(23 days)
The TomoTherapy HI-ART System is intended to be used as an integrated system for the planning and delivery of intensity modulated radiation therapy (IMRT) for the treatment of cancer. The HI-ART System provides precise delivery of radiation to tumors while minimizing the delivery of radiation to vital healthy tissue.
The HI-ART System's planning station is intended to be used by the physician/oncologist to prescribe a radiation therapy plan for a particular patient. The HI-ART System then calculates the treatment plan which the physician reviews and approves.
The HI-ART system's operator station and status console is then intended to be used by the therapist to select and implement the patient's treatment plan. The treatment process will begin by performing a TomoImage™ (MVCT) scan (a CT using the onboard linear accelerator as the radiation source). This TomoImage (MVCT) will confirm that the patient's position is correct for the radiation therapy as well as assist in patient re-positioning when necessary. The Tomolmage (MVCT image) is not for diagnostic use.
When patient positioning is complete, the HI-ART System is then intended to be used by the therapist to treat the patient using the selected treatment plan. The HI-ART System delivers the radiation therapy treatment in accordance with the physician approved plan using IMRT techniques delivered in a helical tomographic pattern.
The TomoTherapy HI-ART System is a radiation therapy system that integrates planning, dose calculation, megavoltage CT scanning, and helical radiation therapy treatment capabilities into a single comprehensive IMRT system.
The HI-ART System's planning station is used by the physician to prescribe and enter the radiation therapy plan. The patient's diagnostic CT image is imported via a DICOM protocol from another diagnostic CT device. The regions of interest, regions to avoid, and other prescribing information are entered in a manner that is similar to other commercially available planning systems.
The HI-ART System utilizes a 6 MV linear accelerator as the radiation source. The linear accelerator along with the primary collimator, multi-leaf collimator (MLC), xenon detector, various control devices and power supplies are mounted on a rotating gantry, much like a CT gantry. During treatment or imaging, the patient is positioned on the couch support, and the couch moves axially through the bore of the gantry, and the radiation is delivered in a helical pattern.
The primary collimator and the MLC control the beam dimensions during radiation delivery so that the range of collimated beam size can vary from 0 to 400 mm wide by 5 to 50 mm at the isocenter. The MLC is constructed of 64 tungsten leaves that open and close as determined by the radiation therapy plan. The intensity of the radiation beam is proportional to the length of time that a particular leaf is open. The opening and closing of various leaves as the radiation is delivered in this helical pattern allows for an IMRT plan to be delivered with precise control. The result is a highly conformal dose to the region of interest with low doses to surrounding healthy tissue.
Because the HI-ART System is operating in a helical mode similar to CT systems, it inherently has the ability to obtain a CT image. The system utilizes the linear accelerator to obtain a megavoltage (MVCT) scan of the region of interest prior to the delivery of radiation therapy. This MVCT image is then used in a non-diagnostic mode to ascertain that the patient is correctly positioned prior to treatment. The radiation dose to the patient from an MVCT scan is comparable to diagnostic CT or portal imaging.
Acceptance Criteria and Device Performance Study for the TomoTherapy HI-ART System
1. Table of Acceptance Criteria and Reported Device Performance:
The provided document (K033347) is a 510(k) summary for a modified TomoTherapy HI-ART System. As such, it does not explicitly state acceptance criteria in a quantitative table format with corresponding performance metrics as would typically be found in a detailed clinical study report. Instead, the document focuses on demonstrating substantial equivalence to a legally marketed predicate device (TomoTherapy Hi-Art System K013673) and confirming the device's safety and effectiveness for its intended use through extensive validation testing.
However, based on the information provided, we can infer the general areas of "acceptance criteria" through the descriptions of the device's intended function and the validation methods. The "reported device performance" is then described in broad terms as successful validation.
