Autistic Regression and Exposure to Industrial Chemicals: Preliminary Observations.

Exposure to industrial pollutants is a potential risk factor not fully explored in ASD with regression (ASD+R). We studied geographical collocation patterns of industrial air chemical emissions and the location of homes of children with ASD+R at different exposure times, compared with ASD cases without regression (ASD-R). Fifteen of 111 emitted chemicals collocated with ASD+R, and 65 with ASD-R. ASD+R collocated more strongly with different neurotoxicants/immunotoxicants a year before diagnosis, whereas ASD-R were moderately collocated with chemicals across all exposure periods. This preliminary exploratory analysis of differences in exposure patterns raises a question regarding potential pathophysiological differences between the conditions.

"What is the actual goal of the pathway?": examining emergency department physician and nurse perspectives on the implementation of a pediatric concussion pathway using the theoretical domains framework.

BACKGROUND: Multiple evidence-based clinical practice guidelines (CPGs) exist to guide the management of concussion in children, but few have been translated into clinical pathways (CP), which operationalize guidelines into accessible and actionable algorithms that can be more readily implemented by health care providers. This study aimed to identify the clinical behaviours, attitudinal factors, and environmental contexts that potentially influence the implementation of a clinical pathway for pediatric concussion. METHODS: Semi-structured interviews were conducted from October 2017 to January 2018 with 42 emergency department clinicians (17 physicians, 25 nurses) at five urban emergency departments in Alberta, Canada. A Theoretical Domains Framework (TDF)-informed interview guide contained open-ended questions intended to gather feedback on the proposed pathway developed for the study, as well as factors that could potentially influence its implementation. RESULTS: The original 14 domains of the TDF were collapsed into 6 clusters based on significant overlap between domains in the issues discussed by clinicians: 1) knowledge, skills, and practice; 2) professional roles and identity; 3) attitudes, beliefs, and motivations; 4) goals and priorities; 5) local context and resources; and 6) engagement and collaboration. The 6 clusters identified in the interviews each reflect 2-4 predominant topics that can be condensed into six overarching themes regarding clinicians' views on the implementation of a concussion CP: 1) standardization in the midst of evolving research; 2) clarifying and communicating goals; 3) knowledge dissemination and alignment of information; 4) a team-oriented approach; 5) site engagement; and 6) streamlining clinical processes. CONCLUSION: Application of a comprehensive, evidence-based, and theory-driven framework in conjunction with an inductive thematic analysis approach enabled six themes to emerge as to how to successfullly implement a concussion CP.

ADHD in children and youth: Part 3-Assessment and treatment with comorbid ASD, ID, or prematurity.

Attention-deficit hyperactivity disorder (ADHD) is a chronic neurodevelopmental disorder. Three position statements have been developed by the Canadian Paediatric Society, following systematic literature reviews. Statement objectives are to: 1) Summarize the current clinical evidence regarding ADHD,2) Establish a standard for ADHD care, and3) Assist Canadian clinicians in making well-informed, evidence-based decisions to enhance care of children and youth with this condition. Specific topics reviewed in Part 3, which focuses on associated autism spectrum disorder, intellectual disability, and prematurity, include the challenges of diagnostic assessment, common presentations, the role of genetics, and treatment, including the benefits of physical activity. Recommendations are based on current guidelines, evidence from the literature, and expert consensus.

Clinical clues for autoimmunity and neuroinflammation in patients with autistic regression.

AIM: Autistic regression is a unique variant within the autism spectrum disorders (ASDs), with recent reports raising the possibility of immune aetiology. This study explores clinical clues for an association between autistic regression and autoimmunity. METHOD: Single-centre charts of children diagnosed with ASD in 2014 were reviewed. We compared the rates of: (1) familial autoimmunity in first-degree and second-degree relatives; (2) febrile illness preceding initial parental concern, as a potential precipitant of immune activation; and (3) possible non-immune precipitants such as pregnancy and postnatal complications. RESULTS: The charts of 206 children with ASD and 33 diagnosed with autistic regression variant were reviewed. The incidence of febrile illness in the 6 months prior to initial parental concern was significantly higher in the children with autistic regression compared with those with ASD (30% vs 0%; p<0.001). The overall prevalence of familial autoimmunity was also higher in children with autistic regression compared with those with ASD (33% vs 12%; p<0.001). Type 1 diabetes and autoimmune thyroiditis were both more common in families with children with autistic regression. Other non-immune risk factors did not differ between the two groups. INTERPRETATION: Our findings suggest that predisposition to autoimmunity, and immune/inflammatory activation, may be associated with autistic regression.

