Tomasz Wysokinski

Spatially resolved measurement of high doses in microbeam radiation therapy using samarium doped fluorophosphate glasses

The measurement of spatially resolved high doses in microbeam radiation therapy has always been a challenging task, where a combination of high dose response and high spatial resolution (microns) is required for synchrotron radiation peaked around 50 keV. The x-ray induced Sm3+ → Sm2+ valence conversion in Sm3+ doped fluorophosphates glasses has been tested for use in x-ray dosimetry for microbeam radiation therapy. The conversion efficiency depends almost linearly on the dose of irradiation up to ∼5 Gy and saturates at doses exceeding ∼80 Gy. The conversion shows strong correlation with x-ray induced absorbance of the glass which is related to the formation of phosphorus-oxygen hole centers. When irradiated through a microslit collimator, a good spatial resolution and high “peak-to-valley” contrast have been observed by means of confocal photoluminescence microscopy.

X-ray induced Sm3+ to Sm2+ conversion in fluorophosphate and fluoroaluminate glasses for the monitoring of high-doses in microbeam radiation therapy

Fluorophosphate and fluoroaluminate glasses doped with trivalent samarium were evaluated as sensors of x-ray radiation for microbeam radiation therapy at the Canadian Light Source using the conversion of trivalent Sm3+ to the divalent form Sm2+. Both types of glasses show similar conversion rates and may be used as a linear sensor up to ∼150 Gy and as a nonlinear sensor up to ∼2400 Gy, where saturation is reached. Experiments with a multi-slit collimator show high spatial resolution of the conversion pattern; the pattern was acquired by a confocal fluorescence microscopy technique. The effects of previous x-ray exposure may be erased by annealing at temperatures exceeding the glass transition temperature Tg while annealing at TA < Tg enhances the Sm conversion. This enhancement is explained by a thermally stimulated relaxation of host glass ionic matrix surrounding x-ray induced Sm2+ ions. In addition, some of the Sm3+-doped glasses were codoped with Eu2+-ions but the results show that there is no marked ...

Optically erasable samarium-doped fluorophosphate glasses for high-dose measurements in microbeam radiation therapy

Previous work has demonstrated that fluorophosphate (FP) glasses doped with trivalent samarium (Sm3+) can be used as a dosimetric detector in microbeam radiation therapy (MRT) to measure high radiation doses and large dose variations with a resolution in the micrometer range. The present work addresses the use of intense optical radiation at 405 nm to erase the recorded dose information in Sm3+-doped FP glass plates and examines the underlying physics. We have evaluated both the conversion and optical erasure of Sm3+-doped FP glasses using synchrotron-generated high-dose x-rays at the Canadian Light Source. The Sm-ion valency conversion is accompanied by the appearance of x-ray induced optical absorbance due to the trapping of holes and electrons into phosphorus-oxygen hole (POHC) and electron (POEC) capture centers. Nearly complete Sm2+ to Sm3+ reconversion (erasure) may be achieved by intense optical illumination. Combined analysis of absorbance and electron spin resonance measurements indicates that th...

Diffraction Enhanced X-ray Imaging of the Distal Radius: A Novel Approach for Visualization of Trabecular Bone Architecture

In Canada, osteoporotic fractures result in direct health care costs that exceed CAD

Factors influencing real time internal structural visualization and dynamic process monitoring in plants using synchrotron-based phase contrast X-ray imaging

1.3 billion annually [1]. Fractures are related to compromised bone strength, a parameter that reflects both density (quantity) and architecture (quality) [2]. The current clinical standard for bone assessment, dual energy x-ray absorptiometry, provides only a 2-dimensional areal measurement of density and no architectural information [3]; therefore, the development of improved methods for visualizing and quantifying of bone architecture remains an important goal with respect to improving detection and treatment of osteoporosis. Advances are currently being sought in the development of new technologies [3], such as high-resolution peripheral quantitative tomography [4], and through texture-based analysis of trabecular structure from radiographs [5]. In this pictorial essay, we explore the use of x-rayebased diffraction enhanced imaging (DEI) by using synchrotron radiation [6] as a novel means of visualizing the internal architecture of the human distal radius, a clinically significant fracture site. Imaging for this study was conducted at the Canadian Light Source (CLS) synchrotron during commissioning of the BioMedical Imaging and Therapy (BMIT) bending magnet beam line [7]. As such, our goal here is 2-fold: (1) establishment of proof-of-principle

Beamlines of the Biomedical Imaging and Therapy Facility at the Canadian Light Source - Part 2

Minimally invasive investigation of plant parts (root, stem, leaves, and flower) has good potential to elucidate the dynamics of plant growth, morphology, physiology, and root-rhizosphere interactions. Laboratory based absorption X-ray imaging and computed tomography (CT) systems are extensively used for in situ feasibility studies of plants grown in natural and artificial soil. These techniques have challenges such as low contrast between soil pore space and roots, long X-ray imaging time, and low spatial resolution. In this study, the use of synchrotron (SR) based phase contrast X-ray imaging (PCI) has been demonstrated as a minimally invasive technique for imaging plants. Above ground plant parts and roots of 10 day old canola and wheat seedlings grown in sandy clay loam soil were successfully scanned and reconstructed. Results confirmed that SR-PCI can deliver good quality images to study dynamic and real time processes such as cavitation and water-refilling in plants. The advantages of SR-PCI, effect of X-ray energy, and effective pixel size to study plant samples have been demonstrated. The use of contrast agents to monitor physiological processes in plants was also investigated and discussed.

