Explore the vast range of titles available.

Purpose To quantify the impact of treatment planning system beam model parameters, based on the actual spread in radiotherapy community data, on clinical treatment plans and determine which complexity metrics best describe the impact beam modeling errors have on dose accuracy. Methods Ten beam modeling parameters for a Varian accelerator were modified in RayStation to match radiotherapy community data at the 2.5, 25, 50, 75, and 97.5 percentile levels. These modifications were evaluated on 25 patient cases, including prostate, non‐small cell lung, H&N, brain, and mesothelioma, generating 1,000 plan perturbations. Differences in the mean planned dose to clinical target volumes (CTV) and organs at risk (OAR) were evaluated with respect to the planned dose using the reference (50th‐percentile) parameter values. Correlation between CTV dose differences, and 18 different complexity metrics were evaluated using linear regression; R‐squared values were used to determine the best metric. Results Perturbations to MLC offset and transmission parameters demonstrated the greatest changes in dose: up to 5.7% in CTVs and 16.7% for OARs. More complex clinical plans showed greater dose perturbation with atypical beam model parameters. The mean MLC Gap and Tongue & Groove index (TGi) complexity metrics best described the impact of TPS beam modeling variations on clinical dose delivery across all anatomical sites; similar, though not identical, trends between complexity and dose perturbation were observed among all sites. Conclusion Extreme values for MLC offset and MLC transmission beam modeling parameters were found to most substantially impact the dose distribution of clinical plans and careful attention should be given to these beam modeling parameters. The mean MLC Gap and TGi complexity metrics were best suited to identifying clinical plans most sensitive to beam modeling errors; this could help provide focus for clinical QA in identifying unacceptable plans.

College students are reporting higher levels of stress and feel they lack adequate coping mechanisms. The purpose of this pilot study was to determine how accurately students can estimate their resonant frequency breaths-per-minute (Optimal BPM) after engaging in 4 weeks of daily breathing practice. Specifically, we wanted to know if daily breathing practice would increase students' awareness of their breathing and improve their accuracy in identifying their current breathing rate. Increasing awareness of current bodily state is a key component of stress management and breathing practice has found to be particularly powerful in reducing stress and improving health. A total of 36 students participated in the study, with an average age of 21 years and 65% female. Optimal BPM was determined using the emWave PC power spectrum display in combination with the EZ-Air Breath Pacer loosely following the protocol for training subjects to breath at their resonant frequency in Lehrer et al. (2000). Students practiced breathing for an average of 20 min per day approximately 5 days a week over the 4-week period. At baseline, 24% of student accurately identified their current breathing rate. At the 4-week follow-up, 50% of students accurately identified their breathing rate. Students also reported decreased total stress (p < .01) and lower levels of headache, fatigue, etc. (p < .01) at the conclusion of the study. As time spent in breathing practice increased, levels of headache, etc., decreased (r = -.38, p = .01). Given the simplicity of breathing exercises and the wide availability of CDs and other portable equipment, breathing practice represents an excellent way to reduce stress and increase well-being in college student populations.