Tolerance Criteria Research Articles

Safety and Risk Analysis of an Operational Heater Using Bayesian Network

Industrials systems, including chemical industries, can be exposed to undesired events that may cause terrible accidents. These accidents must be controlled and reduced. To this end, numerous risk analysis management approaches have been aimed at reducing the risks to a tolerable level to avoid the catastrophic accident. This reduction is achieved by implementing several layers of protection, including organizational and technical barriers, this later known as safety-instrumented systems (SIS). The main objective assigned to a SIS is the detection of dangerous situations and implementation of a set of reactions necessary at a specific time to ensure that the equipment is under control. This function is typically name the safety-instrumented function and is characterized by a safety integrity level (SIL). A SIL is defined as a measure of the confidence to perform the safety function. This paper deals with the uncertainties of SIS using one of several robust probabilistic methods from a group of Bayesian networks (BN). A case study of an operational heater is used to illustrate the application. The results are then compared with the risk tolerance criteria and the safety of the improved process by updating the BN model.

Study of quality assurance regulations for linear accelerators in Korea: A comparison study between the current status in Korea and the international guidelines

Quality assurance (QA) for medical linear accelerators is indispensable for appropriate cancer treatment. Some international organizations and advanced Western countries have provided QA guidelines for linear accelerators. Currently, QA regulations for linear accelerators in Korean hospitals specify a system in which each hospital stipulates its independent hospital-based protocols for QA procedures (HP_QAPs) and conducts QA based on those HP_QAPs while regulatory authorities verify whether items under those HP_QAPs have been performed. However, because this regulatory method cannot guarantee the quality of universal treatment and QA items with tolerance criteria are different in many hospitals, the presentation of standardized QA items and tolerance criteria is essential. In this study, QA items in HP_QAPs from various hospitals and those presented by international organizations, such as the International Atomic Energy Agency, the European Union, and the American Association of Physicist in Medicine, and by advanced Western countries, such as the USA, the UK, and Canada, were compared. Concordance rates between QA items for linear accelerators that were presented by the aforementioned organizations and those currently being implemented in Korean hospitals were shown to exhibit a daily QA of 50%, a weekly QA of 22%, a monthly QA of 43%, and an annual QA of 65%, and the overall concordance rates of all QA items were approximately 48%. In the comparison between QA items being implemented in Korean hospitals and those being implemented in advanced Western countries, concordance rates were shown to exhibit a daily QA of 50%, a weekly QA of 33%, a monthly QA of 60%, and an annual QA of 67%, and the overall concordance rates of all QA items were approximately 57%. The results of this study indicate that the HP_QAPs currently implemented by Korean hospitals as QA standards for linear accelerators used in radiation therapy do not meet international standards. If this problem is to be solved, national standardized QA items and procedures for linear accelerators need to be developed.

Comparative responses of two Trigonella species to salinity and drought stresses in vitro

Effects of salinity and drought on growth, contents of proline, malondialdehyde (MDA), proteinand activity of antioxidative enzymes were studied in two Trigonella species. Seeds andexplants of T. foenum-graecum and T. aphanoneura were grown on Murashige and Skoogmedium (MS) complemented with iso-osmotic concentrations of NaCl (0, 100, 150 mM) andmannitol (0, 180, 275 mM). Growth and relative water content (RWC) of seedlings and callidecreased by increasing of salinity and drought in both species. In contrast to that of calli,proline and protein contents increased in seedlings of both species under both stresses. Theincrease of proline content in seedlings of T. aphanoneura was higher than that of T. foenumgraecumunder NaCl stress. MDA content in seedlings of T. aphanoneura was higher than thatof T. foenum-graecum and increased in both species under salinity. Among antioxidativeenzymes, catalase (CAT) activity increased continuously in seedlings of T. aphanoneuracomparing to that of T. foenum-graecum. Similar increasing trends were obtained regardingCAT activities in calli of both species under both stresses. Increase in activities of SOD, CATand POX was observed in calli of both species under stress. It seems that undifferentiated callirespond more regularly to both stresses. Finally, higher proline content and lower amount ofMDA could be considered as criteria for higher tolerance of T. foenum-graecum seedlingsagainst osmotic stresses.

Transcription Factor Nrf2: a novel target to modulate inflammatory and neuroprotective responses in Parkinson's disease.

