Maximum Step Length Research Articles

Reliability and Validity of Four Step Tests in Older Adults With Dementia.

To determine the test-retest and inter-rater reliability, concurrent and discriminative validity of the Four Square Step Test (FSST), the Choice Stepping Reaction Time Test (CSRTT), the Maximum Step Length Test (MSLT), and the Alternate Step Test (AST) in older adults with dementia. Thirty-seven older adults with dementia who could walk independently for at least 10m were recruited at community centers and day care centers for older adults. The participants completed the step tests conducted by two independent raters on three separate testing occasions within 3weeks. In addition, the physical and cognitive function of the participants were evaluated at baseline. The FSST, CSRTT, and MSLT showed good-to-excellent test-retest reliability (intraclass correlation coefficient [ICC]=0.83-0.91), and the AST exhibited fair test-retest reliability (ICC=0.70). All the step tests showed good-to-excellent inter-rater reliability (ICC=0.75-0.94). The step tests had moderate-to-strong correlations with various physical and cognitive measures (Pearson correlation coefficients=0.34-0.72). The MSLT side step and AST could differentiate between individuals who did and did not use a walking stick to ambulate (p≤0.046). The FSST, CSRTT, and AST could differentiate between individuals with and without a major neurocognitive impairment (p≤0.005). The FSST, CSRTT, and MSLT were reliable and valid for examining the stepping performance of older adults with dementia. Clinicians can use these tests to evaluate the physical and cognitive function of this population and identify those with significant cognitive impairment. Clinical Trial Registration number: NCT04296123.

Osteoporosis, spinal degenerative disorders, and their association with low back pain, activities of daily living, and physical performance in a general population

Osteoporosis, vertebral fractures, and spinal degenerative diseases are common conditions that often coexist in older adults. This study aimed to determine the factors influencing low back pain and its impact on activities of daily living (ADL) and physical performance in older individuals with multiple comorbidities. This cross-sectional study was part of a large-scale population-based cohort study in Japan, involving 1009 participants who underwent spinal magnetic resonance imaging (MRI) to assess cervical cord compression, radiographic lumbar spinal stenosis, and lumbar disc degeneration. Vertebral fractures in the thoracolumbar spine were evaluated using sagittal MRI with a semi-quantitative method. Bone mineral density was measured using dual-energy X-ray absorptiometry. Low back pain, Oswestry Disability Index (ODI), and physical performance tests, such as one-leg standing time, five times chair-stand time, maximum walking speed, and maximum step length, were assessed. Using clinical conditions as objective variables and image evaluation parameters as explanatory variables, multiple regression analysis showed that vertebral fractures were significantly associated with low back pain and ODI. Vertebral fractures and osteoporosis significantly impacted physical performance, whereas osteoporosis alone did not affect low back pain or ODI. Our findings contribute to new insights into low back pain and its impact on ADL and physical performance.

Relationship between respiratory muscle strength and dynamic balance in older persons requiring care or support: Focusing on the maximal single step length test and maximal double step length test as dynamic balance indices

BackgroundFalls are a major health problem. The relationship between dynamic balance related to falls and respiratory muscle strength related to sarcopenia and frailty is poorly understood. Research questionHow do dynamic balance measures, such as maximal single step length test (MSL) and maximal double step length test (MDST), and respiratory muscle strength measures, such as maximal inspiratory (PImax) and maximal expiratory (PEmax), related to the requirement for long-term care or support in older people who live in the community? MethodsThis was a cross-sectional study of 39 older people (17 men, 22 women) aged ≥ 65 years community-dwelling who were certified as requiring long-term care or support under the Japanese system. The participants’ PImax, PEmax, MSL, and MDST results were recorded. The measurement data were evaluated using Pearson’s correlation coefficients and multiple regression analysis. ResultsMDST showed a positive correlation with PImax (r = 0.430, p = 0.006) but no correlation with PEmax. MSL showed no correlation with PImax or PEmax. A positive correlation was found between MDST and MSL (r = 0.851, p < 0.001), and multiple regression analysis with MDST as the dependent variable and PImax and MST as independent variables showed significant differences for MSL (p < 0.001) and PImax (p = 0.027). SignificanceIn older people requiring long-term care or support, MDST had a greater association with inspiratory muscle strength compared with MSL. These results suggest the importance of inspiratory muscle strength training and MDST assessment in the prevention of falls in older people requiring long-term care or support.

