Changes in Volume and Density Parameters Measured on Computed Tomography Images Following Stereotactic Body Radiation Therapy of Nonspine Bone Metastases.

INTRODUCTION: Volumetric and density parameters measured from computed tomography scans were investigated for evaluating treatment response of nonspine bone lesions following stereotactic body radiation therapy. METHODS: Twenty-three patients treated with stereotactic body radiation therapy to nonspine bone metastases with pre- and post-treatment radiological follow-up with computed tomography imaging were identified in a retrospective review. An expert radiologist classified 26 lesions by type (lytic, sclerotic) and by response. Two independent radiation oncologists created separate contours of the bone and soft tissue lesion volumes. Density and volume were assessed relative to baseline values. RESULTS: For bone-only lesions, all lesions designated as local control decreased in volume or remained within 20% of baseline volumes. Lytic lesions classified as progressive disease exhibited much larger volume increases. Lytic bone lesions showed indications of remineralization with some exhibiting immediate increases in density (1-6 months) and others decreasing initially then increasing back toward baseline between 7 and 12 months. The majority of sclerotic lesions, all classified as local control, decreased slightly in both volume and density. Lesions with both soft tissue and boney involvement resulted in contradictory results when employing both radiological and size parameters for assessing treatment response. Classification was dominated by changes in soft tissue volume, despite associated volume or density changes in the corresponding boney lesion. In contrast, when soft tissue volume changes were minimal (<20% increase), classification appeared to be related primarily to density changes and not bone volume. CONCLUSIONS: Volume and density changes show promise as quantitative parameters for classifying treatment responses of nonspine osseous lesions. Further work is required for clarifying how these metrics can be applied to lesions with both boney and soft tissue components.

The Impact of Correcting for Translational and Rotational Errors Using the HexaPOD in Head and Neck Stereotactic Body Radiation Therapy Patients.

BACKGROUND: The HexaPOD has been developed to correct for errors in six degrees of freedom (6DOF), which enables it with the potential to improve setup accuracy. This is critical in hypofractionated head and neck (H&N) stereotactic body radiation therapy (SBRT) plans, which have highly conformal dose distributions and close proximity of critical normal structures. PURPOSE: The purpose of the study was to investigate whether using the HexaPOD to correct for error in 6DOF will increase setup accuracy for H&N SBRT patients. METHODS AND MATERIALS: For each of the 20 SBRT H&N patients in this study, two sets of global computed tomography scans and cone beam computed tomography matches were performed for the first and last fraction of each patient's treatment. One of the global matches included corrections for rotations and the other did not. Next, sub-regions of interest, based on bony landmarks, were identified for each patient and local registrations were performed to match these sub-regions of interest to determine local sub-region errors in the global registration. The differences in local error, with and without rotations, were examined to determine whether the residual local setup errors were significantly different. RESULTS: T-test results demonstrate a statistically significant difference in local error when correcting for rotations vs. not, in all 6DOF. When examining the actual magnitude of residual error reduction using three-dimensional vectors of the average translational differences, an average reduction of 0.9 mm is observed when 6DOF corrections are applied. CONCLUSIONS: Residual setup errors in each of the 6DOF were statistically significant; however, the magnitude depicts a very small reduction in residual error <1 mm. Clinically, this makes a very small difference because the planning target volume (PTV) presumably covers an expansion of 3-5 mm.

Pesticide/environmental exposures and Parkinson's disease in East Texas.

Epidemiological evidence suggests that pesticides and other environmental exposures may have a role in the etiology of idiopathic Parkinson's disease (PD). However, there is little human data on risk associated with specific pesticide products, including organic pesticides such as rotenone with PD. Using a case-control design, this study examined self-reports of exposure to pesticide products, organic pesticides such as rotenone, and other occupational and environmental exposures on the risk of PD in an East Texas population. The findings demonstrated significantly increased risk of PD with use of organic pesticides such as rotenone in the past year in gardening (OR = 10.9; 95% CI = 2.5-48.0) and any rotenone use in the past (OR = 10.0; 95% CI = 2.9-34.3). Use of chlorpyrifos products (OR = 2.0; 95% CI = 1.02-3.8), past work in an electronics plant (OR = 5.1; 95% CI = 1.1-23.6), and exposure to fluorides (OR = 3.3; 95% CI = 1.03-10.3) were also associated with significantly increased risk. A trend of increased PD risk was observed with work history in paper/lumber mill (OR = 6.35; 95% CI = 0.7-51.8), exposure to cadmium (OR = 5.3; 95% CI = 0.6-44.9), exposure to paraquat (OR = 3.5; 95% CI = 0.4-31.6), and insecticide applications to farm animals/animal areas and agricultural processes (OR = 4.4; 95% CI = 0.5-38.1). Cigarette smoking, alcohol use, and fish intake were associated with reduced risk. In summary, this study demonstrates an increased risk of PD associated with organic pesticides such as rotenone and certain other pesticides and environmental exposures in this population.