Rider University

About: Rider University is a education organization based out in Lawrenceville, New Jersey, United States. It is known for research contribution in the topics: Dosimetry & Creativity. The organization has 881 authors who have published 1934 publications receiving 50752 citations.

An investigation of the potential of optical computed tomography for imaging of synchrotron-generated x-rays at high spatial resolution

Abstract: X-ray microbeam radiation therapy (MRT) is a novel form of treatment, currently in its preclinical stage, which uses microplanar x-ray beams from a synchrotron radiation source. It is important to perform accurate dosimetry on these microbeams, but, to date, there has been no accurate enough method available for making 3D dose measurements with isotropic, high spatial resolution to verify the results of Monte Carlo dose simulations. Here, we investigate the potential of optical computed tomography for satisfying these requirements. The construction of a simple optical CT microscopy (optical projection tomography) system from standard commercially available hardware is described. The measurement of optical densities in projection data is shown to be highly linear (r2=0.999). The depth-of-field (DOF) of the imaging system is calculated based on the previous literature and measured experimentally using a commercial DOF target. It is shown that high quality images can be acquired despite the evident lack of telecentricity and despite DOF of the system being much lower than the sample diameter. Possible reasons for this are discussed. Results are presented for a complex irradiation of a 22 mm diameter cylinder of the radiochromic polymer PRESAGE, demonstrating the exquisite 'dose-painting' abilities available in the MRT hutch of beamline ID-17 at the European Synchrotron Radiation Facility. Dose distributions in this initial experiment are equally well resolved on both an optical CT scan and a corresponding transmission image of radiochromic film, down to a line width of 83 microm (6 lp mm(-1)) with an MTF value of 0.40. A group of 33 microm wide lines was poorly resolved on both the optical CT and film images, and this is attributed to an incorrect exposure time calculation, leading to under-delivery of dose. Image artefacts in the optical CT scan are discussed. PRESAGE irradiated using the microbeam facility is proposed as a suitable material for producing phantom samples for quantitative characterization of optical CT microscopy systems.

Investigating end-to-end accuracy of image guided radiation treatment delivery using a micro-irradiator

Abstract: There is significant interest in delivering precisely targeted small-volume radiation treatments, in the pre-clinical setting, to study dose–volume relationships with tumour control and normal tissue damage. For these studies it is vital that image guidance systems and target positioning are accurately aligned (IGRT), in order to deliver dose precisely and accurately according to the treatment plan. In this work we investigate the IGRT targeting accuracy of the X-RAD 225 Cx system from Precision X-Ray using high-resolution 3D dosimetry techniques. Small cylindrical PRESAGE® dosimeters were used with optical-CT readout (DMOS) to verify the accuracy of 2.5, 1.0, and 5.0 mm X-RAD cone attachments. The dosimeters were equipped with four target points, visible on both CBCT and optical-CT, at which a 7-field coplanar treatment plan was delivered with the respective cone. Targeting accuracy (distance to agreement between the target point and delivery isocenter) and cone alignment (isocenter precision under gantry rotation) were measured using the optical-CT images. Optical-CT readout of the first 2.5 mm cone dosimeter revealed a significant targeting error of 2.1 ± 0.6 mm and a cone misalignment of 1.3 ± 0.1 mm. After the IGRT hardware and software had been recalibrated, these errors were reduced to 0.5 ± 0.1 and 0.18 ± 0.04 mm respectively, within the manufacturer specified 0.5 mm. Results from the 1.0 mm cone were 0.5 ± 0.3 mm targeting accuracy and 0.4 ± 0.1 mm cone misalignment, within the 0.5 mm specification. The results from the 5.0 mm cone were 1.0 ± 0.2 mm targeting accuracy and 0.18 ± 0.06 mm cone misalignment, outside of accuracy specifications. Quality assurance of small field IGRT targeting and delivery accuracy is a challenging task. The use of a 3D dosimetry technique, where targets are visible on both CBCT and optical-CT, enabled identification and quantification of a targeting error in 3D. After correction, the targeting accuracy of the irradiator was verified to be within 0.5 mm (or 1.0 mm for the 5.0 mm cone) and the cone alignment was verified to be within 0.2 mm (or 0.4 mm for the 1.0 mm cone). The PRESAGE®/DMOS system proved valuable for end-to-end verification of small field IGRT capabilities.

Classroom Teachers' Perceptions about Inclusion and Preservice Teacher Education

Abstract: The purpose of this article is to share the results of a study that explored the recommendations of practicing teachers about ways to prepare preservice teachers for including children with disabilities into general education classrooms. A survey was distributed to 71 practicing general elementary education teachers. The survey included the following questions: What should the general education student know about teaching students with special needs? Should this information be included in one course or integrated with other course content? General education teachers reported that teacher education programs should include the following content: behavioral strategies, conflict resolution and social skills, identification of students with special needs, adaptation of curriculum and materials, adaptation of instructional strategies, legal regulations and individual education programs, and co-teaching, teaming, and collaboration. These data suggest that preservice teacher preparation programs would include con...

Pronephric duct extension in amphibian embryos: migration and other mechanisms.

Abstract: Initiation of excretory system development in all vertebrates requires (1) delamination of the pronephric and pronephric duct rudiments from intermediate mesoderm at the ventral border of anterior somites, and (2) extension of the pronephric duct to the cloaca. Pronephric duct extension is the central event in nephric system development; the pronephric duct differentiates into the tubule that carries nephric filtrate out of the body and induces terminal differentiation of adult kidneys. Early studies concluded that pronephric ducts formed by means of in situ segregation of pronephric duct tissue from lateral mesoderm ventral to the forming somites; more recent studies highlight caudal migration of the pronephric duct as the major morphogenetic mechanism. The purpose of this review is to provide the historical background on studies of the mechanisms of amphibian pronephric duct extension, to review evidence showing that different amphibians perform pronephric duct morphogenesis in different ways, and to suggest future studies that may help illuminate the molecular basis of the mechanisms that have evolved in amphibians to extend the pronephric duct to the cloaca.

Suppression of the ferromagnetic-insulating phase in self-doped La 0.94 Mn 0.98 O 3 crystals under pressure

Abstract: The effect of hydrostatic pressure P on the magnetic and transport properties of self-doped ${\mathrm{La}}_{0.94}{\mathrm{Mn}}_{0.98}{\mathrm{O}}_{3}$ crystals has been investigated at pressures up to 1 GPa and in the temperature range $15lTl300\mathrm{K}.$ It was found that the applied pressure enhances the double-exchange coupling, increases the magnetization, and lowers the ferromagnetic-insulator transition temperature. The results obtained here for the self-doped crystals are compared with those observed for lightly doped ${\mathrm{La}}_{1\ensuremath{-}x}{\mathrm{Sr}}_{x}{\mathrm{MnO}}_{3}.$ It is shown that similar mechanisms of ferromagnetic clustering and percolative polarons may account also for the magnetic and transport properties of the self-doped manganites.