Navigating the medical physics education and training landscape.

PURPOSE: The education and training landscape has been profoundly reshaped by the ABR 2012/2014 initiative and the MedPhys Match. This work quantifies these changes and summarizes available reports, surveys, and statistics on education and training. METHODS: We evaluate data from CAMPEP-accredited program websites, annual CAMPEP graduate and residency program reports, and surveys on the MedPhys Match and Professional Doctorate degree (DMP). RESULTS: From 2009-2015, the number of graduates from CAMPEP-accredited graduate programs rose from 210 to 332, while CAMPEP-accredited residency positions rose from 60 to 134. We estimate that approximately 60% of graduates of CAMPEP-accredited graduate programs intend to enter clinical practice, however, only 36% of graduates were successful in acquiring a residency position in 2015. The maximum residency placement percentage for a graduate program is 70%, while the median for all programs is only 22%. Overall residency placement percentage for CAMPEP-accredited program graduates from 2011-2015 was approximately 38% and 25% for those with a PhD and MS, respectively. The disparity between the number of clinically oriented graduates and available residency positions is perceived as a significant problem by over 70% of MedPhys Match participants responding to a post-match survey. Approximately 32% of these respondents indicated that prior knowledge of this situation would have changed their decision to pursue graduate education in medical physics. CONCLUSION: These data reveal a substantial disparity between the number of residency training positions and graduate students interested in these positions, and a substantial variability in residency placement percentage across graduate programs. Comprehensive data regarding current and projected supply and demand within the medical physics workforce are needed for perspective on these numbers. While the long-term effects of changes in the education and training infrastructure are still unclear, available survey data suggest that these changes could negatively affect potential entrants to the profession.

Screening for language delay after life-saving therapies in term-born infants.

BACKGROUND: Strong recommendations have been made for the periodic developmental surveillance, screening, and evaluation of children with CHD. This supports similar calls for all at-risk children in order to provide timely, structured early developmental intervention that may improve outcomes. The aim of this study was to determine the accuracy of screening for language delay after life-saving therapies using the parent-completed vocabulary screen of the language Development Survey, by comparing screening with the individually administered language scores of the Bayley Scales of Infant and Toddler Development, Third edition. METHOD: In total, 310 (92.5%) of 335 eligible term-born children, born between 2004 and 2011, receiving complex cardiac surgery, heart or liver transplantation, or extracorporeal membrane oxygenation in infancy, were assessed at 21.5 (2.8) months of age (lost, 25 (7.5%)), through developmental/rehabilitation centres at six sites as part of the Western Canadian Complex Pediatric Therapies Follow-up Group. RESULTS: Vocabulary screening delay was defined as scores ⩽15th percentile. Language delay defined as scores >1 SD below the mean was calculated for language composite score, receptive and expressive communication scores of the Bayley-III. Delayed scores for the 310 children were as follows: vocabulary, 144 (46.5%); language composite, 125 (40.3%); receptive communication, 98 (31.6%); and expressive communication, 124 (40%). Sensitivity, specificity, positive predictive values, and negative predictive values of screened vocabulary delay for tested language composite delay were 79.2, 75.7, 68.8, and 84.3%, respectively. CONCLUSION: High rates of language delay after life-saving therapies are concerning. Although the screening test appears to over-identify language delay relative to the tested Bayley-III, it may be a useful screening tool for early language development leading to earlier referral for intervention.

Confounding Effect in Clinical Research of Otolaryngology and Its Control.

