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Contact angle and indentation velocity dependency for a resonance sensor: Evaluation on soft tissue silicone models
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
2013 (Engelska)Ingår i: Journal of Medical Engineering & Technology, ISSN 0309-1902, E-ISSN 1464-522X, Vol. 37, nr 3, s. 185-196Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Human tissue stiffness can vary due to different tissue conditions such as cancer tumours. Earlier studies show that stiffness may be detected with a resonance sensor that measures frequency shift and contact force at application. Through the frequency shift and the contact force, a tissue stiffness parameter can be derived. This study evaluated how the probe application angle and indentation velocity affected the results and determined the maximum parameter errors. The evaluation was made on flat silicone discs with specified hardness. The frequency shift, the force and the stiffness parameter all varied with contact angle and indentation velocity. A contact angle of ≤10° was acceptable for reliable measurements. A low indentation velocity was recommended. The maximum errors for the system were <1.1% of the measured values. It was concluded that contact angle and indentation velocity have to be considered in the clinical setting. The angular dependency is especially important in clinical use for studying stiffness of human soft tissue, e.g. in prostate cancer diagnosis.

Ort, förlag, år, upplaga, sidor
Informa Healthcare, 2013. Vol. 37, nr 3, s. 185-196
Nyckelord [en]
Contact angle, Frequency shift, Indentation velocity, Resonance sensor, Tissue stiffness
Nationell ämneskategori
Medicinteknik
Identifikatorer
URN: urn:nbn:se:umu:diva-68970DOI: 10.3109/03091902.2013.773097OAI: oai:DiVA.org:umu-68970DiVA, id: diva2:619212
Tillgänglig från: 2013-05-02 Skapad: 2013-05-02 Senast uppdaterad: 2018-06-08Bibliografiskt granskad
Ingår i avhandling
1. A Tactile Resonance Sensor System for Detection of Prostate Cancer ex vivo: Design and Evaluation on Tissue Models and Human Prostate
Öppna denna publikation i ny flik eller fönster >>A Tactile Resonance Sensor System for Detection of Prostate Cancer ex vivo: Design and Evaluation on Tissue Models and Human Prostate
2014 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

Background

The most common form of cancer among males in Europe and the USA is prostate cancer, PCa. Surgical removal of the prostate is the most common form of curative treatment. PCa can be suspected by a blood test for a specific prostate antigen, a PSA-test, and a digital rectal examination, DRE where the physician palpates the prostate through the rectum. Stiff nodules that can be detected during the DRE, and elevated levels of PSA are indications for PCa, and a reason for further examination. Biopsies are taken from the prostate by guidance of a transrectal ultrasound. Superficial cancer tumours can indicate that the cancer has spread to other parts of the body. Tactile resonance sensors can be used to detect areas of different stiffness in soft tissue. Healthy prostate tissue is usually of different stiffness compared to tissue with PCa.

Aim

The general aim of this doctoral thesis was to design and evaluate a flexible tactile resonance sensor system (TRSS) for detection of cancer in soft human tissue, specifically prostate cancer. The ability to detect cancer tumours located under the surface was evaluated through measurements on tissue phantoms such as silicone and biological tissues. Finally measurements on resected whole prostate glands were made for the detection of cancer tumours.

Methods

The sensor principle was based on an oscillating piezoelectric element that was indented into the soft tissue.  The measured parameters were the change in resonance frequency, Δf, and the contact force F during indentation. From these, a specific stiffness parameter  was obtained. The overall accuracy of the TRSS was obtained and the performance of the TRSS was also evaluated on tissue models made of silicone, biological tissue and resected whole human prostates in order to detect presence of PCa. Prostate glands are generally spherical and a special rotatable sample holder was included in the TRSS. Spherically shaped objects and uneven surfaces call for special attention to the contact angle between the sensor-tip and the measured surface, which has been evaluated. The indentation velocity and the depth sensitivity of the sensor were evaluated as well as the effect on the measurements caused by the force with which spherical samples were held in place in the sample holder. Measurements were made on silicone models and biological tissue of chicken and pork muscles, with embedded stiff silicone nodules, both on flat and spherical shaped samples. Finally, measurements were made on two excised whole human prostates.

Results

A contact angle deviating ≤ 10° from the perpendicular of the surface of the measured object was acceptable for reliable measurements of the stiffness parameter. The sensor could detect stiff nodules ≤ 4 mm under the surface with a small indentation depth of 0.4 to 0.8 mm.

Measurements on the surface of resected human prostate glands showed that the TRSS could detect stiff areas (p < 0.05), which were confirmed by histopathological evaluation to be cancer tumours on, and under the surface.

Conclusions

A flexible resonance sensor system was designed and evaluated on soft tissue models as well as resected whole prostate glands. Evaluations on the tissue models showed that the TRSS can detect stiffer volumes hidden below the surface on both flat and spherical samples. The measurements on resected human prostate glands showed that PCa could be detected both on and under the surface of the gland. Thus the TRSS provides a promising instrument aimed for stiffness measurements of soft human tissue that could contribute to a future quantitative palpation method with the purpose of diagnosing cancer. 

Ort, förlag, år, upplaga, sidor
Umeå: Umeå universitet, 2014. s. 47
Serie
Resonance Sensor Lab, ISSN 1653-6789 ; 6
Nationell ämneskategori
Medicinsk apparatteknik
Forskningsämne
elektronik
Identifikatorer
urn:nbn:se:umu:diva-86322 (URN)978-91-7601-006-8 (ISBN)
Disputation
2014-03-20, MA 121, MIT-huset, Umeå universitet, Umeå, 13:00 (Engelska)
Opponent
Handledare
Tillgänglig från: 2014-02-26 Skapad: 2014-02-24 Senast uppdaterad: 2018-06-08Bibliografiskt granskad

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Förlagets fulltexthttp://informahealthcare.com/doi/abs/10.3109/03091902.2013.773097

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Åstrand, AndersJalkanen, VilleAndersson, Britt M.Lindahl, Olof A.

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Åstrand, AndersJalkanen, VilleAndersson, Britt M.Lindahl, Olof A.
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Institutionen för tillämpad fysik och elektronikCentrum för medicinsk teknik och fysik (CMTF)Institutionen för strålningsvetenskaper
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