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Purpose: The aim of this study is to investigate, from a dosimetric perspective, whether helical Tomotherapy (HT) during free breathing (FB) can serve as an alternative technique for treating left-sided breast cancer patients who are unable to comply with the deep inspiration breath hold (DIBH) technique. Material and Methods: For this purpose, the CT images of 20 left breast-only cancer patients acquired in both FB and DIBH phases were utilized. The left breast was contoured as the target volume, while the heart, LAD, ipsilateral and contralateral lungs, and contralateral breast were contoured as organs at risk on the CT images obtained in both DIBH and FB. Planning with the volumetric modulated arc therapy (VMAT) technique was performed on the CT scans obtained in the DIBH (VMAT-DIBH), while planning with the HT technique was carried out on the CT scans obtained in the FB (HT-FB). Subsequently, dosimetric comparison of the plans were done in terms of target coverage and preservation of normal tissues. Results: Both techniques achieved the desired target coverage; however, in terms of D2, Vpres values, Conformity Number (CN), and Homogeneity Index (HI), the HT-FB technique was found to be superior. While the mean doses to the heart were similar for both techniques, doses to the LAD and left lung were found to be superior in plans generated with the HT-FB technique. When compared in terms of contralateral breast and right lung protection, VMAT-DIBH technique was found to be significantly superior. Conclusion: The treatment of left breast-only patients with the HT-FB technique has been observed to provide similar heart protection and better LAD and ipsilateral lung protection compared to the VMAT-DIBH technique without compromising target coverage. However, when the HT-FB technique is used, doses to the contralateral lung and contralateral breast should be carefully evaluated.

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Catatonia is characterized by the loss of voluntary control over the workings of the mind and body. It disrupts daily life by manifesting as idle posture, heightened muscle tone, and repetitive purposeless movements. However, specific physiotherapy methods addressing these symptoms are yet to be established. This case report describes a 63-year-old man hospitalized for schizophrenia who was then diagnosed with stuporous catatonia based on the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision (DSM-IV-TR) criteria, characterized by catalepsy, mutism, and difficulty performing daily activities. This case report aimed to evaluate the effectiveness of a specific muscle relaxation technique, squeeze-hold (SH), in treating catatonia associated with schizophrenia and its impact on daily activities. The patient exhibited catalepsy, mutism, and difficulty in performing daily activities. The SH technique employed temporarily obstructs muscle blood flow to induce ischemia, resulting in the relaxation of vascular smooth muscle due to CO2 retention. Furthermore, shear stress upon reperfusion stimulates nitric oxide production in the vascular endothelium, enhancing blood flow. Following weekly SH on the bilateral thighs, the muscle tone in the lower extremities was alleviated within two weeks, and the patient no longer required a wheelchair by the eighth week. In addition, responsiveness to verbal commands improved. As muscle tone in the lower limbs improved, the patient regained ambulation, and his improved responsiveness facilitated independent eating during activities of daily living (ADLs), potentially enhancing motivation and spontaneity. These findings suggest that muscle tone relaxation due to enhanced blood flow and increased CO2 concentration from blood flow restriction may have promoted ß-endorphin secretion, thereby improving symptoms via brain-derived neurotrophic factor expression through PGC-1α activation. In conclusion, the SH muscle relaxation technique effectively alleviated catatonic symptoms, and improved muscle tone and daily functioning in patients with schizophrenia-associated catatonia. These findings suggest that this physiotherapy approach may be a valuable addition to catatonia treatment, potentially contributing to physical and psychiatric rehabilitation. This case report illustrates the efficacy of a muscle-tone-focused treatment approach in physical therapy for catatonia and posits its contribution to the reacquisition of psychiatric function and ADLs.