Confounding effect is a critical issue in clinical research of otolaryngology because it can distort the research's conclusion. In this review, we introduce the definition of confounding effect, the methods of verifying and controlling the effect. Confounding effect can be prevented by research's design, and adjusted by data analysis. Clinicians would be aware and cautious about confounding effect in their research. They would be able to set up a research's design in which appropriate methods have been applied to prevent this effect.They would know how to adjust confounding effect after data collection. It is important to remember that sometimes it is impossible to eliminate confounding effect completely, and statistical method is not a master key. Solid research knowledge and critical thinking of our brain are the most important in controlling confounding effect.

Genetic Effects on Sensorineural Hearing Loss and Evidence-based Treatment for Sensorineural Hearing Loss.

In this article, the mechanism of inheritance behind inherited hearing loss and genetic susceptibility in noise-induced hearing loss are reviewed. Conventional treatments for sensorineural hearing loss (SNHL), i.e. hearing aid and cochlear implant, are effective for some cases, but not without limitations. For example, they provide little benefit for patients of profound SNHL or neural hearing loss, especially when the hearing loss is in poor dynamic range and with low frequency resolution. We emphasize the most recent evidence-based treatment in this field, which includes gene therapy and allotransplantation of stem cells. Their promising results have shown that they might be options of treatment for profound SNHL and neural hearing loss. Although some treatments are still at the experimental stage, it is helpful to be aware of the novel therapies and endeavour to explore the feasibility of their clinical application.

Supporting the mental health of children and youth of separating parents.

The rising international trend in the number of parents who separate or divorce is raising concerns about long-term consequences for child and youth well-being and adjustment to adulthood. Separation and divorce may increase risks for negative outcomes in physical, mental, educational and psychosocial well-being during childhood and later, as youth transition to adulthood. Most children of separated and divorced families do not have significant or diagnosable impairments. Family processes that have a positive mediating effect on child well-being after parental divorce or separation include improving the quality of parenting, improving the quality of parent-child relationships and controlling hostile conflict. Physicians can offer support and guidance to separating parents by helping them to identify risk factors, strengthen protective factors and enhance children's capacity to cope with family changes.

La tendance internationale croissante des divorces et des séparations soulève des inquiétudes quant aux conséquences à long terme pour le bien-être des enfants et des adolescents et leur adaptation à la vie adulte. La séparation et le divorce peuvent accroître le risque d'issues négatives en matière de bien-être physique, mental, éducatif et psychosocial pendant l'enfance et par la suite, lorsque les adolescents passent à l'âge adulte. La plupart des enfants de familles séparées et divorcées ne présentent pas d'atteintes importantes ou pouvant être diagnostiquées. Certaines dynamiques familiales ont un effet positif important sur le bien-être de l'enfant après le divorce ou la séparation de ses parents, soit l'amélioration de la qualité des pratiques parentales, l'amélioration de la qualité de la relation parent­enfant et le contrôle des conflits hostiles. Les médecins peuvent offrir du soutien et des conseils aux parents qui se séparent en les aidant à déterminer les facteurs de risque, à renforcer les facteurs protecteurs et à améliorer la capacité des enfants à s'adapter aux changements familiaux.

Health care impact of implementing a clinical pathway for acute care of pediatric concussion: a stepped wedge, cluster randomised trial.

OBJECTIVES: To test the effects of actively implementing a clinical pathway for acute care of pediatric concussion on health care utilization and costs. METHODS: Stepped wedge, cluster randomized trial of a clinical pathway, conducted in 5 emergency departments (ED) in Alberta, Canada from February 1 to November 30, 2019. The clinical pathway emphasized standardized assessment of risk for persistent symptoms, provision of consistent information to patients and families, and referral for outpatient follow-up. De-identified administrative data measured 6 outcomes: ED return visits; outpatient follow-up visits; length of ED stay, including total time, time from triage to physician initial assessment, and time from physician initial assessment to disposition; and total physician claims in an episode of care. RESULTS: A total of 2878 unique patients (1164 female, 1713 male) aged 5-17 years (median 11.00, IQR 8, 14) met case criteria. They completed 3009 visits to the 5 sites and 781 follow-up visits to outpatient care, constituting 2910 episodes of care. Implementation did not alter the likelihood of an ED return visit (OR 0.77, 95% CI 0.39, 1.52), but increased the likelihood of outpatient follow-up visits (OR 1.84, 95% CI 1.19, 2.85). Total length of ED stay was unchanged, but time from physician initial assessment to disposition decreased significantly (mean change - 23.76 min, 95% CI - 37.99, - 9.52). Total physician claims increased significantly at only 1 of 5 sites. CONCLUSIONS: Implementation of a clinical pathway in the ED increased outpatient follow-up and reduced the time from physician initial assessment to disposition, without increasing physician costs. Implementation of a clinical pathway can align acute care of pediatric concussion more closely with existing clinical practice guidelines while making care more efficient. TRIAL REGISTRATION: ClinicalTrials.gov NCT05095012.