Stopping the succession of events that lead to development of Parkinson’s disease (PD) is a principal challenge that requires a brain protective approach in early diagnosed patients. Although PD ethiopathology may not have a single causative factor, information from sporadic and familial cases together with chemical and genetic animal models strongly suggests that low-grade chronic inflammation and oxidative stress play a critical role. Our team is studying the relevance of the transcription factor NRF2 (Nuclear factor (erythroid-derived 2)-like 2), a master regulator of oxidant and inflammatory defense, as a new therapeutic target in PD. The pro-inflammatory activation of microglia and astroglia in response to LPS, MPTP and human α-synuclein over-expression is exacerbated in Nrf2-deficient mice, thus demonstrating an immunomodulatory role of this protein. In PD patients, some evidence gathered from epidemiological, genetic and anatomopathologic studies also support a protective role of NRF2. Several compounds activate NRF2 and provide an immunomodulator and cytoprotective response in preclinical animal models of PD. At this time a crucial point to translate these promising results to the clinic is the discovery of a drug with good pharmacokinetics and pharmacodynamics that fulfill criteria of safety, tolerability and efficacy. The use of repurposing drugs, such as dimethyl fumarate used nowadays for treatment of remitting relapsing multiple sclerosis, may provide excellent candidates.

The establishment of gas accident risk tolerability criteria based on F–N curve in China

The serious situation of China coal mine safety has caused great concern in China. Gas accidents have been the subject of statistical analysis studies in some of the literature, and little research has focused on societal risk and tolerability criteria. This paper reports the results of a preliminary study of societal risk and tolerability criteria of gas accidents in China. This analysis is based on a study of 10 years of gas accidents statistical data from 2004 to 2013. After applying hierarchical cluster analysis, eight sets of data are available. Subsequently, regression analysis is used to establish F–N curves for gas accidents; these F–N curves are then revised to reflect the practical situation in China. Moreover, gas accidents’ risk tolerability criteria are decided according to the ALARP principle. This study reveals that tolerability criteria in developed countries are stricter than those in China. The findings of the paper give an in-depth look at the severity of gas accidents and may contribute to the improvement of the safety conditions of China’s coal industry.

SU‐E‐T‐360: End‐To‐End Dosimetric Testing of a Versa HD Linear Accelerator with the Agility Head Modeled in Pinnacle3

Purpose:The Versa HD incorporates a variety of upgrades, primarily including the Agility head. The distinct dosimetric properties of the head from its predecessors combined with flattening‐filter‐free (FFF) beams require a new investigation of modeling in planning systems and verification of modeling accuracy.Methods:A model was created in Pinnacle3 v9.8 with commissioned beam data. Leaf transmission was modeled as <0.5% with maximum leaf speed of 3 cm/s. Photon spectra were tuned for FFF beams, for which profiles were modeled with arbitrary profiles rather than with cones. For verification, a variety of plans with varied parameters were devised, and point dose measurements were compared to calculated values. A phantom of several plastic water and Styrofoam slabs was scanned and imported into Pinnacle3. Beams of different field sizes, SSD, wedges, and gantry angles were created. All available photon energies (6 MV, 10 MV, 18 MV, 6 FFF, 10 FFF) as well four clinical electron energies (6, 9, 12, and 15 MeV) were investigated. The plans were verified at a calculation point (8 cm deep for photons, variable for electrons) by measurement with a PTW Semiflex ionization chamber. In addition, IMRT testing was performed with three standard plans (step and shoot IMRT, small and large field VMAT plans). The plans were delivered on the Delta4 IMRT QA phantom (ScandiDos, Uppsala, Sweden).Results:Homogeneous point dose measurement agreed within 2% for all photon and electron beams. Open field photon measurements along the central axis at 100 cm SSD passed within 1%. Gamma passing rates were >99.5% for all plans with a 3%/3mm tolerance criteria. The IMRT QA results for the first 23 patients yielded gamma passing rates of 97.4±2.3%.Conclusion:The end‐to‐end testing ensured confidence in the ability of Pinnacle3 to model photon and electron beams with the Agility head.

SU‐F‐BRB‐09: Measurement Based Dose‐Volume Metrics for the Quality Assurance of VMAT Plans‐Are We There Yet?

