(71 days)
The XiO RTP System is used to create treatment plans for any cancer patient for whom external beam radiation therapy or brachytherapy 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 XiO Radiation Treatment Planning system accepts a) patient diagnostic imaging data from CT and MR scans, or from films, and b) "source" dosimetry data, typically from a linear accelerator. The system then permits the user to display and define (contour) the target volume, which is the structure to be treated, and critical structures, or organs-atrisk, to which radiation dose must be limited.
Based on the dose prescribed, the user, typically a Dosimetrist or Medical Physicist, can then create multiple treatment scenarios involving the type, 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 XiO system produces a display of radiation dose distribution within the patient, indicating doses to the target volume and critical structures. Appropriate clinical personnel select the plan that they believe most effectively maximizes dose to the target volume while minimizing dose to critical structures. The parameters of the plan are output in hard-copy format for later reference placed in the patient file.
This Premarket Notification addresses the addition of the Electron Monte Carlo dose calculation algorithm. XiO provides the user with the ability to choose between multiple dose calculation algorithms, selecting the algorithm most appropriate for the given clinical scenario. More accurate dose computation increases the probability that disease will be effectively treated and decreases the probability of undesirable side effects. No algorithm produces a perfectly accurate description of dose distribution; all algorithms have limitations, which are generally well understood and documented in scientific literature.
The addition of the Monte Carlo dose calculation algorithm gives users a new option for electron treatment plans. The algorithm represents the state of the art in radiation treatment planning and is widely recognized as the most accurate method currently available for computing the dose delivered by a beam of high-energy electrons.
The provided text describes the XiO RTP System with the addition of an Electron Monte Carlo dose calculation algorithm. While it mentions verification testing and algorithmic accuracy, it does not explicitly define acceptance criteria in a quantitative table or detail a study that directly proves the device meets such criteria through a clinical or reader study.
Here's a breakdown of the available information against your requested points:
1. Table of Acceptance Criteria and Reported Device Performance
The document does not provide a formal table of acceptance criteria or specific quantitative performance metrics beyond stating that XiO "successfully passed verification testing" and that algorithmic testing was performed to "ensure dose calculation accuracy." No specific numerical targets for accuracy or precision are given.
| Acceptance Criteria | Reported Device Performance |
|---|---|
| Not explicitly defined in the provided text. The document states "Pass/fail requirements and results of this testing can be found in the XiO Verification Test Report, which is included in section 18 of this submittal." However, these specifics are not detailed in the provided excerpt. | "XiO successfully passed verification testing." |
| "Algorithm testing was performed to compare calculated against measured doses to ensure dose calculation accuracy." |
2. Sample Size Used for the Test Set and Data Provenance
The document states:
- "Algorithm testing was performed to compare calculated against measured doses to ensure dose calculation accuracy."
- "In addition, clinically oriented validation test cases were written and executed in-house by CMS customer support personnel."
The specific sample size for this "algorithm testing" or these "validation test cases" is not mentioned.
The data provenance (e.g., country of origin, retrospective or prospective) for this testing is not specified. It's implied to be internal data ("in-house by CMS customer support personnel") rather than real-world patient data from specific countries.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications
- Number of Experts: The document does not specify a number of experts involved in establishing ground truth for the test set. It mentions "qualified clinicians" review plans and "CMS customer support personnel" executed validation test cases, but it doesn't detail their role in establishing ground truth for an independent test set.
- Qualifications of Experts: It refers to "qualified clinicians" and "Dosimetrist or Medical Physicist" as typical users of the system. However, it does not specify the qualifications (e.g., years of experience, board certification) of individuals who might have established ground truth for testing.
4. Adjudication Method for the Test Set
The document does not describe an adjudication method for a test set. The testing mentioned appears to be primarily algorithm verification against measured doses and internal validation cases, not a process involving multiple human reviewers resolving discrepancies.
5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study
No MRMC comparative effectiveness study was done. The document explicitly states: "Clinical trials were not performed as part of the development of this product." It focuses on algorithm accuracy and internal validation.
6. Standalone (Algorithm Only Without Human-in-the-Loop Performance) Study
Yes, a standalone study was done, but not in a formal clinical sense. The "Algorithm testing was performed to compare calculated against measured doses to ensure dose calculation accuracy" is a standalone evaluation of the algorithm's performance against a physical standard. The "clinically oriented validation test cases" also represent an evaluation of the algorithm's output without direct human-in-the-loop performance measurement that would typically be seen in a reader study.
7. Type of Ground Truth Used
The primary type of "ground truth" implied for the algorithm testing is measured doses. This means physical measurements of radiation dose distribution, likely obtained from phantoms or experimental setups, were used as the reference standard against which the Monte Carlo algorithm's calculated doses were compared. The "clinically oriented validation test cases" likely involved scenarios with expected or known outcomes based on physics principles or established clinical practices, rather than pathology or patient outcomes data.
8. Sample Size for the Training Set
The document does not mention a discrete training set sample size. The Monte Carlo algorithm is a physics-based simulation method rather than a machine learning model that would typically have a "training set" in the conventional sense. Its development would involve calibrating physical parameters and validating the underlying physics models, rather than training on a dataset of examples.
9. How the Ground Truth for the Training Set Was Established
As the Monte Carlo algorithm is not a typical machine learning model trained on a "training set" of data, the concept of establishing ground truth for a training set in this context is not applicable or described. The "ground truth" for the development of such an algorithm would be based on fundamental physics principles, experimentally validated cross-sections, and particle interaction data, rather than annotated clinical cases.
§ 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.