ABSTRAIT: OBJECTIFS: Mettre à l'essai les effets de la mise en œuvre active d'une voie clinique pour le traitement aigu des commotions cérébrales chez les enfants sur l'utilisation et les coûts des soins de santé. MéTHODES: Essai randomisé en grappes d'une voie clinique, échelonné, mené dans cinq services d'urgence en Alberta, au Canada, du 1 février au 30 novembre 2019. Le cheminement clinique mettait l'accent sur l'évaluation normalisée du risque de symptômes persistants, la fourniture de renseignements uniformes aux patients et aux familles, et l'aiguillage vers un suivi externe. Les données administratives dépersonnalisées ont permis de mesurer six résultats : visites de retour à l'urgence; visites de suivi en clinique externe; durée du séjour à l'urgence, y compris le temps total. le temps entre le triage et l'évaluation initiale du médecin, et le temps entre l'évaluation initiale du médecin et la décision; et le nombre total de demandes de remboursement du médecin dans un épisode de soins. RéSULTATS: Un total de 2878 patients uniques (1164 femmes, 1713 hommes) âgés de 5 à 17 ans (médiane 11,00, IQR 8, 14) répondaient aux critères de cas. Ils ont effectué 3009 visites aux 5 sites et 781 visites de suivi aux soins ambulatoires, ce qui représente 2910 épisodes de soins. La mise en œuvre n'a pas modifié la probabilité d'une visite de retour à l'urgence (RC 0,77, IC à 95 %, 0,39, 1,52), mais a augmenté la probabilité de visites de suivi en clinique externe (RC 1,84, IC à 95 %, 1,19, 2,85). La durée totale du séjour à l'urgence est demeurée inchangée, mais le temps écoulé entre l'évaluation initiale du médecin et la décision a diminué considérablement (changement moyen : -23,76 minutes, IC à 95 %, -37,99, -9,52). Le nombre total de demandes de règlement de médecins a augmenté de façon significative à seulement 1 site sur 5. CONCLUSIONS: La mise en œuvre d'un cheminement clinique à l'urgence a augmenté le suivi des patients externes et réduit le temps entre l'évaluation initiale du médecin et son élimination, sans augmenter les coûts des médecins. La mise en œuvre d'un cheminement clinique peut harmoniser davantage les soins de courte durée en cas de commotion cérébrale pédiatrique avec les lignes directrices de pratique clinique existantes tout en rendant les soins plus efficaces. ENREGISTREMENT D'ESSAI: ClinicalTrials.gov NCT05095012.

Medical physics staffing for radiation oncology: a decade of experience in Ontario, Canada.

The January 2010 articles in The New York Times generated intense focus on patient safety in radiation treatment, with physics staffing identified frequently as a critical factor for consistent quality assurance. The purpose of this work is to review our experience with medical physics staffing, and to propose a transparent and flexible staffing algorithm for general use. Guided by documented times required per routine procedure, we have developed a robust algorithm to estimate physics staffing needs according to center-specific workload for medical physicists and associated support staff, in a manner we believe is adaptable to an evolving radiotherapy practice. We calculate requirements for each staffing type based on caseload, equipment inventory, quality assurance, educational programs, and administration. Average per-case staffing ratios were also determined for larger-scale human resource planning and used to model staffing needs for Ontario, Canada over the next 10 years. The workload specific algorithm was tested through a survey of Canadian cancer centers. For center-specific human resource planning, we propose a grid of coefficients addressing specific workload factors for each staff group. For larger scale forecasting of human resource requirements, values of 260, 700, 300, 600, 1200, and 2000 treated cases per full-time equivalent (FTE) were determined for medical physicists, physics assistants, dosimetrists, electronics technologists, mechanical technologists, and information technology specialists, respectively.