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INTRODUCTION: B-lines on lung ultrasound have been found in asymptomatic competitive breath-hold divers, but their significance and time to resolution are not well understood. We sought to investigate the relationship between B-lines, oxygen saturation, and respiratory symptoms after competitive dives to diagnose pulmonary injury. METHODS: We performed lung ultrasounds before (predive), immediately after (postdive), and within 1 h (follow-up) of a competitive dive. B-lines were counted in each intercostal space in the anterior, lateral, and posterior lung fields, and the highest number of B-lines within a space was recorded for each lung region. At follow-up, each diver's oxygen saturation and respiratory symptoms were recorded. Statistical analysis included the Kruskal-Wallis test, Spearman's correlation, and sensitivity and specificity calculations. RESULTS: Forty-four divers completed 143 individual dives of four different disciplines. The median number of B-lines was 0 (IQR inclusive=0) predive, 1 (IQR=3) postdive, and 0 (IQR=1) at follow-up. There was a significant difference in total B-lines between measurement times (p<0.001). Sensitivity and specificity of hypoxemia, clinically significant B-lines, and both measures in tandem in detecting respiratory symptomatology were 52% and 76%, 24% and 92%, and 24% and 95%, respectively. CONCLUSIONS: B-lines are a common phenomenon in competitive breath-hold divers on surfacing and decrease within 1 h, suggesting a physiologic fluid shift. B-lines are negatively correlated with oxygen saturation, indicating that extravascular fluid impairs gas exchange in the lung. Neither hypoxemia nor clinically significant B-lines were found to be reliable indicators for respiratory symptomatology, suggesting that there may be multiple phenotypes of freediving-induced pulmonary syndrome.

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By reversing the questions and focusing on the perpetrator's behavior, the notion of coercive control revolutionizes the apprehension and understanding of violence within the family for all its members. This heuristic approach, which represents a genuine paradigm shift, has legal, semiological and diagnostic effects. It creates a new professional ecosystem that enables us to respond differently to two fundamental missions: caring and justice.

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While existing literature covers significant detail on the physiology of human freediving, the lack of standardized protocols has hindered comparisons due to confounding variables such as exercise and depth. By accounting for these variables, direct depth-dependent impacts on cardiovascular and blood oxygen regulation can be investigated. In this study, depth-dependent effects on 1) cerebral hemodynamic and oxygenation changes, 2) arterial oxygen saturation (SpO2), and 3) heart rate during breath-hold diving without confounding effects of exercise were investigated. Six freedivers (51.0 ± 12.6 years; mean ± s.d.), instrumented with continuous-wave near-infrared spectroscopy for monitoring cerebral hemodynamic and oxygenation measurements, heart rate and SpO2, performed sled-assisted breath-hold dives to 15 m and 42 m. Arterial blood gas tensions were validated through cross-sectional periodic blood sampling. Cerebral hemodynamic changes were characteristic of breath-hold diving, with changes during ascent from both depths likely driven by decreasing SpO2 due to lung expansion. While SpO2 was significantly lower following 42 m dives (t(5) = -4.183, p < 0.05), mean cerebral arterial-venous blood oxygen saturation remained at 74% following dives to both depths. Cerebral oxygenation during ascent from 42 m may have been maintained through increased arterial delivery. Heart rate was variable with no significant difference in minimum heart rate between both depths (t(5) = -1.017, p > 0.05). This study presents a standardized methodology, which could provide a basis for future research on human freediving physiology and uncover ways in which freedivers can reduce potential risks of the sport.

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Background: Daily image-guided radiotherapy (IGRT) and deep inspiration breath hold (DIBH) technique are recommended for locoregional RT of breast cancer. The optimal workflow for a combination of surface-guided RT (SGRT) with DIBH technique is of current clinical interest. Materials and methods: The setup accuracy at three hospitals was evaluated using different SGRT workflows. A total of 150 patients (2269 image pairs) were analyzed in three groups: patient setup with the AlignRT® SGRT system in Tampere (Site 1, n = 50), the Catalyst™ SGRT system in Turku (Site 2, n = 50) and the Catalyst™ SGRT system in Jönköping (Site 3, n = 50). Each site used their routine workflow with SGRT-based setup and IGRT positioning. Residual errors of the bony chest wall, thoracic vertebra (Th 1) and humeral head were evaluated using IGRT images. Results: Systematic residual errors in the cranio-caudal (CC) direction and in pitch were generally larger at Site 2 than those at Sites 1 and 3 (p = 0.01-0.7). With daily IGRT, only a small difference (p = 0.01-0.9) was observed in residual random errors of bony structures in other directions between sites. Conclusion: The introduction of SGRT and the use of daily IGRT lead to small residual errors when combining the best workflow practices from different hospitals. Our multicenter evaluation led to improved workflow by tightening the SGRT tolerances on Site 2 and fixation modification. Because of mainly small random errors, systematic posture errors in the images need to be corrected after posture correction with new setup surfaces. We recommend tight SGRT tolerances, good fixation and correction of systematic errors.