Factors associated with gait efficiency in children with cerebral palsy: association between gait abnormality and balance ability.

[Purpose] Children with cerebral palsy require more gait energy than healthy children. The association between gait abnormalities and gait efficiency remains unclear. We investigated the association between gait abnormalities, balance, and maximum step length to determine contributors to gait efficiency in children with cerebral palsy. [Participants and Methods] The study included 33 patients with cerebral palsy, who could walk without the use of walking aids. All participants were instructed to walk for 6 min, and the Total Heart Beat Index was calculated as a measure of walking efficiency. The Edinburgh Visual Gait Score was used to assess gait abnormalities. Additionally, the maximum step length was recorded, and all participants performed the Berg Balance Scale. Correlation analysis and stepwise multiple regression analysis were used to confirm the association between the aforementioned parameters and the Total Heart Beat Index. [Results] The Edinburgh Visual Gait Score was correlated with the heel lift during the stance, knee position during the terminal swing of gait as factors associated with the Total Heartbeat Index. The Berg Balance Scale was correlated with turning 360°, standing with feet together. [Conclusion] Our findings emphasize the need for treatment strategies focused on gait abnormalities and balance.

PREDICTORS OF MAXIMUM STEP LENGTH IN OLDER ADULTS: ROLES FOR STRENGTH AND ACE GENOTYPE

Abstract Deficits in step length, assessed clinically by the maximum step length (MSL) test, are associated with poor balance and falls, in older adults. Determining predictors of MSL would facilitate targeted interventions to improve balance and reduce falls in older adults. Angiotensin-converting enzyme (ACE) insertion/deletion polymorphism genotypes interact with strength to predict stepping speed, but the interplay between ACE genotype, strength and MSL is unclear. Our objective was to determine whether strength and ACE DD genotype, through main effects or interactively, are associated with MSL, in older adults. Adults (N=103, female=58.2%, mean age 72.1 years, range 65-85 years) provided demographic, health and balance confidence information, completed grip strength and MSL testing, and provided saliva for genotyping. Multiple regression determined variance in MSL explained by strength, DD genotype (present/absent), and strength x genotype interaction, while controlling for covariates (age, sex, self-rated health and balance confidence). Covariates (model 1) explained 47.7% of MSL variance, while adding grip strength (model 2) explained additional 9.7% of variance. Adding DD genotype (model 3) explained .2%, while adding a strength x genotype interaction term (model 4) explained additional 3.4%, of MSL variance. The final model explained 61% of the variance in MSL (p&amp;lt;.001). DD genotype did not independently predict MSL (β=-.053; p=.421), but was interactively with strength, a significant predictor (β=.216; p=.005) of MSL. Strength was a significant predictor (β=.264; p=.003) of MSL, and as a modifiable physiological factor should be a focus of rehabilitation interventions to improve MSL and reduce falls risk in older adults.

Three-dimensional kinematic analysis of knee joint after anterior cruciate ligament reconstruction with personalized femoral positioner based on apex of deep cartilage

