Validation of a Method to Measure Soft Tissue Thickness Using Near Infrared Laser Light

Study Overview
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Brief Summary
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The study is intended to verify a newly developed method to measure the thickness of cranial soft tissue. In the study, a high-resolution MRI scan is used as ground truth for a laser scan of the forehead. The laser scan is acquired point by point with a prototype scanning unit developed at the University of Luebeck's Institute for Robotics. The measured tissue thickness using the near-infrared scanning approach is validated against the ground truth obtained by the MRI scan. The average accuracy of the reconstruction method is then computed over all subjects from the individual study arms. The required laser intensity and exposure time as well as the achieved measurement accuracy is evaluated with respect to the different skin types of the test subjects. Correlation between these features and the skin type according to the Fitzpatrick scale will be computed. For 1/3 of the subjects, the laser and MRI scans are repeated after 2 and 8 weeks. The results of the scans are compared and time dependency is analysed.

Official Title
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Validierung Der Bestimmung Der Gewebedicke Mit Hilfe Von Licht im Infrarotbereich

Conditions
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Cranial Soft Tissue

Intervention / Treatment
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* Device: MRI scan
* Device: Laser scan
* Procedure: Dental cast creation


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: male and female adults variations in skin type (at least 10 subjects with skin types I & II, at least 2 subjects with skin type III, at least 3 subjects with skin type IV, at least 3 subjects with skin types V & VI) optional: availability of high-resolution CT or CBCT (cone-beam CT) scan of the forehead Exclusion Criteria: allergies or intolerances against ABS (acrylonitrile butadiene styrene), PMMA (polymethyl methacrylate) or alginate elevated light sensitivity of the skin exclusion criteria for MRI (claustrophobia, motoric disorders, tattoos, body piercings, metallic implants in the skull, epilepsy, cardiac pacemakers)

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Allocation: Non-Randomized
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Skin types I and II<br>Volunteers classified as skin types I and II according to the Fitzpatrick Scale Procedures: dental cast creation, MRI scan, laser scan | Device: MRI scan<br>* Acquisition of a high-resolution MRI scan (0.15 x 0.15 x 1.0 mm³) aligned with the AC-PC (anterior commissure-posterior commissure) line<br>Device: Laser scan<br>* A near-infrared laser scan of the subject's forehead is acquired<br>Procedure: Dental cast creation<br>* A dental cast made of PMMA (polymethyl methacrylate) of the subject's maxilla is created<br>|
| Experimental: Skin type III<br>Volunteers classified as skin type III according to the Fitzpatrick Scale Procedures: dental cast creation, MRI scan, laser scan | Device: MRI scan<br>* Acquisition of a high-resolution MRI scan (0.15 x 0.15 x 1.0 mm³) aligned with the AC-PC (anterior commissure-posterior commissure) line<br>Device: Laser scan<br>* A near-infrared laser scan of the subject's forehead is acquired<br>Procedure: Dental cast creation<br>* A dental cast made of PMMA (polymethyl methacrylate) of the subject's maxilla is created<br>|
| Experimental: Skin type IV<br>Volunteers classified as skin type IV according to the Fitzpatrick Scale Procedures: dental cast creation, MRI scan, laser scan | Device: MRI scan<br>* Acquisition of a high-resolution MRI scan (0.15 x 0.15 x 1.0 mm³) aligned with the AC-PC (anterior commissure-posterior commissure) line<br>Device: Laser scan<br>* A near-infrared laser scan of the subject's forehead is acquired<br>Procedure: Dental cast creation<br>* A dental cast made of PMMA (polymethyl methacrylate) of the subject's maxilla is created<br>|
| Experimental: Skin types V and VI<br>Volunteers classified as skin types V and VI according to the Fitzpatrick Scale Procedures: dental cast creation, MRI scan, laser scan | Device: MRI scan<br>* Acquisition of a high-resolution MRI scan (0.15 x 0.15 x 1.0 mm³) aligned with the AC-PC (anterior commissure-posterior commissure) line<br>Device: Laser scan<br>* A near-infrared laser scan of the subject's forehead is acquired<br>Procedure: Dental cast creation<br>* A dental cast made of PMMA (polymethyl methacrylate) of the subject's maxilla is created<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Average accuracy of tissue thickness measurement method [mm] |  | up to 6 months | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| System dependency on skin color - required intensity | Correlation between skin types (according to the Fitzpatrick scale) and the outcome (required laser intensity [mW]) | up to 6 months | 
| Long-term stability of measured features - accuracy | Change in measurement accuracy [mm] | up to 8 months | 
| Long-term stability of measured features - required intensity | Change in required laser intensity [mW] | up to 8 months | 
| Long-term stability of measured features - required exposure time | Change in required exposure time [ms] | up to 8 months | 
| System dependency on skin color - accuracy | Correlation between skin types (according to the Fitzpatrick scale) and the outcome (accuracy of tissue thickness measurement [mm]) | up to 6 months | 
| System dependency on skin color - exposure time | Correlation between skin types (according to the Fitzpatrick scale) and the outcome (required exposure time [ms]) | up to 6 months | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Patient, localisation, in cranial, radiation, therapy, thickness of