Purpose:To validate ArcCHECK measurement‐based 3DVH dose‐volume metrics for use with volumetric modulated arc therapy (VMAT) plans.Methods:Five each of prostate and head and neck (H&N) VMAT plans were considered for this study. Three types of errors were introduced into the original plans: gantry angle independent MLC shift (ranging from −5mm to 5mm), gantry angle dependent MLC error (ranging from 1mm to 7mm) and gantry angle dependent dose error (ranging from 1% to 10%). The percentage difference in PTV‐D95 as estimated by 3DVH for the error‐introduced delivery was compared with a similar metric calculated by comparing the dose matrices of the error‐free and error‐introduced plans calculated in the TPS. The gamma analysis with 2%L/2mm and 3%L/3mm tolerance criteria was also calculated by comparing the dose matrices.Results:For MLC shift errors, the TPS dose matrix comparison showed that the PTV‐D95 for the prostate plans reduced by a maximum (SD) of −8.4(3.3)% for the 5mm error. The 3DVH‐estimated D95 reduced from −0.5(2.0) for no‐error plans to −1.0(3.3)% for the 5mm MLC shift. Similarly for H&N plans the TPS‐calculated PTV‐D95 reduced by −5.1(3.8)%, with the 3DVH‐estimated D95 reducing from −1.5(2.2)% to −3.2(5.8)%. For gantry dependent MLC errors, the TPS D95 of prostate plans reduced to a maximum of −14.1(8.5)%, while the 3DVH‐estimated D95 reduced to 0.6(4.2)%. For H&N plans the TPS D95 reduced to −1.7(1.7)%, while the 3DVH‐estimated D95 reduced to −4.0(4.1)%. No major change in D95 was observed for gantry dependent dose errors for the TPS or 3DVH. In all error scenarios the gamma pass rate decreased as the magnitude of error increased.Conclusion:The gamma comparison of dose matrices was shown to detect all type of errors considered. The 3DVH‐estimated D95 agreed with the TPS more closely in H&N plans than prostate plans.This project was funded through a Cancer Council NSW Project Grant (RG14‐11)

SU‐E‐T‐179: Clinical Impact of IMRT Failure Modes at Or Near TG‐142 Tolerance Criteria Levels

Purpose:Quantitatively assess the clinical impact of 11 critical IMRT dose delivery failure modes.Methods:Eleven step‐and‐shoot IMRT failure modes (FMs) were introduced into twelve Pinnacle v9.8 treatment plans. One standard and one highly modulated plan on the IROC IMRT phantom and ten previous H&N patient treatment plans were used. FMs included physics components covered by basic QA near tolerance criteria levels (TG‐142) such as beam energy, MLC positioning, and MLC modeling. Resultant DVHs were compared to those of failure‐free plans and the severity of plan degradation was assessed considering PTV coverage and OAR and normal tissue tolerances and used for FMEA severity scoring. Six of these FMs were physically simulated and phantom irradiations performed. TLD and radiochromic film results are used for comparison to treatment planning studies.Results:Based on treatment planning studies, the largest clinical impact from the phantom cases was induced by 2 mm systematic MLC shift in one bank with the combination of a D95% target under dose near 16% and OAR overdose near 8%. Cord overdoses of 5%–11% occurred with gantry angle, collimator angle, couch angle, MLC leaf end modeling, and MLC transmission and leakage modeling FMs. PTV coverage and/or OAR sparing was compromised in all FMs introduced in phantom plans with the exception of CT number to electron density tables, MU linearity, and MLC tongue‐and‐groove modeling. Physical measurements did not entirely agree with treatment planning results. For example, symmetry errors resulted in the largest physically measured discrepancies of up to 3% in the PTVs while a maximum of 0.5% deviation was seen in the treatment planning studies. Patient treatment plan study results are under analysis.Conclusion:Even in the simplistic anatomy of the IROC phantom, some basic physics FMs, just outside of TG‐142 tolerance criteria, appear to have the potential for large clinical implications.

SU‐E‐T‐563: Multi‐Fraction Stereotactic Radiosurgery with Extend System of Gamma Knife: Treatment Verification Using Indigenously Designed Patient Simulating Multipurpose Phantom

