PhD candidate: Andre Asena
Project Title: Dose distribution in the vicinity of high-density implants in radiotherapy
Pricipal Supervisor: Dr Jamie Trapp
Research Area: Dosimetry
This research aims to establish the impact of high-density materials on dose distributions in radiotherapy, with particular interest in using Monte Carlo modelling and 3D gel dosimetry. It is currently recommended to avoid treatments where the beams pass through the high-Z media before they reach the target volume, but sometimes this isn’t possible or often it results in a sub-optimal treatment being delivered to avoid uncertainties. Specific clinical situations are being investigated, and improved accuracy in these treatments is expected. This includes tissue expander ports in post-mastectomy breast reconstructions for breast cancer patients, and hip prostheses in patients with pelvic malignancies. It is expected that this research will result in a methodology whereby this avoidance of the metallic implant during radiation delivery is no longer necessary. If these dosimetric effects could be predicted during treatment planning, the accurate delivery of radiotherapy treatments would be ensured, resulting in improved patient outcomes worldwide.
This research aims to establish the impact of high-density materials on dose distributions in radiotherapy, with particular interest in using Monte Carlo modelling and 3D gel dosimetry. It is currently recommended to avoid treatments where the beams pass through the high-Z media before they reach the target volume, but sometimes this isn’t possible or often it results in a sub-optimal treatment being delivered to avoid uncertainties. Specific clinical situations are being investigated, and improved accuracy in these treatments is expected. This includes tissue expander ports in post-mastectomy breast reconstructions for breast cancer patients, and hip prostheses in patients with pelvic malignancies. It is expected that this research will result in a methodology whereby this avoidance of the metallic implant during radiation delivery is no longer necessary. If these dosimetric effects could be predicted during treatment planning, the accurate delivery of radiotherapy treatments would be ensured, resulting in improved patient outcomes worldwide.
PhD Candidate: Shaun Smith
Project Title: Development of three-dimensional dosimetry for
radiotherapy
Pricipal Supervisor: Dr Jamie Trapp
Research Area: Dosimetry
With the advent of the modern dose delivery techniques such as IMRT and VMAT, planning systems and treatment units are capable of delivering highly conformal doses with steep field gradients; however, dosimetry systems have not been developed to a sufficient level to allow complete 3D verification. It has been considered that radio-sensitive gels are an appropriate candidate for this dose verification application. Over the last 30 years, a number of different gel dosimeters have been created operating via unique mechanisms, yet all offer distinct advantages over other dosimetry techniques. Aside from the obvious advantage of scoring dose in three dimensions, gels can be moulded to create anthropomorphic phantoms, eliminating the requirement of external humanoid phantoms. Additionally, gel dosimeters show a significant degree of radiological tissue equivalence, and by acting as the humanoid phantom, avoid dose perturbations behind the point of measurement.
With the advent of the modern dose delivery techniques such as IMRT and VMAT, planning systems and treatment units are capable of delivering highly conformal doses with steep field gradients; however, dosimetry systems have not been developed to a sufficient level to allow complete 3D verification. It has been considered that radio-sensitive gels are an appropriate candidate for this dose verification application. Over the last 30 years, a number of different gel dosimeters have been created operating via unique mechanisms, yet all offer distinct advantages over other dosimetry techniques. Aside from the obvious advantage of scoring dose in three dimensions, gels can be moulded to create anthropomorphic phantoms, eliminating the requirement of external humanoid phantoms. Additionally, gel dosimeters show a significant degree of radiological tissue equivalence, and by acting as the humanoid phantom, avoid dose perturbations behind the point of measurement.
Despite this, the routine use of gels
in the clinic has been inhibited by a number of issues including diffusion of
radiation induced changes in 'Fricke' gels resulting in lower resolution dose
maps, as well as oxygen sensitivity and toxicity of polymer gels
causing inconsistencies in their radio-sensitivity and a
lack of convenience for clinical use. As such, gel dosimetry
currently requires time and specialized manufacturing facilities for users who
intend to perform everything from gel manufacture to evaluation
themselves. However, this may not be necessary and potentially a
‘standard’ dosimeter could be shipped from manufacturers to users. The
development of gels, which are non-toxic, independent of oxygen levels and not
affected by diffusion, will aid this process and make gel dosimetry more widely
accessible. Accordingly, the objective of this project is to develop a
novel gel dosimeter that conforms to the above criteria, thus being viable for
clinical commissioning.
PhD Candidate: Saeed Mueed A Al Qahtani
Project Title: validation and development of ultrasound transit time spectroscopy in complex media
Pricipal Supervisor: Prof. Christian Langton
Research Area:Ultrasound
In
the medical field, Ultrasound is the second most popular imaging technique for
diagnosis since it is a non-invasive, portable, safe and relatively low-cost,
real-time, and almost no side-effects compared to other modalities. It is used
for several areas of clinical practice, particularly obstetrics, cardiology,
oncology (e.g. breast) and general surgery (e.g. abdominal).
