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Biomedical subjects

Chris Moore

Publications and source records attributed to Chris Moore.

11 recordsLinked to original sources
PubMed2006

Online adaptive radiotherapy of the bladder: small bowel irradiated-volume reduction.

PURPOSE: To assess the potential reduction of small bowel volume receiving high-dose radiation by using kilovoltage X-ray cone beam computed tomography (CBCT) and quantized margin selection for adaptive bladder cancer treatment. METHODS AND MATERIALS: Twenty bladder patients were planned conformally using a four-field, 15-mm uniform margin technique. Two additional planning target volumes (PTVs) were created using margins quantized to 5 and 10 mm in the superior direction only. CBCTs (approximately 8 scans/patient) were acquired during treatment. CBCT volumes were registered with CT planning scans to determine setup errors and to select the appropriate PTV of the day. Margin reduction in other directions was considered. Outlining of small bowel in every fraction is required to properly quantify the volume of small bowel spared from high doses. In the case of CBCT this is not always possible owing to artifacts created by small bowel movement and the presence of gas. A simpler method was adopted by considering the volume difference between PTVs created using uniform and adapted margins, which corresponds to the potential volume of small bowel sparing. RESULTS: The average small bowel volume that can be spared by this form of adaptive radiotherapy is 31 +/- 23 cm3 (+/-1 SD). The bladder for 1 patient was systematically smaller than the planning scan and hence demonstrated the largest average reduction of 76 cm3. The clinical target volume to PTV margins in other directions can be safely reduced to 10 mm except in the anterior direction where, like the superior direction, the bladder showed significant variation. CONCLUSIONS: Online CBCT-assisted plan selection based on quantized margins can significantly reduce the volume of small bowel receiving high doses for some bladder patients. CBCT allows the 15-mm margins used in some directions to be safely reduced to 10 mm.

Humans↗
PubMed2006

X-ray volume imaging in bladder radiotherapy verification.

PURPOSE: To assess the clinical utility of X-ray volume imaging (XVI) for verification of bladder radiotherapy and to quantify geometric error in bladder radiotherapy delivery. METHODS AND MATERIALS: Twenty subjects undergoing conformal bladder radiotherapy were recruited. X-ray volume images and electronic portal images (EPIs) were acquired for the first 5 fractions and then once weekly. X-ray volume images were co-registered with the planning computed tomography scan and clinical target volume coverage assessed in three dimensions (3D). Interfraction bladder volume change was described by quantifying changes in bladder volume with time. Bony setup errors were compared from both XVI and EPI. RESULTS: The bladder boundary was clearly visible on coronal XVI views in nearly all images, allowing accurate 3D treatment verification. In 93.5% of imaged fractions, the clinical target volume was within the planning target volume. Most subjects displayed consistent bladder volumes, but 25% displayed changes that could be predicted from the first three XVIs. Bony setup errors were similar whether calculated from XVI or EPI. CONCLUSIONS: Coronal XVI can be used to verify 3D bladder radiotherapy delivery. Image-guided interventions to reduce geographic miss and normal tissue toxicity are feasible with this technology.

Aged↗
PubMed2006

Decision making in children with ADHD only, ADHD-anxious/depressed, and control children using a child version of the Iowa Gambling Task.

OBJECTIVE: The goal of this study is to investigate decision making in children with ADHD using a child version of the Iowa Gambling Task (IGT). The effect of internalizing symptoms is also of interest. METHOD: Twenty-one children with ADHD (high anxiety/depression and no anxiety/depression) are compared to an age- and sex-matched control group on the gambling task. Children in the ADHD-alone group demonstrate impaired performance on the IGT. In contrast, children in the control group and the ADHD-anxiety/depression group learn to choose more from the advantageous decks over time. RESULTS: These findings of impaired decision making in children with ADHD parallel findings of real-life decision-making problems in this population. CONCLUSION: Furthermore, the findings suggest that having a high number of internalizing symptoms leads to better performance for children with ADHD on this variant of the IGT.

Anxiety↗
PubMed2005

Does gaze direction really trigger a reflexive shift of spatial attention?

Previous studies have found that the gaze direction of a centrally presented face facilitates response time (RT) to a lone peripheral target. The widely accepted interpretation of this finding is that gaze direction triggers a cortically mediated reflexive shift of spatial attention. In the present study we tested an alternative explanation, that a target appearing abruptly on its own in the visual field triggers a subcortically mediated reflexive shift of spatial attention, which is modulated by compatibility with gaze direction. Using central gaze cues, we compared RT to a single peripheral onset target with RT to a peripheral onset target accompanied by an equivalent distractor at the mirror opposite location. In both cases the facilitation effect was the same, demonstrating conclusively that the observed orienting is attributable to the reflexive effects of the gaze cue.

Adult↗
PubMed2004

Complex decision-making in early childhood.

Decision-making over time is an important aspect of adaptive social functioning. The main goal of this study was to investigate the development of this ability in young children. A simplified version of the Iowa Gambling Task was given to 69 children at 3 ages (3, 4, and 6 years). Children were also given an awareness test to assess their knowledge of the task. Significant age differences were found for awareness of the task while significant sex effects were found for performance on the task. Females chose significantly more from the advantageous decks than would be expected by chance in the second block. Males demonstrated no significant difference in choice of decks. Further analysis indicated female superiority in the task was not due to greater knowledge of the game. One interpretation of these results is that there are two systems affecting decision-making over time.

Adaptation, Psychological↗
PubMed2003

Inhibition of return in children and adolescents.

Inhibition of return (IOR), slowed responding to targets at a cued location after attention is removed from this location, has been shown to occur both in adults and in infants. To explore suggestion that the timecourse of IOR depends on factors that might affect the efficiency with which attention is removed from the cued location, we compared the performance of young children (5-10-year-olds, N=49, M=8 years, 4 months) to older children and adolescents (11-17-year-olds, N=61, M=14 years) in single and double cue procedures. Cue-target interval was varied to measure the timecourse of IOR in this within-subjects localization task. Whereas no IOR was found in the young group unless a double cue procedure was used, in the older group, we found IOR at all intervals with the double cue procedure and the typical crossover pattern, with early facilitation followed by inhibition in the single cue procedure.

Adolescent↗
PubMed2002

Identification of the sex pheromone of Holotrichia reynaudi.

The male attractant pheromone of the scarab beetle Holotrichia reynaudi, an agricultural pest native to southern India, was extracted from abdominal glands of females with hexane and analyzed by gas chromatography-mass spectrometry. Field testing of the candidate chemicals, indole, phenol, and anisole, both alone and as binary mixtures, led us to conclude that anisole was the major component of the sex pheromone. Neither male nor female beetles were attracted to indole or phenol on their own. Similarly, when indole and anisole were combined, the attractiveness of the solution did not increase over that obtained with anisole alone. However, combination of phenol and anisole did alter the attractiveness of anisole, with fewer male beetles attracted to the binary mixture than to anisole on its own. The behavior of female beetles was not altered by any of the chemicals tested. Anisole is also the sex pheromone of H. consanguinea, making this the first known example of two melolonthine scarabs sharing the same pheromone.

Animals↗