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Background: The objective was to compare dosimetry in left-sided breast cancer (LSBC) patients receiving deep inspiration breath hold (DIBH) radiotherapy (RT) with free-breathing (FB) treatment plans. Materials and methods: Voluntary DIBH with a spirometer-based video-assisted system and CT-simulation were performed under FB and DIBH conditions on 40 LSBC patients, segmented according Duane's atlas. IMRT plans kept the same dosimetric goals on FB and DIBH conditions. Target, lungs and heart volumes were measured. Planning target volume (PTV) dose distribution, organs at risk (OARs) dose/volume parameters, including cardiac substructures, were calculated. Results: Lungs and left-lung volumes increased in DIBH conditions (ΔV = 1637.8 ml ± 555.3 and 783.5 ml ± 286.4, respectively). Heart volume slightly decreased in apnea (p = 0.04), but target volumes, CTV and PTV were similar in FB or DIBH plans. PTV dose coverage was similar irrespective of respiratory conditions (median D50% = 41.1 Gy vs 41.0 Gy, p = 0.665; V95% = 96.9% vs. 97%). Mean dose for the whole heart (MHD), left ventricle (LV), and LV segments were significantly reduced in DIBH plans. V20 values for heart subvolumes were significantly different only for those that received considerable doses (apical and anterior). DIBH plans provided significantly smaller doses (Dmax, D2%, and V20) to the LAD artery. Conclusion: Important dosimetric improvements can be achieved with DIBH technique for LSBC patients, reducing the dose to the LAD artery and heart, particularly to the segments closer to the chest wall. Apical/anterior LV segments, should be considered as separate organ at risk in breast RT.

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Background: Periprosthetic joint infections (PJI) are among the most morbid complications in total hip arthroplasty (THA). The ideal incubation time, however, for intraoperative cultures for PJI diagnosis remains unclear. As such, the aim of this study was to determine if any differences existed in culture-positive rates and organism detection between five-day and fourteen-day cultures. Methods: This retrospective cohort study consisted of THA cases diagnosed with PJI performed between May 2014 and May 2020 at a single tertiary-care institution. Analyses compared five-day and fourteen-day cultures and carried out a pre-specified subgroup analysis by organism and PJI type. Results: A total of 147 surgeries were performed in 101 patients (57.1% females), of which 65% (n = 98) obtained five-day cultures and 34% (n = 49) obtained fourteen-day cultures. The positive culture rate was 67.3% (n = 99) with Staphylococcus aureus being the most common pathogen identified (n = 41 specimens, 41.4%). The positive culture rate was not significantly different between groups (66.3% five-day, 69.4% fourteen-day, p = 0.852). Fourteen-day cultures had a significantly longer time-to-positive culture (5.0 days) than five-day cultures (3.0 days, p < 0.001), a higher rate of fungi (5.6% vs. 0%), and a lower rate of Gram-negatives (4.5% vs. 18.7%, p = 0.016). Conclusions: Fourteen-day cultures did not increase the positivity rate, had higher rates of slow-growth pathogens, and had a longer time-to-positivization than five-day cultures. Prolonged culture holds may provide more thorough organism detection for PJI without increasing the diagnostic culture yield.

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A general method for the calculation of the flow and pressure of a gas in a network of cylindrical capillaries is presented. This method is used specifically for gas chromatographic systems in this work. With this approach, it is possible to easily calculate flow and pressures in complex gas chromatographic systems, like flow-modulated or thermal-modulated multidimensional gas chromatographic systems, or systems with multiple outlets at different pressures. A mathematic abstraction using graph theory is used to represent the system of capillaries. With this graph, the flow balance equations at the connections of the capillaries can easily be set up. Using a computer algebra system, the system of flow balance equations can be solved for the pressures at the connection points. For simple systems, this approach is presented, and calculated flows, pressures, and hold-up times are compared with measured values. In addition, two complex systems (4-Way-Splitter, Deans Switch system) of capillaries are presented with calculations only. For these systems, certain conditions were formulated, that is, a certain difference in hold-up times and a defined split ratio between different paths of these systems. Using a numeric non-linear solver, configurations of these systems were found, that fulfill these conditions.

