Limbus Contour is a software-only medical device intended for use by trained radiation oncologists, dosimetrists and physicists to derive optimal contours for input to radiation treatment planning. Supported image modalities are Computed Tomography and Magnetic Resonance. The Limbus Contour Software assists in the following scenarios:

· Operates in conjunction with radiation treatment planning systems or DICOM viewing systems to load, save, and display medical images and contours for treatment evaluation and treatment planning.

· Creation, transformation, and modification of contours for applications including, but not limited to: transferring contours to radiotherapy treatment planning systems, aiding adaptive therapy and archiving contours for patient follow-up.

· Localization and definition of healthy anatomical structures.

Limbus Contour is not intended for use with digital mammography.

Limbus Contour is not intended to automatically contour tumor clinical target volumes.

Device Description

Limbus Contour is a stand-alone software medical device. It is a single purposes cross-platform application for automatic contouring (segmentation) of CT/MRI DICOM images via pre-trained and expert curated machine learning models. The software is intended to be used by trained medical professionals to derive contours for input to radiation treatment planning. The Limbus Contour software segments normal tissues using models and further post-processing on machine learning model prediction outputs. Limbus Contour does not display or store DICOM images and relies on existing radiotherapy treatment planning systems (TPS) and DICOM image viewers for display and modification of generated segmentations. Limbus Contour interfaces with the user's operating system file system (importing DICOM image .dcm files and exporting segmented DICOM RT-Structure Set .dcm files).

AI/ML Overview

Here's a breakdown of the acceptance criteria and study information for the Limbus Contour device based on the provided FDA 510(k) summary:

Acceptance Criteria and Device Performance

The document does not explicitly state a table of "acceptance criteria" with numerical targets and reported performance in a pass/fail format. Instead, it refers to validation testing to demonstrate that the software meets "user needs and intended uses" and performs "in accordance with specifications." The implicit acceptance is that the automatic contouring function is accurate and comparable to the predicate device.

However, based on the general context of premarket submissions, the underlying acceptance criteria for automatic contouring typical involves metrics related to overlap, distance, and shape similarity. Since specific numerical metrics and targets are not provided, I will infer the successful demonstration of functionality as the reported device performance.

Acceptance Criteria Category	Reported Device Performance
Automatic Contouring	Validation testing demonstrated that the software meets user needs and intended uses for automatic contouring and performs in accordance with specifications. Performance is comparable to the predicate device.

Study Details

2. Sample Size for Test Set and Data Provenance

The document does not specify the exact sample size (number of cases or patients) used for the test set. It mentions "Validation testing of the following functions of the Limbus Contour application demonstrated that the software meets user needs and intended uses and to support substantial equivalence: Automatic Contouring – Validation Test."

The data provenance (economic area, retrospective/prospective) is also not specified in the provided text.

3. Number of Experts and Qualifications for Ground Truth

The document does not specify the number of experts or their qualifications used to establish the ground truth for the test set. It mentions "pre-trained and expert curated machine learning models" in the device description, implying expert involvement in the training data, but does not explicitly describe it for the test set.

4. Adjudication Method

The document does not specify any adjudication method (e.g., 2+1, 3+1) used for establishing the ground truth of the test set.

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

No Multi-Reader Multi-Case (MRMC) comparative effectiveness study was mentioned, nor was any effect size of human readers improving with AI assistance reported. The study focused on the standalone performance of the device and its substantial equivalence to a predicate.

6. Standalone Performance Study

Yes, a standalone (algorithm only without human-in-the-loop performance) study was performed. The document explicitly states: "Validation testing of the following functions of the Limbus Contour application demonstrated that the software meets user needs and intended uses and to support substantial equivalence: Automatic Contouring – Validation Test." This is a validation of the autonomous contouring capability.

7. Type of Ground Truth Used

The document does not explicitly state the type of ground truth used (e.g., expert consensus, pathology, outcomes data) for the test set. The device description mentions "expert curated machine learning models," which suggests expert annotations were used at some stage, likely for training. However, the exact nature of the ground truth for the independent validation (test) set is not detailed.

