Artikel
Investigations on novel imaging techniques for ion beam therapy
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Veröffentlicht: | 24. September 2009 |
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Gliederung
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Purpose: Ion beams exhibit a finite range and an "inverted" depth-dose profile - the Bragg peak. These favourable physical properties enable superior tumour-dose conformality. However, they introduce sensitivity to range uncertainties. Although range uncertainties are typically taken into account in treatment planning, delivery of the intended treatment has to be assured to prevent underdosage of the tumour or overdosage of surrounding critical structures. Thus, dedicated Quality Assurance procedures are desirable to enable in-vivo range verification before or during ion therapeutic irradiation.
Material and methods: Monte Carlo (MC) calculations based on the FLUKA code [1], [2] and experimental investigations are being carried out to address the feasibility and to compare the performances of particle-based radiographic or tomographic transmission and emission imaging techniques. The aim is to identify complementary methods to Positron-Emission-Tomography (Enghardt W, et al. Nucl Instrum Meth. 2004;A 525:284-8.) for future application at HIT (Heidelberg Therapy Center). These novel imaging techniques could use 1) transmitted high energy primary particles (Ohno Y, et al. Nucl Instrum Meth. 2004;A 525:279-83.), [3] for low dose 2D and 3D imaging to evaluate the correct patient positioning and verify the ion range before treatment, or 2) emerging secondaries (Min CH, et al. Nucl Instrum Meth. 2007;A580:562., Testa E, et al. Appl Phys Lett. 2008;93:093506.), in particular protons, from the therapeutic beams to verify simultaneously and in-vivo the treatment delivery.
Results: First MC results and experimental data taken with simple radiographic films qualitatively support the feasibility of heavy ion computed tomography. In addition, it has been determined that the energy range availabe at the HIT accelerator would be sufficient for clinical application to head cases. For prostate and sacral cases, a reduction of the beam projections could be employed to avoid the pelvic bones. Further investigations are ongoing and the results will be presented.
Conclusion and outlook: Following the so far promising results, MC activities are in progress to identify and optimize a more suitable detector system for particle radiography and tomography, and to investigate the feasibility of imaging of prompt particle emission during ion irradiation.
References
- 1.
- Battistoni G, et al. Proceedings of the Hadronic Shower Simulation Workshop. In: Albrow M, Raja R, editors. AIP Conference Proceeding; 2007;896. p. 31-49.
- 2.
- Fassò A, et al. CERN-2005-10; INFN/TC_05/11, SLAC-R-773. 2005.
- 3.
- Shinoda H, et al. Application of heavy-ion CT. Phys Med Biol. 2006;51(16):4073-8.