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PURPOSES: To explore the clinical feasibility and efficacy of a deep inspiration breath-hold (BH) PET/CT using [18F]AlF-NOTA-LM3 on upper abdominal lesions in patients with neuroendocrine tumors (NETs). METHODS: Twenty-three patients underwent a free-breath (FB) whole-body PET/CT, including a 10 min/bed scan for the upper abdomen with a vital signal monitoring for respiratory gating (RG) followed by a 20-second BH PET/CT covering the same axial range. For the upper abdomen bed, the following PET series was reconstructed: a 2-min FB PET; RG PET (6 bins); a 20-second and 15-second BH PET (BH_15 and BH_20). Semi-quantitative analysis was performed to compare liver SUVmean, lesion SUVmax, MTV, its percentage difference and target-to-background ratio (TBR) between both BH PET and RG PET images. Subgroup analysis considered lesion location, MTV and SUVmax. A 5-point Likert scale was used to perform visual analysis and any missed or additional lesions were identified compared with RG PET. RESULTS: Quantitative analysis on overall lesions (n = 78) revealed higher SUVmax and TBR, and smaller MTV for both BH PET compared to FB and RG PET, with lesion location-specific variations. Neither significant difference was observed in all metrics between RG and FB PET in larger lesions, nor in MTV in lower-uptake lesions. However, both BH PET significantly enhanced these measurements. In the visual analysis, both BH PET showed noninferior performance to RG PET, and were evaluated clinically acceptable. Additional and missed lesions were observed in FB and both BH PET compared with RG PET, but didn't alter the clinical management. The BH_15 PET showed comparable performance to BH_20 PET in any comparison. CONCLUSION: The BH PET/CT using [18F]AlF-NOTA-LM3 is effective in detecting upper abdominal lesions, offering more accurate quantitative measurements. Using a novel PET/CT scanner, a 15-second BH PET can provide comparable and superior performance to RG PET, indicating potential feasibility in clinical routines.

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Pakistan has limited natural gas reserves, and most are found onshore. This article reports on the problems of an onshore gas gathering network (GGN) analysed through steady-state simulation modelling using PIPESIM software. The research methodology incorporates a comprehensive steady-state hydraulic analysis considering fluid flowing velocity limitations, liquid holdup and slugging along with other issues faced by gas gathering networks. The steady-state hydraulic analysis has led us to pinpoint specific GGN pipelines facing critically low gas velocities and consequent liquid holdup. Addressing these issues involved application of PIPESIM software for modelling, considering various operating schemes of gas-producing wells and their associated pipelines. To select an optimal operating scheme, the study utilized the Analytic Hierarchy Process (AHP) for operational optimization, to identify the most effective solution for reduced liquid holdup, improving production, and ensuring the safe operation among available alternatives. Findings from our hydraulic analysis highlight the importance of reducing GGN outlet pressure to mitigate challenges associated with liquid holdup which causes slugging and back pressure effect at source leading to low production and poor performance of the GGN. Study of three alternative cases reveals that decreasing outlet pressure lowers the liquid holdup, improve gas flowing velocities, and enhanced overall production. These findings validate our hypothesis that reducing GGN outlet pressure is a viable strategy to lower the liquid holdup in pipelines. This research offers significant value by providing a comprehensive solution to GGN liquid holdup, low flowing velocities, back pressure and low production challenges. The integration of steady-state hydraulic analysis, simulation modelling with PIPESIM, and the application of AHP for optimization contributes novel insights into the optimization of operation of gas gathering networks. Emphasizing the reduction of liquid holdup and enhancing production through outlet pressure adjustments offers a practical framework for optimizing the functionality of gas gathering networks.

