Gender differences in outcomes following endoscopic sinus surgery: a systematic review and meta-analysis.

BACKGROUND: The extent to which gender affects outcomes in chronic rhinosinusitis (CRS) is unclear. The objective of this study was to examine differential outcomes between genders following endoscopic sinus surgery (ESS) among CRS patients. METHODS: PubMed/Ovid, Embase and Cochrane databases were queried. Outcomes included disease burden on imaging and endoscopy, patient-reported outcome measures (PROMs) including the Sinonasal Outcome Test (SNOT-22), revision rates, and olfactory outcomes. Meta-analysis was performed using the Mantel-Haenszel method with random effects model. RESULTS: Of 4,656 articles screened, 32 (n=103,499) were included for qualitative analysis and four (n=2,602) for meta-analysis. On qualitative analysis, 19 of the 32 studies noted a significant gender difference in post-operative outcomes, with five studies favoring women and 14 favoring men. Nine of 18 studies with PROMs noted a difference between genders, all favoring men. Olfactory outcomes were mixed with studies divided on favoring men vs women. No studies noted significant gender differences of disease burden on imaging or endoscopy. Across four studies included in the meta-analysis, women had higher preoperative and post-operative SNOT-22 scores. CONCLUSION: Meta-analysis shows that women patients have worse pre and postoperative SNOT-22 scores. Postoperative gender differences are most apparent in studies that examined PROMs. Further research is needed to investigate the underlying causes and to mitigate disparities between genders.

Patients' acceptability of self-selected digital health services to support diet and exercise among people with complex chronic conditions: Mixed methods study.

Objective: The acceptability of being offered a choice from a suite of digital health service options to support optimal diet and exercise behaviors in adults with complex chronic conditions was evaluated. This study sought to understand many areas of acceptability including satisfaction, ease of use, usefulness and user appropriateness and perceived effectiveness. Methods: This mixed-methods study was embedded within a randomized-controlled feasibility trial providing digital health services managing diet and exercise for adults from specialist kidney and liver disease clinics. Post study surveys and semistructured interviews were used to determine patients' acceptability of the trial interventions. Quantitative (surveys) and qualitative (surveys and interviews) results were merged using integrative analysis and mapped to each construct of the modified version of the Theoretical Framework of Acceptability. Results: Seventeen interviews (intervention group) and 50 surveys (n = 24 intervention, n = 26 comparator) completed from a possible 67 participants were analyzed. In the intervention group, the survey results revealed high areas of acceptability for the digital health services including overall support received, ease of use, timely advice and feeling safe. The interviews also revealed high areas of acceptability including convenience, ability to adopt healthier behaviors and having regular interactions with health professionals. However, the interviews also revealed lower areas of acceptability as a result of absence of individualization, low digital literacy, and limitations from life circumstances. Conclusions: Recipients of digital health services that supported diet and exercise interventions found these useful, effective, and safe. Individualized care, technical support and patient confidence remain important to improve the acceptability of digital health service interventions.

Tetanus prophylaxis in horses: guidelines for New Zealand and Australia based on a critical appraisal of the evidence.

Horses are exquisitely sensitive to tetanus neurotoxin and are exposed to the risk of infection with Clostridium tetani throughout life. The vaccine against tetanus is highly effective at preventing disease, whereas tetanus in unvaccinated populations is associated with high mortality rates. Current guidelines in New Zealand and Australia for the available vaccine contain contradictions and limitations surrounding the optimal tetanus immunisation protocols for both adult horses and foals. This review critically evaluates the scientific literature on tetanus prophylaxis in horses within the context of equine practice and available products in New Zealand and Australia. The review was conducted by a panel of industry and specialist veterinarians to obtain agreement on nine equine tetanus prophylaxis guidelines for practising veterinarians. The primary protocol for tetanus toxoid (TT) immunisation consists of a three-dose series IM for all horses ≥ 6 months of age, and a four-dose series IM is proposed if commencing vaccination in foals between 3 and 6 months of age. Tetanus prophylaxis in foals < 3 months of age relies on passive immunity strategies. Following the completion of the primary protocol, a TT booster dose IM should be administered within 5 years, and every 5 years thereafter. When followed, these protocols should provide adequate protection against tetanus in horses. Additional tetanus prophylaxis guidelines are provided for veterinarians attending a horse experiencing a known "risk event" (e.g. wound, hoof abscess, surgery, umbilical infection). When a correctly vaccinated horse experiences a risk event, pre-existing immunity provides protection against tetanus. When an unvaccinated horse or one with unknown vaccination status, or a foal born to an unvaccinated dam, experiences a risk event, TT IM and tetanus antitoxin (TAT) 1,500 IU SC should be administered simultaneously at separate sites, and the TT primary immunisation protocol should subsequently be completed for the horse's respective age. In previously immunised pregnant broodmares, a TT booster dose administered 4-8 weeks prior to parturition optimises the transfer of passive immunity against tetanus to the newborn foal via colostrum; provided that post-natal IgG concentration in serum is > 800 mg/dL (8 g/L), such foals should be passively protected against tetanus up to 6 months of age. Survivors of clinical tetanus must still receive the primary protocol for vaccination against tetanus. In summary, all horses in New Zealand and Australia should be vaccinated against tetanus with protection maintained throughout life via TT booster doses, facilitated by accurate medical record keeping and client education.