Purpose:Aim of the study is to evaluate mechanical and radiological accuracy of multi‐fraction regimen and validate Gamma knife based fractionation using newly developed patient simulating multipurpose phantom.Methods:A patient simulating phantom was designed to verify fractionated treatments with extend system (ES) of Gamma Knife however it could be used to validate other radiotherapy procedures as well. The phantom has options to insert various density material plugs and mini CT/MR distortion phantoms to analyze the quality of stereotactic imaging. An additional thorax part designed to predict surface doses at various organ sites. The phantom was positioned using vacuum head cushion and patient control unit for imaging and treatment. The repositioning check tool (RCT) was used to predict phantom positioning under ES assembly. The phantom with special inserts for film in axial, coronal and sagittal plane were scanned with X‐Ray CT and the acquired images were transferred to treatment planning system (LGP 10.1). The focal precession test was performed with 4mm collimator and an experimental plan of four 16mm collimator shots was prepared for treatment verification of multi‐fraction regimen. The prescription dose of 5Gy per fraction was delivered in four fractions. Each fraction was analyzed using EBT3 films scanned with EPSON 10000XL Scanner.Results:The measurement of 38 RCT points showed an overall positional accuracy of 0.28mm. The mean deviation of 0.28% and 0.31 % were calculated as CT and MR image distortion respectively. The radiological focus accuracy test showed its deviation from mechanical center point of 0.22mm. The profile measurement showed close agreement between TPS planned and film measured dose. At tolerance criteria of 1%/1mm gamma index analysis showed a pass rate of > 95%.Conclusion:Our results show that the newly developed multipurpose patient simulating phantom is highly suitable for the verification of fractionated stereotactic radiosurgery using ES of Gamma knife.The study is a part of intramural research project of Research Section, All India Institute of Medical Sciences New Delhi India (A 247).

SU‐E‐T‐105: An FMEA Survey of Intensity Modulated Radiation Therapy (IMRT) Step and Shoot Dose Delivery Failure Modes

Purpose:To assess the perception of TG‐142 tolerance level dose delivery failures in IMRT and the application of FMEA process to this specific aspect of IMRT.Methods:An online survey was distributed to medical physicists worldwide that briefly described 11 different failure modes (FMs) covered by basic quality assurance in step‐ and‐shoot IMRT at or near TG‐142 tolerance criteria levels. For each FM, respondents estimated the worst case H&N patient percent dose error and FMEA scores for Occurrence, Detectability, and Severity. Demographic data was also collected.Results:181 individual and three group responses were submitted. 84% were from North America. Most (76%) individual respondents performed at least 80% clinical work and 92% were nationally certified. Respondent medical physics experience ranged from 2.5–45 years (average 18 years). 52% of individual respondents were at least somewhat familiar with FMEA, while 17% were not familiar. Several IMRT techniques, treatment planning systems and linear accelerator manufacturers were represented. All FMs received widely varying scores ranging from 1–10 for occurrence, at least 1–9 for detectability, and at least 1–7 for severity. Ranking FMs by RPN scores also resulted in large variability, with each FM being ranked both most risky (1st ) and least risky (11th) by different respondents. On average MLC modeling had the highest RPN scores. Individual estimated percent dose errors and severity scores positively correlated (p<0.10) for each FM as expected. No universal correlations were found between the demographic information collected and scoring, percent dose errors, or ranking.Conclusion:FMs investigated overall were evaluated as low to medium risk, with average RPNs less than 110. The ranking of 11 FMs was not agreed upon by the community. Large variability in FMEA scoring may be caused by individual interpretation and/or experience, thus reflecting the subjective nature of the FMEA tool.

SU‐E‐T‐760: Tolerance Design for Site‐Specific Range in Proton Patient QA Process Using the Six Sigma Model

Purpose:To show how tolerance design and tolerancing approaches can be used to predict and improve the site‐specific range in patient QA process in implementing the Six Sigma.Methods:In this study, patient QA plans were selected according to 6 site‐treatment groups: head &neck (94 cases), spine (76 cases), lung (89 cases), liver (53 cases), pancreas (55 cases), and prostate (121 cases), treated between 2007 and 2013. We evaluated a model of the Six Sigma that determines allowable deviations in design parameters and process variables in patient‐specific QA, where possible, tolerance may be loosened, then customized if it necessary to meet the functional requirements. A Six Sigma problem‐solving methodology is known as DMAIC phases, which are used stand for: Define a problem or improvement opportunity, Measure process performance, Analyze the process to determine the root causes of poor performance, Improve the process by fixing root causes, Control the improved process to hold the gains.Results:The process capability for patient‐specific range QA is 0.65 with only ±1 mm of tolerance criteria. Our results suggested the tolerance level of ±2–3 mm for prostate and liver cases and ±5 mm for lung cases. We found that customized tolerance between calculated and measured range reduce that patient QA plan failure and almost all sites had failure rates less than 1%. The average QA time also improved from 2 hr to less than 1 hr for all including planning and converting process, depth‐dose measurement and evaluation.Conclusion:The objective of tolerance design is to achieve optimization beyond that obtained through QA process improvement and statistical analysis function detailing to implement a Six Sigma capable design.

Influence of dose adjustment on afatinib safety and efficacy in patients (pts) with advanced EGFR mutation-positive (EGFRm+) non-small cell lung cancer (NSCLC).

