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MIDCO has recently developed a quality Couchmount System (Patient Head Support System) for use in radiosurgery. This couchmount system complements the cass collimator set and enables MIDCO to provide its customers with a full set of instrumentation necessary for radiosurgery. The design of this couchmount is such that it will fit most linear accelerators with only slight modifications to the couchmount adapter assembly. The cass Couchmount System has six axes of adjustment which allows for easy setup with the Linac couch/gantry system. An additional feature of the system is a unique laser measurement apparatus for precisely measuring an isocenter of a target volume for Linac-based radiosurgery/stereotactic radiotherapy. These two features also allow for the correction of alignment errors during treatment planning setup, such as errors inherent in the use of room lasers and errors due to couch shifts during patient positioning. It will also give an index of gantry sag or misalignment. Most commercially available stereotactic headrings can be mounted to the cass Couchmount System by the use of a stereotactic frame holder made specifically for the headring. Although most headrings are similar, each has a slightly different adapter plate which rigidly holds the headring. The stereotactic localization features of most frames are similar, differing mainly in the organization of the frame's coordinate system and its mechanical dimensions.
Here's a breakdown of the acceptance criteria and study information for the cass Linac Radiosurgery Hardware Couchmount Stereotactic Frame Support System, based on the provided text:
Acceptance Criteria and Device Performance
| Acceptance Criteria (Target Accuracy) | Reported Device Performance (Accuracy) |
|---|---|
| ≤1.0 mm for gantry rotational intersection with rotational axis of the couch (for the base Linac) | The base Varian 2100 C Linac was determined to be ≤1.0 mm. |
| Generally accepted accuracy requirement for delivery of radiation beam to target volume isocenter: fractions of a millimeter. Some floorstand systems reported ≤1mm. | Overall system error range (Lutz method): 0.48 mm ± 0.262 mm |
| Established guidelines of many institutions using radiosurgery: ≤1 mm | Overall system error range (Lutz method): 0.48 mm ± 0.262 mm |
| Fischer System reported localization accuracy: +/- 0.5 mm | Total alignment error for in vivo verification tests (using Laser Measurement System and Precision Localization Box): 0.492 mm +/- 0.155 mm |
| Radionics System reported localization accuracy: 0.5 mm +/- 0.2 mm | Total alignment error for in vivo verification tests (using Laser Measurement System and Precision Localization Box): 0.492 mm +/- 0.155 mm |
Study Details
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Sample Size used for the test set and the data provenance:
- Sample Size:
- For the Lutz method test: "random phantom targets throughout the extremes of the coordinate system of the Leksell frame and BRW frame" were set up. No specific number is given, but it implies a range of targets.
- For the overall system accuracy (humanoid phantom and dosimetry film): A single "humanoid phantom" was used, with a target point radiated.
- For port film tests: "various predetermined target sites" were used. No specific number is given.
- Data Provenance: The tests were conducted using a Varian 2100 C Linac, which is a common radiation therapy machine. The data is prospective, generated specifically for these tests by MIDCO and its consultants/instructors. There's no mention of specific countries of origin beyond the machine type.
- Sample Size:
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Number of experts used to establish the ground truth for the test set and the qualifications of those experts:
The document does not explicitly state the number or specific qualifications of experts used to establish the ground truth for the test set. However, it indicates involvement of:- "appropriate consultants and instructors" from MIDCO for on-site instructions.
- "radiation oncologists and radiation physicists" at each institution being "ultimately responsible for accurate measurements and gathering of data for the use of this system."
- The studies cited (Lutz, Serago, et al.) are foundational in the field, implying that the ground truth methodology is based on established scientific and medical consensus within the radiosurgery community, as recognized by qualified physicists and clinicians.
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Adjudication method for the test set:
The document does not describe a formal "adjudication method" in the sense of multiple independent reviewers resolving discrepancies for the test set results. The results (e.g., error ranges for Dx, Dy, Dz displacements) appear to be direct measurements from the phantom studies. The methodology relies on established protocols from cited literature (Lutz method, Serago et al. method), which inherently incorporate methods for accurate measurement and calculation of discrepancies. -
If a multi-reader multi-case (MRMC) comparative effectiveness study was done, If so, what was the effect size of how much human readers improve with AI vs without AI assistance:
No, an MRMC comparative effectiveness study involving human readers and AI assistance was not done. This device is a hardware system (couchmount and collimators) for radiosurgery, not an AI or imaging diagnostic tool that would typically involve human readers interpreting output. -
If a standalone (i.e., algorithm only without human-in-the-loop performance) was done:
This question is not entirely applicable as the device is a hardware system. However, the performance reported (e.g., accuracy measurements like 0.48 mm ± 0.262 mm) represents the "standalone" mechanical accuracy of the system (Linac + collimators + couchmount) as configured and operated according to established protocols, without additional human interpretive input influencing the measurement of accuracy itself. The laser measurement system is an automated component for precise targeting. While humans operate the system, the reported accuracies are objective measurements of the system's physical performance. -
The type of ground truth used (expert consensus, pathology, outcomes data, etc.):
The ground truth for the mechanical accuracy tests was established through phantom studies and dosimetry film analysis.- Lutz method: Uses a phantom pointer to simulate test targets at known stereotactic coordinates. Radiographic images are then taken, and x, y, z displacements are measured against the known phantom target positions.
- Overall accuracy test: A humanoid phantom with a known target point is radiated, and the isocenter of the multiple intersecting beams is compared to the known position of the phantom target point indicator.
- Port film tests: Predetermined target sites are set (aided by the Laser Measurement System), and then A-P and lateral port films are used to verify the actual versus intended target locations.
- This is a form of empirical ground truth based on physical measurements against precisely known phantom positions.
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The sample size for the training set:
The document does not describe a "training set" in the context of machine learning. This device is a mechanical system, not an AI or software algorithm that requires a training set of data. The development process involved engineering design, prototyping, and testing, not machine learning model training. -
How the ground truth for the training set was established:
As there is no training set mentioned for this hardware device, this question is not applicable.
§ 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.