Patient dose considerations for routine megavoltage cone-beam CT imaging

Megavoltage cone-beam CT (MVCBCT), the recent addition to the family of in-room CT imaging systems for image-guided radiation therapy (IGRT), uses a conventional treatment unit equipped with a flat panel detector to obtain a three-dimensional representation of the patient in treatment position. MVCBCT has been used for more than two years in our clinic for anatomy verification and to improve patient alignment prior to dose delivery. The objective of this research is to evaluate the image acquisition dose delivered to patients for MVCBCT and to develop a simple method to reduce the additional dose resulting from routine MVCBCT imaging. Conventional CT scans of phantoms and patients were imported into a commercial treatment planning system (TPS: Phillips, Pinnacle) and an arc treatment mimicking the MVCBCT acquisition process was generated to compute the delivered acquisition dose. To validate the dose obtained from the TPS, a simple water-equivalent cylindrical phantom with spaces for MOSFETs and an ion chamber was used to measure the MVCBCT image acquisition dose. Absolute dose distributions were obtained by simulating MVCBCTs of 9 and 5 monitor units (MU) on pelvis and head and neck patients, respectively. A compensation factor was introduced to generate composite plans of treatment and MVCBCT imaging dose. The article provides a simple equation to compute the compensation factor. The developed imaging compensation method was tested on routinely used clinical plans for prostate and head and neck patients. The quantitative comparison between the calculated dose by the TPS and measurement points on the cylindrical phantom were all within 3%. The dose percentage difference for the ion chamber placed in the center of the phantom was only 0.2%. For a typical MVCBCT, the dose delivered to patients forms a small anterior-posterior gradient ranging from 0.6 to 1.2 cGy per MVCBCT MU. MVCBCT acquisitions in the pelvis and head and neck areas deliver slightly more dose than current portal imaging but render soft tissue information for positioning. Overall, the additional dose from daily 9 MU MVCBCTs of prostate patients is small compared to the treatment dose (<4%). Dose-volume histograms of compensated plans for pelvis and head and neck patients imaged daily with MVCBCT showed no additional dose to the target and small increases at low doses. The results indicate that the dose delivered for MVCBCT imaging can be precisely calculated in the TPS and therefore included in the treatment plan. This allows simple plan compensations, such as slightly reducing the treatment dose, to minimize the total dose received by critical structures from daily positioning with MVCBCT. The proposed compensation factor reduces the number of MU per treatment beam per fraction. Both the number of fractions and the beam arrangement are kept unchanged. Reducing the imaging volume in the cranio-caudal direction can further reduce the dose delivered for MVCBCT. This is a useful feature to eliminate the imaging dose to the eyes or to focus on a specific region of interest for alignment.     

Personal Digital Assistants are Comparable to Traditional Diaries for Dietary Self-Monitoring During a Weight Loss Program

Dietary self-monitoring is considered the core of behavioral weight control programs. As software for personal digital assistants (PDA) has become more available, this study investigated whether the use of a PDA would improve dietary self-monitoring frequency and subsequent weight loss over the use of traditional paper diaries. One-hundred-seventy-six adults (BMI 25–39.9) participated in a 6-month behavioral weight control program. Treatment subjects (n = 61) were provided with a PalmZire 21 with Calorie King’s Diet Diary software installed. Their self-monitoring habits and weight loss were compared with the results from a previous program (n = 115) which followed the same protocol using paper diaries for self-monitoring. No significant differences in weight loss or dietary self-monitoring were found. More frequent self-monitoring correlated with weight loss in both groups (p<.001). People seeking to lose weight should be encouraged to self-monitor and be matched with a mode of self-monitoring that is fitting to their lifestyle and skills.     

Use of bifunctional hybrid beta-lactamases for epitope mapping and immunoassay development

Mapping of epitopes is a crucial step for the study of immune pathways, the engineering of vaccines and the development of immunoassays. In this work, the Bacillus licheniformis beta-lactamase BlaP has been engineered to display heterologous polypeptides in a permissive and solvent-exposed loop. When combined with phage display, this modified enzyme can be used for epitope mapping by cloning random gene fragments. The procedure presented in this paper allows the selection of large infectious phage libraries with high diversity and efficient beta-lactamase activities. A useful aspect of the proposed technique results from the possibility of using the beta-lactamase activity carried by phages to evaluate the proportion of immobilised phages during the successive enrichment steps of the library or competition experiments with the selected phages. Another advantage of the technique derives from the fact that the epitope is selected as a bifunctional hybrid protein, which can be overproduced and purified. The resulting recombinant protein associates an epitope with a specific and efficient enzymatic activity. This constitutes an original tool for immunoassay development. A virus influenza hemagglutinin (HA1)-gene fragment library has been generated with this system and used to identify a linear epitope.     

