(197 days)
Mobius3D software is used for quality assurance, treatment plan verification, and patient alignment and anatomy analysis in radiation therapy. It calculates radiation dose three-dimensionally in a representation of a patient or a phantom. The calculation is based on read-in treatment plans that are initially calculated by a treatment planning system, and may additionally be based on external measurements of radiation fields from other sources such as linac delivery log data. Patient alignment and anatomy analysis is based on read-in treatment planning images (such as computed tomography) and read-in daily treatment images (such as registered cone beam computed tomography).
Mobius3D is not a treatment planning system. It is only to be used by trained radiation oncology personnel as a quality assurance tool.
Mobius3D is a software product used within a radiation therapy clinic for quality assurance and treatment plan verification. It is important to note that while Mobius3D operates in the field of radiation therapy, it is neither a radiation delivery device (e.g. a linear accelerator), nor is it a treatment planning system (TPS). Mobius3D cannot design or transmit instructions to a delivery device, nor does it control any other medical device. Mobius3D is an analysis tool meant solely for quality assurance (QA) purposes when used by trained medical professionals. Being a software-only QA tool, Mobius3D never comes into contact with patients.
Mobius3D performs dose calculation verifications for radiation treatment plans by doing an independent calculation of radiation dose. Radiation dose is initially calculated by a treatment planning system (TPS), which is a software tool that develops a detailed set of instructions (i.e. a plan) for another system (e.g. a linear accelerator) to deliver radiation to a patient. The dose calculation performed by Mobius3D uses a proprietary collapsed cone convolution superposition (CCCS) algorithm.
Mobius3D also performs dose delivery quality assurance for radiation treatment plans by using the measured data recorded in a linear accelerator's delivery log files to calculate a delivered dose. This is presented to the end user in a software component of Mobius3D called MobiusFX. The MobiusFX component is available to users through licensing as an add-on to the core Mobius3D software features.
Compared to the previously cleared Mobius3D v 1.3.2 (K140660), Mobius3D v 2.0.0 contains the additional intended use of performing quality assurance of a patient's alignment and anatomy analysis. This analysis is based on comparison of Cone Beam Computed Tomography (CBCT) images taken immediately before treatment to the images used for treatment planning, which are typically acquired using standard Computed Tomography (CT). This analysis is presented to the end user in an add-on software module within Mobius3D called CBCT Checks.
Here's an analysis of the acceptance criteria and the study that proves the device meets them, based on the provided text:
1. Table of Acceptance Criteria and Reported Device Performance:
The document does not explicitly state acceptance criteria in a quantitative, measurable format (e.g., "sensitivity must be > X%", "accuracy must be > Y%"). Instead, it describes a functional evaluation.
| Acceptance Criteria (Implied) | Reported Device Performance |
|---|---|
| Software Functionality | "Software development, verification, and validation have been carried out in accordance with FDA guidelines. The software was tested against the established Software Design Specifications and passed all required tests." (This indicates the software functions as designed according to internal specifications.) |
| Risk Mitigation | "A Risk Management Report was completed which identified and verified the mitigation of all required hazards." (Suggests potential risks identified during development were addressed.) |
| Patient Positioning/Anatomy Analysis (CBCT Module) | "The report demonstrates the Mobius3D CBCT module’s ability to notify users to a potential patient positioning or anatomical difference." (This is the primary functional performance claim for the new feature, indicating its ability to detect the specified differences.) |
2. Sample Size Used for the Test Set and Data Provenance:
- Sample Size: "anonymized data from 22 different patients over 163 different fractions"
- Data Provenance: The document does not specify the country of origin. It states the data was "anonymized," implying it was real patient data, but it does not clarify if it was retrospective or prospective. Given it was "bench testing" and "anonymized data from 22 different patients over 163 different fractions," it is highly likely to be retrospective real-world patient data.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts:
The document does not explicitly state how many experts were used or their qualifications for establishing ground truth in the "Mobius3D CBCT Module Evaluation" study. The study focuses on the module's ability to notify users of differences, not necessarily on the module's accuracy compared to expert consensus. Ground truth, in this context, might implicitly refer to the actual patient positioning/anatomical differences that the module was designed to detect, which would typically be evaluated by a medical physicist or radiation oncologist in a clinical setting, but this is not detailed.
4. Adjudication Method for the Test Set:
The document does not describe any adjudication method (e.g., 2+1, 3+1). The study's focus, as described, is on the module's ability to notify users of differences, rather than a comparison against an adjudicated "correct" answer for each case.
5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study Was Done, and Effect Size:
No, a multi-reader multi-case (MRMC) comparative effectiveness study was not reported in the provided text. The study described focuses on the standalone performance of the CBCT module ("ability to notify users") rather than comparing human readers with and without AI assistance.
6. If a Standalone Study (Algorithm Only Without Human-in-the-Loop Performance) Was Done:
Yes, a standalone study was done for the Mobius3D CBCT module. The "bench testing" described in "Mobius3D CBCT Module Evaluation - Patient Positioning / Anatomical Changes Bench Testing" evaluated the algorithm's performance in identifying potential patient positioning or anatomical differences without human interaction being part of the module's core evaluation. The report demonstrates the module's "ability to notify users," which indicates the algorithm itself is performing the detection and flagging.
7. Type of Ground Truth Used:
The document does not explicitly state the type of ground truth used for the CBCT module evaluation. However, based on the description ("ability to notify users to a potential patient positioning or anatomical difference"), the implied ground truth would be the actual presence of patient positioning shifts or anatomical changes between the planning CT and daily CBCTs. How this actual presence was definitively established is not detailed (e.g., an expert review of the images themselves, comparison to log files, etc.). It's likely an existing clinical assessment that the software is designed to emulate or flag.
8. Sample Size for the Training Set:
The document does not provide any information regarding the sample size used for the training set for Mobius3D or its CBCT module. It mentions the "proprietary collapsed cone convolution superposition (CCCS) algorithm" for dose calculation, which is a physics-based model, not typically "trained" on a dataset in the same way a machine learning algorithm is. For the CBCT module features, if any machine learning was used, the training data is not disclosed.
9. How the Ground Truth for the Training Set Was Established:
Since no information about a training set is provided, there is no information on how ground truth for a training set 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.