8. Sample Size for Training Set

The document does not specify the sample size used for the training set.

9. How Ground Truth for Training Set was Established

The device description states that the Limbus Contour operates via "pre-trained and expert curated machine learning models." This indicates that the ground truth for the training set was established through expert curation, meaning medical experts (likely radiation oncologists, dosimetrists, or physicists) manually contoured structures which were then used to train the machine learning models.

Summary

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August 13, 2020

Image /page/0/Picture/1 description: The image contains the logo of the U.S. Food and Drug Administration (FDA). On the left is the Department of Health & Human Services logo. To the right of that is the FDA logo, which is a blue square with the letters "FDA" in white. To the right of the square is the text "U.S. FOOD & DRUG ADMINISTRATION" in blue.

Limbus AI Inc. % Ms. Mary Vater 510(k) Consultant Medical Device Academy 245 Lincoln Hill Road SHREWSBURY VT 05738

Re: K201232

Trade/Device Name: Limbus Contour Regulation Number: 21 CFR 892.2050 Regulation Name: Picture archiving and communications system Regulatory Class: Class II Product Code: LLZ Dated: July 17, 2020 Received: July 17, 2020

Dear Ms. Vater:

We have reviewed your Section 510(k) premarket notification of intent to market the device referenced above and have determined the device is substantially equivalent (for the indications for use stated in the enclosure) to legally marketed predicate devices marketed in interstate commerce prior to May 28, 1976, the enactment date of the Medical Device Amendments, or to devices that have been reclassified in accordance with the provisions of the Federal Food, Drug, and Cosmetic Act (Act) that do not require approval of a premarket approval application (PMA). You may, therefore, market the device, subject to the general controls provisions of the Act. Although this letter refers to your product as a device, please be aware that some cleared products may instead be combination products. The 510(k) Premarket Notification Database located at https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfpmn/pmn.cfm identifies combination product submissions. The general controls provisions of the Act include requirements for annual registration, listing of devices, good manufacturing practice, labeling, and prohibitions against misbranding and adulteration. Please note: CDRH does not evaluate information related to contract liability warranties. We remind you, however, that device labeling must be truthful and not misleading.

If your device is classified (see above) into either class II (Special Controls) or class III (PMA), it may be subject to additional controls. Existing major regulations affecting your device can be found in the Code of Federal Regulations, Title 21, Parts 800 to 898. In addition, FDA may publish further announcements concerning your device in the Federal Register.

Please be advised that FDA's issuance of a substantial equivalence determination does not mean that FDA has made a determination that your device complies with other requirements of the Act or any Federal statutes and regulations administered by other Federal agencies. You must comply with all the Act's requirements, including, but not limited to: registration and listing (21 CFR Part 807); labeling (21 CFR Part 801); medical device reporting of medical device-related adverse events) (21 CFR 803) for devices or postmarketing safety reporting (21 CFR 4, Subpart B) for combination products (see https://www.fda.gov/combination-products/guidance-regulatory-information/postmarketing-safety-reporting

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combination-products); good manufacturing practice requirements as set forth in the quality systems (QS) regulation (21 CFR Part 820) for devices or current good manufacturing practices (21 CFR 4, Subpart A) for combination products; and, if applicable, the electronic product radiation control provisions (Sections 531-542 of the Act); 21 CFR 1000-1050.

Also, please note the regulation entitled, "Misbranding by reference to premarket notification" (21 CFR Part 807.97). For questions regarding the reporting of adverse events under the MDR regulation (21 CFR Part 803), please go to https://www.fda.gov/medical-device-safety/medical-device-reportingmdr-how-report-medical-device-problems.

