A preclinical microbeam facility with a conventional x‐ray tube

Abstract

Purpose:Microbeam radiation therapy is an innovative treatment approach in radiation therapy that uses arrays of a few tens of micrometer wide and a few hundreds of micrometer spaced planar x‐ray beams as treatment fields. In preclinical studies these fields efficiently eradicated tumors while normal tissue could effectively be spared. However, development and clinical application of microbeam radiation therapy is impeded by a lack of suitable small scale sources. Until now, only large synchrotrons provide appropriate beam properties for the production of microbeams.Methods:In this work, a conventional x‐ray tube with a small focal spot and a specially designed collimator are used to produce microbeams for preclinical research. The applicability of the developed source is demonstrated in a pilot in vitro experiment. The properties of the produced radiation field are characterized by radiochromic film dosimetry.Results:50 μm wide and 400 μm spaced microbeams were produced in a 20 × 20 mm2 sized microbeam field. The peak to valley dose ratio ranged from 15.5 to 30, which is comparable to values obtained at synchrotrons. A dose rate of up to 300 mGy/s was achieved in the microbeam peaks. Analysis of DNA double strand repair and cell cycle distribution after in vitro exposures of pancreatic cancer cells (Panc1) at the x‐ray tube and the European Synchrotron leads to similar results. In particular, a reduced G2 cell cycle arrest is observed in cells in the microbeam peak region.Conclusions:At its current stage, the source is restricted to in vitro applications. However, moderate modifications of the setup may soon allow in vivo research in mice and rats.

Evaluation of a pixelated large format CMOS sensor for x‐ray microbeam radiotherapy

“…). The values calculated for the PVDR were comparable to what one might expect for this microbeam collimator when comparing to previous measurements in a similar collimator by Bartzsch et al (where 15.5 ± 1.5 was measured at 10 mm depth), especially when considering the significantly larger SSD of this investigation.…”

Microbeam evolution: from single cell irradiation to pre-clinical studies

“…However, the possibility to use a conventional X-ray tube or carbon nanotubes (S. to produce microbeams for preclinical studies has also been explored. This study used an X-ray tube with a small focal spot and a specially designed collimator were used to produce microbeams for preclinical research (Bartzsch et al 2016).…”

Minibeam radiation therapy at a conventional irradiator: Dose-calculation engine and first tumor-bearing animals irradiation

“…We have recently shown the feasibility of transferring this technique to a small-animal irradiator [6]. In contrast to some other work [18,19], our implementation allows the irradiation of intracranial tumors in rodents, as has been shown in the present technical note. Therefore, our system offers the possibility of performing systematic and comprehensive radiobiological experiments to investigate the distinct biological effects that occur when a spatial fractionation of the dose is used.…”

“…Finally, we have used the developed tools to evaluate the dose distributions delivered to a series of F98 tumor-bearing rats. Unlike other MBRT table-top solutions [18,19], our system allows the irradiation of intracranial tumors in rodents, as has been shown in the present technical note. Following our previous paper [6], demonstrating that normal rats do not exhibit any important brain damage after an MBRT irradiation with a 58 Gy peak dose, the pilot experiment reported here aimed at assessing whether this dose prescription was also enough to achieve some tumor response.…”