Evaluating the Potential of a Novel Metabolic Syndrome Severity Score to Inform Exercise Interventions for People with Complex Chronic Conditions.

Aims: Exercise interventions positively affect numerous cardiometabolic risk factors. To better evaluate the health effects of exercise training, it may be more appropriate to evaluate risk factors together. The Metabolic Syndrome Severity Score (MetSSS) is a composite score representing cardiometabolic risk. Purpose: To evaluate the relationships between physical activity, neuromuscular fitness, exercise capacity, and the MetSSS in a heterogenous sample of people with complex chronic disease. Material and Methods: Fifty-three people with kidney or liver disease and at least one feature of the metabolic syndrome (MetS) were included. Pearson correlations were conducted between physical activity, neuromuscular fitness, exercise capacity, and the MetSSS. Linear regressions were performed for multi-level categorical variables. Independent variables with an association with MetSSS (P ≤ 0.2) were included in a multiple regression analysis. Results: The 6-minute walk test (6MWT) distance was inversely and independently associated with MetSSS [standardized beta coefficient (ß) = -0.31, P = 0.04]. No relationship was found between MetSSS and physical activity or neuromuscular fitness. Mean 6MWT in the highest tertile was 550 m (range: 505-620 m) and 346 m (range: 233-408 m) in the lowest. The analysis showed a medium-large between-group effect for the difference in MetSSS for the lowest and highest tertile of 6MWT [Eta squared (η2) = 0.16, P = 0.01]. Conclusions: Exercise capacity was inversely and independently associated with MetSSS in people with complex chronic disease. Clinical trials with exercise interventions are needed to further investigate if improvements in exercise capacity result in clinically significant changes in the MetSSS.

A dynamic compositional equilibrium governs mRNA recognition by eIF3.

Eukaryotic translation initiation factor (eIF) 3 is a multi-subunit protein complex that binds both ribosomes and messenger RNAs (mRNAs) in order to drive a diverse set of mechanistic steps during translation. Despite its importance, a unifying framework explaining how eIF3 performs these numerous activities is lacking. Using single-molecule light scattering microscopy, we demonstrate that Saccharomyces cerevisiae eIF3 is an equilibrium mixture of the full complex, subcomplexes, and subunits. By extending our microscopy approach to an in vitro reconstituted eIF3 and complementing it with biochemical assays, we define the subspecies comprising this equilibrium and show that, rather than being driven by the full complex, mRNA binding by eIF3 is instead driven by the eIF3a subunit within eIF3a-containing subcomplexes. Our findings provide a mechanistic model for the role of eIF3 in the mRNA recruitment step of translation initiation and establish a mechanistic framework for explaining and investigating the other activities of eIF3.

Development of a multidimensional military readiness assessment.

There is a need to be able to accurately evaluate whether an injured service member is able to return to duty. An effective assessment would challenge and measures physical and cognitive performance in a military-relevant context. Current assessments are lacking in one or more of these aspects. The simulation and data capture abilities of virtual reality systems are promising for use as the basis of multidimensional assessments. The team has previously developed a military-specific assessment in the Computer Assisted Rehabilitation Environment (CAREN) called the Readiness Evaluation During simulated Dismounted Operations (REDOp). Due to notable limitations in the original assessment, we have developed the next iteration, REDOp2. The assessment is able to challenge and measure a broader range of physical and cognitive performance domains in a more streamlined fashion. While limited to facilities with a CAREN, REDOp2 has the potential to provide an effective tool for highly trained and experienced wounded service members that require thorough assessment prior to returning to duty to ensure the safety of the team and mission. This methods paper describes the specific limitations in REDOp, how they were addressed in REDOp2, and suggested next steps to prepare the assessment for implementation.

