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Evaluation of dosimetric characteristics of a virtual micro-multileaf collimator - Siemens HD270 MLC [Meeting Abstract]

Mitra, RK; Mah, D; Das, Indra; Horwitz, E; Hanks, G
ISSN: 0094-2405
CID: 2234762

Image fusion based analysis of post implant prostate edema with I-125 brachytherapy : spatial and temporal dose volume histogram implications [Meeting Abstract]

Mitra, RK; Das, Indra J; Horwitz, E; Pinover, W; Hanks, G; Schulheiss, T
ISSN: 0167-8140
CID: 2238972

Clinical evaluation and implementation of MLC dose undulation using Siemens HD-270 [Meeting Abstract]

Mitra, RK; Das, Indra J; Mah, D; Horwitz, E; Pinover, W; Movsas, B; Hanks, G; Schultheiss, T
ISSN: 0167-8140
CID: 2238992

The orienting response in schizophrenia and mania

Schnur, D B; Smith, S; Smith, A; Marte, V; Horwitz, E; Sackeim, H A; Mukherjee, S; Bernstein, A S
We examined skin conductance (SCR) and finger pulse amplitude response (PULSE) in 53 schizophrenic, 30 manic, and 28 control subjects to provide information on orienting response (OR) dysfunction in severe psychiatric disorders. SCR and PULSE to neutral and task-relevant tones were measured in acutely ill inpatients and normal control subjects on two occasions separated by a 3-week interval. There were no significant group differences in proportions of SCR and PULSE non-responders to neutral tones. PULSE frequency to task-relevant tones in both the schizophrenic and manic patients was lower than that for the control subjects in both OR sessions, but did not differ significantly between patient groups. Although PULSE frequency was inversely related to neuroleptic dose in the schizophrenia sample, reanalysis of unmedicated patients did not change our results. OR frequency to task-relevant but not to neutral tones exhibited test-retest reliability. Certain aspects of OR dysfunction may overlap in schizophrenia and bipolar disorder. Our failure to demonstrate excessive OR non-responding to neutral tones in schizophrenia patients is inconsistent with many previous studies but may be due to a high proportion of OR non-responders among the control subjects
PMID: 10641585
ISSN: 0165-1781
CID: 136555

A comparison of daily CT localization to a daily ultrasound-based system in prostate cancer

Lattanzi, J; McNeeley, S; Pinover, W; Horwitz, E; Das, I; Schultheiss, T E; Hanks, G E
PURPOSE: Daily CT localization has been demonstrated to be a precise method of correcting radiation field placement by reducing setup and organ motion variations to facilitate dose escalation in prostate carcinoma. The purpose of this study was to evaluate the feasibility and accuracy of daily ultrasound-guided localization utilizing daily CT as a standard. The relatively simple computer-assisted ultrasound-based system is designed to be an efficient means of achieving daily accuracy. METHODS AND MATERIALS: After five weeks of conformal external beam radiation therapy, 23 patients underwent a second CT simulation. Prostate-only fields based on this scan were created with no PTV margin. On each of the final conedown treatment days, a repeat CT simulation and isocenter comparison was performed. Ten of the above patients also underwent prostate localization with a newly developed ultrasound-based system (BAT) that is designed to facilitate patient positioning at the treatment machine. The portable system, which electronically imports the CT simulation target contours and isocenter, is situated adjacent to the treatment couch. Transverse and sagittal suprapubic ultrasound images are captured, and the system overlays the corresponding CT contours relative to the machine isocenter. The CT contours are maneuvered in three dimensions by a touch screen menu to match the ultrasound images. The system then displays the 3-D couch shifts required to produce field alignment. RESULTS: The BAT ultrasound system produced good quality images with minimal operator training required. The localization process was completed in less than 5 min. The absolute magnitude difference between CT and ultrasound was small (A/P range 0 to 5.9 mm, mean 3 mm +/- 1.8; Lat. range 0 to 7.9 mm, mean 2.4 mm +/- 1.8; S/I range 0 to 9 mm, mean 4.6 mm +/- 2.8). Analysis confirmed a significant correlation of isocenter shifts (A/P r = 0.66, p < 0.0001; Lat. r = 0.58, p < 0.003; S/I r = 0.78, p < 0.0001) in all dimensions, and linear regression confirmed the equivalence of the two modalities. CONCLUSIONS: Daily CT localization is a precise method to improve daily target localization in prostate carcinoma. However, it requires significant human and technical resources that limit its widespread applicability. Conversely, localization with the BAT ultrasound system is simple and expeditious by virtue of its ability to image the prostate at the treatment machine in the treatment position. Our initial evaluation revealed ultrasound targeting to be functionally equivalent to CT. This ultrasound technology is promising and warrants further investigation in more patients and at other anatomical sites.
PMID: 10098426
ISSN: 0360-3016
CID: 2223842