For comprehensive regulatory information about medical devices and radiation-emitting products, including information about labeling regulations, please see Device Advice (https://www.fda.gov/medicaldevices/device-advice-comprehensive-regulatory-assistance) and CDRH Learn (https://www.fda.gov/training-and-continuing-education/cdrh-learn). Additionally, you may contact the Division of Industry and Consumer Education (DICE) to ask a question about a specific regulatory topic. See the DICE website (https://www.fda.gov/medical-device-advice-comprehensive-regulatoryassistance/contact-us-division-industry-and-consumer-education-dice) for more information or contact DICE by email (DICE@fda.hhs.gov) or phone (1-800-638-2041 or 301-796-7100).

Sincerely,

For

Thalia T. Mills, Ph.D. Director Division of Radiological Health OHT7: Office of In Vitro Diagnostics and Radiological Health Office of Product Evaluation and Quality Center for Devices and Radiological Health

Enclosure

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Indications for Use

510(k) Number (if known) K201232

Device Name Limbus Contour

Indications for Use (Describe)

· Operates in conjunction with radiation treatment planning systems or DICOM viewing systems to load, save, and display medical images and contours for treatment evaluation and treatment planning.

· Creation, transformation, and modification of contours for applications including, but not limited to: transferring

contours to radiotherapy treatment planning systems, aiding adaptive therapy and archiving contours for patient follow-up.

· Localization and definition of healthy anatomical structures.

Limbus Contour is not intended for use with digital mammography.

Limbus Contour is not intended to automatically contour tumor clinical target volumes.

Type of Use (Select one or both, as applicable)
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X Prescription Use (Part 21 CFR 801 Subpart D)

Over-The-Counter Use (21 CFR 801 Subpart C)

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510(k) SUMMARY

K201232

This summary of 510(k) safety and effectiveness information is submitted in accordance with the requirements of 21 CFR §807.92:

l. SUBMITTER Limbus AI, Inc. 2076 Athol Street Regina, Saskatchewan, Canada, S4T3E5 Tel: 1-306-502-5982
Contact Person: Mary Vater Date Prepared: May 1, 2020

II. DEVICE
Name of Device:	Limbus Contour
Classification Name:	Radiological Image Processing System
Regulation:	21 CFR §892.2050
Regulatory Class:	Class II
Product Classification Code:	LLZ

PREDICATE DEVICE ============================================================================================================================================================================== Predicate Manufacturer: Microsoft Corp. Predicate Trade Name: Radiomics App v1.0 Predicate 510(k): K173420

No reference devices were used in this submission.

DEVICE DESCRIPTION IV.

INDICATIONS FOR USE V.

Operates in conjunction with radiation treatment planning systems to load, save, and display ● medical images and contours for treatment evaluation and treatment planning.
. Creation, transformation, and modification of contours for applications including, but not limited to: transferring contours to radiotherapy treatment planning systems, aiding adaptive therapy and archiving contours for patient follow-up.

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o Localization and definition of anatomical structures.
Limbus Contour is not intended for use with digital mammography.

Limbus Contour is not intended to automatically contour tumor clinical target volumes.

COMPARISON OF TECHNOLOGICAL CHARACTERISTICS WITH THE VI. PREDICATE DEVCE

The following characteristics were compared between the subject device and the predicate device in order to demonstrate substantial equivalence:

Indications for Use The predicate and subject device are identical with the exception that the . predicate has additional indications specific to tumor and organ contouring, whereas the subject device is not specifically indicated for that purpose.
o Materials - The predicate and subject device are software-only devices and do not inherently contain material.
Design - The predicate and subject device have equivalent designs.
o Energy Source - The predicate and subject device are software-only devices, powered by the computer system.
Other Design Features - The contours generated from Limbus Contour are edited in external treatment planning or contouring tools and it does not contain an image viewer, whereas the predicate has these features integrated. The subject device also does not perform image fusion or subsequent contouring of fused images, or 3D image rendering, which are not necessary to achieve the intended use. Both devices are offered as a stand-alone package that operate on Microsoft Windows operating system. Limbus Contour also functions on a Mac OS.
. Performance Testing - The predicate and subject device were both were validated using an automatic contouring test to ensure the contours were accurate.

