Search Results

The CORVUS system is a radiation treatment planning package designed to allow medical physicists, dosimetrists, and radiation oncologists to create conformal treatment plans using photon (x-ray, gamma ray) external beam radiation therapy. The treatment plans generated by CORVUS are based upon treatment machine-specific data and are intended to provide a guide to delivering external beam radiation therapy which conforms to the target volume defined by the radiation oncologist.

The CORVUS system is valid for use only with external beam photon therapy; calculations for electrons and intracavity sources (Brachytherapy) are NOT supported.

CORVUS is a semi-automatic planning system: rather than simply verifying a user-designed plan, the system itself suggests a plan. A clinician then reviews and approves the plan.

CORVUS is designed to generate plans for treatment delivery systems that can create multiple radiation patterns composed of pencil beams on which the intensity can be individually controlled. The treatment beams are weighted so that when they are projected into the treatment space they superimpose to give the desired dose distribution.

Each radiation field is generated using one of several optimization methods provided with the system, including simulated annealing and gradient descent.

The treatment beams are set not only to deliver the prescribed dose to the identified target volume, but also to keep the dose to other sensitive volumes below user-defined limits. Planning is done volumetrically: the beam weights for treating the entire target volume are generated simultaneously. The dose matrix is volumetric. The dose to each point is calculated to be that received from all beams and from all gantry angles. Dosage is calculated using a finite size pencil beam (FSPB) algorithm based on the beam characterization of clinically measured data. The degree to which a treatment plan is optimized is determined in part by constraints placed on the planning algorithm. The user has direct control over these constraints, which include dose goals to the target structures, dose limits to the sensitive structures, and the specification of arcs or fixed gantry positions in the treatment plan.

CORVUS treatment plans need not have the isocenter located within the target volume. An unlimited number of targets falling within the treatment volume can be planned for at the same time. Dose may be prescribed for up to 32 structures, 29 of them user-selectable, any number of which may be separate targets or radiation-sensitive structures. Each structure can have a separate dose prescription.

Here's an analysis of the acceptance criteria and study information for the CORVUS Radiation Therapy Planning System, based on the provided document:

This document describes a premarket notification (510(k)) for the CORVUS Radiation Therapy Planning System (K151469), which is an accessory to medical devices of Major Level of Concern. The submission focuses on the upgrade from CORVUS 09 to CORVUS 2011, primarily adding support for Cobalt-60 based external beam radiation treatment planning (Gamma Tomotherapy) and updated operating system/hardware.

1. Table of Acceptance Criteria and Reported Device Performance

The acceptance criteria provided are mostly qualitative (e.g., "clinically acceptable," "similar") or defined by pass/fail thresholds for dosimetric accuracy.

2. Sample Size Used for the Test Set and Data Provenance

• Sample Size: The document does not explicitly state the numerical sample size for patient cases or plans used in the test sets for most clinical validation tests. It mentions "various pencil beam sizes" (Test 4), "multiple test results" (Test 4), and "all Cobalt validation plans" (Test 8), which are not specific numbers. For Test 1 (Linac Dose Equivalence) and Test 2 (Clinical Comparison), it refers to "the same patients" and "treatment plans created for Cobalt treatment," but no specific count of patients or plans is given.
• Data Provenance: The document does not specify the country of origin of the data. It also does not explicitly state whether the data was retrospective or prospective. Given the context of clinical comparison and re-calculation, it is likely retrospective, using existing patient data or phantom measurements, but this is not definitively stated.

3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of those Experts

• The document mentions that the CORVUS system is "designed to allow medical physicists, dosimetrists, and radiation oncologists to create conformal treatment plans." And that "It is the physician's responsibility to verify that the dose distributions... are appropriate for a particular patient."
• However, for the specific validation studies on the test set, the document does not explicitly state the number of experts or their qualifications used to establish the "ground truth" or to review the clinical acceptability of plans. The "clinical acceptability" (Test 2) implies expert review, but details are not provided. The dosimetric accuracy tests (Tests 3, 4, 8) rely on direct physical measurements (film and ionization chambers) rather than expert consensus as the ground truth.

4. Adjudication Method for the Test Set

• The document does not describe any explicit adjudication method for expert review (e.g., 2+1, 3+1). For the dosimetric tests, the adjudication is based on direct measurement comparison against defined physical thresholds (e.g., 4% / 4mm).

5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study

• No, a MRMC comparative effectiveness study was not done as described in the document. The studies were primarily focused on comparing the CORVUS 2011 algorithm's output against:
  • Previous version (CORVUS 09) outputs (Tests 1, 2, 7)
  • Physical measurements (Tests 3, 4, 8)
  • Expected computational outcomes (Test 5)
• There is no mention of human readers, their performance without AI (the planning system itself), or an effect size of improvement with AI assistance. The system is a planning tool, not an AI for interpretation or diagnosis that would augment human review in that manner.

6. Standalone (Algorithm Only Without Human-in-the-Loop Performance) Study

• Yes, the studies are largely standalone in terms of the algorithm's performance. The tests primarily evaluate the calculations and outputs of the CORVUS 2011 system itself (dose equivalence, dosimetric accuracy, consistency of calculations, transfer of data).
• While the system is a "semi-automatic planning system" that "suggests a plan" which a "clinician then reviews and approves," the validation tests described focus on the accuracy and equivalence of the generated plans and calculations themselves, rather than the overall human-in-the-loop workflow's effectiveness. Test 2 (Clinical comparison) does allude to "clinical efficacy" and "clinical acceptability" but without specifying a human-in-the-loop scenario. The dosimetric tests are purely algorithmic output vs. physical measurement.

7. Type of Ground Truth Used

• Mixed:
  • For dosimetric accuracy (Tests 3, 4, 8): Physical measurements using EDR2 film and ionization chambers (0.125 cc chamber, CC01 ionization chamber). This is a objective, empirical ground truth.
  • For clinical comparisons and equivalence (Tests 1, 2, 7): The ground truth is established by comparison to the predicate device's output (CORVUS 09) and expert consensus on "clinical acceptability" or "clinical similarity," though the specifics of this expert consensus are not detailed.
  • For dose comparison consistency (Test 5) and system transfer (Test 6): Expected computational outcomes and predefined data formats (DICOM RT) serve as the ground truth.

8. Sample Size for the Training Set

• The document does not provide any information about the sample size for a training set. CORVUS is described as a "semi-automatic planning system" using "optimization methods including simulated annealing and gradient descent," and dosage is calculated "using a finite size pencil beam (FSPB) algorithm based on the beam characterization of clinically measured data." This suggests a model-based approach with measured beam data, rather than a machine learning model that would typically have a "training set" in the modern sense. The "clinically measured data" for beam characterization itself would be a foundational dataset, but its size is not specified as a "training set."

9. How the Ground Truth for the Training Set Was Established

• As a "training set" in the modern AI/ML sense is not explicitly mentioned, the concept of establishing ground truth for it is not addressed. The "beam characterization of clinically measured data" for the FSPB algorithm would have its ground truth established through direct physical measurements of radiation beam properties.

Ask a specific question about this device