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Developing Technologies for Small Animal Radiotherapy
Published in George C. Kagadis, Nancy L. Ford, Dimitrios N. Karnabatidis, George K. Loudos, Handbook of Small Animal Imaging, 2018
Frank Verhaegen, James Stewart, David Jaffray
The growing need for broad-purpose precision irradiation platforms for preclinical studies has led to the recent development of several devices, some of which are now commercially available. Most of the development took place in North America, but some recent work has emerged from European research centers as well. The development process is expected to continue for several more years, eventually leading to powerful research platforms equipped to address a wide range of radiation research questions potentially leading to progress in clinical radiotherapy. We will now address efforts by several groups to develop precision irradiation, often combined with high-resolution imaging. Microbeam irradiators based on photon beams generated by synchrotron technology are excluded from the overview (Slatkin et al. 1992; Laissue et al. 2007; Martinez-Rovira et al. 2012).
Special Delivery Techniques
Published in Ben Mijnheer, Clinical 3D Dosimetry in Modern Radiation Therapy, 2017
The consideration of different radiation types, point “e” in the list above, is beyond the scope of this chapter. Protons and carbon ions are covered in Chapters 12 and 23. Possibly the pinnacle in dosimetric challenge is the use of microbeams (Slatkin et al., 1992; Brauer-Krisch et al., 2015). This refers to kV x-rays typically from a synchrotron with very small divergence and extremely high dose rates (>100 Gy/s). These beams are collimated to “microbeams” of 20–50 μm width separated by gaps of some 200 μm. There is preclinical evidence that these “spatially” intensity-modulated beams provide normal tissues with a significant radiobiological advantage (Dilmanian et al., 2001). Dosimetry in these beams is difficult due to the use of kV beams, the high spatial resolution required, and the extremely high dose rate. Medical physics issues related to microbeam radiotherapy are covered in more detail in Chapter 25.
Use of radiochromic film with synchrotron radiation
Published in Indra J. Das, Radiochromic Film, 2017
Tomas Kron, Elizabeth Kyriakou, Jeffrey C. Crosbie
However, microbeam radiation is probably the most important challenge as high and low doses need to be assessed at the same time and in close proximity as can be seen in Figure 19.5. As the peak valley dose ratio is considered one of the key parameters to determine the efficacy of microbeam treatment [49,50], it is important to asses both peak and valley dose at the same time. An elegant method has been used by Crosbie et al. [27] who used two types of radiochromic film in combination, albeit with too high an uncertainty in the EBT film. A modified double exposure technique could also be used to deliver high and low doses to just one film type (HD-V2) as a function of sample scan speed; a fast scan speed for measurable peak doses (e.g., 50 Gy or 150 Gy) and a slow scan speed (100 times slower) for high but measureable valley doses (e.g., 50 Gy), with both fields delivered to HD film.
Focus small to find big – the microbeam story
Published in International Journal of Radiation Biology, 2018
A microbeam is a micrometer or sub-micrometer diameter beam of radiation that allows damage to be precisely deposited at specific locations within a biological target. Because of the beam size, it is easy to focus on a very small target and deliver radiation without damaging surrounding tissues. Therefore, microbeam irradiators are of valuable use to understanding the communication between radiated cells or tissues to the surrounding environments. Another advantage of microbeam is it allows delivery of low doses of radiation. The modern charged particle microbeam delivers a precise number of ions to individual targets with a micrometer lateral resolution, which offers low and controlled doses of radiation that cannot be achieved by other irradiators. Because of these unique features, microbeam irradiators have been used at various institutions, contributed to many important basic science discoveries, and now is being developed into a new radiation therapy approach.
Microbeam evolution: from single cell irradiation to pre-clinical studies
Published in International Journal of Radiation Biology, 2018
Mihaela Ghita, Cristian Fernandez-Palomo, Hisanori Fukunaga, Pil M. Fredericia, Giuseppe Schettino, Elke Bräuer-Krisch, Karl T. Butterworth, Stephen J. McMahon, Kevin M. Prise
This review follows the development of microbeam technology from the early days of single cell irradiations to the development of new treatment modalities using microbeams focusing on pre-clinical developments and translation towards clinical applications