School of Physics and Astrophysics

Projects

Summary of current and upcoming projects in the Medical Physics research group

  1. Current projects

Current and on-going projects

 

RADAR trial longitudinal analysis

We accrued 1070 prostate cancer patients across Aus/NZ and collected digital data on their radiotherapy treatment. We are now assessing the relationships between that data and the treatment side-effects the participants have experienced up to 5 years later.

Bystander effect modelling

When cells are exposed to radiation they can 'communicate' the event to neighbouring cells. This has implications for how tissues respond to radiation.  We are combining laboratory studies with mathematical modelling to make predictions regarding the likely effects and how they might be manipulated to optimise radiotherapy treatment.

Tissue repair mechanisms

We are examining the way that cells and tissues can repair themselves after damage from radiation. This will allow us to manipulate the timing of radiotherapy treatment in order to get the best chance of cancer eradication with minimal treatment side-effects.

Radiotherapy monitoring tools

We are using Monte Carlo simulation to design radiation detectors that will be able to monitor, in real time, the radiation fields patients are being exposed to during radiotherapy. The intention is to develop hardware that will be used to monitor the accuracy of the radiotherapy delivery.

Patient waiting list optimisation

We are using mathematical models of cancer cure to examine how populations of patients should be scheduled when there is a waiting list for radiotherapy treatment. This relies on us being able to use objective measures of the effect of treatment delays on efficacy of treatment, and the design of an optimisation problem that maximises the greatest chance of cure for the greatest number of patients (the 'utilitarian' objective). 

Uniform total body irradiation

Total Body Irradiation (TBI) is a radiation oncology technique used for the treatment of advanced lymphoma or leukemia patients. Combined with chemotherapy, TBI is intended to kill white blood cells and the bone marrow that produces white blood cells. With CT‐based planning and beam modulation it is expected that better dose uniformity across the whole body can be achieved and doses to the key organs at risk – the lungs and kidneys – can be reduced. 

Volumetric modulated arc therapy

Volumetric modulated arc therapy (VMAT) treatments are being evaluated and compared to standard static-field and arc treatments of lung tumours on a new generation linear accelerator with 5 mm-wide multileaf collimators.

Solid target isotope production

The positron emission tomography metallo-radionuclide 89Zr is a good candidate for immuno-PET imaging and 'dose-scouting' for radioimmunotherapy. Challenges in purification of 89Zr and its radiolabelling to a monoclonal-antibody (to enhance tumour penetration) have restricted its use. Research has succeeded in the production of radionuclidically-pure and chemically-pure 89Zr using solid targetry with 11.7MeV protons, and the reliable measurement of 89Zr specific activity. 

Phenomenological Models

We hypothesise that a phenomenological model of radiobiology will be easier to apply, more widely applicable, and potentially more accurate than current mechanistic models. We model cell survival as a function of easily determined, easy-to-control, independent variables such as total dose, fractional dose, total dose rate and fractional dose rate to predict how tumours and normal tissues will respond to radiation.

Radioguided lesion localisation

At least half of malignant breast lesions requiring surgical removal are asymptomatic and are identified by mammography or ultrasound. We are introducing a new technique, ROLLIS (radioguided occult lesion localisation using I-125 seeds), in Australia for the first time to assist with localising impalpable breast lesions. Initially run as a pilot study, ROLLIS has the potential to improve surgical outcomes for hundreds of West Australian women every year.

Prostate treatment toxicity

Dose escalation was shown to improve biochemical outcome for patients with prostate carcinoma. However, along with dose escalation, toxicity events escalate too. We seek to understand: how dose-volume, clinical and treatment factors influence acute and late genitourinary toxicity; and how other factors like regional dose distribution and endpoint definition in normal tissue complicate modelling.

Kidney responses to radiation

There is a limited understanding of kidney functional response to radiation and this is hindering efforts to introduce advanced treatment techniques, such as intensity-modulated radiotherapy (IMRT), for treatment of upper-abdominal cancers. The recent Quantitative Analyses of Normal Tissue Effects in the Clinic (QUANTEC) review of radiation-induced kidney concluded that, among other things, it is necessary to develop a kidney response predictive model based on its spatial variation in radiation sensitivity. We are utilising radiotherapy data and combined anatomical/functional imaging to better understand how kidneys respond to radiation and to provide predictive models for optimising upper abdominal radiation therapy.

Hepatic steatosis

Hepatic steatosis is one of the most common liver disorders in the developed world today, with alcoholic liver disease (ALD) and non-alcoholic fatty liver disease (NAFLD) being the two most common conditions being associated with fatty liver. Currently liver biopsy is seen as the gold standard for the assessment of liver fat. However, with the increasing capabilities of medical imaging modalities such as proton magnetic resonance spectroscopy (MRS) and the three-point Dixon (3PD) method, non-invasive methods are emerging as safer potential diagnostic alternatives to biopsy.

IMRT dose verification

We are evaluating the accuracy of dose delivery for IMRT fields using the dynamic treatment log (Dynalog) files provided by a linear accelerator system. The data is used to find the delivered dose in each fraction, which is compared with the treatment planning system predictions and also with an independent 2D array dosimeter such as MapCheck or MatriXX.

Novel brachytherapy

Brachytherapy could be optimized by adding degrees of freedom to the design of the radioactive sources that are used. We consider solid radioactive source designs which have inherent non-uniform emission characteristics. Shielded gamma-emitting sources, or a beta-emitting source with a specially designed target are considered. Monte Carlo simulation methods are used to examine the characteristics of such sources.

Electronic brachytherapy source

Electronic brachytherapy sources (EBS) are low energy compact x-ray sources used for radiological treatment. They incorporate spherical applicators to deliver the beam to a specific point. These EBS sources have higher relative biological effectiveness (RBE) than the high energy photons of brachytherapy sources with an increased double strand break yield. We are using Monte Carlo based simulation to characterise an EBS and compare against treatment results and beam characteristics, enabling optimisation of treatment planning.

Dynamic Conformal Arc Therapy in Stereotactic Ablative Radiotherapy

Stereotactic Ablative Radiotherapy (SABR) is the treatment of small cancers in the body using very high doses of radiation in a small number of fractions. It is characterised by superior tumour control and greatly reduces the number of treatments required per patient. In this research we aim to introduce a new technique – Dynamic Conformal Arc Therapy – for use in SABR treatments at Perth Radiation Oncology and compare it dosimetrically to other technique options such as VMAT.

Can Personal Electronic Dosimeters replace TLDs in PET? 

Personal electronic dosimeters are already in use to warn radiation works of high dose rates in many workplaces, and new models of electronic dosimeters can log the recorded doses to a database as a permanent record.  At present all radiation workers in WA (and most of the world) must wear passive dosimeters such as TLDs to log their exposure to ionising radiation.  Can logging electronic personal dosimeters replace TLDs as the sole means of personal radiation dosimetry?  We compare results from electronic and passive dosimeters in a controlled set of experiments, and for two groups of staff with exposure to PET radiopharmaceuticals.


 

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Last updated:
Monday, 24 July, 2017 3:19 PM

http://www.physics.uwa.edu.au/2318283