| Feature/Function | Implicit Acceptance Criteria (based on intended use & validation) | Reported Device Performance |
|---|---|---|
| Planning Station | Accurately prescribes and enters radiation therapy plans; similar functionality to other systems. | "The HI-ART System was extensively validated for system functionality, including planning... " (Page 2). "The HI-ART System's planning station is intended to be used by the physician/oncologist to prescribe a radiation therapy plan for a particular patient. The HI-ART System then calculates the treatment plan which the physician reviews and approves." (Page 0, Intended Use). Implies successful calculation and physician approval. |
| Dose Calculation | Provides accurate dose calculations for IMRT. | "The HI-ART System was extensively validated for system functionality, including... dose calculation..." (Page 2). "The HI-ART System delivers the radiation therapy treatment in accordance with the physician approved plan using IMRT techniques delivered in a helical tomographic pattern." (Page 0, Intended Use). This implies the dose calculation is accurate enough to enable physician-approved treatment delivery. |
| Megavoltage CT (MVCT) Scan (TomoImage™) | Confirms correct patient positioning; assists in repositioning; not for diagnostic use. | "The HI-ART System was extensively validated for system functionality, including... imaging..." (Page 2). "This TomoImage (MVCT) will confirm that the patient's position is correct for the radiation therapy as well as assist in patient repositioning when necessary. The TomoImage (MVCT image) is not for diagnostic use." (Page 0, Intended Use). "MVCT allows for reliable patient positioning." (Page 1, Safety Considerations). |
| Radiation Therapy Delivery (IMRT) | Delivers precise radiation to tumors while minimizing exposure to healthy tissue, in a helical pattern. | "The HI-ART System was extensively validated for system functionality, including... delivery..." (Page 2). "The HI-ART System provides precise delivery of radiation to tumors while minimizing the delivery of radiation to vital healthy tissue." (Page 0, Intended Use). "The HI-ART System delivers the radiation therapy treatment in accordance with the physician approved plan using IMRT techniques delivered in a helical tomographic pattern." (Page 0, Intended Use). "The result is a highly conformal dose to the region of interest with low doses to surrounding healthy tissue." (Page 1, Description). |
| System Functionality (General) | Reliable operation of integrated components (planning, imaging, delivery, database, DICOM). | "The HI-ART System was extensively validated for system functionality, including planning, imaging, delivery, database management, DICOM communications, etc." (Page 2). This indicates all these functionalities met their intended requirements. |
| Safety | Complies with relevant IEC safety standards; promotes patient safety (no falling blocks, covered gantry, photon mode only). | "The HI-ART System is designed to comply with relevant sections of the IEC 60601-1, IEC 60601-2-1, IEC 60601-1-2, IEC 60601-1-4 safety standards." (Page 1, Standards Compliance). "The HI-ART System has several characteristics that promote its safety - no beam blocks are used that can fall off onto the patient; the rotating gantry is covered so that the patient cannot contact moving gantry parts; the linear accelerator operates in photon mode only so inadvertent electron exposure is virtually eliminated: MVCT allows for reliable patient positioning." (Page 1, Safety Considerations). |
2. Sample Size Used for the Test Set and Data Provenance:
- Sample Size: The document does not specify a "test set" in terms of patient data. The validation relied on "test tools" such as "IMRT phantoms, ion chambers and other test phantoms" (Page 2). Therefore, the sample size refers to the number of tests performed using these phantoms, which is not quantified.
- Data Provenance: The study described is a device validation study performed by the manufacturer (TomoTherapy Incorporated). It is an internal, retrospective validation using specified test tools, not prospective clinical data from human subjects. The data is not from a specific country of origin in terms of patient population, as it involves phantoms.
3. Number of Experts Used to Establish Ground Truth for the Test Set and Qualifications of Those Experts:
- The document does not describe the use of "experts" to establish ground truth in the context of a clinical study or image review. The "ground truth" for the device's technical performance (e.g., dose delivery accuracy, image quality for positioning) was established through measurements with physical phantoms and established measurement devices (ion chambers).
- The validation process would have been overseen by engineers, physicists, and quality assurance personnel within TomoTherapy Incorporated, whose qualifications are not detailed in this summary but would be relevant to radiation therapy device development and testing.
4. Adjudication Method for the Test Set:
- No adjudication method (like 2+1, 3+1 consensus) is mentioned or applicable, as the validation was based on physical measurements of device output against established standards and expected performance, rather than human review of cases.
5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study Was Done, What was the Effect Size of How Much Human Readers Improve with AI vs. Without AI Assistance:
- No MRMC comparative effectiveness study was done. The HI-ART System is a radiation therapy delivery system, not an AI-assisted diagnostic or image interpretation tool for human readers in the traditional sense. Its "AI" or advanced component is the intensity-modulated radiation therapy (IMRT) plan calculation and delivery, which is integral to its function, not a separate assistance tool for human interpretation.
6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) Was Done:
- The validation described is essentially a standalone performance assessment of the device's technical functionalities (planning, imaging, delivery, etc.) through testing with phantoms and measurements. The "algorithm only" aspect refers to the planning and dose calculation algorithms within the system, which were tested for accuracy and functionality.
- However, the device is explicitly designed for "human-in-the-loop" operation: a "physician/oncologist" prescribes the plan, reviews, and approves it, and a "therapist" selects and implements the plan, performs the MVCT scan, and treats the patient (Page 0, Intended Use). The validation ensures these components (algorithms and hardware) function correctly when used by qualified personnel as intended.
7. The Type of Ground Truth Used:
- The "ground truth" used for this validation study was physical measurements and established scientific principles related to radiation dose delivery, image quality for positioning, and system functionality. This involved:
- IMRT phantoms: Used to simulate patient anatomy and allow for precise dose measurements in a controlled environment.
- Ion chambers: Standard devices for measuring radiation dose, providing objective quantitative data.
- Other test phantoms: For various aspects of system performance.
- Compliance with IEC safety standards (Page 1).
8. The Sample Size for the Training Set:
- The concept of a "training set" in the context of machine learning or AI algorithm development is not directly applicable here. The document describes a traditional medical device validation for a radiation therapy system, not a study focused on a deep learning model. The system's design and algorithms would have been developed over time, incorporating engineering principles and potentially internal iterations and refinements, but not typically a discrete "training set" phase as seen in current AI development.
9. How the Ground Truth for the Training Set Was Established:
- As a "training set" is not explicitly mentioned or relevant in the context of this 510(k) summary for a modified radiation therapy system (not an explicit AI/ML device), the method for establishing its ground truth is not applicable to the information provided. The development of such a complex system would involve extensive engineering, physics, and clinical input during its design and optimization phases.
§ 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.