Biomedical Imaging Using Synchrotron Radiation: Experience at the Biomedical Imaging and Therapy (BMIT) Facility at the Canadian Light Source

The BioMedical Imaging and Therapy (BMIT) facility provides a world class facility with unique synchrotron-specific imaging and therapy capabilities. This paper describes Insertion Device (ID) beamline 05ID-2 with the beam terminated in the first experimental hutch: POE-2. The experimental methods available in POE-2 include: Microbeam Radiation Therapy (MRT), Synchrotron Stereotactic Radiation Therapy (SSRT) and absorption imaging (projection and Computed Tomography (CT)). The source for the ID beamline is a multi-pole superconductive 4.3 T wiggler, which can generate ~30 kW of radiative power and deliver dose as high as 3000 Gy/s required for MRT program. The optics in POE-1 hutch prepares either monochromatic or filtered white beam that is used in POE-2. The Double Crystal (DC), bent Laue monochromator will prepare a beam over 10 cm wide at sample point, while spanning an energy range appropriate for imaging studies of animals (20-100+ keV). The experimental hutch will have a flexible positioning system that can handle subjects up to 120 kg. Several different cameras will be available with resolutions ranging from 4 μm to 150 μm. The latest update on the status of 05B1-1 bending magnet (BM) beamline, described in Part 1 [1], is also included.

Human factors design for the BMIT biomedical beamlines

The Biomedical Imaging and Therapy (BMIT) beamlines at the Canadian Light Source (CLS) comprise a multi-modality synchrotron imaging facility capable of imaging objects with 2–200 μm resolution with beam sizes up to ~200 mm wide and ~10 mm high in the experimental hutches [1–3]. BMIT hosts two beamlines, a bend magnet 05B1-1 and an insertion device 05ID-2, with capabilities to apply absorption imaging, in-line phase contrast imaging (PCI), analyzer-based imaging (ABI) or diffraction-enhanced imaging (DEI), and K-Edge Subtraction (KES) imaging. Talbot or grating interferometry is under development.

BMIT facility at the Canadian Light Source: Advances in X-ray phase-sensitive imaging

Operation of a biomedical beamline poses a unique set of operational and instrumentation challenges for a synchrotron facility. From proper handling and care of live animals and animal tissues, to a user community drawn primarily from the medical and veterinary realms, the work of a biomedical beamline is unique when compared to other beamlines. At the Biomedical Imaging and Therapy (BMIT) beamlines at Canadian Light Source (CLS), operation of the beamlines is geared towards our user community of medical personnel, in addition to basic science researchers. Human factors considerations have been incorporated wherever possible on BMIT, including in the design of software and hardware, as well as ease-of-use features of beamline control stations and experiment hutches. Feedback from users continues to drive usability improvements to beamline operations.

25+2 poles, 4.3 T wiggler at BMIT – 7 years operational experience

The BioMedical Imaging and Therapy (BMIT) facility [1,2] located at the Canadian Light Source, provides synchrotron-specific imaging and radiation therapy capabilities. There are two separate beamlines used for experiments: the bending magnet (05B1-1) and the insertion device (05ID-2) beamline. The bending magnet beamline provides access to monochromatic beam spanning a spectral range of 15-40keV, and the beam is 240mm wide in the POE-2 experimental hutch. Users can also perform experiments with polychromatic (pink) beam. The insertion device beamline was officially opened for general user program in 2015. The source for the ID beamline is a multi-pole, superconducting 4.3T wiggler. The high field gives a critical energy over 20keV. The optics hutches prepare a beam that is 220mm wide in the last experimental hutch SOE-1. The monochromatic spectral range spans 25-150+keV. Several different X-ray detectors are available for both beamlines, with resolutions ranging from 2μm to 200μm. BMIT provides a number of imaging techniques including standard absorption X-ray imaging, K-edge subtraction imaging (KES), in-line phase contrast imaging (also known as propagation based imaging, PBI) and Diffraction Enhanced Imaging/Analyzer Based Imaging (DEI/ABI), all in either projection or CT mode. PBI and DEI/ABI are particularly important tools for BMIT users since these techniques enable visualization of soft tissue and allow for low dose imaging.