Physics update for radiation oncologists

Transcription

1 Cancer Care Services, Radiation Oncology Medical Physics Physics update for radiation oncologists Scott 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

2 Overview 1. Service development Including Catalyst HD, SABR and Monte Carlo 2. Interns and students 3. Research output 4. What s on the horizon? 2

3 Service development 3

4 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

5 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 16 th May 5

6 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

7 Monte Carlo cluster 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 7

8 Internships and students 8

9 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

10 Students in 2016 & 2017 (Blue / bold = RBWH) Andre Asena, PhD Dose distributions in the vicinity of high-density materials in radiotherapy Diana Binny, PhD Orrie Dancewicz, PhD Johnny Morales, PhD Samuel Peet, PhD James Rijken, PhD Shaun Smith, PhD Nancy Yu, PhD Abdullah Alharbi, MSc David Garrott, MSc Candice Milewski, MSc Shamirah Nabankema, MSc Anthony Orth, MSc Emma Spelleken, MSc Timothy Tang, MSc Sheldon Uprichard, MSc Yongqian Yin, MSc Somayeh Zolfaghari, MSc Optimizing patient plan deliveries by characterizing treatment planning systems in radiotherapy Development and verification of a novel 3D dosimetry technique for tomotherapy Independent Monte Carlo analysis for stereotactic radiosurgery treatments Out-of-field dose in contemporary radiation therapy Optimisation and uncertainties in SABR spine treatment Development of three-dimensional dosimetry for radiotherapy Developing new methods of dose evaluation for VMAT patient specific plans Developing patient specific quality assurance for spine SABR plans Monte Carlo modelling of electron beam output for irregular cut-outs Effect of skin colour on optical surface monitoring of radiotherapy patients Wearable in-vivo dosimetry for total body irradiation and total skin electron irradiation Total skin electron therapy treatment techniques Evaluating published film dosimetry methods Evaluating patient specific pre-treatment QA practices Acuros XB dose calculations for lung SABR dose treatments Investigation of interplay in IMRT treatments for breast cancer Stereotactic radiosurgery for multiple brain metastases: a dose-volume study 10

11 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 thermoluminescent properties 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

12 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-offield 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

13 Higher degree research projects 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 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 13

14 Higher degree research projects 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. 14

15 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. 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). 15

16 Research and publications 16

17 Research output Significant output since 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

18 Collaborations 18

19 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): , 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): , 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): , 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): , 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): , 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): , 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): , 2016 SC Peet, R Wilks, T Kairn, JV Trapp, SB Crowe, Calibrating radiochromic film in beams of uncertain quality, Medical Physics 43(10): , 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): , 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): , 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): ,

20 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 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,

21 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