To investigate the changes of knee joint kinematics after anterior cruciate ligament (ACL) reconstruction assisted by personalized femoral positioner based on the apex of deep cartilage (ADC). Between January 2021 and January 2022, a total of 40 patients with initial ACL rupture who met the selection criteria were randomly divided into the study group (using the personalized femoral positioner based on ADC design to assist ACL reconstruction) and the control group (not using the personalized femoral positioner to assist ACL reconstruction), with 20 patients in each group. Another 20 volunteers with normal knee were collected as a healthy group. There was no significant difference in gender, age, body mass index, and affected side between groups ( P>0.05). Gait analysis was performed at 3, 6, and 12 months after operation using Opti _ Knee three-dimensional knee joint motion measurement and analysis system, and the 6 degrees of freedom (flexion and extension angle, varus and valgus angle, internal and external rotation angle, anteroposterior displacement, superior and inferior displacement, internal and external displacement) and motion cycle (maximum step length, minimum step length, and step frequency) of the knee joint were recorded. The patients' data was compared to the data of healthy group. In the healthy group, the flexion and extension angle was (57.80±3.45)°, the varus and valgus angle was (10.54±1.05)°, the internal and external rotation angle was (13.02±1.66)°, and the anteroposterior displacement was (1.44±0.39) cm, the superior and inferior displacement was (0.86±0.20) cm, and the internal and external displacement was (1.38±0.39) cm. The maximum step length was (51.24±1.29) cm, the minimum step length was (45.69±2.28) cm, and the step frequency was (12.45±0.47) step/minute. Compared with the healthy group, the flexion and extension angles and internal and external rotation angles of the patients in the study group and the control group decreased at 3 months after operation, and the flexion and extension angles of the patients in the control group decreased at 6 months after operation, and the differences were significant ( P<0.05); there was no significant difference in the other time points and other indicators when compared with healthy group ( P>0.05). In the study group, the flexion and extension angles and internal and external rotation angles at 6 and 12 months after operation were significantly greater than those at 3 months after operation ( P<0.05), while there was no significant difference in the other indicators at other time points ( P>0.05). There was a significant difference in flexion and extension angle between the study group and the control group at 6 months after operation ( P<0.05), but there was no significant difference of the indicators between the two groups at other time points ( P>0.05). Compared with conventional surgery, ACL reconstruction assisted by personalized femoral positioner based on ADC design can help patients achieve more satisfactory early postoperative kinematic results, and three-dimensional kinematic analysis can more objectively and dynamically evaluate the postoperative recovery of knee joint.

Effect of Gait Alteration on Fatigability during Walking in Adult Women with High Body Fat Composition.

Background and Objective: The risk factors for injury due to alterations in gait efficiency and fatigability during walking are a rising concern. Therefore, the aims of this study were to characterize the changes in gait pattern and performance fatigability among adult women with a high body fat percentage and to study the association between the gait pattern and performance fatigability during walking. Materials and Methods: A total of 160 adult women were enrolled in the study and were divided into two groups: a high-body-fat percentage group (HBF; n = 80; fat% = 42.49 ± 3.51) and a comparison group with a normal body fat percentage (NBF; n = 80; fat% = 29.68 ± 4.30). The 10 min walking test (10-MWT) was used to measure performance fatigability. Treadmill-based gait analysis was used for the acquisition of gait parameters. The correlation between the variables was examined using Pearson’s correlation coefficient. Forward stepwise linear regression was carried out to examine the association between all independent variables, and performance fatigability was adjusted for age and height. The level of statistical significant was set at p-value < 0.05 in all analyses. Results: The mean performance fatigability during the 10-MWT was reported to be high (1.4 ± 0.13) among the participants with HBF, as compared with a fatigability of 1.25 ± 0.11 in the NBF group. The data analysis of the spatial parameters indicated that stride length and step length were statistically smaller in the participants with HBF, as compared with the NBF group. The effects of average maximum force, speed, cadence, step length, and stride length explained the variation in the performance fatigability by 61% (p = 0.007). Conclusion: The findings of this study showed that gait alteration due to excess body fat induced a reduction in performance, as reflected by the high fatigability performance during walking. The study demonstrated a significant association between the severity of performance fatigability and spatial gait parameters.

STEP EXECUTION TIME: EXAMINING ITS RELIABILITY AND ASSOCIATION WITH PARTICIPATION IN OLDER ADULTS

Abstract The projected rise in the number of older adults warrants increased attention to selecting reliable and meaningful clinical assessments. Compared to more frequently used balance measures, step execution time (SET) has not been studied extensively. The purpose of the current study was twofold. First, we investigated the association of several balance measures [SET, Activities-specific Balance Confidence Scale (ABC-6), Five-times-sit-to-stand (5TSTS), Four-square step test (4SST), and maximum step length (MSL)] with participation (LIFE-H). Second, reliability of SET was investigated. The study included 32 community-dwelling older adults between the ages of 65 and 83 years (88% White, 66% female). Results indicated that SET was the only balance measure associated with both participation accomplishment (r = -.54, p = .001) and participation satisfaction (r = -.55, p = .001); 5TSTS (r = -.64, p &amp;lt; .001) and 4SST (r = .37, p = .039) were also significantly correlated with participation accomplishment while MSL (r = .37, p = .040) showed a significant association with participation satisfaction. SET demonstrated excellent test-retest reliability (ICC = .92). Bland-Altman analysis determined the 95% Limits of Agreement to be -258.5 ms to +271.5 ms (mean difference = 6.5 ms; 95% CI of difference = -43.1 to 56.1), suggesting that bias was not a concern. SEM (100.5 ms) and MDC95 (278.5 ms) for SET represented 9.3% and 25.8% of the mean, respectively. Collectively, findings suggest that SET may have clinical utility as a reliable assessment in older adults that relates to meaningful constructs, such as participation.

