured data. |
2. Sample Size Used for the Test Set and Data Provenance
The document does not specify the sample size used for the test set for any of the non-clinical tests.
Regarding data provenance:
- Country of Origin: The software addition was developed at the Mallinckrodt Institute of Radiology of the Washington University School of Medicine in St. Louis, Missouri, USA.
- Retrospective or Prospective: Not explicitly stated. The tests were performed "to evaluate the performance of the system," implying they were conducted during the development and validation phase. The dose calculation algorithm was verified against "calculated and measured data collected especially for this project," suggesting some prospectively collected data for validation.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Their Qualifications
The document does not specify the number or qualifications of experts used to establish ground truth for the test set. It mentions verification of the coordinate transformation algorithm against a "current marketed device" and dose calculation verification against "calculated and measured data," but doesn't detail the human expertise involved in establishing this reference. It does state that "Normal QA of treatment planning activities, including review of the plans by a Medical Physicist and a Radiation Oncologist/Neurosurgeon prior to their use, is recommended," but this is a recommendation for clinical use, not a description of how ground truth was established for the validation study.
4. Adjudication Method for the Test Set
The document does not describe any adjudication method (e.g., 2+1, 3+1) for the test set.
5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study was done, and its effect size
No, a Multi-Reader Multi-Case (MRMC) comparative effectiveness study was not done. The document explicitly states: "Summary of Clinical Tests: Clinical testing was not performed as part of the development of this feature... Clinical testing is not required to demonstrate substantial equivalence or safety and effectiveness."
6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) was done
Yes, the describe tests are essentially standalone performance evaluations of the system's various algorithms and functionalities. The tests focused on the system's ability to:
- Transfer images
- Perform coordinate transformations
- Localize fiducial markers
- Measure accurately
- Verify target points
- Align isodoses
- Calculate dose accurately
These are all inherent functions of the algorithm and system without human interaction beyond inputting data and verifying outputs.
7. The Type of Ground Truth Used
The ground truth used appears to be a combination of established methods and calculated/measured data:
- For the Coordinate Transformation algorithm: Verification was performed "against a current marketed device." This implies using the known or accepted output of a predicate device as ground truth.
- For the Dose Calculation algorithm: Verification was performed "against calculated and measured data collected especially for this project." This suggests using established physical calculations and possibly phantom measurements as ground truth.
- For other verifications (e.g., rulers, target points, image transfer), the ground truth would likely be based on known inputs and expected outputs as per engineering specifications and established medical physics principles.
8. The Sample Size for the Training Set
The document does not specify any sample size for a training set. The device description discusses the development of the stereotactic radiosurgery capability as an "add-on" to an existing system, and the tests performed are primarily for validation, not for training a machine learning model. This suggests the system is based on deterministic algorithms rather than a machine learning approach that would require a dedicated training set.
9. How the Ground Truth for the Training Set was Established
As no training set is mentioned or implied for a machine learning model, the question of how its ground truth was established is not applicable. The underlying algorithms are likely based on established physics and geometric principles for radiation treatment planning.
§ 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.