Publications by authors named "Wen Chien Hsi"

Purpose: To demonstrate the feasibility of improving prostate cancer patient outcomes with PBS proton LET optimization.

Methods: SFO, IPT-SIB, and LET-optimized plans were created for 12 patients, and generalized-tissue and disease-specific LET-dependent RBE models were applied. The mean LET in several structures was determined and used to calculate mean RBEs.

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Treating and imaging patients in the upright orientation is gaining acceptance in radiation oncology and radiology and has distinct advantages over the recumbent position. An IRB approved study to investigate the positions and orientations of the male pelvic organs between the supine and upright positions was conducted. The study comprised of scanning 15 male volunteers (aged 55-75 years) on a 0.

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Purpose: To commission MCsquare (a multi-cores CPU-based dose calculation engine) for pencil beam scanning (PBS) proton therapy, integrate it into RayStation treatment plan system (TPS) to create a dedicated platform for fast independent dose verification.

Method: A MCsquare-based independent dose verification platform (MC2InRS) was developed to realize automatic dose re-calculation for clinical use, including data preparation, dose calculation, 2D/3D gamma analysis. MCsquare was commissioned based on in-air lateral dose profiles, integrated depth dose, and the absolute dose of different beam energies for ProteusONE.

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Proton therapy is an expanding radiotherapy modality in the United States and worldwide. With the number of proton therapy centers treating patients increasing, so does the need for consistent, high-quality clinical commissioning practices. Clinical commissioning encompasses the entire proton therapy system's multiple components, including the treatment delivery system, the patient positioning system, and the image-guided radiotherapy components.

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Purpose: An isocentric rotating chair for a positioner was developed as a nongantry solution to provide multiple nonplanar radiation fields with a maximum tilt of 20 for treating head and neck cancer patients at an upright seated position in a fixed carbon-ion beamline.

Methods: The preclinical validation of the chair was present for this study funded by a grant through the Shanghai Proton and Heavy Ion Center (SPHIC) in Shanghai, China. The chair was installed in SPHIC.

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Purpose: The aim of the present study was to compare the dose distribution generated from photon volumetric modulated arc therapy (VMAT), intensity modulated proton therapy (IMPT), and intensity modulated carbon ion therapy (IMCIT) in the delivery of hypo-fractionated thoracic radiotherapy.

Methods And Materials: Ten selected patients who underwent thoracic particle therapy between 2015 and 2016 were re-planned to receive a relative biological effectiveness (RBE) weighted dose of 60 Gy (i.e.

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Large area, shallow fields are well suited to proton therapy. However, due to beam production limitations, such volumes typically require multiple matched fields. This is problematic due to the relatively narrow beam penumbra at shallow depths compared to electron and photon beams.

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Purpose: Determine prostate intrafraction motion with Cine-magnetic resonance imaging (MRI) and deformable registration.

Methods: A total of 68 cine-MRI studies were done in 17 different series with 4 scans per series in 7 patients. In without rectal balloon (WORB) scans, 100 mL of water was infused in the rectum.

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Compensator-based proton therapy of lung cancer using an un-gated treatment while allowing the patient to breathe freely requires a compensator design that ensures tumor coverage throughout respiration. Our investigation had two purposes: one is to investigate the dosimetric impact when a composite compensator correction is applied, or is not, and the other one is to evaluate the significance of using different respiratory phases as the reference computed tomography (CT) for treatment planning dose calculations. A 4D-CT-based phantom study and a real patient treatment planning study were performed.

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Lung cancer treatment presents a greater treatment planning and treatment delivery challenge in proton beam therapy compared to conventional photon therapy due to the proton beam's energy deposition sensitivity to the breathing-induced dynamic tissue density variations along the beam path. Four-dimensional computed tomography (4D-CT) has been defined as the explicit inclusion of temporal changes of tumor and normal organ mobility into an image series. It allows more accurate delineation of lung cancer target volumes by suppression of any breathing motion artifacts present in the CT images.

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Accurate dose calculation is essential to precision radiation treatment planning and this accuracy depends upon anatomic and tissue electron density information. Modern treatment planning inhomogeneity corrections use x-ray CT images and calibrated scales of tissue CT number to electron density to provide this information. The presence of metal in the volume scanned by an x-ray CT scanner causes metal induced image artefacts that influence CT numbers and thereby introduce errors in the radiation dose distribution calculated.

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We present our results regarding the cosmetic outcome achieved and the rate of infection using the MammoSite breast brachytherapy applicator to treat patients with partial breast irradiation. In addition, factors associated with cosmetic outcome and infection are analyzed. The study population consisted of 30 patients with early stage breast cancer treated using the MammoSite device from October 28, 2002, to February 13, 2004.

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A hospital-based magnetic guidance system (MGS) was installed to assist a physician in navigating catheters and guide wires during interventional cardiac and neurosurgical procedures. The objective of this study is to examine the performance of this magnetic field-guided navigation system. Our results show that the system's radiological imaging components produce images with quality similar to that produced by other modern fluoroscopic devices.

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Purpose: We present a technique to optimize the dwell times and positions of a high-dose-rate (192)Ir source using the MammoSite breast brachytherapy applicator. The surface optimization method used multiple dwell positions and optimization points to conform the 100% isodose line to the surface of the planning target volume (PTV).

Methods And Materials: The study population consisted of 20 patients treated using the MammoSite device between October 2002 and February 2004.

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Purpose: Limited information has been reported on the dosimetry achieved with the MammoSite breast brachytherapy applicator. We present our results regarding the volume of treatment and a comparison of a single prescription point, single dwell position optimization technique with a six prescription point, multiple dwell position method.

Methods And Materials: Between October 14, 2002 and February 28, 2003, 21 patients with early-stage breast cancer were treated using the MammoSite device.

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