Relationship between foot morphology, muscle strength, and physical performance test in women aged 65 years and older: a cross-sectional study

BackgroundHallux valgus is a foot deformity that may affect gait, thus increasing the risk of falls among older people. We investigated the relationship between foot morphology, muscle strength, and physical performance.MethodsIn this study, community-dwelling older people aged ≥65 years were included. A three-dimensional footprint automatic measurement apparatus was used to measure the hallux valgus angle, arch height ratio, and heel-floor angle. Furthermore, the toe flexor strength and ankle plantar flexion strength were measured. Physical performance tests included the five-repetition sit-to-stand test, one-leg standing time, maximal step length, functional reach test, and 5-m fastest walking time (walking time). The relationship between the hallux valgus angle and foot morphology and muscle strength was examined. In addition, factors affecting physical performance testing were assessed. Two-group comparisons, correlation, and multiple comparisons were used for statistical analyses.ResultsOf the 133 women (age 77.7 ± 6.2 years), 57 had hallux valgus and 76 had no hallux valgus. There was a significant difference in the arch height ratio and heel-floor angle between women with and without hallux valgus (p < 0.001). A correlation was found between the hallux valgus angle and the heel-floor angle (r = 0.468, p < 0.001) and arch height ratio (r = − 0.337, p < 0.001), respectively. Multiple regression analysis showed that the hallux valgus angle was related to functional reach (β = − 0.162, p = 0.042), and toe flexor strength was related to five-repetition sit-to-stand (β = − 0.182, p = 0.036), maximal step length (β = 0.328, p < 0.001), and walking time (β = − 0.219, p = 0.006).ConclusionsA relationship was found between the hallux valgus angle, arch height rate, and inward inclination angle of the calcaneus. Functional reach was predicted based on the hallux valgus angle, whereas the five-repetition sit-to-stand, maximal step length, and walking time were predicted based on toe flexor strength. Hallux valgus predicted not only the forefoot but also the foot morphology and was related to physical performance. From the perspective of motor function and fall prevention, efforts should be made to better understand and prevent the onset and progression of hallux valgus.

Effects of Insole with Toe-Grip Bar on Barefoot Balance and Walking Function in Patients with Parkinson's Disease: A Randomized Controlled Trial.

The maintenance and improvement of balance and walking function in patients with Parkinson's disease (PD) is essential. Toe dysfunction in patients with PD is related to balance and walking. Recently, insoles have been developed to improve toe function, but their effects on the physical functions of patients with PD remain unclear. In this randomized controlled study, we investigated the effects of insoles with a toe-grip bar on balance and walking function in such patients. Twenty-nine patients with PD in Hoehn and Yahr stages II-IV were randomly assigned to an intervention or control group. Patients in the intervention and control groups wore shoes having insoles with and without a toe-grip bar for 4 weeks, respectively. The center of gravity sway of standing posture (total trajectory length, envelope area, and maximum anterior-posterior center of pressure [AP-COP] distance) and walking parameters at normal and fast speeds were measured pre- and post-intervention in the rehabilitation room. All measurements were performed with the participants being barefoot. The maximum AP-COP distance and step length of the fast-walking condition were significantly improved in the intervention compared to the control group (p &lt; 0.05). Thus, insoles with a toe-grip bar may improve balance and walking function in patients with PD.

FP.07 Experiences with systematic video recordings of individualized physiotherapy for 111 patients with neuromuscular disorders in a 7-year quality project