Exercise care by general practitioners: Providing sustainable solutions for patients living with chronic disease.

BACKGROUND: Most Australian adults are insufficiently physically active, creating an economic and moral imperative to support exercise care in general practice. OBJECTIVE: To provide an overview of exercise care in general practice to support sustained solutions for patients living with chronic disease. DISCUSSION: Exercise care should be considered a fundamental component of high-quality consultations, including assessing, advocating and monitoring for physical activity. Exercise levels and cardiorespiratory fitness can be considered 'vital signs' for tracking over time. Modest gains in physical activity levels have clinical benefits, warranting approaches that engage patients in any amount of time in exercise. Resources are available to support general practitioners (GPs) to incorporate exercise care into routine consultations. GPs can print or save the links provided in this paper and use platforms such as GoShare to connect patients to the resources. Over 15 exercise-specific clinical practice guides are available through The Royal Australian College of General Practitioners' Handbook of non-drug interventions.

Custom-Trained Deep Learning-Based Auto-Segmentation for Male Pelvic Iterative CBCT on C-Arm Linear Accelerators.

PURPOSE: The purpose of this investigation was to evaluate the clinical applicability of a commercial artificial intelligence-driven deep learning auto-segmentation (DLAS) tool on enhanced iterative cone beam computed tomography (iCBCT) acquisitions for intact prostate and prostate bed treatments. METHODS AND MATERIALS: DLAS models were trained using 116 iCBCT data sets with manually delineated organs at risk (bladder, femoral heads, and rectum) and target volumes (intact prostate and prostate bed) adhering to institution-specific contouring guidelines. An additional 25 intact prostate and prostate bed iCBCT data sets were used for model testing. Segmentation accuracy relative to a reference structure set was quantified using various geometric comparison metrics and qualitatively evaluated by trained physicists and physicians. These results were compared with those obtained for an additional DLAS-based model trained on planning computed tomography (pCT) data sets and for a deformable image registration (DIR)-based automatic contour propagation method. RESULTS: In most instances, statistically significant differences in the Dice similarity coefficient (DSC), 95% directed Hausdorff distance, and mean surface distance metrics were observed between the models, as the iCBCT-trained DLAS model outperformed the pCT-trained DLAS model and DIR-based method for all organs at risk and the intact prostate target volume. Mean DSC values for the proposed method were ≥0.90 for these volumes of interest. The iCBCT-trained DLAS model demonstrated a relatively suboptimal performance for the prostate bed segmentation, as the mean DSC value was <0.75 for this target contour. Overall, 90% of bladder, 93% of femoral head, 67% of rectum, and 92% of intact prostate contours generated by the proposed method were deemed clinically acceptable based on qualitative scoring, and approximately 63% of prostate bed contours required moderate or major manual editing to adhere to institutional contouring guidelines. CONCLUSIONS: The proposed method presents the potential for improved segmentation accuracy and efficiency compared with the DIR-based automatic contour propagation method as commonly applied in CBCT-based dose evaluation and calculation studies.

Expression of MHC II in DRG neurons attenuates paclitaxel-induced cold hypersensitivity in male and female mice.

Chemotherapy is often a life-saving treatment, but the development of intractable pain caused by chemotherapy-induced peripheral neuropathy (CIPN) is a major dose-limiting toxicity that restricts cancer survival rates. Recent reports demonstrate that paclitaxel (PTX) robustly increases anti-inflammatory CD4+ T cells in the dorsal root ganglion (DRG), and that T cells and anti-inflammatory cytokines are protective against CIPN. However, the mechanism by which CD4+ T cells are activated, and the extent cytokines released by CD4+ T cells target DRG neurons are unknown. Here, we are the first to detect major histocompatibility complex II (MHCII) protein in mouse DRG neurons and to find CD4+ T cells breaching the satellite glial cell barrier to be in close proximity to neurons, together suggesting CD4+ T cell activation and targeted cytokine release. MHCII protein is primarily expressed in small nociceptive neurons in male and female mouse DRG but increased after PTX in small nociceptive neurons in only female DRG. Reducing one copy of MHCII in small nociceptive neurons decreased anti-inflammatory IL-10 and IL-4 producing CD4+ T cells in naïve male DRG and increased their hypersensitivity to cold. Administration of PTX to male and female mice that lacked one copy of MHCII in nociceptive neurons decreased anti-inflammatory CD4+ T cells in the DRG and increased the severity of PTX-induced cold hypersensitivity. Collectively, our results demonstrate expression of MHCII protein in mouse DRG neurons, which modulates cytokine producing CD4+ T cells in the DRG and attenuates cold hypersensitivity during homeostasis and after PTX treatment.

