Sara St James

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For the radiation treatment of lung cancer patients, four-dimensional computed tomography (4D-CT) is a common practice used clinically to image tumor motion and subsequently determine the internal target volume (ITV) from the maximum intensity projection (MIP) images. ITV, which is derived from short pre-treatment 4D-CT scan (<6 s per couch position), may(More)
UNLABELLED Detectors with depth-encoding allow a PET scanner to simultaneously achieve high sensitivity and high spatial resolution. METHODS A prototype PET scanner, consisting of depth-encoding detectors constructed by dual-ended readout of lutetium oxyorthosilicate (LSO) arrays with 2 position-sensitive avalanche photodiodes (PSAPDs), was developed. The(More)
The spatial resolution in PET is poorer than that of CT or MRI. All modern PET scanners use block detectors, i.e., clusters of scintillation crystals coupled to four photomultiplier tubes. Some of the loss of spatial resolution in PET is attributed to the use of block detectors, because a photon that interacts with one crystal in the cluster may be(More)
Improvements to current small animal PET scanners can be made by improving the sensitivity and the spatial resolution of the scanner. In the past, efforts have been made to minimize the crystal dimensions in the axial and transaxial directions to improve the spatial resolution and to increase the crystal length to improve the sensitivity of the scanner. We(More)
Digital phantoms continue to play a significant role in modeling and characterizing medical imaging. The currently available XCAT phantom incorporates both the flexibility of mathematical phantoms and the realistic nature of voxelized phantoms. This phantom generates images based on a regular breathing pattern and can include arbitrary lung tumor(More)
Many laboratories develop depth-encoding detectors to improve the trade-off between spatial resolution and sensitivity in positron emission tomography (PET) scanners. One challenge in implementing these detectors is the need to calibrate the depth of interaction (DOI) response for the large numbers of detector elements in a scanner. In this work, we(More)
PURPOSE The XCAT phantom is a realistic 4D digital torso phantom that is widely used in imaging and therapy research. However, lung mass is not conserved between respiratory phases of the phantom, making detailed dosimetric simulations unphysical. A framework is presented for enforcing local mass conservation in the XCAT lung and is combined with a dose(More)
An in vitro model system is described, using metatarsal explants from 15-day mouse embryos (E15) cultured in serumless chemically defined medium, to study fetal skeletal development with particular emphasis on de novo osteoclast formation. The normal pattern of growth and differentiation observed in vitro, assessed by ultrastructure and morphometry,(More)
PURPOSE The purpose of this work is to present a framework to evaluate the accuracy of four-dimensional treatment planning in external beam radiation therapy using measured patient data and digital phantoms. METHODS To accomplish this, 4D digital phantoms of two model patients were created using measured patient lung tumor positions. These phantoms were(More)
RaySearch Americas Inc. (NY) has introduced a commercial Monte Carlo dose algorithm (RS-MC) for routine clinical use in proton spot scanning. In this report, we provide a validation of this algorithm against phantom measurements and simulations in the GATE software package. We also compared the performance of the RayStation analytical algorithm (RS-PBA)(More)