Physics update for radiation oncologistsScott Crowe, Alastair Dick, Alex Livingstone, Bob Fitchew, Candice Milewski, Craig Lancaster, Darren Cassidy,
Diana Binny, Kirby Francis, Nancy Yu, Phil Back, Rachael Wilks, Samuel Peet, Steven Sylvander, Somayeh Zolfaghari
Cancer Care Services, Radiation Oncology Medical Physics
1. Service development
Including Catalyst HD,
SABR and Monte Carlo
2. Interns and students
3. Research output
4. What’s on the horizon?
Overview
2
Servicedevelopment
3
Catalyst HD
• Optical surface monitoring system, produced by C-RAD
• Includes Sentinel 4DCT tracking solution
• Similar to system being packaged with Varian Edge SRS solution
4
Catalyst HD
• Research questions:
−What is the accuracy of the system?
−How does the performance compare to on board imaging?
−How does the Sentinel system perform, compared to RPM?
−How does the system perform with darker skin tones? Reflection of
optical light varies with melanin concentration.
• We expect that the system could be used for
−Assisting RTs during patient setup (efficient and accurate)
−Monitoring intrafraction motion (reducing need for CBCT image
acquisitions)
−Respiratory gating (for DIBH and beyond)
• For more information, please see Sam’s presentation at the Tuesday
forum on the 16th May
5
Spinal SABR
• In anticipation of the introduction of spine SABR
treatments a QUT master’s project is investigating a
delivery QA method and the accuracy achievable
− Design and 3D printing of bespoke phantoms for
both ion chamber and film plane dose
measurements
− Multiple and repeated deliveries of SABR spine
treatment with sub-millimetre changes in setup
positioning using fine adjustment stand
− Establishing the precision limits for geometric dose
validation considering the film dose measurement
and analysis chain
• Results of this investigation will allow for refinements
in the QA method, and inform the practically reliable
and achievable QA tolerance on point dose and film
measurements for SABR spine treatments
6
• Monte Carlo methods are the gold standard for dose calculations.
Commercial dose calculation algorithms frequently produce poor dose
calculations at inhomogeneities.
• Alex Livingstone has produced dose-checking software that takes
exported beam arrangements and calculates dose using MC code
• Software produces reports suitable for inclusion in Mosaiq, and
facilitates comparison with TPS dose calculations
Monte Carlo cluster
7
Internshipsand students
8
2017 internships
• Candice Milewski, MSc student at Université
Paris-Saclay.
• Position funded by RBWH Foundation
scholarship to Samuel Peet (for his PhD project).
• Working on Catalyst system, in addition to study
of metal artefact reduction techniques.
• Somayeh Zolfaghari, 2016 graduate of QUT MSc
course. MSc research project involved SRS for
brain metastases.
• Position funded by New Technology Grant.
• Published a paper on film cutting system.
9
Students in 2016 & 2017 (Blue / bold = RBWH)
Andre Asena, PhD Dose distributions in the vicinity of high-density materials in radiotherapy
Diana Binny, PhD Optimizing patient plan deliveries by characterizing treatment planning systems in radiotherapy
Orrie Dancewicz, PhD Development and verification of a novel 3D dosimetry technique for tomotherapy
Johnny Morales, PhD Independent Monte Carlo analysis for stereotactic radiosurgery treatments
Samuel Peet, PhD Out-of-field dose in contemporary radiation therapy
James Rijken, PhD Optimisation and uncertainties in SABR spine treatment
Shaun Smith, PhD Development of three-dimensional dosimetry for radiotherapy
Nancy Yu, PhD Developing new methods of dose evaluation for VMAT patient specific plans
Abdullah Alharbi, MSc Developing patient specific quality assurance for spine SABR plans
David Garrott, MSc Monte Carlo modelling of electron beam output for irregular cut-outs
Candice Milewski, MSc Effect of skin colour on optical surface monitoring of radiotherapy patients
Shamirah Nabankema, MSc Wearable in-vivo dosimetry for total body irradiation and total skin electron irradiation
Anthony Orth, MSc Total skin electron therapy treatment techniques
Emma Spelleken, MSc Evaluating published film dosimetry methods
Timothy Tang, MSc Evaluating patient specific pre-treatment QA practices
Sheldon Uprichard, MSc Acuros XB dose calculations for lung SABR dose treatments
Yongqian Yin, MSc Investigation of interplay in IMRT treatments for breast cancer
Somayeh Zolfaghari, MSc Stereotactic radiosurgery for multiple brain metastases: a dose-volume study
10
Higher degree research projects
• We currently use OSLDs for in-vivo skin dose measurements(for TSET patients, patients with pacemakers, StrataXRT trial)
• These OSLDs are taped to the patients, who in some cases have uncomfortable skin conditions
• Glass beads (used in creation of jewellery) exhibit thermoluminescentproperties – if you heat them up, they give off an amount of light dependent on radiation dose received. Patients could possibly wear beads on a string – resulting in less discomfort
• Unfortunately the uncertainties were too high for clinical introduction. Paper published discussing our findings, and work presented in the UK.