Clinical-pathologic correlation: The impact of grossing at the bedside.

The unenlightened clinician may submit a skin specimen to the lab and expect an "answer." The experienced clinician knows that in performing skin biopsies, it is critical to select the most appropriate: 1) anatomic location for the biopsy1,2; 2) type of biopsy1,2; 3) depth and breadth of the biopsy; and 4) medium for hematoxylin and eosin staining (formalin) or direct immunofluorescence (Michel's Transport Medium or normal saline).2 Demographic information, anatomic location, clinical context, and differential diagnosis are all critical components of a properly completed requisition form.3-5 Proper biopsy design and appropriate grossing of the tissue at the bedside should be added to this list. In this article, we review the basics of gross pathologic examination and then provide four examples to demonstrate that optimal clinical-pathologic correlation requires the clinician consider the needs of the pathologist when tissue is presented to the lab.

Rapid, label-free enrichment of lymphocytes in a closed system using a flow-through microfluidic device.

The majority of adoptive cellular therapies are produced from peripheral mononuclear cells obtained via leukapheresis and further enriched for the cells of interest (e.g., T cells). Here, we present a first-of-its-kind closed system, which effectively removes ~85% of monocytes and ~88% of platelets, while recovering ~88% of concentrated T cells in a separate output stream, as the leukapheresis sample flows through a microfluidic device at 5 mL/min. The system is driven by a common peristaltic pump, enabled by a novel pressure wave dampener, and operates in a closed bag-to-bag configuration, without requiring any specialized, dedicated equipment. When compared to standard density gradient centrifugation on paired samples, the new system demonstrated a 1.5-fold increase in T cell recovery and a 2-fold reduction in inter-sample variability for this separation outcome. The T cell-to-monocyte ratio of the leukapheresis sample was increased to 20:1, whereas with density gradient processing it decreased to 2:1. As a result of superior purity and/or gentler processing, T cells enriched by the system showed a 2.7-times higher fold expansion during subsequent culture, and an overall 3.5-times higher cumulative yield. This centrifugation-free and label-free closed system for enriching lymphocytes could significantly simplify and standardize the manufacturing of life-saving cellular therapies.

Genetic Silencing of AKT Induces Melanoma Cell Death via mTOR Suppression.

Aberrant activation of the PI3K-AKT pathway is common in many cancers, including melanoma, and AKT1, 2 and 3 (AKT1-3) are bona fide oncoprotein kinases with well-validated downstream effectors. However, efforts to pharmacologically inhibit AKT have proven to be largely ineffective. In this study, we observed paradoxical effects following either pharmacologic or genetic inhibition of AKT1-3 in melanoma cells. Although pharmacological inhibition was without effect, genetic silencing of all three AKT paralogs significantly induced melanoma cell death through effects on mTOR. This phenotype was rescued by exogenous AKT1 expression in a kinase-dependent manner. Pharmacological inhibition of PI3K and mTOR with a novel dual inhibitor effectively suppressed melanoma cell proliferation in vitro and inhibited tumor growth in vivo. Furthermore, this single-agent-targeted therapy was well-tolerated in vivo and was effective against MAPK inhibitor-resistant patient-derived melanoma xenografts. These results suggest that inhibition of PI3K and mTOR with this novel dual inhibitor may represent a promising therapeutic strategy in this disease in both the first-line and MAPK inhibitor-resistant setting.

Risk Assessment of Industrial Microbes Using a Terrestrial Mesocosm Platform.

Industrial microbes and bio-derived products have emerged as an integral component of the bioeconomy, with an array of agricultural, bioenergy, and biomedical applications. However, the rapid development of microbial biotechnology raises concerns related to environmental escape of laboratory microbes, detection and tracking thereof, and resultant impact upon native ecosystems. Indeed, though wild-type and genetically modified microbes are actively deployed in industrial bioprocesses, an understanding of microbial interactivity and impact upon the environment is severely lacking. In particular, the persistence and sustained ecosystem impact of industrial microbes following laboratory release or unintentional laboratory escape remains largely unexplored. Herein, we investigate the applicability of soil-sorghum mesocosms for the ecological risk assessment of the industrial microbe, Saccharomyces cerevisiae. We developed and applied a suite of diagnostic and bioinformatic analyses, including digital droplet PCR, microscopy, and phylogenomic analyses to assess the impacts of a terrestrial ecosystem perturbation event over a 30-day time course. The platform enables reproducible, high-sensitivity tracking of S. cerevisiae in a complex soil microbiome and analysis of the impact upon abiotic soil characteristics and soil microbiome population dynamics and diversity. The resultant data indicate that even though S. cerevisiae is relatively short-lived in the soil, a single perturbation event can have sustained impact upon mesocosm soil composition and underlying microbial populations in our system, underscoring the necessity for more comprehensive risk assessment and development of mitigation and biocontainment strategies in industrial bioprocesses.