Physiotherapy is a cornerstone in the management of hereditary neuromuscular disorders (NMDs). The National Neuromuscular Centre Norway (NMK) provides a two-week individualized physiotherapy intervention focusing on optimization of movement strategies in relevant activities. From 2014 to 2021, NMK documented the content of the tailored intervention in a quality project using systematic video recordings. The aims were to investigate the video recordings' contribution in the clinical communication with community physiotherapists (cPTs), and to explore how the PTs at NMK could develop and enhance their clinical practice by analyzing the patients' changes in movement quality and -strategies. 111 patients with NMDs participated. Video recordings of selected sequences of individualized treatment approaches were captured for all patients, and further conveyed to the patients' cPTs after discharge. 83 patients were recorded during standardized pre and post testing, consisting of 10m walk test, maximum step length, single leg stance and walking figure of eight. Patients unable to walk were not tested. Video recordings of pre and post tests clearly display positive changes in movement quality for the majority of patients, and have been vital in improving clinical competence for the PTs at NMK. The videos are valuable in case-presentations on clinical courses and in webinars, and highlight how specific and individualized treatment techniques contribute towards optimization of movement in people with NMDs. Recordings of particularly relevant treatment sequences conveyed to cPTs, in combination with written reports, enhanced their clinical reasoning processes and served as helpful input in the daily follow-up of patients. Video recording of people with NMDs participating in specialized physiotherapy treatment is a valuable tool to improve clinical competence, and may enhance clinical communication with cPTs.

Accuracy and precision of simpler and lower-cost technologies to measure the initial lean angle, step length and step velocity for forward lean releases

Current technologies to measure the maximum forward lean angle, step length and velocity in a clinical setting are neither simple nor cheap. Therefore, the purpose of this study was to determine the accuracy and precision of four live and one post-processing measurement methods compared to the 3D motion analysis gold standard. Twelve healthy younger adults recovered balance, after being released from six randomly ordered forward initial lean angles, using four different live measurement methods: LabVIEW, load cell, inclinometer and protractor. The initial lean angle, step length and velocity were also calculated in post-processing using 2D video analysis and 3D motion analysis. The LabVIEW method was the most accurate and precise, followed by the protractor, inclinometer and load cell methods. The load cell method was the most complex, followed by the LabVIEW, inclinometer and protractor methods. The LabVIEW method was the most expensive, followed by the load cell, inclinometer and protractor methods. Video analysis was sufficiently accurate and precise, equal in complexity and much less expensive than the gold standard. Simpler and lower-cost technologies to measure the initial lean angle, step length and velocity are sufficiently accurate and precise (live: protractor, post-processing: video analysis) to potentially use in a clinical setting.

Most Falls of Active Elderly People are not Caused by Decreases in Physical Function

Several healthy, community-dwelling elderly people who live independently experience falls. However, their falls are not always attributed to decreased physical function. We aimed to examine the cause of falls in active elderly people. They were divided into fallers (n = 49) and non-fallers (n = 170) based on their fall experience during the previous year. The subjects participated in the following tests: transferring velocity during the sit-to-stand, one-leg stand time, functional reach, 10-m maximal walking time, muscle strength (foot grip, ankle plantar flexion, hip flexion, knee extension strength), systemic reaction time, agility stepping, and maximal side step length after completing the ADL questionnaire, fall risk assessment sheet, fall risk profile from Demura et al, and life-space assessment sheet. No significant differences were observed in physical functions, which were the basis of fall prevention (muscle strength, balance, and gait) and fall avoidance (systemic reactions, agility stepping, and maximal side step length) between both groups. A significant difference was observed in the ADL score but not between both fall risk scores, and the Life-Space Assessment scores. Moreover, no significant differences were observed between the high risk ratio for falls and nursing care based on each questionnaire. In conclusion, the differences in physical function and fall risk factors between the fallers and non-fallers in active, independent elderly people living in the community were not observed. The cause of these falls (22.4%) was not attributed to physical function decreases or other fall risk factors. These may mainly depend on accidents resulting from high activity.

Evaluation of the electron transport algorithm in magnetic field in EGS5 Monte Carlo code.

To evaluate the accuracy of electron transport in the magnetic field of Electron Gamma Shower version 5 (EGS5) by using the special Fano cavity test. To simulate electron transport in the magnetic field, the trajectory of the electron was reconstructed with a short step length to restrict fractional energy loss, and the maximum user step length (mxustep) was set at 0.01cm or 0.001cm. For the special Fano cavity test, three-layer slab Fano test geometry was used, and uniform and isotropic per unit mass mono-energetic electrons with 0.01, 0.1, 1.0, and 10MeV were permitted from the central axis of geometry in 0.35T and 1.5T. Furthermore, the magnetic field strength was scaled based on the mass density of the material. The relative difference between the calculated dose to gap and the theoretical value was evaluated. Furthermore, the special Fano cavity test was also performed using EGSnrc with the electron-enhanced electric and magnetic field macros under the same conditions, and the results were compared with those of EGS5. Deviations in 0.35T were within 0.3% regardless of the parameter settings. In 1.5T, stable results within 0.3% were obtained using 0.001cm as the mxustep, except for one at 10MeV. Further, the accuracy of EGSnrc was within 0.2%, except for 10MeV for a 0.2-cm gap in 1.5T. EGS5 with the appropriate parameter settings enable electron transport in magnetic fields similar with the accuracy of EGSnrc.