	Limbus AI	Radiomics App v1.0 –K173420	Similarities /Differences
ClassificationRegulation	892.2050 – Picture Archivingand Communication System	892.2050 – Picture Archivingand Communication System	Same
Product Code	LLZ	LLZ	Same
Indications forUse	Limbus Contour is a software-only medical device intendedfor use by trained radiationoncologists, dosimetrists andphysicists to derive optimalcontours for input to radiationtreatment planning.Supported image modalitiesare Computed Tomographyand Magnetic Resonance. TheLimbus Contour Softwareassists in the followingscenarios:• Operates in conjunction withradiation treatment planningsystems or DICOM viewingsystems to load, save, anddisplay medical images andcontours for treatmentevaluation and treatmentplanning.	Microsoft Radiomics App v1.0is a software-only medicaldevice intended for use bytrained radiation oncologists,dosimetrists and physicists toderive optimal organ andtumor contours for input toradiation treatment planning.Supported image modalitiesare Computed Tomographyand Magnetic Resonance.Radiomics App assists in thefollowingscenarios:• Load, save and display ofmedical images and contoursfor treatment evaluation andtreatment planning.• Creation, transformation, andmodification of contours for	Indications foruse are similarother than thedevice notdisplayingmedicalimages andcontours.Related to thatdifference; thedevice is alsonot capable offusingcompatibleimages fortreatmentplanning orthree-dimensionalrendering ofmedical

	• Creation, transformation, andmodification of contours forapplications including, but notlimited to: transferringcontours to radiotherapytreatment planning systems,aiding adaptive therapy andarchiving contours for patientfollow-up.• Localization and definitionof healthy anatomicalstructures.Limbus Contour is notintended for use with digitalmammography.Limbus Contour is notintended to automaticallycontour tumors or tumorclinical target volumes.	applications including, but notlimited to: transferringcontours to radiotherapytreatment planning systems,aiding adaptive therapy, andarchiving contours for patientfollow-up.• Localization and definition ofboth solid tumors and healthyanatomical structures.• Fusion display of compatibleimages for treatment planning.• Three-dimensional renderingof medical images and thesegmented contours.Images reviewed using theRadiomics App softwareshould not be used for primaryimage interpretations.Radiomics App is not for usewith digital mammography.	images andsegmentedcontour.Unlike thepredicatedevice, theLimbusContour doesnot displayimages, andtherefore itcannot be usedfor "primaryimageinterpretations"so that is notincluded in theLimbusContourindications.In addition, thedevice onlylocalizes anddefines healthyanatomicalstructures (notsolid tumorslike thepredicatedevice).
Intended User	Healthcare providers	Healthcare providers	Same
ContouringModes	Automatic	Assisted and Automatic	Contoursgenerated fromLimbusContour areedited inexternaltreatment-planning orcontouringtools.
Measurements	No measurement function.	2D distance measurement,average tissue density within aregion (for CT), segmentationvolume	LimbusContour doesnot contain animage viewer.Nomeasurementfunctionality isprovidedbecause of this.