Client and Clinician Experiences and Perspectives of Exercise Physiology Services During the COVID-19 Pandemic: Qualitative Study.

BACKGROUND: The COVID-19 pandemic led to changes in the delivery of exercise physiology services. The lived experience of those who continued to provide or receive exercise physiology services during the heightened public health restrictions of the inaugural year of the COVID-19 pandemic has received little attention to date. Acquiring this knowledge will be fundamental in addressing whether telehealth is a viable option for service delivery in exercise care, research, and policy. This is especially pertinent in the wake of the COVID-19 pandemic and subsequent global interest in digital health delivery of health care services. OBJECTIVE: This study aims to explore the clinician and client experiences and perspectives of exercise physiology services delivered in person or via telehealth during the inaugural year of the COVID-19 pandemic (after January 25, 2020; the date of the first confirmed case in Australia). METHODS: Eligible participants for this study were adult (aged 18 years or older; capable of understanding and writing in English) clients who received and clinicians who delivered 1 or more exercise physiology sessions in Australia during the first year of the COVID-19 pandemic (June 2020 to June 2021). The data collection period spanned from January 20, 2021, to September 24, 2021. A total of 18 semistructured individual interviews were conducted with accredited exercise physiologists (n=7) and clients (n=11) who engaged with exercise physiology services during this period. All interviews were digitally recorded and transcribed verbatim. Thematic analysis was conducted with themes and subthemes derived using deductive and inductive approaches. RESULTS: A total of 3 dominant themes, each with 2 subthemes, were identified. The first theme was that telehealth enables access to services but limits the use of some clinical tools. Remote access to services was valued by both clinicians and clients, but the exercise clinical environment could not be replicated over telehealth. This was especially true regarding access to exercise equipment. Second, engagement and the "relational space" are limited by telehealth. Perceived challenges regarding social interactions and a sense of community were a limitation for clients, and difficulties fostering clinician-client report were noted by clinicians. Finally, technological challenges are pervasive in the telehealth delivery of exercise services. Both clinicians and clients noted that systems necessary to facilitate telehealth frequently disrupted delivery, and client-based technical issues were influenced by digital health literacy. CONCLUSIONS: Shared client and accredited exercise physiologist experiences highlight key considerations for the ongoing implementation of telehealth to facilitate the uptake and effectiveness of exercise physiology services. These findings imply that the co-design of solutions to client-perceived limitations of telehealth delivery is warranted.

The mechanism of mRNA activation.

During translation initiation, messenger RNA molecules must be identified and activated for loading into a ribosome. In this rate-limiting step, the heterotrimeric protein eukaryotic initiation factor eIF4F must recognize and productively interact with the 7-methylguanosine cap at the 5' end of the messenger RNA and subsequently activate the message. Despite its fundamental, regulatory role in gene expression, the molecular events underlying cap recognition and messenger RNA activation remain mysterious. Here, we generate a unique, single-molecule fluorescence imaging system to interrogate the dynamics with which eIF4F discriminates productive and non-productive locations on full-length, native messenger RNA molecules. At the single-molecule level, we observe stochastic sampling of eIF4F along the length of the messenger RNA and identify allosteric communication between the eIF4F subunits which ultimately drive cap-recognition and subsequent activation of the message. Our experiments uncover novel functions for each subunit of eIF4F and we conclude by presenting a model for messenger RNA activation which precisely defines the composition of the activated message. This model provides a general framework for understanding how messenger RNA molecules may be discriminated from one another, and how other RNA-binding proteins may control the efficiency of translation initiation.

Are vertebrates constrained to two sets of paired appendages? The morphology, development, and evolution of pre-pelvic claspers in the Holocephali.