Gait Symmetry Analysis in Patients after Treatment of Pilon Fractures by the Ilizarov Method

The aim of this study was to comprehensively assess the gait parameters in patients who had undergone treatment of pilon fractures by the Ilizarov method. We analyzed gait parameters in patients who had undergone treatment for pilon fractures by the Ilizarov method; 20 patients aged 47.0 years (25.2–78.6) were included in the study. The control group consisted of 32 healthy volunteers. Gait examination was performed using the pedobarographic platform. Statistically significant differences in the following gait parameters: maximum forefoot force (%), step length (cm), and step time (s) were found between the study group and the control group, between the nonoperated leg, and both the operated leg and the dominant limb. Statistically significant differences in the study group between the treated lower limb and the healthy lower limb were only observed in the case of the maximum forefoot force parameter (%). Healthy subjects from the control group obtained significantly higher values during locomotion for stride time, cadence step, and velocity than the patients, with stride time being statistically significantly shorter and the velocity and the cadence step higher. We observed symmetry in the gait parameters after treating pilon fractures by the Ilizarov method. This method of stabilization allows the restoration of gait parameters, with results similar to those obtained after the treatment of other motor organ pathologies described in the literature, although different from those observed in healthy subjects. In particular, the biomechanics of the lower limbs remain disturbed.

Sedimentary structure of inferred cyclic‐step bedforms in submarine volcaniclastic slope deposits, Cuatro Calas, south‐east Spain

AbstractCyclic steps are widespread on submarine slopes of many modern insular volcanoes. This paper provides the first detailed description and interpretation of the sedimentary structures and depositional architecture of cyclic‐step deposits of such bedforms formed on the submarine slope of an ancient volcano. The partially depositional cyclic steps are preserved in a 67 m thick coset of 1 to 12 m thick cobble‐based units of middle Miocene submarine volcaniclastics, exposed along a cliff outcrop in south‐east Spain. The main structure in the units is unidirectional crude low‐angle cross‐bedding passing upward to centimetre to decimetre‐scale diffuse stratification more or less parallel to the unit bounding surfaces. The depositional architecture produced by inferred sinuous to straight‐crested cyclic steps is compared with deposits of crescent‐shaped cyclic steps formed in confined settings. With a novel method, a maximum cyclic step height and length of 22 m and 460 m, respectively, have been calculated. The architecture of some of the thicker cyclic‐step units is complicated by structures that were formed as cyclic‐step trough‐fills, by superimposed cyclic steps or downstream migrating antidunes. These structures possibly reflect adaptation processes of the bedform morphology to a lower strength of the hydraulic jumps and related density flows. In the upper, less well‐exposed part of the succession more steeply inclined gravel backsets that probably represent deposits of crescent‐shaped cyclic steps accreted in a more energetic, confined setting proximal to the coastal source of the density flows. A facies model of straight‐crested cyclic steps is presented that may aid in the identification of similar bedforms in submarine volcaniclastic environments and comparable non‐volcanic settings.

Community detection based on first passage probabilities

Community detection is of fundamental significance for understanding topology characters and spreading dynamics on complex networks. While random walk is widely used in previous algorithms, there still exist two major defects: (i) the maximal length of random walk in some methods is too large to distinguish different communities; (ii) the useful community information at all other step lengths are missed if using a pre-assigned maximal length. Here we propose a novel community detection algorithm named as First Passage Probability Method (FPPM), equipped with a new similarity measure that incorporates the complete structural information within the maximal step length. The diameter of the network is chosen as an appropriate boundary of random walks, which is adaptive to different networks. Numerical simulations show that FPPM performs best compared to several classic algorithms on both synthetic benchmarks and real-world networks, especially those with weak community structures.

