We are going to introduce one of our brilliant Medical Physics graduates, Mr. Joshua Hiatt.
Josh started his MPhys (Medical Physics) at UWA mid-2016. His research project was on “MultiLeaf Collimator Positioning for Small Fields: A New Investigation into Automatic EPID-based Verification” supervised by Dr. Pejman Rowshanfarzad from Medical Physics Group at UWA, Mr. Godfrey Mukwada from the Department of Radiation Oncology, Sir Charles Gairdner Hospital (SCGH), Dr. Hans Lynggaard Riis from Odense University Hospital in Denmark, Dr. Du Huynh from the School of Computer Science and Software Engineering at UWA and Mr. Michael Barnes from the Department of Radiation Oncology, Calvary Mater Hospital in Newcastle, NSW.
Josh was awarded the Muriel and Colin Ramm prize and medal, and the Medical Physics prize in 2018 for the highest course weighted average mark (WAM) among all graduates who completed the Master of Physics in all specializations in 2017. We congratulate Josh on his achievements and are very proud of him.

Part of Joshua’s research outcome is published in the Australasian Physical & Engineering Sciences in Medicine (2018) 41:945–955. (Link to his paper)
The manuscript title is : MLC positioning verification for small fields: a new investigation into automatic EPID-based verification methods”

jushua-hiatt(click on the picture to enlarge)

Here are comments on his performance from his Supervisor and the Medical Physics Program Chair:
Pejman Rowshanfarzad said, “Josh was one of our most talented postgraduate students. He proved to be extremely hard working with a creative mind. I found Josh a highly organized, self-motivated, and active student with impressive attention to details in answering assignment questions. His reports were always on-time and he was well prepared for progress meetings. Josh was awarded High Distinction in his Masters with the record highest marks in the history of the UWA Medical Physics group. His research outcome was also highly satisfactory. Overall, Josh had outstanding scientific achievements for such a short period of time.
In addition to all of this, Josh has very good communication skills and a pleasant personality which helps him overcome difficulties. It was a pleasure to be his supervisor and program coordinator.

And comments from one of his clinical supervisors:
Godfrey Mukwada said, “Determined, self-motivated, hardworking, diligent and polite is Josh in a few words. It was a pleasure to supervise him. I didn’t have to push him to do his research. He was self-motived and focused. His analytical and communication skills were excellent. All these qualities and his politeness will definitely take him to greater heights in his endeavours.”


Joshua kindly accepted to answer a few questions about his experience in our Medical Physics Research Group.

– Introduction and your current position and role:
My name is Joshua Hiatt, I graduated from UWA in 2017 with a Master of Physics: Medical Physics. I am currently a radiation oncology medical physics (ROMP) registrar at Liverpool Hospital in Sydney, NSW.
A ROMP registrar is the pathway to becoming an accredited medical physicist in radiation oncology, my role is to undertake on the job training so as to be able to provide management and scientific support for patient treatment and clinical radiotherapy equipment maintenance; including treatment planning, radiation safety, radiation dosimetry, research and development. In order to be able to satisfy the requirements of the ACPSEM training education and assessment program.

– What did you enjoy most about UWA, and Medical Physics research group?
UWA is an especially beautiful campus, the scenery and peacocks make for a nice back drop to your studies.
The Medical Physics research group is a very warm and welcoming community. There are engaging weekly research meetings with supervisors, fellow students and sometimes visiting academics. The discussions at these meetings provide a rich opportunity to develop communication and scientific problem-solving skills.
My favourite aspect of the UWA medical physics program was the practical element. I had lectures as well as the opportunity to attend observer placements in several different hospitals and clinics around Perth, often seeing the machines we had just learned about in theory. Attending these practical sessions were invaluable learning experiences, the most memorable of which entailed shadowing medical physicists as they work, and this really helped shape my career.

– Can you give us your top three reasons to study Medical Physics?
(1) It is a very meaningful field of study that has a direct impact on people’s lives, (2) medical physics is interesting, you get the chance to delve into topics like the complex interplay between the physics of radiation interactions with matter and radiobiology, (3) it is a highly challenging field with appropriate financial remuneration.

– How do you feel you have made a difference in your field of research?
With the help of my supervisors we developed an algorithm that was able to detect the pre-treatment position of the Multileaf Collimators (an integral part of the beam collimation system) using images from an EPID, better than conventional algorithms for the case of small radiation fields. We also demonstrated that some commonly used edge-detection algorithms in computer vision were unsuitable for this task. This has the potential to direct future research and improve pre-treatment quality assurance processes for treatments involving small radiation fields, which often deliver high doses.

– What is your best advice to current students and Medical Physics applicants?
Time spent studying is the biggest predictor of academic success. Plan for success by setting a realistic study schedule (and then stick to it!). Make the path to success the one of least resistance by choosing a research project you are genuinely interested in. Volunteer and try to be involved in the medical physics community whenever the opportunity presents itself. This will make you easier to hire when you complete the course.


Abstract of Joshuah’s thesis:
MLC defined small fields in radiotherapy are used in high dose, ultra-conformal techniques such as Stereotactic Radiotherapy and Stereotactic Radiosurgery. Proximity to critical structures and irreversible damage arising from inaccurate delivery mean that correct positioning of the MLC system is of the utmost importance. Some of the existing techniques for MLC positioning QA make use of Electronic Portal Imaging Devices (EPIDs). However, conventional collimation verification algorithms based on the FWHM fail when applied to small field images acquired by an EPID due to overlapping aperture penumbrae, lateral electron disequilibrium and source occlusion.
With the aim of developing an automatic and autonomous EPID-based method suitable for MLC positional verification of small fields with arbitrary shapes, this study investigates subpixel edge detection techniques from the field of computer vision including derivative interpolation, Laplacian of Gaussian and an algorithm based on the partial area effect hypothesis. Some of which are novel to the task of MLC detection in EPID images. As well developing an empirical approach by creating a modified FWHM algorithm. The methods are first verified in large field conditions against the conventional FWHM as well as a commercially available software package that uses the port film graticule. Before testing in smaller field sizes using a comparison of the planned and measured MLC positions for gap widths ranging from 10-2 mm from over 198 EPID images containing more than 6776 leaf pairs, acquired from 3 Elekta and 3 Varian linacs at multiple clinics.
It was found that sensitivity to noise indicated the Laplacian of Gaussian is unsuitable for this application. The empirical approach was determined to be manufacturer-specific and demonstrated the most promising improvement over standard algorithms in the small field range, with a measured mean absolute difference from planned position for Varian linacs of 0.48 ± 0.40 mm, compared with the FWHM value of 0.70 ± 0.51 mm. For Elekta linacs the empirical approach returned 0.26 ± 0.25 mm, in contrast to the FWHM result of 1.79 ± 1.07 mm.


Part of Josh’s work entitled “MLC positioning verification for small fields: a new investigation into automatic EPID-based verification methods” is published in the Australasian Physical & Engineering Sciences in Medicine, and is available through this link.



Once again we congratulate Joshua for his great achievements and wish him all the best for his future career as a Medical Physicist. 




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