Jason W. Sohn

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To evaluate and define treatment prognostic factors and selection criteria for patients with solitary brain metastasis treated with stereotactic radiosurgery. Between March 1990 and January 1995, 48 patients with solitary brain metastasis were treated with stereotactic radiosurgery at our tertiary care institution. Eleven patients were treated for(More)
PURPOSE To develop a new metric for image registration that incorporates the (sub)pixelwise differential importance along spatial location and to demonstrate its application for image guided radiation therapy (IGRT). METHODS It is well known that rigid-body image registration with mutual information is dependent on the size and location of the image(More)
PURPOSE The indications for treating the seminal vesicles (SV) in patients with clinically localized carcinoma of the prostate are controversial. We sought to define subgroups of patients in whom coverage could be avoided, using pretreatment prostate specific antigen (PSA) values and the Gleason score. Because the rectum is the major dose-limiting(More)
The performance of a variational regularization technique to improve robustness of inverse treatment planning for intensity modulated radiotherapy is analyzed and tested. Inverse treatment planning is based on the numerical solutions to the Fredholm integral equation of the first kind which is ill-posed. Therefore, a fundamental problem with inverse(More)
Stereotactic body radiation therapy (SBRT) is an emerging technology for the treatment of spinal metastases, although the dosimetric impact of the calculation method on spinal dose distribution is unknown. This study attempts to determine whether CyberKnife (CK)-based SBRT using a Ray Tracing (RyTc) algorithm is comparable dosimetrically to that of Monte(More)
This article proposes quantitative analysis tools and digital phantoms to quantify intrinsic errors of deformable image registration (DIR) systems and establish quality assurance (QA) procedures for clinical use of DIR systems utilizing local and global error analysis methods with clinically realistic digital image phantoms. Landmark-based image(More)
PURPOSE Three-dimensional treatment planning was performed to evaluate three standard coplanar irradiation techniques (two-field parallel-opposed, three-field, and 110 degrees bilateral arcs), the 330 degrees single rotational arc, and a four noncoplanar arc technique for the treatment of pituitary adenomas. We sought to identify the optimal technique for(More)
During a standard course of breast radiotherapy, the contralateral breast generally receives approximately 2.5 to 6.0 Gy of scattered radiation. Although most studies have not found an overall increase in metachronous contralateral breast cancers in patients undergoing radiotherapy, a cohort of younger women may be genetically more susceptible to(More)
Stereotactic radiosurgery (SRS) is used to treat acoustic neuromas, but additional information is needed to firmly establish its safety and efficacy. We review our experience over 7 years treating 29 consecutive patients with a modified linear accelerator (linac) SRS system. Between August 1989 and October 1995, 29 patients with a median age of 67 years(More)
The characteristics of a commercial multileaf collimator (MLC) to deliver static and dynamic multileaf collimation (SMLC and DMLC, respectively) were investigated to determine their influence on intensity modulated radiation therapy (IMRT) treatment planning and quality assurance. The influence of MLC leaf positioning accuracy on sequentially abutted SMLC(More)