Monte Carlo implementation of new algorithms for the evaluation of averaged-dose and -track linear energy transfers in 62 MeV clinical proton beams

We exploited the power of the Geant4 Monte Carlo toolkit to study and validate new approaches for the averaged linear energy transfer (LET) calculation in 62 MeV clinical proton beams. The definitions of the averaged LET dose and LET track were extended, so as to fully account for the contribution of secondary particles generated by target fragmentation, thereby leading to a more general formulation of the LET total. Moreover, in the proposed new strategies for the LET calculation, we minimised the dependencies in respect to the transport parameters adopted during the Monte Carlo simulations (such as the production cut of secondary particles, voxel size and the maximum steplength). The new proposed approach was compared against microdosimetric experimental spectra of clinical proton beams, acquired at the Italian eye proton therapy facility of the Laboratori Nazionali del Sud, Istituto Nazionale di Fisica Nucleare (INFN-LNS, Catania, I) from two different detectors: a mini-tissue equivalent proportional chamber (TEPC), developed at the Legnaro National Laboratories of the National Institute for Nuclear Physics (LNL-INFN) and a silicon-on-insulator (SOI) microdosimeter with 3D sensitive volumes developed by the Centre for Medical Radiation Physics of Wollongong University (CMRP-UoW). A significant increase of the LET in the entrance region of the spread out Bragg peak (SOBP) was observed, when the contribution of the generated secondary particles was included in the calculation. This was consistent with the experimental results obtained.

Standardizing Monte Carlo simulation parameters for a reproducible dose-averaged linear energy transfer.

Dose-averaged linear energy transfer (LETD) is one of the factors which determines relative biological effectiveness (RBE) for treatment planning in proton therapy. It is usually determined from Monte Carlo (MC) simulation. However, no standard simulation protocols were established for sampling of LETD. Simulation parameters like maximum step length and range cut will affect secondary electrons production and have an impact on the accuracy of dose distribution and LETD. We aim to show how different combinations of step length and range cut in GEANT4 will affect the result in sampling of LETD using different MC scoring methods. In this work, different step length and range cut value in a clinically relevant voxel geometry were used for comparison. Different LETD scoring methods were established and the concept of covariance between energy deposition per step and step length is used to explain the differences between them. We recommend a maximum step length of 0.05 mm and a range cut of 0.01 mm in MC simulation as this yields the most consistent LETD value across different scoring methods. Different LETD scoring methods are also compared and variation up to 200% can be observed at the plateau of 80 MeV proton beam. Scoring Method one has one of the lowest percentage differences compared across all simulation parameters. We have determined a set of maximum step length and range cut parameters to be used for LETD scoring in a 1 mm voxelized geometry. LETD scoring method should also be clearly defined and standardized to facilitate cross-institutional studies. Establishing a standard simulation protocol for sampling LETD would reduce the discrepancy when comparing data across different centres, and this can improve the calculation for RBE.

Effects of interactive video-game\u2013based exercise on balance in older adults with mild-to-moderate Parkinson\u2019s disease

BackgroundThis study aimed to evaluate the effectiveness of a customized interactive video game-based (IVGB) training on balance in older adults with mild-to-moderate Parkinson’s disease (PD).MethodsIn this 12-week crossover trial, PD patients ≥65 years of age were randomly divided into Group A (a 6-week intervention phase followed by a 6-week control phase) and Group B (a 6-week control phase followed by a 6-week intervention phase). Participants received IVGB exercise training during the intervention phase and no exercise during the control phase. Functional outcomes were measured using behavioral evaluation scales and questionnaires at baseline, week 6 and week 12.ResultsTwenty-four PD patients were included in this study, and were evenly divided into two groups. After Bonferroni adjustment, the changes in Modified Falls Efficacy Scale (MFES) and two subscales of Multi-Directional Reach Test were significantly different between two groups in the first 6-week period. In addition, the changes in Berg Balance Scale, MFES, and two subscales of Maximum Step Length were significantly different between two groups in the second 6-week period. Compared to controls, 6-week IVGB exercise intervention significantly improved different but overlapping functional outcomes in two groups of PD patients.ConclusionsThe customized IVGB exercise training improves balance, postural stability and confidence in preventing falls in older adults with mild-to-moderate PD. However, this IVGB exercise doesn’t have a significant impact on quality of life.Trial registrationClinicalTrials.gov. NCT03689764. Registered 27 September 2018, retrospectively registered.