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Seismocardiographic (SCG) signals are chest wall vibrations induced by cardiac activity and are potentially useful for cardiac monitoring and diagnosis. SCG waveform is observed to vary with respiration, but the mechanism of these changes is poorly understood as alterations in autonomic tone, lung volume, heart location and intrathoracic pressure are all varying during the respiratory cycle. Understanding SCG variability and its sources may help reduce variability and increase SCG clinical utility. This study investigated SCG variability during breath holding (BH) at two different lung volumes (i.e., end inspiration and end expiration) and five airway pressures (i.e., 0, ± 2-4, and ± 15-20 cm H2O). Variability during normal breathing was also studied with and without grouping SCG beats into two clusters of similar waveform morphologies (performed using the K-medoid algorithm in an unsupervised machine learning fashion). The study included 15 healthy subjects (11 Females and 4 males, Age: 21 ± 2 y) where SCG, ECG, and spirometry were simultaneously acquired. SCG waveform variability was calculated at each experimental state (i.e., lung volume and airway pressure). Results showed that breath holding was more effective in reducing the intra-state variability of SCG than clustering normal breathing data. For the BH states, the intra-state variability increased as the airway pressure deviated from zero. The subaudible-to-audible energy ratio of the BH states increased as the airway pressure decreased below zero which may be related to the effect of the intrathoracic pressure on cardiac afterload and blood ejection. When combining the BH waveforms at end inspiration and end expiration states (at the same airway pressures) into one group, the intra-state variability increased, which suggests that the lung volume and associated change in heart location were a significant source of variability. The linear trend between airway pressure and waveform changes was found to be statistically significant for BH at end expiration. To confirm these findings, more studies are needed with a larger number of airway pressure levels and larger number of subjects.

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The effects of face immersion and concurrent exercise on the diving reflex evoked by breath-hold (BH) differ, yet little is known about the combined effects of different BH conditions on aerobic fitness in elite athletes. This study aimed to assess the acute effects of various BH conditions on 18 male elite rugby players (age: 23.5 ± 1.8 years; height: 183.3 ± 3.4 cm; body mass: 84.8 ± 8.5 kg) and identify the BH condition eliciting the greatest aerobic fitness activation. Participants underwent five warm-up conditions: baseline regular breathing, dynamic dry BH (DD), static dry BH (SD), wet dynamic BH (WD), and wet static BH (WS). Significant differences (p < 0.05) were found in red blood cells (RBCs), red blood cell volume (RGB), and hematocrit (HCT) pre- and post-warm-up. Peak oxygen uptake (VO2peak) and relative oxygen uptake (VO2/kgpeak) varied significantly across conditions, with BH groups showing notably higher values than the regular breathing group (p < 0.05). Interaction effects of facial immersion and movement conditions were significant for VO2peak, VO2/kgpeak, and the cardiopulmonary optimal point (p < 0.05). Specifically, VO2peak and peak stroke volume (SVpeak) were significantly higher in the DD group compared to that in other conditions. Increases in VO2peak were strongly correlated with changes in RBCs and HCT induced by DD warm-up (r∆RBC = 0.84, r∆HCT = 0.77, p < 0.01). In conclusion, DD BH warm-up appears to optimize subsequent aerobic performance in elite athletes.

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This study researched the prediction of the BSR noise evaluation quantitative index, Loudness N10, for sound sources with noise using statistics and machine learning. A total of 1170 data points was obtained from 130 automotive seats measured at 9-point positions, with Gaussian noise integrated to construct synthetic sound data. Ten physical quantities related to sound quality and sound pressure were used and defined as dB and fluctuation strength, considering statistical characteristics and Loudness N10. BSR quantitative index prediction was performed using regression analysis with K-fold cross-validation, DNN in hold-out, and DNN in K-fold cross-validation. The DNN in the K-fold cross-validation model demonstrated relatively superior prediction accuracy, especially when the data quantity was relatively small. The results demonstrate that applying machine learning to BSR prediction allows for the prediction of quantitative indicators without complex formulas and that specific physical quantities can be easily estimated even with noise.

