Biomedical subjects

Lee Myers

Publications and source records attributed to Lee Myers.

3 recordsLinked to original sources

PubMed2004

Implementing advanced access in a group practice network.

The leadership efforts in this complex process emphasize the importance of communication, education and buy-in to implement advanced access in a group practice network. These key components, along with timely feedback, staff support and necessary resources, are especially significant when the end point and the benefits are not immediately apparent to those directly affected by the change. Once these elements are in place, however, any practice has the ability to establish advanced access, increase its patient base and improve its economic performance.

Appointments and Schedules↗

PubMed2003

Intrafractional stability of the prostate using a stereotactic radiotherapy technique.

PURPOSE: To evaluate the stability of the prostate during stereotactic radiation therapy. MATERIALS AND METHODS: Forty-seven patients underwent placement of three fiducial markers into the prostate as part of a pilot study of hypofractionated stereotactic radiotherapy. Portal images before and subsequent to 227 radiotherapy fractions were analyzed for prostate movement. Six patients also underwent localizing radiographs at 6-min intervals for 24 min. Relative motion of the bony landmarks and prostate markers was calculated. RESULTS: Analysis of portal images revealed the undirected average prostate movement of 2.0 mm (superior/inferior), 1.9 mm (anterior/posterior), and 1.4 mm (right/left) with maximum standard deviation (SD) of 2.0. Analysis of radiographs at 6-min intervals showed the greatest undirected average prostate motion between 0-6 min; 1.5 mm (superior/inferior), 1.4 mm (anterior/posterior), and 0.4 mm (right/left). Beyond 6 min, movements decreased to 0.4, 0.9, and 0.8 mm, respectively. Bony landmark motion was 0.9 mm (superior/inferior), 0.9 mm (anterior/posterior), and 0.4 mm (right/left) between 0-6 min. Beyond 6 min, motion decreased to less than 0.5 mm in any direction. CONCLUSIONS: Stereotactic prostate radiotherapy, utilizing fiducial marker localization, resulted in average intrafractional prostate movement of 2.0 mm or less. Most patient and organ movement occurs early and a settling-in period is advisable before treatment.

Computer Simulation↗

PubMed2003

Isocenter accuracy in frameless stereotactic radiotherapy using implanted fiducials.

PURPOSE: The stereotactic radiotherapy (SRT) system verifies isocenter accuracy in patient space. In this study, we evaluate isocenter accuracy in frameless SRT using implanted cranial gold markers. MATERIALS AND METHODS: We performed frameless SRT on 43 intracranial tumor patients between August 1997 and December 2000. The treatment technique was determined by the tumor shape and volume, and by the location of critical organs. The coordinates of anterior-posterior and lateral port film were inputted to ISOLOC software, which calculated (1) the couch moves translation distance required to bring the target point to the isocenter, and (2) the intermarker distance comparisons between the CT study and the treatment machine films. We evaluated the isocenter deviation based on the error between orthogonal film target coordinates and isocenter coordinates. RESULTS: The mean treatment isocenter deviations (x, y, z) were -0.03, 0.14, and -0.04 mm, respectively. The systematic component isocenter standard deviations were 0.28, 0.31, and 0.35 mm (1 SD), respectively, and the random component isocenter standard deviations were 0.53, 0.52, and 0.50 mm (1 SD), respectively. CONCLUSIONS: The isocenter accuracy in the frameless SRT-implanted fiducial system is highly reliable and is comparable to that of other stereotactic radiosurgery systems.

Brain↗