Design and Testing of a Smartphone Application for Real-Time Tracking of CSII and CGM Site Rotation Compliance in Patients With Type 1 Diabetes.

INTRODUCTION: Glycemic control in patients with type 1 diabetes can be difficult to achieve. One critical aspect of insulin delivery is site rotation, which is necessary to reduce dermatologic complications of repeated insulin infusion. No current application is designed to help patients track sites and instruct on overused sites. OBJECTIVE: The objectives of this study were to (1) design a smartphone app, Insulin Site Guide, to gather real-time information on continuous subcutaneous insulin infusion (CSII) and continuous glucose monitor (CGM) site location and rotation compliance and instruct subjects on the use of an overused site; (2) conduct a usability study to measure site rotation compliance; and (3) report subject satisfaction with the app. DESIGN: The app is installed on the subject's smartphone. Subjects use the app to record CSII and CGM placement in real-time. Data are sent to the study team at the end of the study. Subjects complete a questionnaire concerning the app. RESULTS: We report site rotation compliance data for eight subjects and survey responses for 10 subjects. Initial data from eight subjects indicate a high site rotation compliance of 84% for insulin pumps. In general, the majority of users indicate high satisfaction with the app. CONCLUSIONS: Insulin Site Guide is a mobile app that uses a novel algorithm to better guide site rotation. Use of the app has the potential to improve site rotation and decrease dermatologic complications of diabetes with long-term use.

Position-probability-sampled Monte Carlo calculation of VMAT, 3DCRT, step-shoot IMRT, and helical tomotherapy dose distributions using BEAMnrc/DOSXYZnrc.

PURPOSE: The commercial release of volumetric modulated arc therapy techniques using a conventional linear accelerator and the growing number of helical tomotherapy users have triggered renewed interest in dose verification methods, and also in tools for exploring the impact of machine tolerance and patient motion on dose distributions without the need to approximate time-varying parameters such as gantry position, MLC leaf motion, or patient motion. To this end we have developed a Monte Carlo-based calculation method capable of simulating a wide variety of treatment techniques without the need to resort to discretization approximations. METHODS: The ability to perform complete position-probability-sampled Monte Carlo dose calculations was implemented in the BEAMnrc/DOSXZYnrc user codes of EGSnrc. The method includes full accelerator head simulations of our tomotherapy and Elekta linacs, and a realistic representation of continous motion via the sampling of a time variable. The functionality of this algorithm was tested via comparisons with both measurements and treatment planning dose distributions for four types of treatment techniques: 3D conformal, step-shoot intensity modulated radiation therapy, helical tomotherapy, and volumetric modulated are therapy. RESULTS: For static fields, the absolute dose agreement between the EGSnrc Monte Carlo calculations and measurements is within 2%/1 mm. Absolute dose agreement between Monte Carlo calculations and treatment planning system for the four different treatment techniques is within 3%/3 mm. Discrepancies with the tomotherapy TPS on the order of 10%/5 mm were observed for the extreme example of a small target located 15 cm off-axis and planned with a low modulation factor. The increase in simulation time associated with using position-probability sampling, as opposed to the discretization approach, was less than 2% in most cases. CONCLUSIONS: A single Monte Carlo simulation method can be used to calculate patient dose distribution for various types of treatment techniques delivered with either tomotherapy or a conventional linac. The method simplifies the simulation process, improves dose calculation accuracy, and involves an acceptably small change in computation time.

Integration of on-line imaging, plan adaptation and radiation delivery: proof of concept using digital tomosynthesis.