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PURPOSE: To investigate the impact of voluntary hypoventilation at low lung volumes (VHL) during upper body repeated sprints (RS) on performance, metabolic markers and muscle oxygenation in Brazilian Jiu-Jitsu (BJJ) athletes. METHODS: Eighteen male well-trained athletes performed two randomized RS sessions, one with normal breathing (RSN) and another with VHL (RS-VHL), on an arm cycle ergometer, consisting of two sets of eight all-out 6-s sprints performed every 30 s. Peak (PPO), mean power output (MPO), and RS percentage decrement score were calculated. Arterial oxygen saturation (SpO2), heart rate (HR), gas exchange, and muscle oxygenation of the long head of the triceps brachii were continuously recorded. Blood lactate concentration ([La]) was measured at the end of each set. Bench press throw peak power (BPPP) was recorded before and after the RS protocol. RESULTS: Although SpO2 was not different between conditions, PPO and MPO were significantly lower in RS-VHL. V ˙ E, HR, [La], and RER were lower in RS-VHL, and VO2 was higher in RS-VLH than in RSN. Muscle oxygenation was not different between conditions nor was its pattern of change across the RS protocol influenced by condition. [La] was lower in RS-VHL than in RSN after both sets. CONCLUSION: Performance was significantly lower in RS-VHL, even though SPO2 was not consistent with hypoxemia. However, the fatigue index was not significantly affected by VHL, nor was the neuromuscular upper body power after the RS-VHL protocol. Additionally, [La] was lower, and oxygen consumption was higher in RS-VHL, suggesting a higher aerobic contribution in this condition.

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Hypoxia, centralization of blood in pulmonary vessels, and increased cardiac output during physical exertion are the pathogenetic pathways of acute pulmonary edema observed during exposure to extraordinary environments. This study aimed to evaluate the effects of breath-hold diving at altitude, which exposes simultaneously to several of the stimuli mentioned above. To this aim, 11 healthy male experienced divers (age 18-52y) were evaluated (by Doppler echocardiography, lung echography to evaluate ultrasound lung B-lines (BL), hemoglobin saturation, arterial blood pressure, fractional NO (Nitrous Oxide) exhalation in basal condition (altitude 300m asl), at altitude (2507m asl) and after breath-hold diving at altitude. A significant increase in E/e' ratio (a Doppler-echocardiographic index of left atrial pressure) was observed at altitude, with no further change after the diving session. The number of BL significantly increased after diving at altitude as compared to basal conditions. Finally, fractional exhaled nitrous oxide was significantly reduced by altitude; no further change was observed after diving. Our results suggest that exposure to hypoxia may increase left ventricular filling pressure and, in turn, pulmonary capillary pressure. Breath-hold diving at altitude may contribute to interstitial edema (as evaluated by BL score), possibly because of physical efforts made during a diving session. The reduction of exhaled nitrous oxide at altitude confirms previous reports of nitrous oxide reduction after repeated exposure to hypoxic stimuli. This finding should be further investigated since reduced nitrous oxide production in hypoxic conditions has been reported in subjects prone to high-altitude pulmonary edema.

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INTRODUCTION: Deep inspiration breath-hold (DIBH) has proven effective in minimizing radiation exposure to organs at risk (OARs) in right-sided breast cancer patients requiring regional nodal irradiation (RNI). However, there has been no dosimetric evaluation comparing DIBH techniques to free-breathing (FB) conditions on the TrueBeam (TB) HD linear accelerator (LINAC). To address this gap and accommodate breast cancer patients requiring RNI on the TB HD LINAC, an innovative method involving a 90-degree rotation of the regional lymph nodes' field during treatment planning was devised. CASE DESCRIPTION: The study focused on a 39-year-old woman who underwent right breast-conserving radical surgery and subsequently required postoperative adjuvant radiotherapy. Both noncontrast FB and DIBH computed tomography (CT) scans were performed using a CT simulator. Due to limitations in MLC field length, a 90-degree rotation was employed for planning the regional lymph nodes' field on the TB LINAC. Patient positioning accuracy was ensured by aligning based on body surface under both FB and DIBH conditions, facilitated by an optical surface management system (OSMS). The target volume and OARs were meet the dose limit on the TB HD LINAC. Noteworthy reductions in radiation exposure to the right lung and liver were evident with DIBH. The mean dose reduction rate for the right lung was 11.9%, while the mean dose reduction rate for the liver was 68.9%. Parameters such as V5, V20, V30, and mean dose (Dmean) also demonstrated decreases with DIBH compared to FB. CONCLUSIONS: This case report underscores the potential of TB HD LINAC for formulating treatment approaches for breast cancer involving RNI. Furthermore, it emphasizes the effectiveness of DIBH radiotherapy in mitigating doses to OARs when implemented on the TB LINAC.

