(112 days)
Halcyon and Ethos radiotherapy system are indicated for the delivery of stereotactic radiosurgery and precision radiotherapy for lesions, tumors and conditions anywhere in the body where radiation is indicated for adults and pediatric patients.
The Halcyon and Ethos Radiotherapy System produce CBCT images that can be used in Image Guided Radiation Therapy, and the simulation and planning for radiation therapy.
Halcyon and Ethos radiotherapy system are single energy medical linear accelerators (linacs) designed to deliver Image Guided Radiation Therapy and radiosurgery, using Intensity Modulated and Volumetric Modulated Arc Therapy techniques. They consist of the accelerator and patient support within a radiation shielded treatment room and a control console outside the treatment room.
An electron gun generates electrons which are accelerated by radio frequency (RF) power from a magnetron. The electrons strike a tungsten target producing photons (X-rays) for treatment and MV Imaging. The photons produced by the target are monitored and controlled by a pressurized ion chamber.
A beam collimation subsystem consisting of a primary and secondary collimator and two stacked multileaf collimators (MLCs) shapes the photon beam to define the treatment area.
X-Ray images of the patient are used by the treater to verify the correct treatment location. MV Imaging uses the treatment beam and a flat panel imager whereas kV imaging uses a high-capacity kV X-ray tube, a kV collimation system with full fan bowtie filter with movable y-blades to define the imaging beam size and to capture the image, a kV imager.
Halcyon and Ethos radiotherapy system deliver a treatment generated by a Treatment Planning System from a physician's prescription. kV CBCT images from HyperSight can additionally be used for planning treatments. Ethos radiotherapy system is capable of delivering adaptive treatments which can take into account changes in tumour geometry between treatment sessions.
The provided text describes a 510(k) submission for the Halcyon and Ethos Radiotherapy System, focusing on expanding the indications for use of its HyperSight CBCT images for primary treatment planning, effectively proving it is clinically equivalent to plans generated from conventional and simulator CT images.
Here's an analysis of the acceptance criteria and the study that proves the device meets them:
1. A table of acceptance criteria and the reported device performance:
| Acceptance Criteria | Reported Device Performance/Outcome |
|---|---|
| Patient-Specific QA | The test results demonstrate that the Halcyon 4.0 with HyperSight imaging system produces primary treatment plans that are clinically equivalent to plans generated from conventional and simulator CT images. The dose calculation specifications demonstrate equivalence to standard CT scanners. |
| Ionization chamber measured dose ±3% as predicted by treatment planning system | No specific performance metrics for this criterion are provided in the text beyond the overall conclusion of clinical equivalence. |
| 2D gamma analysis of predicted planar dose distribution as compared to measured signal from the portal imaging panel - at least 95% of analyzed points passed 3%/2mm gamma criteria | No specific performance metrics for this criterion are provided in the text. |
| Image Acquisition and Contouring | |
| Successful creation of contours for each dataset | Implied to be successful, as cases provided "contours, and clinical planning objectives" and plans were created. |
| All relevant organs-at-risk and targets are discernable | The clinical cases "comprise a wide range of tissues to challenge the treatment planning tasks of organ segmentation and dose calculation, including metal artifacts (as in dentition, fiducials, or hip prosthesis)," suggesting discernibility was achieved. |
| Treatment Plan Comparison | |
| From established, published Clinical Goals for each anatomical site | "Each type of plan (CT- and HyperSight-based) was evaluated against clinical objectives, consisting of target coverage goals and normal tissue constraints." The overall conclusion states clinical equivalence. |
2. Sample size used for the test set and the data provenance:
- Sample Size: 26 human subject cases.
- Data Provenance: Obtained from three institutions in the US and Europe. The data was from institutionally approved prospective single-site clinical studies. All cases were adult patients planned to receive radiation therapy for head/neck, thorax (including breast), abdomen, or pelvis conditions.
3. Number of experts used to establish the ground truth for the test set and the qualifications of those experts:
- The text states that for each case, a "summary list identifying the dosimetrist and physician involved with each case" was provided. It does not specify the exact number of experts involved in establishing ground truth (e.g., contours, clinical planning objectives) for the test set, nor their specific qualifications (e.g., years of experience).
4. Adjudication method for the test set:
- The text does not explicitly describe an adjudication method for the test set data. It mentions that "planning CT and HyperSight CBCT image sets, contours, and clinical planning objectives were provided to Varian," implying these were already established by the contributing institutions.
5. If a multi-reader multi-case (MRMC) comparative effectiveness study was done, and if so, what was the effect size of how much human readers improve with AI vs without AI assistance:
- No, a multi-reader multi-case (MRMC) comparative effectiveness study was not done in the context of human readers improving with AI assistance. This study focused on the equivalence of treatment plans generated from different image sources (conventional CT vs. HyperSight CBCT) by the system (RapidPlan), rather than evaluating human reader performance with or without AI assistance. The "AI" aspect is more embedded in or implied by the "RapidPlan" system's ability to generate plans.
6. If a standalone (i.e., algorithm only without human-in-the-loop performance) was done:
- Yes, a standalone study was effectively performed. Varian "created radiation treatment plans for each type of image separately, using a standardized planning approach (RapidPlan) available in the Varian Eclipse treatment planning system." This indicates an algorithm-driven comparison of plans generated from different image inputs, rather than focusing on human interaction with the device for performance improvement.
7. The type of ground truth used:
- The ground truth primarily consisted of:
- Clinical Planning Objectives: These were established by the contributing institutions, including target coverage goals and normal tissue constraints.
- Contours: Provided for each case, likely drawn by clinicians at the institutions, representing the anatomical structures for planning.
- Conventional CT Images: These served as a "gold standard" or reference against which the HyperSight CBCT image-based plans were compared for clinical equivalence.
- Measurements: Ionization chamber measured dose and 2D gamma analysis were used for patient-specific QA, which are objective physical measurements.
8. The sample size for the training set:
- The document does not specify the sample size for the training set. The study described is a clinical validation (test set) for the expanded indication of the already existing device. It focuses on the performance comparison for the intended use, not on the details of the model's training.
9. How the ground truth for the training set was established:
- Not applicable/Not provided in the document. The document describes a study to support a change in the Indications for Use for an existing device, specifically validating the use of HyperSight CBCT images for primary treatment planning. It does not detail how the ground truth for the original training of the Halcyon/Ethos system or its RapidPlan component was established.
§ 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.