Physics update for radiation oncologists (2)Scott Crowe, Alastair Dick, Alex Livingstone, Craig Lancaster, Darren Cassidy, Kirby Francis,
Nancy Yu, Phil Back, Rachael Wilks, Samuel Peet, Steven Sylvander, Tanya Kairn
Cancer Care Services, Radiation Oncology Medical Physics
1. Service delivery
2. Staff, interns and students
3. Research output
4. What’s on the horizon?
Overview
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Servicedelivery
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Acuros XB
• Current dose calculation engine in Eclipse is AAA (type-B algorithm)
−Errors in dose calculated both in and downstream of lung have been
observed (and reported by others, such as ACDS)
• New dose calculation engine in Eclipse is Acuros XB (type-C algorithm)
−Studies have reported improved accuracy and better agreement with
Monte Carlo dose calculations
oLung VMAT in simple inhomogeneous phantom: AAA up to 2.7%
disagreement, Acuros XB within 0.8% (Yan et al.)
oNasopharyngeal IMRT in anthropomorphic phantom: AAA up to 10%
disagreement, Acuros XB within 3% (Kan et al.)
• Allows reporting of dose as dose-to-water (like earlier TPS algorithms)
and dose-to-medium (like Monte Carlo)
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Acuros XB
• We are commissioning based on international guidelines (IAEA/AAPM): entering beam to allow the system to accurately calculate the dose in water
• System does this by optimising various source parameters (energy spectrum, penumbra, etc.)
• Model is being tested across a range of treatment and phantom complexity (square fields > small modulated fields; water tanks > anthropomorphic phantoms)
• Commissioning is being completed under supervision of Rachael
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Varian Portal Dosimetry
• Many centres across Australia have switched to EPID-based pre-treatment patient-specific quality assurance systems
−e.g. Varian Portal Dose, Epiqa, Adaptivo, PerFraction
−Benefits include high resolution, reduction in QA time and improved workflow integration
−Downsides include lack of gantry angle verification, system potentially not testing the same dose calculation approach used to calculate dose in patient
• This system is currently being commissioned and tested under supervision of Nancy
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Gel Dosimetry
• Gel dosimeters change optical properties with ionisation
• We are able to measure 3D dose distributions, with tremendous
potential for verification of, e.g., SABR treatments with high dose
gradients, or treatments of multiple mets
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• Physics will be reviewing (in conjunction with RTs) the contents of a couple of new reports, with reference to local practice
• ICRU 91: “Prescribing, recording, and reporting of stereotactic treatments with small photon beams”
−Tanya and I have a paper cited in this report! ☺
• AAPM TG132: “Use of image registration and fusion algorithms and techniques in radiotherapy”
−Discusses image registration errors, testing procedures
Recent international reports
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Staff, internsand students
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Staffing changes
• A/Prof Tanya Kairn has joined the physics team, as principal physicist(role previously filled by Bob Fitchew)
• Tanya previously worked at Genesis Wesley, where she was responsible for stereotactic physics service area and, most recently, the commissioning of a TrueBeam system for use in SRS/SBRT
• Strong research track record including 78 peer reviewed papers, ARC Linkage grant success and PhD supervision completions
• Standing includes adjunct A/Prof appointment at QUT, associate editorship at JMIRO & APESM, Boyce Worthley ACPSEM award (2016)
• Diana Binny has left for ROC Redlands (though her PhD candidature
continues with RBWH supervisors)10
2018 internships
• During 2017 we have had two paid internships in the department: Candice Milewski (Université Paris-Saclay MSc student) and Somayeh Zolfaghari (QUT MSc graduate)
• Projects included metal artefact reduction techniques for CT systems (which we expect to have access to in the department soon) and dosimetric film preparation (published)
• Funded in part by RBWH Foundation scholarship for Samuel Peet
• Samuel Peet and Nancy Yu were both successful in securing
scholarships for funding in 2018!
• These funds will be used to bring in interns once again (for which there
are many suitable candidates).
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Students in 2017 (Blue / bold = RBWH)
Andre Asena PhD (conferred) Dose distributions in the vicinity of high-density materials in radiotherapy
Diana Binny PhD Optimizing patient plan deliveries by characterizing TPSs 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 (conferred) 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
Dylan McGrath MSc Commissioning of the Varian Portal Dosimetry (VPD) QA solution
Candice Milewski MSc Metal artefact reduction algorithms in CT imaging
Emma Whittle Volunteer Commissioning an optical CT solution for gel dosimetry
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Research andpublications
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Peer reviewed papers 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 847: 012070, 2017
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 847: 012071, 2017
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 44(4): 1545-1551, 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 38: 105-110, 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 38: 111-118, 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 40(2): 449-453, 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 140: 314-318, 2017
D Binny, CM Lancaster, JV Trapp, SB Crowe, “Statistical Process Control and verifying positional accuracy of a cobra motion couch using step-wedge quality
assurance tool”, Journal of Applied Clinical Medical Physics 18(5): 70-79, 2017
B Perrett, P Charles, T Markwell, T Kairn, S Crowe, “Feasibility of 3D printed air slab diode caps for small field dosimetry”, Australasian Physical and
Engineering Sciences in Medicine (in press), 2017
T Aland, E Jhala, T Kairn, J Trapp, “Film dosimetry using a smart device camera: a feasibility study for point dose measurements”, Physics in Medicine and
Biology (in press), 2017
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Textbook chapters in 2017
T Kairn. “Application of Radiochromic Film to IMRT and VMAT Dosimetry”, Radiochromic Film for Radiation Dosimetry. Ed: Indra Das. Abingdon, UK: Taylor and
Francis, 2017.
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.
Output measures
• Aiming to publish at least 12 papers a year (met in ‘15 and ‘16)
• Other papers in review or being drafted include
−Use of gel dosimeters for brachytherapy
−Dose corrections for Fricotan moulds
−Film dosimetry method comparison
−Eclipse optimiser behaviour
−Out of field dosimetry for Tomotherapy
−History of Australas Phys Eng Sci Med
−Dose errors in BrainLab SRS calculations
−Software development and testing in the clinic
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Recent research results
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• Sliding window IMRT treatment being delivered to tonic water: quinine
fluoresces in response to ionising radiation
• Captured with camera: potential uses for high-dose-rate brachy QA,
tomographic dose reconstruction in 4D, superficial dose measurement
Animation, not for PDF
What is on the horizon?
• New systems to be commissioned: superficial, brachytherapy and CT
−New functionality will be tested on CT system, including:
oDirect density assignment, in which CT numbers are adjusted for
consistency across scanning energies, allowing simpler use of
multiple scanning energies
oDual energy X-ray, allowing improved contrast imaging and more
accurate material identification (with potential implications on Monte
Carlo dose simulations)
oMetal artefact reduction algorithms, on which we are currently
preparing a scientific manuscript for publication
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What is on the horizon?
• Nancy and I have organised a school on IGRT systems (including
Catalyst, Calypso, ExacTrac, ultrasound) for Queensland physicists
tomorrow; at which Sam will be presenting
• 7 presentations and 2 posters selected for national Engineering and
Physical Sciences in Medicine conference in Hobart (29/10 – 01/11):
four resulting from student supervision
• Presentations at World Congress in Prague next year planned
• 2 of us are taking part in a “Future Medical Physics – Rethinking
Cancer” forum in October
• NHMRC grant application for small field radiotherapy planned
• rodash – to be presented by Sam
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