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Acute breath-holding (apnoea) induces a spleen contraction leading to a transient increase in haemoglobin concentration. Additionally, the apnoea-induced hypoxia has been shown to lead to an increase in erythropoietin concentration up to 5 h after acute breath-holding, suggesting long-term haemoglobin enhancement. Given its potential to improve haemoglobin content, an important determinant for oxygen transport, apnoea has been suggested as a novel training method to improve aerobic performance. This review aims to provide an update on the current state of the literature on this topic. Although the apnoea-induced spleen contraction appears to be effective in improving oxygen uptake kinetics, this does not seem to transfer into immediately improved aerobic performance when apnoea is integrated into a warm-up. Furthermore, only long and intense apnoea protocols in individuals who are experienced in breath-holding show increased erythropoietin and reticulocytes. So far, studies on inexperienced individuals have failed to induce acute changes in erythropoietin concentration following apnoea. As such, apnoea training protocols fail to demonstrate longitudinal changes in haemoglobin mass and aerobic performance. The low hypoxic dose, as evidenced by minor oxygen desaturation, is likely insufficient to elicit a strong erythropoietic response. Apnoea therefore does not seem to be useful for improving aerobic performance. However, variations in apnoea, such as hypoventilation training at low lung volume and repeated-sprint training in hypoxia through short end-expiratory breath-holds, have been shown to induce metabolic adaptations and improve several physical qualities. This shows promise for application of dynamic apnoea in order to improve exercise performance. HIGHLIGHTS: What is the topic of this review? Apnoea is considered as an innovative method to improve performance. This review discusses the effectiveness of apnoea (training) on performance. What advances does it highlight? Although the apnoea-induced spleen contraction and the increase in EPO observed in freedivers seem promising to improve haematological variables both acutely and on the long term, they do not improve exercise performance in an athletic population. However, performing repeated sprints on end-expiratory breath-holds seems promising to improve repeated-sprint capacity.

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PURPOSE: Apnea duration is dependent on three factors: oxygen storage, oxygen consumption, hypoxia and hypercapnia tolerance. While current literature focuses on maximal apneas to improve apnea duration, apnea trained individuals use timed-repeated submaximal apneas, called "O2 and CO2 tables". These tables claim to accommodate the body to cope with hypoxia and hypercapnia, respectively. The aim of this study was twofold. First, to investigate the determinants of maximal apnea duration in apnea novices. Second, to compare physiologic responses to maximal apneas, O2 and CO2 tables. METHODS: After medical screening, lung function test and hemoglobin mass measurement, twenty-eight apnea novices performed three apnea protocols in random order: maximal apneas, O2 table and CO2 table. During apnea, peripheral oxygen saturation (SpO2), heart rate (HR), muscle (mTOI) and cerebral (cTOI) tissue oxygenation index were measured continuously. End-tidal carbon dioxide (EtCO2) was measured before and after apneas. RESULTS: Larger lung volumes, higher resting cTOI and lower resting EtCO2 levels correlated with longer apnea durations. Maximal apneas induced greater decreases in SpO2 (- 16%) and cTOI (- 13%) than O2 (- 8%; - 8%) and CO2 tables (- 6%; - 6%), whereas changes in EtCO2, HR and mTOI did not differ between protocols. CONCLUSION: These results suggest that, in apnea novices, O2 and CO2 tables did not induce a more profound hypoxia and hypercapnia, but a similar reduction in oxygen consumption than maximal apneas. Therefore, apnea novices should mainly focus on maximal apneas to improve hypoxia and hypercapnia tolerance. The use of specific lung training protocols can help to increase oxygen storage capacity.