The
use of quantitative ultrasound (QUS) for the determination of osteoporosis in
cancellous bone at the calcaneus is one of most recent clinical applications.
Measurement parameters are broadband ultrasound attenuation (BUA), first
described by Langton in 1984 and speed of sound, both dependent upon bone
density and structure. The measurement of BUA characterises the slope of the
linear relationship between ultrasound attenuation and frequency, usually
between 0.2 - 0.6 MHz, conducted in transmission mode utilising two transducers
(1MHz broadband ¾” diameters) aligned co-axially, one acting as transmitter and
the other as receiver with the sample in between. The
relation between BUA and bone volume fraction (BVF) follows a parabolic
relationship within cancellous bone, showing minima values corresponding to
both entire marrow (0% BVF) and entire bone (100% BVF); whereas bone mineral
density (BMD) follows a linear relationship with BVF. The parabolic
relationship is unexplained to date, noting that there are several attenuation
processes taking place during the propagation of ultrasound through bone
including scattering, absorption, diffraction, reflection, mode conversion, and
phase cancelation. In
2010, Langton proposed a new paradigm; that phase cancellation is the
significant attenuation mechanism due to variations in transit time of parallel
‘sonic rays’ over the receive transducer; noting that the transit time of each
sonic ray will be determined by the amount of bone and marrow. The transit time
spectroscopy (UTTS) is based upon the superposition principle which can be
determined from the summation of the individual signals; where minimum transit
time is solely through bone and maximum transit time is solely through marrow.
The
primary aim of this project is to create a unified model for all input signals
and samples in the investigation of transit time spectroscopy for complex
media. It also aims to explain the mechanism of BUA and its behavior during the
propagation of ultrasound through cancellous bone.
PhD Candidate:Majdi Almualimi
Project Title: Development and Validation of Pulse-Echo Ultrasound Transit Time Spectroscopy (PE-UTTS)
Pricipal Supervisor: Prof. Christian Langton
Research Area: Ultrasound
This project
will investigate the potential to significantly improve the spatial resolution
of both conventional 2D and novel 3D computed tomography ultrasound imaging
through the cutting-edge signal processing technique of deconvoluting the input
and output ultrasound signals; it is believed that such an approach has not
been previously reported. Further potential applications of PE-UTTS include the
creation of acoustically non-reflective coatings and assessment of non-planar
surfaces.
PhD Candidate: Tonima S Ali
PhD Candidate: Tonima S Ali
Project Title: Quantitative MRI assessment of Osteoarthritis development in animal model
Pricipal Supervisor: Dr. Konstantin Momot
Research Area: MRI
Osteoarthritis (OA) is the most common joint disease
worldwide and a leading cause of chronic pain and disability. It is
characterized by degenerative changes in joint tissues including articular
cartilage (AC), subchondral bone, trabecular bone, ligaments, menisci, and
synovial tissues. Although it is not yet curable, early diagnosis is crucial
for successful treatment through improved understanding of the disease. OA commonly affects the large weight bearing
joints, such as the knees and the hips. Improvement of OA management requires
detailed information on its initiation and development over time. As OA is a
whole joint disease, the identification of the simultaneous alterations in
multiple joint tissues is also of vital importance. The use of MRI is widely
accepted in knee OA examination. The imaging superiority of MRI lies in its
inherent ability to analyze multiple tissue structures concurrently in great
detail and in a three-dimensional perspective. This thesis investigates the use
of MRI techniques to make quantitative assessment of the whole joint knee OA
and its evolution over time. As a human OA model is not appropriate for the
variability in volunteer data due to age, physical structure, stage and type of
OA, a rat knee OA model is chosen for this study, which has been established to
replicate human OA with significant similarity. For improved signal quality,
this project will design and implement ex
vivo PD, T1, T2* and T2 weighted MRI experiments on an NMR microimaging
system. Findings from this research will contribute to the understanding of
whole knee OA, the tissue alterations at different time points of disease
progression and thereby benefit in developing preventative treatment measures.
Masters by Research Student: Mark Young
Masters by Research Student: Mark Young
Project Title: Computer simulation optimisation of ultrasound computed tomography imaging
Principal Supervisor: Prof. Christian Langton
Research Area: Ultrasound
This research project intends to use computer
simulation software, such as SCALP and WavePro to optimise a transmission
ultrasound beam for computed tomography medical imaging.
The aim is to develop an ultrasound Computed Tomography scanner, particularly
for pediatric abdominal scans, that will allow for high resolution 3D real time
medical imaging that is safer, more affordable and more portable than existing
x-ray CT. The benefits will include
reducing exposure to ionizing radiation, minimising costs for diagnostic
imaging and making CT imaging accessible across regional locations throughout
the world.