Holocephalans exhibit auxiliary appendages called pre-pelvic claspers (PPCs) that are located anterior to the pelvic fins, while pelvic claspers are pelvic fin modifications located posteriorly as modified metapterygia. Articulation points of the PPCs have not previously been imaged or evaluated in a comparative context, therefore, they may represent modified pelvic fin structures if they articulate with the propterygium. Alternatively, they could represent the only example of an independent third set of paired appendages in an extant taxon, if they articulate independently from any pelvic fin basal cartilages, challenging the current paradigm that extant jawed vertebrates are constrained to two sets of paired appendages. Two extinct groups, including Placoderms and Acanthodians, exhibit variation in the number of paired appendages, suggesting this may be a plesiomorphic trait. We evaluated PPC developmental growth rates, morphology, and articulation points in spotted ratfish (Hydrolagus Colliei, Holocephali). We also compared variation in PPC morphology among representatives of the three extant holocephalan families. Both, the pre-pelvic and pelvic claspers exhibit a dramatic surge in growth at sexual maturity, and then level off, suggesting synchronous development via shared hormonal regulation. While mature females are larger than males, pelvic fin growth and development is faster in males, suggesting a selective advantage to larger fins with faster development. Finally, microcomputed tomography scans revealed that PPCs are not modified propterygia, nor do they articulate with the propterygium. They articulate with the anterior pre-pelvic process on the anterior puboischiadic bar (or pelvic girdle), suggesting that while they are associated with the pelvic girdle, they may indeed represent a third, independent set of paired appendages in extant holocephalans.

Novel expression of major histocompatibility complex II in dorsal root ganglion neurons attenuates paclitaxel-induced cold hypersensitivity in male and female mice.

Chemotherapy is often a life-saving treatment, but the development of intractable pain caused by chemotherapy-induced peripheral neuropathy (CIPN) is a major dose-limiting toxicity that restricts survival rates. Recent reports demonstrate that paclitaxel (PTX) robustly increases anti-inflammatory CD4+ T cells in the dorsal root ganglion (DRG), and that T cells and anti-inflammatory cytokines are protective against CIPN. However, the mechanism by which CD4+ T cells are activated, and the extent cytokines released by CD4+ T cells target DRG neurons are unknown. Here, we found novel expression of functional major histocompatibility complex II (MHCII) protein in DRG neurons, and CD4+ T cells in close proximity to DRG neurons, together suggesting CD4+ T cell activation and targeted cytokine release. MHCII protein is primarily expressed in small nociceptive neurons in male mouse DRG regardless of PTX, while MHCII is induced in small nociceptive neurons in female DRG after PTX. Accordingly, reducing MHCII in small nociceptive neurons increased hypersensitivity to cold only in naive male mice, but increased severity of PTX-induced cold hypersensitivity in both sexes. Collectively, our results demonstrate expression of MHCII on DRG neurons and a functional role during homeostasis and inflammation.

Evaluating on-board kVCT- and MVCT-based dose calculation accuracy using a thorax phantom for helical tomotherapy treatments.

Purpose.To evaluate the impact of CT number calibration and imaging parameter selection on dose calculation accuracy relative to the CT planning process in thoracic treatments for on-board helical CT imaging systems used in helical tomotherapy.Methods and Materials.Direct CT number calibrations were performed with appropriate protocols for each imaging system using an electron density phantom. Large volume and SBRT treatment plans were simulated and optimized for planning CT scans of an anthropomorphic thorax phantom and transferred to registered kVCT and MVCT scans of the phantom as appropriate. Relevant DVH metrics and dose-difference maps were used to evaluate and compare dose calculation accuracy relative to the planning CT based on a variation in imaging parameters applied for the on-board systems.Results.For helical kVCT scans of the thorax phantom, median differences in DVH parameters for the large volume treatment plan were less than ±1% with dose to the target volume either over- or underestimated depending on the imaging parameters utilized for CT number calibration and thorax phantom acquisition. For the lung SBRT plan calculated on helical kVCT scans, median dose differences were up to -2.7% with a more noticeable dependence on parameter selection. For MVCT scans, median dose differences for the large volume plan were within +2% with dose to the target overestimated regardless of the imaging protocol.Conclusion.Accurate dose calculations (median errors of <±1%) using a thorax phantom simulating realistic patient geometry and scatter conditions can be achieved with images acquired with a helical kVCT system on a helical tomotherapy unit. This accuracy is considerably improved relative to that achieved with the MV-based approach. In a clinical setting, careful consideration should be made when selecting appropriate kVCT imaging parameters for this process as dose calculation accuracy was observed to vary with both parameter selection and treatment type.