Image Fusion	No fusion support.	Fuse only two 3D images, CTand MR	measurementsare notnecessary toachieveintended use.LimbusContour doesnot performimage fusionand subsequentcontouring onfused images.Not necessaryto achieveintended use.
3D imagerendering	No image rendering function.	Yes	LimbusContour doesnot contain aviewer. Imagesare rendered ina separateviewing tool.
Image Modalities	CT and MR	CT and MR	Same
Platform	Stand-alone package whichoperates on MicrosoftWindows operating systemand MacOS operating system	Stand-alone package whichoperates on MicrosoftWindows operating systemonly.	LimbusContour willalso supportMac OSoperatingsystems
Environment ofUse	Healthcare environment	Healthcare environment	Same
Materials	N/A – Standalone Software	N/A – Standalone Software	Same
Energy Source	N/A – Standalone Software	N/A – Standalone Software	Same
FeatureComparison:	Operating System• Windows 10 / WindowsServer 2016• Mac OS 10.14	Operating System• Not specified.
HardwareRequirementsEtc.	Hardware Requirements• 2 GHz or faster multi-coreprocessor• 4 GB of RAM• For GPU versions, aCUDA capable NVIDIAGPU is required
PerformanceTesting	Two different types ofverification testing wereconducted to verify thesoftware requirements:	Two different types ofverification testing wereconducted to verify thesoftware requirements:	Rendering andmeasurementtests are notapplicable forthe subject
Manual and Automated. Alltests passed, demonstratingthat the software performanceis in accordance with thestated software requirements.	Manual and Automated. Alltests passed, demonstratingthat the software performanceis in accordance with thestated software requirements.	device becauseit does nothave thosefunctions.
Validation testing of thefollowing functions of theLimbus Contour applicationdemonstrated that the softwaremeets user needs and intendeduses and to support substantialequivalence:• Automatic Contouring –Validation Test	Validation testing of thefollowing functions of theRadiomics App demonstratedthat the software meets userneeds and intended uses and tosupport substantialequivalence:• Measurements - ValidationTest• Volumetric Rendering –Validation Test• Multi-Planar Reconstruction– Validation Test• Assisted Contouring –Validation Test• Automatic Contouring –Validation Test

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VII. PERFORMANCE DATA

The following performance data were provided in support of the substantial equivalence determination.

Sterilization & Shelf-life Testing

The subject device is a software-only device. Therefore sterilization and shelf-life are not applicable.

Biocompatibility

The subject device is a software-only device. There are no direct patient-contacting components of the subject device. Therefore, patient contact information is not needed for this device

Electrical safety and electromagnetic compatibility (EMC)

The subject device is a software-only device. It contains no electric components, generates no electrical emissions, and uses no electrical energy of any type; therefore, this section is not applicable.

Software Verification and Validation Testing

Software verification and validation testing were conducted as recommended by FDA's Guidance for Industry and FDA Staff, "Guidance for the Content of Premarket Submissions for Software Contained in Medical Devices." The software for this device was considered as a major level of concern.

Two different types of verification testing were conducted to verify the software requirements: Manual and Automated. All tests passed, demonstrating that the software performance is in accordance with the stated software requirements.

Validation testing of the following functions of the Limbus Contour application demonstrated that the software meets user needs and intended uses and to support substantial equivalence:

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Automatic Contouring - Validation Test

Mechanical and Acoustic Testing

Not Applicable (Standalone Software)

Animal Study

Animal performance testing was not required to demonstrate safety and effectiveness of the device.

Clinical Studies

Clinical testing was not required to demonstrate the safety and effectiveness of Limbus Contour. Instead, substantial equivalence is based upon benchtop performance testing.

VIII. CONCLUSIONS

The minor differences in indications of use between the subject Limbus Contour software and the predicate Radiomics software do not constitute a different intended use. The technological characteristics of the Limbus Contour software are similar to those of the Radiomics App. Results of software verification and validation testing demonstrate that the Limbus Contour software performs in accordance with specifications and that the performance is comparable to that of the predicate device. Therefore, the Limbus Contour software can be found to be substantially equivalent to the predicate Radiomics App software device.

Regulation Number and Section

§ 892.2050 Medical image management and processing system.

(a)
Identification. A medical image management and processing system is a device that provides one or more capabilities relating to the review and digital processing of medical images for the purposes of interpretation by a trained practitioner of disease detection, diagnosis, or patient management. The software components may provide advanced or complex image processing functions for image manipulation, enhancement, or quantification that are intended for use in the interpretation and analysis of medical images. Advanced image manipulation functions may include image segmentation, multimodality image registration, or 3D visualization. Complex quantitative functions may include semi-automated measurements or time-series measurements.(b)
Classification. Class II (special controls; voluntary standards—Digital Imaging and Communications in Medicine (DICOM) Std., Joint Photographic Experts Group (JPEG) Std., Society of Motion Picture and Television Engineers (SMPTE) Test Pattern).