Potential High Resolution Dosimeters For MRT

Journal Article · Fri Jul 23 00:00:00 EDT 2010 · AIP Conference Proceedings

DOI:https://doi.org/10.1063/1.3478205· OSTI ID:21410599

Braeuer-Krisch, E; Brochard, T; Prezado, Y; Bravin, A; Berkvens, P ^[1]; Rosenfeld, A; Lerch, M; Petasecca, M ^[2]; Akselrod, M; Sykora, J; Bartz, J ^[3]; Ptaszkiewicz, M; Olko, P ^[4]; Berg, A; Wieland, M ^[5]; Doran, S ^[6]; Kamlowski, A ^[7]; Cellere, G ^[8]; Paccagnella, A ^[9]; Siegbahn, E A ^[10]

---

1. European Synchrotron Radiation Facility (ESRF), 6 rue Horowitz, BP220, F-38043 Grenoble (France)
2. Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW 2522 (Australia)
3. Landauer, Inc., Stillwater Crystal Growth Division, Stillwater OK, 74074 (United States)
4. Henryk Niewodniczanski Institute of Nuclear Physics Polish Academy of Sciences, Department of Radiation Physics and Dosimetry, ul. Radzikowskiego 152, PL 31-342 Krakow (Poland)
5. Medizinische Universitaet Wien, Zentrum f. Biomedizinische Technik und Physik (Austria)
6. Department of Physics, University of Surrey, Guildford (United Kingdom)
7. Bruker Biospin, Rheinstetten (Germany)
8. DEI, Department of Information Engineering, via Gradenigo, 6/B, 35131 PADOVA (Italy) and Applied Materials Baccini Via Postumia Ovest, 244, 31050 San Biagio di Callalta, Treviso
9. DEI, Department of Information Engineering, via Gradenigo, 6/B, 35131 PADOVA (Italy)
10. Department of Medical Physics, Karolinska Universitetssjukhuset, 17176 Stockholm (Sweden)

Microbeam Radiation Therapy (MRT) uses highly collimated, quasi-parallel arrays of X-ray microbeams of 50-600 keV, produced by 2nd and 3rd generation synchrotron sources, such as the National Synchrotron Light Source (NSLS) in the U.S., and the European Synchrotron Radiation Facility (ESRF) in France, respectively. High dose rates are necessary to deliver therapeutic doses in microscopic volumes, to avoid spreading of the microbeams by cardiosynchronous movement of the tissues. A small beam divergence and a filtered white beam spectrum in the energy range between 30 and 250 keV results in the advantage of steep dose gradients with a sharper penumbra than that produced in conventional radiotherapy. MRT research over the past 20 years has allowed a vast number of results from preclinical trials on different animal models, including mice, rats, piglets and rabbits. Microbeams in the range between 10 and 100 micron width show an unprecedented sparing of normal radiosensitive tissues as well as preferential damage to malignant tumor tissues. Typically, MRT uses arrays of narrow ({approx}25-100 micron-wide) microplanar beams separated by wider (100-400 microns centre-to-centre, c-t-c) microplanar spaces. We note that thicker microbeams of 0.1-0.68 mm used by investigators at the NSLS are still called microbeams, although some invesigators in the community prefer to call them minibeams. This report, however, limits it discussion to 25-100 {mu}m microbeams. Peak entrance doses of several hundreds of Gy are surprisingly well tolerated by normal tissues. High resolution dosimetry has been developed over the last two decades, but typical dose ranges are adapted to dose delivery in conventional Radiation Therapy (RT). Spatial resolution in the sub-millimetric range has been achieved, which is currently required for quality assurance measurements in Gamma-knife RT. Most typical commercially available detectors are not suitable for MRT applications at a dose rate of 16000 Gy/s, micron resolution and a dose range over several orders of magnitude. This paper will give an overview of all dosimeters tested in the past at the ESRF with their advantages and drawbacks. These detectors comprise: Ionization chambers, Alanine Dosimeters, MOSFET detectors, Gafchromic registered films, Radiochromic polymers, TLDs, Polymer gels, Fluorescent Nuclear Track Detectors (Al{sub 2}O{sub 3}:C, Mg single crystal detectors), OSL detectors and Floating Gate-based dosimetry system. The aim of such a comparison shall help with a decision on which of these approaches is most suitable for high resolution dose measurements in MRT. The principle of these detectors will be presented including a comparison for some dosimeters exposed with the same irradiation geometry, namely a 1x1 cm{sup 5} field size with microbeam exposures at the surface, 0.1 cm and 1 cm in depth of a PMMA phantom. For these test exposures, the most relevant irradiation parameters for future clinical trials have been chosen: 50 micron FWHM and 400 micron c-t-c distance. The experimental data are compared with Monte Carlo calculations.

• OSTI ID: 21410599
• Journal Information: AIP Conference Proceedings, Vol. 1266, Issue 1; Conference: 6. international conference on medical applications of synchrotron radiation, Melbourne (Australia), 15-18 Feb 2010; Other Information: DOI: 10.1063/1.3478205; (c) 2010 American Institute of Physics; ISSN 0094-243X
• Country of Publication: United States
• Language: English

Related Subjects

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
62 RADIOLOGY AND NUCLEAR MEDICINE
CLINICAL TRIALS
DAMAGE
DOSE RATES
DOSEMETERS
DOSIMETRY
FLUORESCENCE
IONIZATION CHAMBERS
KEV RANGE
MONTE CARLO METHOD
NEOPLASMS
NMR IMAGING
PEAKS
QUALITY ASSURANCE
RADIATION DOSES
RADIOTHERAPY
SPATIAL RESOLUTION
SPECTRA
SURFACES
SYNCHROTRON RADIATION
X RADIATION
BREMSSTRAHLUNG
CALCULATION METHODS
DIAGNOSTIC TECHNIQUES
DISEASES
DOSES
ELECTROMAGNETIC RADIATION
EMISSION
ENERGY RANGE
IONIZING RADIATIONS
LUMINESCENCE
MEASURING INSTRUMENTS
MEDICINE
NUCLEAR MEDICINE
PHOTON EMISSION
RADIATION DETECTORS
RADIATIONS
RADIOLOGY
RESOLUTION
TESTING
THERAPY