The main objective of this manuscript is to propose a new approach to on-line adaptive radiation therapy (ART) in which daily image acquisition, plan adaptation and radiation delivery are integrated together and performed concurrently. A method is described in which on-line ART is performed based on intra-fractional digital tomosynthesis (DTS) images. Intra-fractional DTS images were reconstructed as the gantry rotated between treatment positions. An edge detection algorithm was used to automatically segment the DTS images as the gantry arrived at each treatment position. At each treatment position, radiation was delivered based on the treatment plan re-optimized for the most recent DTS image contours. To investigate the feasibility of this method, a model representing a typical prostate, bladder and rectum was used. To simulate prostate deformations, three clinically relevant, non-rigid deformations (small, medium and large) were modeled by systematically deforming the original anatomy. Using our approach to on-line ART, the original treatment plan was successfully adapted to arrive at a clinically acceptable plan for all three non-rigid deformations. In conclusion, we have proposed a new approach to on-line ART in which plan adaptation is performed based on intra-fractional DTS images. The study findings indicate that this approach can be used to re-optimize the original treatment plan to account for non-rigid anatomical deformations. The advantages of this approach are 1) image acquisition and radiation delivery are integrated in a single gantry rotation around the patient, reducing the treatment time, and 2) intra-fractional DTS images can be used to detect and correct for patient motion prior to the delivery of each beam (intra-fractional patient motion).

Systematic reviews of psychosocial interventions for autism: an umbrella review.

AIM: A wide range of psychosocial interventions for the treatment of individuals with autism-spectrum disorders (ASDs) have been evaluated in systematic reviews. We conducted an umbrella review of systematic reviews of the effectiveness of psychosocial interventions for ASD. METHOD: Comprehensive searches were conducted in 25 bibliographic databases, relevant journals and reference lists up to May 2007. Studies included were systematic reviews on any psychosocial intervention for individuals with ASDs. Two reviewers independently assessed study relevance and quality. RESULTS: Thirty systematic reviews were included. The majority of reviews evaluated interventions based on behavioural theory (n=9) or communication-focused (n=7) therapies. Positive intervention outcomes were reported in the majority of the reviews. Methodological quality of the reviews was generally poor. INTERPRETATION: The reviews reported positive outcomes for many of the interventions, suggesting that some form of treatment is favourable over no treatment. However, there is little evidence for the relative effectiveness of these treatment options. Many of the systematic reviews had methodological weaknesses that make them vulnerable to bias. There is a need for further systematic reviews that adhere to strict scientific methods and for primary studies that make direct comparisons between different treatment options.

On-line rapid palliation using helical tomotherapy: a prospective feasibility study.

Rapid delivery of radiation therapy is expected to benefit patients requiring palliation. We investigated the feasibility of employing a helical tomotherapy unit to scan, plan, and deliver a radiation treatment in a single radiation therapy appointment. Eleven patients each had an MVCT scan acquired, a plan created, and delivery completed while the patient was on the treatment couch. Timelines for each step of the process were recorded for each patient, and compared with the conventional process for similar patients. Preliminary results show that patients routinely can be treated within a 1 hour appointment for the first fraction.

Anniversary Paper: the role of medical physicists in developing stereotactic radiosurgery.

This article is a tribute to the pioneering medical physicists over the last 50 years who have participated in the research, development, and commercialization of stereotactic radiosurgery (SRS) and stereotactic radiotherapy utilizing a wide range of technology. The authors have described the evolution of SRS through the eyes of physicists from its beginnings with the Gamma Knife in 1951 to proton and charged particle therapy; modification of commercial linacs to accommodate high precision SRS setups; the multitude of accessories that have enabled fine tuning patients for relocalization, immobilization, and repositioning with submillimeter accuracy; and finally the emerging technology of SBRT. A major theme of the article is the expanding role of the medical physicist from that of advisor to the neurosurgeon to the current role as a primary driver of new technology that has already led to an adaptation of cranial SRS to other sites in the body, including, spine, liver, and lung. SRS continues to be at the forefront of the impetus to provide technological precision for radiation therapy and has demonstrated a host of downstream benefits in improving delivery strategies for conventional therapy as well. While this is not intended to be a comprehensive history, and the authors could not delineate every contribution by all of those working in the pursuit of SRS development, including physicians, engineers, radiobiologists, and the rest of the therapy and dosimetry staff in this important and dynamic radiation therapy modality, it is clear that physicists have had a substantial role in the development of SRS and theyincreasingly play a leading role in furthering SRS technology.

