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In this paper we investigate the dosimetric effects target inhomogeneities on VHEE (Very High Energy Electron) beam dose profiles. Dose profile sensitivity to high and low density ( 0.001 - 2.2 g / cm 3 ) embedded media in water was measured for 156 MeV VHEE beams. To the knowledge of the authors, this is the first systematic experiment on dose penetration in inhomogeneous targets at this high energy electron beams. The results of the dosimetry experiments were compared with simulation results acquired with the TOPAS/GEANT4 Monte Carlo codes and were compared with the sensitivity of photon and proton beams. Dosimetry experiments with VHEE beams at 156 MeV were performed by embedding various density inserts in a cuboid 30 × 30 × 10 cm3 water phantom. This setup was then irradiated with a narrow ( σ = 1.2 mm) Gaussian VHEE beams. Transverse dose profiles were recorded at various depths within the water phantom using radosensitive EBT-XD Gafchromic films. Simulations were performed using the TOPAS user wrap for the GEANT4 Monte Carlo toolkit with the measured beam and target geometry parameters from the CLEAR facility and compared with sensitivity of photon and protons beams to inhomogeneities in water phantoms. Less than 8% dose deviation was shown for all measured dose data across all recorded depths (0–20 cm). Monte Carlo simulations within the whole water phantom volume showed a 15% dose deviation. Simulation studies indicated that using proton and photon beams within a therapeutic energy range in MC simulations of this experimental setup resulted in dose change in the central plane up to 100% and 74% of the dose maximum in the central plane respectively. The dosimetry results of these experiments and TOPAS/GEANT4 simulations compare well. Dose profiles of VHEE beams were found to be relatively insensitive ( 15 % dose difference across the central plane) to embedded high and low density geometries compared to simulation results with therapeutic proton beams (up to 100% of dose maximum in the plane). Therefore, VHEE is robust to anatomical changes and has the potential to be a reliable mode of radiotherapy for treating tumors in highly inhomogeneous and mobile regions such as the lung.

The development of compact quasimonoenergetic x-ray radiation sources based on laser Compton scattering (LCS) offers opportunities for novel approaches to medical imaging. However, careful experimental design is required to fully utilize the angle-correlated x-ray spectra produced by LCS sources. Direct simulations of LCS x-ray spectra are computationally expensive and difficult to employ in experimental optimization. In this manuscript, we present a computational method that fully characterizes angle-correlated LCS x-ray spectra at any end point energy within a range defined by three direct simulations. With this approach, subsequent LCS x-ray spectra can be generated with up to 200 times less computational overhead.

Spatially resolved Laser Compton X-ray spectra are computationally expensive to simulate and thus difficult to utilize in precision optimization tasks. Through discretized interpolation we report a reliable and efficient approach for rapid production of spectra.

An optimization of laser-Compton scattering sources for medically-relevant, K-edge subtraction imaging with gadolinium contrast agents is presented. Careful choice of source, on-axis X-ray energy and bandwidth enable potential reductions in patient dose of nearly 30x.

Conventional x-ray sources for medical imaging utilize bremsstrahlung radiation. These sources generate large bandwidth (BW) x-ray spectra with large fractions of photons that impart a dose, but do not contribute to image production. X-ray sources based on laser-Compton scattering can have inherently small energy BWs and can be tuned to low dose-imparting energies, allowing them to take advantage of atomic K-edge contrast enhancement. This paper investigates the use of gadolinium-based K-edge subtraction imaging in the context of mammography using a laser-Compton source through simulations quantifying contrast and dose in such imaging systems as a function of laser-Compton source parameters. Our simulations indicate that a K-edge subtraction image generated with a 0.5% BW (FWHM) laser-Compton x-ray source can obtain an equal contrast to a bremsstrahlung image with only 3% of the dose.

We show that by design we can create a new resist materials for electron beam lithography, based on a supramolecular assembly. The initial studies show that via this supramolecular approach high resolution structures can be written which showunprecedented selectivity when exposed to etch conditions involving plasmas.