• Radiochromic film has a high spatial resolution, suitable for
quality assurance of SRS/SBRT treatment deliveries
• Many of our student projects have involved film dosimetry –
evaluating its use as a QA tool, and developing methods to
reduce the uncertainties associated with it
• One study replicated numerous handling protocols that had
been published in the literature to evaluate performance for
equipment at the RBWH and other centres
11
Higher degree research projects
• The complexity of opposed pair treatments has increased
with time. For sliding window IMRT, leaf movement occurs
along the same axis as respiratory motion, by necessity
• This can result in interplay between the leaf movement and
respiratory motion – i.e. positive or negative correlation.
• We performed film measurements using a wax chest wall,
sitting on a moving platform. Interplay was observed over
single fractions, but was averaged out by 8 fractions.
• IMRT and arc therapies are associated with larger out-of-field doses than 3DCRT. This is important in cases involving radiosensitive implants and pregnant patients.
• Out-of-field doses are still typically estimated using square field reference data, and so new techniques must be developed to provide greater accuracy and precision.
• Out-of-field dosimetry is complex due to uncertainties in energy, dose rate, and geometry. Conventional and emerging dosimeters are being assessed, to develop new models to apply measurement corrections.
12
Higher degree research projects
• Evaluating artefacts for Toshiba, Toshiba w/
SEMAR, Siemens, Siemens w/ iMAR and
TomoTherapy MVCT scans of coins
• Follow-up study to earlier publication
examining HU assignment in implants
• Potential to inform contouring of density
overrides structures in treatment planning
• 3D printing of tissue equivalent materials, nominally for the production of anthropomorphic phantoms. Need to characterise the radiological properties of 3D printed media
• We have a few printers in the department
• We have experience in printing jigs for dosimeters and homogeneous phantoms
• Our published work was recently cited in a Nature Scientific Reports paper
13
• The RBWH is one of few radiotherapy centres
with a gel dosimetry system
• Gels are a continuous medium, measuring dose
in 3 dimensions in high resolution
− Perfect for measuring dose with sharp falloff,
such as SABR treatments
• We’ve assisted QUT in developing new non-toxic
safe-to-handle gel formulations
• High density implants perturb dose distributions
• Temporary tissue expanders are sometimes
present in radiotherapy of post-mastectomy
patients. These TTEs can have neodymium
magnets for guiding saline injections.
• We 3D printed an insert with the TTE port for
submersion in a gel dosimeter, to better
understand perturbance of the beam.
• Multiple publications.
Higher degree research projects
14
Higher degree research projects
• Eclipse recently updated it’s optimiser, from “progressive
resolution optimiser” (PRO) to “photon optimiser” (PO).
• Plans were created for multiple treatment sites using
identical protocol and optimiser iterations.
• PO was capable of producing plans with generally
improved OAR sparing, but increased complexity (leaf
variability and MU) Introduction for routine use therefore
requires careful routine QA.
15
• We frequently have students located in the
department, in the Level 3 workshop (pictured).
• We are averaging at least 2 MSc students per
semester from QUT.
• Supervising PhD students in Sydney (Lifehouse)
and Adelaide (ARC/Genesis).
Research andpublications
16
Research output
• Significant output since 2016
−20 peer reviewed papers. (Exceeding mean output for field of research
code 0299, contributing to QUT receiving an ERA rating of 4 – ‘above
world standard’. Approx. 75% of papers from QUT involve the RBWH)
−17 conference presentations
−1 text book chapter
• Principle research areas since 2016
−Dosimetric plan quality (breast and spine)
−Treatment deliverability metrics
−Film and gel dosimetry
−3D printing
−Small field / SRS dose measurements
• Grant applications to ARC, NHMRC, PdCCRS, RBWH, WMR
17
Collaborations
18
Publications in 2016 (Blue / bold = RBWH; Grey = collaborative)
P Bridge, SB Crowe, G Gibson, NJ Ellemor, C Hargrave, M Carmichael, “A virtual radiation therapy workflow training simulation”,
Radiography 22(1): e59-e63, 2016
SB Crowe, B Sutherland, R Wilks, S Sylvander, V Seshadri, JV Trapp, T Kairn, “Relationships between gamma criteria and action
levels: Results of a multi-center audit of gamma agreement index results”, Medical Physics 43(3): 1501-1506, 2016
