Speaker
Prof.
Michael Lerch
(University of Wollongong)
Description
Microbeam radiation therapy (MRT) implements spatially-fractionated kilovoltage x-rays for deep-seated tumour treatment [1,2] to provide better normal tissue sparing [3]. However, tumour treatment with MRT can be further optimized with high-Z nanoparticles (NPs), which have been shown to enhance the dose delivered by conventional radiotherapies [4]. Tantalum pentoxide (Ta2O5) NPs are novel nano-structured ceramic particles that are non-toxic [4] and show optimal x-ray absorption in kilovoltage energies [5,6]. This research assesses the ability of ceramic NPs, including Ta2O5 NPs, to selectively raise the tumour valley dose in MRT. This multi-modal approach is named: Synchrotron Microbeam Activated Radiation Therapy (SMART).
Geant4 [7,8] simulations investigated the physical dose enhancement of Ta2O5 NPs to a population of cells due to monoenergetic broad-beams and microbeams (50-200 keV).
Simulation results were correlated to in-vitro experiments obtained in hutch 1B and 2B at the Imaging and Medical Beamline (IMBL), Australian Synchrotron, using tumorous 9L gliosarcoma and normal Madin Darby Canine Kidney cells. NPs were added to cells in T12.5cm2 flasks 24hrs before 90-100% confluence. Cells were irradiated using a 1.4T or 3T wiggler field to produce 50µm/400µm or 50µm/200µm microbeams with weighted average energies of 42 keV and 95 keV respectively. Cell survival following treatment was evaluated with clonogenic assays after 15 doubling times.
Ta2O5 NPs improved the MRT and broad-beam selectivity towards tumour cells, due to the NPs clustering about the nucleus of 9L tumour cells. Other ceramic NPs such as bismuth oxide, with more homogeneous NP distributions, also saw improvement to the MRT treatment efficiency.
Simulations confirmed that NP clusters produced the most selective dose enhancement to MRT. Modelling micro- and broad-beams showed that NP dose enhancement is energy dependent. For Ta2O5 NPs, 40 keV x-rays are optimum for dose enhancement in broad-beam cases, and microbeam energies greater than 100 keV produce better NP dose enhancement with more secondary electrons that raise the valley dose (>100 µm from the microbeam).
References:
1. Slatkin DN, et al. (1992).
2. Crosbie JC, et al. (2010).
3. Laissue JA, et al. (2007).
4. Brown R, et al. (2014).
5. Hubbell JH, (1982).
6. Seltzer SM, (1993).
7. Agostinelli S, et al. (2003).
8. Allison J, et al. (2006).
| Keywords or phrases (comma separated) | Microbeam Radiation Therapy, Nanoparticles, Dose Enhancement, Radiobiology, Monte Carlo |
|---|---|
| Are you a student? | Yes |
| Do you wish to take part in</br>the Student Poster Slam? | No |
| What is your gender? | Female |
| Are you an ECR? (<5 yrs</br>since PhD/Masters) | Yes |
Primary author
Prof.
Michael Lerch
(University of Wollongong)
Co-authors
Prof.
Anatoly Rosenfeld
(Centre for Medical Radiation Physics, University of Wollongong)
Mr
Andrew Dipuglia
(University of Wollongong)
Dr
Andrew Stevenson
(Australian Synchrotron/ CSIRO)
Ms
Elette Engels
(University of Wollongong)
Dr
Jeremy Davis
(University of Wollongong)
Mr
Matthew Cameron
(CMRP University of Wollongong)
Dr
Moeava Tehei
(University of Wollongong)
Dr
Nan Li
(University of Wollongong)
Ms
Natalia Roberts
(University of Wollongong)
Ms
Sally McKinnon
(University of Wollongong)
Dr
Sianne Oktaria
(University of Wollongong)
Dr
Stephanie Corde-Tehei
(Prince of Wales Hospital, UOW)
Dr
Susanna Guatelli
(University of Wollongong)