Direct aperture optimization for online adaptive radiation therapy.

This paper is the first investigation of using direct aperture optimization (DAO) for online adaptive radiation therapy (ART). A geometrical model representing the anatomy of a typical prostate case was created. To simulate interfractional deformations, four different anatomical deformations were created by systematically deforming the original anatomy by various amounts (0.25, 0.50, 0.75, and 1.00 cm). We describe a series of techniques where the original treatment plan was adapted in order to correct for the deterioration of dose distribution quality caused by the anatomical deformations. We found that the average time needed to adapt the original plan to arrive at a clinically acceptable plan is roughly half of the time needed for a complete plan regeneration, for all four anatomical deformations. Furthermore, through modification of the DAO algorithm the optimization search space was reduced and the plan adaptation was significantly accelerated. For the first anatomical deformation (0.25 cm), the plan adaptation was six times more efficient than the complete plan regeneration. For the 0.50 and 0.75 cm deformations, the optimization efficiency was increased by a factor of roughly 3 compared to the complete plan regeneration. However, for the anatomical deformation of 1.00 cm, the reduction of the optimization search space during plan adaptation did not result in any efficiency improvement over the original (nonmodified) plan adaptation. The anatomical deformation of 1.00 cm demonstrates the limit of this approach. We propose an innovative approach to online ART in which the plan adaptation and radiation delivery are merged together and performed concurrently-adaptive radiation delivery (ARD). A fundamental advantage of ARD is the fact that radiation delivery can start almost immediately after image acquisition and evaluation. Most of the original plan adaptation is done during the radiation delivery, so the time spent adapting the original plan does not increase the overall time the patient has to spend on the treatment couch. As a consequence, the effective time allotted for plan adaptation is drastically reduced. For the 0.25, 0.5, and 0.75 cm anatomical deformations, the treatment time was increased by only 2, 4, and 6 s, respectively, as compared to no plan adaptation. For the anatomical deformation of 1.0 cm the time increase was substantially larger. The anatomical deformation of 1.0 cm represents an extreme case, which is rarely observed for the prostate, and again demonstrates the limit of this approach. ARD shows great potential for an online adaptive method with minimal extension of treatment time.

Hearing preservation following fractionated stereotactic radiotherapy for vestibular schwannomas: prognostic implications of cochlear dose.

OBJECT: The goal in this study was to evaluate hearing preservation rates and to determine prognostic factors for this outcome following fractionated stereotactic radiotherapy (FSRT) of vestibular schwannoma. METHODS: Thirty-four consecutive patients with serviceable hearing who received FSRT between May 1998 and December 2003 were identified. Clinical and audiometry data were collected prospectively. The prescription dose was 45 Gy in 25 fractions prescribed to the 90% isodose line. The median follow-up duration was 36.5 months (range 12-85 months). The actuarial 2- and 4-year local control rates were 100 and 95.7%, respectively. Permanent trigeminal and facial nerve complications were 0 and 6%, respectively. The actuarial 2- and 3-year serviceable hearing preservation rates were both 63%. The median loss in speech reception threshold was 15 dB (range--10 to 65 dB). The radiotherapy dose to the cochlea was the only significant prognostic factor for hearing deterioration. Radiotherapy dose to the cochlear nucleus, patient age, sex, pre-FSRT hearing grade, tumor volume, and intracanalicular tumor volume failed to show any significance as prognostic factors. RESULTS: Five cases were replanned with four different radiotherapy techniques (namely arcs, dynamic arcs, static conformal fields, and intensity-modulated radiotherapy), with the cochlea defined as an organ at risk. In all cases, replanning resulted in statistically significant reduction in radiation to the cochlea (p = 0.001); however, no single replanning technique was found to be superior. CONCLUSIONS: The radiation dose to the cochlea is strongly predictive for subsequent hearing deterioration. It is essential for the cochlea to be outlined as an organ at risk, and for radiation techniques to be optimized, to improve long-term hearing preservation.