Treatment of lupus-prone mice with a dual inhibitor of TLR7 and TLR9 leads to reduction of autoantibody production and amelioration of disease symptoms

The presence of autoantibodies specific for nucleic acid-associated antigens is the hallmark of systemic lupus erythematosus (SLE). We have recently developed a specific inhibitor of TLR7 and TLR9, called immunoregulatory sequence (IRS) 954, and showed that it inhibits the induction of IFN-alpha by human plasmacytoid dendritic cells in response to DNA and RNA viruses and isolated immune complexes from lupus patients. In this study, we show that IRS 954 can prevent progression of disease when injected in the lupus prone (NZBxNZW)F1 mice. Following treatment, we observed a significant reduction of serum levels of nucleic acid-specific autoantibodies as well as decreased proteinuria, reduced glomerulonephritis, end-organ damage and increased survival. These data demonstrate that in addition to its ability to block IFN-alpha, IRS 954 can reduce symptoms in a lupus model and thus represents a promising therapeutic agent for the treatment of SLE.     

Perceived influence of intrinsic/extrinsic factors on participation in life activities after spinal cord injury

Background

Various types of limitations on community participation are experienced by people with spinal cord injury (SCI).

Added Sugar Intake among Pregnant Women in the United States: National Health and Nutrition Examination Survey 2003-2012

Background

Despite associations of dietary added sugar with excess weight gain and chronic disease risk, intake among most Americans exceeds the recommended limits (<10% total energy). Maternal diet plays an important role in pregnancy-related outcomes, but little is known about the extent of added sugar intake during pregnancy.

Validation of a Collaboration Readiness Assessment Tool for Use by Supplemental Nutrition Assistance Program–Education (SNAP-Ed) Agencies and Partners

Objective

To evaluate content and face validity of a collaboration readiness assessment tool developed to facilitate collaborative efforts to implement policy, systems, and environment changes in Supplemental Nutrition Assistance Program–Education (SNAP-Ed).

Frailty and Clinical Outcomes in Advanced Heart Failure Patients Undergoing Left Ventricular Assist Device Implantation: A Systematic Review and Meta-analysis

Background

Frailty has been identified as a risk factor for adverse clinical outcomes after cardiac intervention or surgery. However, whether it increases the risk of adverse outcomes in patients undergoing left ventricular assist device (LVAD) therapy has been controversial. Therefore, we conducted a systematic review and meta-analysis of the frailty measures and clinical outcomes of length of stay and mortality in this setting.

The roles of physical activity and sedentary behavior on Hispanic children’s mental health: a motor skill perspective

Purpose

Motor competence (MC) has been recognized as the foundation for life-time moderate-to-vigorous physical activity (MVPA) as well as an influential factor in reducing sedentary behavior during childhood. Guided by Blair et al.’s health model, the purpose of this study was to examine the behavioral mechanism of mental health including physical, psychosocial, and cognitive health among Hispanic children related to MC and MVPA.

Methods

A prospective research design was used with two-wave assessments across one academic year. A total of 141 Hispanic kindergarteners (Mean_age = 5.37, SD = 0.48) were recruited in Texas. Nearly all (94.3%) of the participants were from low-income families based on the Income Eligibility Guidelines. The study was approved by the University Research Review Board, and informed consent was obtained from parents/guardians prior to starting the study.

Results

Multiple regressions indicated that manipulative skill was a significant predictor of physical and psychosocial health (β = 0.21, β = 0.26, p < 0.05, respectively) and locomotor skill served as a significant predictor for cognitive health (β = 0.22, p < 0.01), after controlling for BMI. Bootstrapping analyses supported the statistical significance of indirect effects of MC on mental health outcomes through MVPA (95% CI [0.031, 0.119]) and sedentary behavior (95% CI [0.054, 0.235]), respectively.

Conclusion

The results suggest that skill-based activities/games, with instructions, should be encouraged during school-based physical activity and health promotion programs in childhood education. Better understanding of the early effects of MC may contribute to designing strategies to promote Hispanic children’s well-being.