Perspectives for microbeam irradiation at the SYRMEP beamline

Abstract

It has been shown previously both in vitro and in vivo that microbeam irradiation (MBI) can control malignant tumour cells more effectively than the clinically established concepts of broad beam irradiation. With the aim to extend the international capacity for microbeam research, the first MBI experiment at the biomedical beamline SYRMEP of the Italian synchrotron facility ELETTRA has been conducted. Using a multislit collimator produced by the company TECOMET, arrays of quasi-parallel microbeams were successfully generated with a beam width of 50 µm and a centre-to-centre distance of 400 µm. Murine melanoma cell cultures were irradiated with a target dose of approximately 65 Gy at a mean photon energy of ∼30 keV with a dose rate of 70 Gy s−1 and a peak-to-valley dose of ∼123. This work demonstrated a melanoma cell reduction of approximately 80% after MBI. It is suggested that, while a high energy is essential to achieve high dose rates in order to deposit high treatment doses in a short time in a deep-seated target, for in vitro studies and for the treatment of superficial tumours a spectrum in the lower energy range might be equally suitable or even advantageous.

Quantification of Differential Response of Tumour and Normal Cells to Microbeam Radiation in the Absence of FLASH Effects

“…The dose rates used here (<0.2 Gy/s) fall well below the range of dose rates previously attributed to FLASH effects [39]. Previous work employed synchrotron sources [21,26,40,41], and therefore, it has been impossible to distinguish if any differential effects of MRT and BB irradiation were due to the spatial fractionation or a result of FLASH effects. Here, we can discount any involvement of FLASH effects and attribute the differential response of normal and tumour cells wholly to the irradiation with high (peak) and low (valley) doses, either in the form of MRT or by post-mixing of separate BB irradiations.…”

The Microbeam Insert at the White Beam Beamline P61A at the Synchrotron PETRA III/DESY: A New Tool for High Dose Rate Irradiation Research

“…The importance to study the effects of high dose rate radiotherapy in veterinary patients before proposing human clinical trials has been recognized because dogs, for instance, suffer from spontaneous tumors which are very similar in size, histology, and natural course of the disease, compared to human patients [ 45 , 46 ]. The first successful veterinary studies were and are conducted with FLASH radiotherapy [ 21 , 22 ] and with MRT, the latter focused on the treatment of dogs with malignant brain tumors [ 28 ].…”

“…Internationally, there are currently two biomedical beamlines dedicated to the development of microbeam radiotherapy: ID17 at the Europeans Synchrotron Radiation Facility (ESRF) in France and the Imaging and Biomedical Beamline (IMBL) at the Australian Synchrotron in Melbourne [ 22 , 23 , 24 ]. Microbeam studies have also been conducted at Spring 8 [ 25 , 26 , 27 ] and the feasibility to conduct MRT at the biomedical beamline SYRMEP at the Elettra Sincrotrone Trieste in Italy has been demonstrated [ 28 ].…”

Effects of Microbeam Irradiation on Rodent Esophageal Smooth Muscle Contraction

“…Over the last decade, high-dose-rate irradiation has increasingly come into focus for superior preservation of normal tissue [19]. Microbeam irradiation (MBI) is an experimental irradiation technique characterized by a high dose rate and spatial dose fractionation of synchrotron-generated X-ray beams in the micrometer range [19]. A multislit collimator (MSC) is inserted into the X-ray beam, producing an array of quasi-parallel microbeams.…”