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Investigation of ultrasonic properties of MAGIC gels for pulse-echo gel dosimetry

Investigation of ultrasonic properties of MAGIC gels for pulse-echo gel dosimetry
Investigation of ultrasonic properties of MAGIC gels for pulse-echo gel dosimetry
This thesis describes investigations into the design and evaluation of novel ultrasonic methods for 3-dimensional ionising radiation dose verification. Pulse-echo ultrasound methods were investigated for the measurement and analysis of complex radiation therapy dose delivery.

The physical properties of MAGIC (Methacrylic and Ascorbic acid in Gelatin Initiated by Copper) polymer gel dosimeters have been characterized. The variations of speed of sound, ultrasonic attenuation coefficient and density of MAGIC gel with radiation dose and temperature have been quantified. This extends work that has previously been reported for the properties of this gel to the effect of measurement temperature on the results. The facilities to perform these measurements were specified, constructed and evaluated as part of the project.

The measurement of radiation dose using ultrasound back scatter from an interface between the polymer gel dosimeter and an inert reflector is demonstrated. To enable the measurement of radiation dose using pulse-echo ultrasound methods a novel inert material has been specified, manufactured and characterised. This material is matched to the acoustic impedance of MAGIC gel to produce the most dose-sensitive reflections.

The reflections from the interface between the inert reflector and dose-dependent MAGIC gel have been analysed using both a single element transducer and a commercial ultrasound scanner. Both measurement systems demonstrate the same dose and temperature dependence of the ultrasonic reflection. A methodology has been developed to relate pixel values from the ultrasound scanner to the amplitude of the reflected ultrasound signal. A phantom consisting of an array of threads formed from the inert backscattering material has been designed and constructed and a method of extracting pixel data from images of the array acquired using a commercial ultrasound scanner has been developed, so that multiple imaging positions could be used to perform a 3-dimensional assessment of radiation dose distributions.

It has been demonstrated that a pulse-echo technique using a commercial ultrasound scanner shows promise for radiation gel dosimetry. Further investigation and alternative polymer gel and inert reflector combinations may improve these techniques.
Atkins, Timothy John
1a5e9e46-d508-45a6-bad5-2bbf922e2a31
Atkins, Timothy John
1a5e9e46-d508-45a6-bad5-2bbf922e2a31
Humphrey, Victor
23c9bd0c-7870-428f-b0dd-5ff158d22590

Atkins, Timothy John (2014) Investigation of ultrasonic properties of MAGIC gels for pulse-echo gel dosimetry. University of Southampton, Engineering and the Environment, Doctoral Thesis, 227pp.

Record type: Thesis (Doctoral)

Abstract

This thesis describes investigations into the design and evaluation of novel ultrasonic methods for 3-dimensional ionising radiation dose verification. Pulse-echo ultrasound methods were investigated for the measurement and analysis of complex radiation therapy dose delivery.

The physical properties of MAGIC (Methacrylic and Ascorbic acid in Gelatin Initiated by Copper) polymer gel dosimeters have been characterized. The variations of speed of sound, ultrasonic attenuation coefficient and density of MAGIC gel with radiation dose and temperature have been quantified. This extends work that has previously been reported for the properties of this gel to the effect of measurement temperature on the results. The facilities to perform these measurements were specified, constructed and evaluated as part of the project.

The measurement of radiation dose using ultrasound back scatter from an interface between the polymer gel dosimeter and an inert reflector is demonstrated. To enable the measurement of radiation dose using pulse-echo ultrasound methods a novel inert material has been specified, manufactured and characterised. This material is matched to the acoustic impedance of MAGIC gel to produce the most dose-sensitive reflections.

The reflections from the interface between the inert reflector and dose-dependent MAGIC gel have been analysed using both a single element transducer and a commercial ultrasound scanner. Both measurement systems demonstrate the same dose and temperature dependence of the ultrasonic reflection. A methodology has been developed to relate pixel values from the ultrasound scanner to the amplitude of the reflected ultrasound signal. A phantom consisting of an array of threads formed from the inert backscattering material has been designed and constructed and a method of extracting pixel data from images of the array acquired using a commercial ultrasound scanner has been developed, so that multiple imaging positions could be used to perform a 3-dimensional assessment of radiation dose distributions.

It has been demonstrated that a pulse-echo technique using a commercial ultrasound scanner shows promise for radiation gel dosimetry. Further investigation and alternative polymer gel and inert reflector combinations may improve these techniques.

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More information

Published date: August 2014
Organisations: University of Southampton, Inst. Sound & Vibration Research

Identifiers

Local EPrints ID: 371793
URI: http://eprints.soton.ac.uk/id/eprint/371793
PURE UUID: d0840d03-5de6-43aa-a7d5-64268b3e9803
ORCID for Victor Humphrey: ORCID iD orcid.org/0000-0002-3580-5373

Catalogue record

Date deposited: 14 Nov 2014 17:09
Last modified: 26 Feb 2019 01:33

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