SU-E-T-416: Performance Test Comparing Three Pre-Treatment Isocenter Localization Techniques for Single Fraction Cranial Stereotactic Radiosurgery.

PURPOSE: To develop a performance test comparing three pre-treatment isocenter localization techniques when using head-frame vs. immobilization mask for cranial Stereotactic Radiosurgery (SRS). This study will compare pre-treatment positioning techniques using laser alignment vs x-ray verification using ExacTrac or On Board Imaging. METHODS: A RANDO anthropomorphic head phantom was fitted with an in-house polystyrene insert to allow EDR2 film measurements in two orthogonal planes. A pin hole was pricked on each film to serve as a target during treatment planning. for each trial (three total), a CT scan was acquired of the phantom equipped with either an immobilization mask or invasive head frame. Treatment planning employed iPlan Image v4.1 and iPlan Dose v4.1.1. Positioning of the phantom equipped with the head-frame was performed by aligning vault lasers to coincide with cross-hair labels on a target positioner box. Setups utilizing an immobilization mask were verified by x-ray verification using ExacTrac and On Board Imaging, and if alignment were not within tolerance, then shifts were made using a 6D robotic couch. Gantry star-shot irradiation was performed using a 5mm cone to evaluate the differences between radiation isocenter and the target. The mean and standard deviations were calculated for differences in the x-, y-, and z-coordinate axes. RESULTS: Positional accuracy using ExacTrac for mask based SRS resulted in 1.10±0.86, 0.67±0.83, and 0.59±0.48mm for cross plane, inline, and vertical measurements, respectively. Differences for frame based SRS were 0.93±0.43, 0.76±0.18, and 0.34±0.12mm for cross plane, inline, and vertical measurements, respectively. Results for mask based SRS using OBI will soon follow. CONCLUSIONS: Although the frame-based SRS techniquegenerated smaller standard deviations, the mean difference from target to radiation isocenter for both techniques fall within the statistical uncertainty of one another. Planning margins must take into account target size when treating small lesions for both techniques. Project funded by CARTI.

Effects of transdermal estrogens on endothelial function in postmenopausal women with coronary disease.

OBJECTIVE: Oral estrogens improve endothelial function, and for this reason may be considered cardioprotective; however, in women with coronary heart disease there may also be an increase in the risk of thrombosis. Although transdermal estrogen administration may decrease this adverse effect, there are few data on endothelial function in women with coronary heart disease treated using such therapy. This study aimed to report the endothelial response in postmenopausal women with coronary heart disease treated with transdermal estrogen. MATERIALS AND METHODS: This was a double-blind, prospective, randomized study. Eighteen patients with a history of acute coronary syndrome and nine healthy women were studied over 4 weeks. Coronary patients were assigned at random to receive a patch containing either 50 microg estradiol or placebo on a weekly basis. Endothelial function was assessed by flow-mediated vasodilatation of the brachial artery. Baseline blood flow (brachial artery diameter) was measured after 30 min rest and following ischemia, prior to treatment and after 4 weeks. RESULTS: Flow-mediated vasodilatation in normal patients was 17.8%, whereas in women with coronary disease it was 1.2% (p = 0.0001). Arterial diameter for the resting period in coronary disease subjects increased from 4.22 +/- 0.59 to 4.41 +/- 0.56 mm (p < 0.004) after 4 weeks of estrogen therapy, whereas, in women receiving placebo, it did not change. Flow-mediated vasodilatation in the estrogen group was 3.4% and in the placebo group was 0.5% (p = 0.05). CONCLUSIONS: Transdermal estrogen may improve endothelial function in women with coronary heart disease.

Management of the oral and maxillofacial surgery patient with end-stage renal disease.

Chronic renal failure (CRF) is the consequence of a multitude of diseases that cause permanent destruction of the nephron. Concurrent with renal failure are a host of changes affecting the homeostatic functioning of the individual. This report outlines the pathophysiology of CRF and highlights its effects on surgical manipulation of the oral and maxillofacial region in this patient population. In addition, some of the common physical findings and alterations in blood chemistries frequently observed in these patients are discussed.