Feasibility of MV CBCT-based treatment planning for urgent radiation therapy: dosimetric accuracy of MV CBCT-based dose calculations.

Unlike scheduled radiotherapy treatments, treatment planning time and resources are limited for emergency treatments. Consequently, plans are often simple 2D image-based treatments that lag behind technical capabilities available for nonurgent radiotherapy. We have developed a novel integrated urgent workflow that uses onboard MV CBCT imaging for patient simulation to improve planning accuracy and reduce the total time for urgent treatments. This study evaluates both MV CBCT dose planning accuracy and novel urgent workflow feasibility for a variety of anatomic sites. We sought to limit local mean dose differences to less than 5% compared to conventional CT simulation. To improve dose calculation accuracy, we created separate Hounsfield unit-to-density calibration curves for regular and extended field-of-view (FOV) MV CBCTs. We evaluated dose calculation accuracy on phantoms and four clinical anatomical sites (brain, thorax/spine, pelvis, and extremities). Plans were created for each case and dose was calculated on both the CT and MV CBCT. All steps (simulation, planning, setup verification, QA, and dose delivery) were performed in one 30 min session using phantoms. The monitor units (MU) for each plan were compared and dose distribution agreement was evaluated using mean dose difference over the entire volume and gamma index on the central 2D axial plane. All whole-brain dose distributions gave gamma passing rates higher than 95% for 2%/2 mm criteria, and pelvic sites ranged between 90% and 98% for 3%/3 mm criteria. However, thoracic spine treatments produced gamma passing rates as low as 47% for 3%/3 mm criteria. Our novel MV CBCT-based dose planning and delivery approach was feasible and time-efficient for the majority of cases. Limited MV CBCT FOV precluded workflow use for pelvic sites of larger patients and resulted in image clearance issues when tumor position was far off midline. The agreement of calculated MU on CT and MV CBCT was acceptable for all treatment sites

Patient-Specific Fetal Dose Determination for Multi-Target Gamma Knife Radiosurgery: Computational Model and Case Report.

A 42-year-old woman at 29 weeks gestation via in vitro fertilization who presented with eight metastatic brain lesions received Gamma Knife stereotactic radiosurgery (GKSRS) at our institution. In this study, we report our clinical experience and a general procedure of determining the fetal dose from patient-specific treatment plans and we describe quality assurance measurements to guide the safe practice of multi-target GKSRS of pregnant patients. To estimate fetal dose pre-treatment, peripheral dose-to-focal dose ratios (PFRs) were measured in a phantom at the distance approximating the fundus of uterus. Post-treatment, fetal dose was calculated from the actual patient treatment plan. Quality assurance measurements were carried out via the extrapolation dosimetry method in a head phantom at increasing distances along the longitudinal axis. The measurements were then empirically fitted and the fetal dose was extracted from the curve. The computed and measured fetal dose values were compared with each other and associated radiation risk was estimated. Based on low estimated fetal dose from preliminary phantom measurements, the patient was accepted for GKSRS. Eight brain metastases were treated with prescription doses of 15-19 Gy over 143 min involving all collimator sizes as well as composite sector mixed shots. Direct fetal dose computation based on the actual patient's treatment plan estimated a maximum fetal dose of 0.253 cGy, which was in agreement with surface dose measurements at the level of the patient's uterine fundus during the actual treatment. Later phantom measurements also estimated fetal dose to be in the range of 0.21-0.28 cGy (dose extrapolation curve R2 = 0.998). Using the National Council on Radiation Protection and Measurements (NCRP) population-based model, we estimate the fetal risk of secondary malignancy, which is the primary toxicity after 25 weeks gestation, to be less than 0.01%. Of note, the patient delivered the baby via scheduled cesarean section at 36 weeks without complications attributable to the GKSRS procedure. GKSRS of multiple brain metastases was demonstrated to be safe and feasible during pregnancy. The applicability of a general patient-specific fetal dose determination method was also demonstrated for the first time for such a treatment

Introduction : Latour and eighteenth-century literary studies

Bruno Latour’s formulation of modernity as a particular intertwining of persons and things has shaped recent efforts to rethink the legacy of the Enlightenment. What is more, Latour has often reverted to the eighteenth century as a site of origins—whether it is for the sort of practices that characterize the modern laboratory, the social formations that are the objects of Actor-Network Theory generally, and the kinds of false conceptual breaks that obscure the nature of these very formations and practices. Scholars studying the literature and arts of the long eighteenth century are therefore uniquely positioned to evaluate and engage with Latour’s most important contributions to modern thought. This introduction to a special issue of The Eighteenth Century discusses the development of Latour’s formulation of modernity, indicating its special relevance to eighteenth-century thought (and vice versa)

Best Practice for Insomnia Patients at a Sleep Center

Sleep disorders affect millions of people worldwide. The purpose of this project was to determine if individuals with sleep disorders can achieve better outcomes with treatment that includes education classes and cognitive therapy than with current treatments which utilize medication and equipment. Seven articles, obtained from a search of CINAHL, JBI, Medline, and Psych Info, were reviewed and critiqued. Studies contained samples of men and women with sleep disorders, reviews of previous studies, and reviews of effective alternative treatments. Designs included systematic reviews, meta-analysis, randomized control, longitudinal two group pre-test posttest, and a narrative review. Findings showed that when traditional pharmacological treatments are combined with alternative therapies, patients have much better outcomes. A decision to include cognitive behavioral therapy (CBT) and music therapy was made. A new education program will include a briefing about therapies for individuals with sleep disorders and a discussion about how to help patients incorporate CBT and music therapy into their current plan for treatment. In the future, patients will be educated about the importance of keeping a sleep journal to evaluate their progress. Patient success will be measured using data from patient journals and a sleep center survey

Phonetic Detail and the Role of Exposure in Dialect Imitation

International audienceSpeakers are able to adjust their prosodic patterns to approximate those of a different dialect, at least when the dialects involved are phonologically similar [6, 7]. Our study explores imitation across two dialects of English (Singaporean and American) whose prosodic systems are phonologically very distinct. Singaporean speakers were recorded both in their native dialect and while attempting to imitate sentences produced by an American English speaker. Our results show that in spite of the structural differences, speakers of Singapore English are able to rapidly adapt and shift from an edge-based system to an accentual system within the time of the experiment, as well as to finely tune the phonetic detail of their intonation patterns in a way that closely tracked that of the American English model speaker. We further show that the degree of variability in successfully reproducing the target values is dependent on amount of exposure to the non-native dialect