T Kairn, T Aland, SB Crowe, JV Trapp, “Use of electronic portal imaging devices for electron treatment verification”, Australasian
Physical and Engineering Sciences in Medicine 39(1): 199-209, 2016
SB Crowe, T Kairn, “Women in Medical Physics: a preliminary analysis of workforce and research participation in Australia and New
Zealand”, Australasian Physical and Engineering Sciences in Medicine 39(2): 525-532, 2016
JE Morales, M Butson, SB Crowe, R Hill, JV Trapp, “An experimental extrapolation technique using Gafchromic EBT3 film for
relative output factor measurements in small x-ray fields”, Medical Physics 43(8): 4687-4692, 2016
T Kairn, D Papworth, SB Crowe, J Anderson, DRH Christie, “Dosimetric quality, accuracy and deliverability of modulated
radiotherapy treatments for spinal metastases”, Medical Dosimetry 41(3): 258-266, 2016
T Kairn, SB Crowe, CM Langton, JV Trapp, “Bulk evaluation and comparison of radiotherapy treatment plans for breast cancer”,
Australasian Physical and Engineering Sciences in Medicine 39(3): 633-644, 2016
T Kairn, PH Charles, SB Crowe, JV Trapp, “Effects of inaccurate small field dose measurements on calculated treatment doses”,
Australasian Physical and Engineering Sciences in Medicine 39(3): 747-753, 2016
SC Peet, R Wilks, T Kairn, JV Trapp, SB Crowe, “Calibrating radiochromic film in beams of uncertain quality”, Medical Physics
43(10): 5647-5652, 2016
D Binny, CM Lancaster, T Kairn, JV Trapp, SB Crowe, “Monitoring Daily QA3 constancy for routine quality assurance on linear
accelerators”, Physica Medica 32(11): 1479-1487, 2016
SC Peet, R Wilks, T Kairn, SB Crowe, “Measuring dose from radiotherapy treatments in the vicinity of a cardiac pacemaker”,
Physica Medica 32(12): 1529-1536, 2016
D Binny, CM Lancaster, T Kairn, JV Trapp, P Back, R Cheuk, SB Crowe, “Investigating the use of image thresholding in
brachytherapy catheter reconstruction”, Australasian Physical and Engineering Sciences in Medicine 39(4): 913-919, 2016
19
Publications in 2017 (Blue / bold = RBWH; Grey = collaborative)
C Chamunyonga, S Crowe, J Burbery, “Review of the clinical benefits and implementation of peer review of treatment plans in
undergraduate medical dosimetry and radiation therapy training”, Journal of Radiotherapy in Practice 16(1): 85-91, 2017
A Asena, ST Smith, T Kairn, SB Crowe, RD Franich, JV Trapp “Reduction of artefacts caused by missing ray-sum data in optical-
CT imaging of implants in gel dosimeters”, Journal of Physics: Conference Series (in press), 2016
T Kairn, A Asena, SB Crowe, A Livingstone, D Papworth, S Smith, B Sutherland, S Sylvander, RD Franich, JV Trapp, “Can a
commercial gel dosimetry system be used to verify stereotactic spinal radiotherapy treatment dose distributions?”, Journal of
Physics: Conference Series (in press), 2016
A Asena, ST Smith, T Kairn, SB Crowe, K Hosokawa, SR Sylvander, JV Trapp, “Dose distributions in the vicinity of high-density
implants using 3D gel dosimeters”, Medical Physics (in press), 2017
SK Nabankema, SM Jafari, SC Peet, D Binny, SR Sylvander, SB Crowe, “Wearable glass beads for in vivo dosimetry of total skin
electron irradiation treatments”, Radiation Physics and Chemistry (in press), 2017
S Zolfaghari, KE Francis, T Kairn, SB Crowe, “Commissioning a hobby cutting device for radiochromic film preparation”,
Australasian Physical and Engineering Sciences in Medicine (in press), 2017
D Binny, E Mezzenga, CM Lancaster, JV Trapp, T Kairn, SB Crowe, “Investigating output and energy variations and their
relationship to delivery QA results using Statistical Process Control for helical tomotherapy”, Physica Medica (in press), 2017
O Dancewicz, SR Sylvander, TS Markwell, SB Crowe, JV Trapp, “Radiological properties of 3D printed materials in kilovoltage and
megavoltage photon beams”, Physica Medica (in press), 2017
20
Textbook chapter
T Kairn, J Lehmann, S Crowe et al. “Postal and clinical trial dosimetry”, Radiochromic Film for Radiation Dosimetry. Ed: Indra Das.
Abingdon, UK: Taylor and Francis, 2017.
What else is on the horizon?
• Acuros XB dose calculation algorithm for Eclipse, which will have an
impact on dose calculations for lung treatments
• Patient specific QA using the EPID, with the Varian Portal Dose suite
• Gel dosimetry in the clinic, particularly for spinal SABR dose verification
• Out of field dose estimation tool for TomoTherapy and VMAT treatments
• Monte Carlo simulation of TomoTherapy system, for dose checks
• Augmented reality glasses allowing confirmation of patient setup
• Knowledge-based optimisation of planning peer review processes
• More students, papers and grant applications
• If you have any physics questions you want answered, come and ask!
21