8073 Background: Afatinib 40 mg/day (oral) is approved for the treatment of pts with advanced EGFRm+ NSCLC. Dose adjustment is recommended according to pre-defined tolerability criteria. We perform...

A Mechanistic Empirical Approach Utilizing Controlled Tolerable Deflection for the Design of Thin Surfaced Asphalt Pavements

Thin surfaced asphalts are designed in a similar manner to spray sealed asphalts considering only rutting as the major mode of failure while there is no consideration for fatigue in the current mechanistic empirical pavement design method adopted by Austroads. However, sprayed seal surfacing are less sensitive to vertical deflection compared to thin surfaced asphalts. Thin surfaced asphalts are commonly prematurely failed by fatigue before any major rutting failure. In this research, the Austroads tolerable deflection criteria was investigated utilizing deflection and cumulative traffic data from 30 thin asphalt pavement sections from Queensland. The data showed that the current Austroads tolerable deflection criterion is largely overestimating the design life of these pavement sections. A new calibrated tolerable deflection criterion was developed. The calibrated tolerable deflection criterion was used with synthetic deflection data and pavement responses generated by multilayer elastic analysis using Circly software for 200 pavement sections to develop a new subgrade criterion. The new subgrade criterion is designed to limit the maximum pavement deflection to be within the calibrated tolerable deflection. By limiting the maximum deflection of the thin asphalt pavements to the new calibrated tolerable deflection, it is expected that surface curvature will be reduced and therefore the fatigue life of these pavements will be significantly improved and it will limit the premature failures of these surfaces. The new criterion produces a stiffer pavement structure compared to the current method. The high stiffness can be achieved by using thicker base course or stabilized bases and subbases structures.

Use of Time Temperature Integrators in food safety management

Distribution, retail and domestic storage of food are considered as the weaker links in a food safety management system. Conditions during the above stages of the food chain are out of manufacturer's direct control and often deviate from specifications. This lack of control may result to increased microbial growth and negate the efforts made in improving and maintaining food safety at the earlier stages of the chain via Hazard Analysis and Critical Control Points system, Good Manufacturing and Hygiene Practices. Ideally, a cost-effective way to individually monitor the temperature conditions of food products throughout distribution, retail and domestic storage, indicating their real time–temperature history, would be an effective safety management tool. Time Temperature Integrators (TTIs) could potentially fulfill the above requirements. Despite the extensive research on the application of TTIs for monitoring food spoilage and quality, however, limited information is available for their use in food safety management. The objective of the present study is to present the state of the art and application scheme of TTIs in food safety management. The effectiveness of TTIs in improving food safety is demonstrated through a case study for Listeria monocytogenes in Ready-to-Eat foods. We show that a microbial TTI can assure a maximum limit in the growth of the pathogen from production to consumption time by informing the consumers when this limit is exceeded in a product unit. The latter limit, which we call Growth Tolerance Criterion, can be considered as a Performance Criterion for the growth of L. monocytogenes during distribution and storage. The applicability of the microbial TTI in reducing consumer exposure to L. monocytogenes is also presented using a probabilistic approach.

Major Depressive Disorder in View of Bipolar Spectrum

Bipolar disorder is complex and it can be difficult to diagnose. Hypomania is considered normal and not diagnosed, so bipolar II disorder often it is misdiagnosed as recurrent major depressive disorder. How much of major depresiv disorder is actually bipolar disorder? The concept of bipolar spectrum will help in reducing undiagnosed bipolarity. Disclose of hypomania is a important factor for the identification of bipolar II disorder. Bipolar spectrum disorder is a continuum from pure depression to symptoms of mania along a horizontal and vertical plan. This study aims to examinante major depression according to a new view of the bipolar spectrum and provide to answer the question: What part of major depression is in fact bipolar depression? Were interviewed 190 patients adult with MDD, first episode or recurrent depression. Used the Hypomania Checklist-32 and Mood Disorder Questioner to identify symptoms of hypomania which will show us bipolar disorder hidden between major depresiv disorder. Patients underwent a detailed psychiatric assessment using categorical criteria of DSM-IV for bipolar disorder and dimensional criteria (tolerant criteria) of Zurich study (2005). Interviews were taken over a one year period 2011-2012. The tests HCL-32 and MDQ showed that about 20% (1/5) of depresive patients meet criteria for hypomania according to DSM-IV criteria. These patients are in fact bipolar disorder, treated as major depressive disorder. Refereed dimensional criteria, 24-39% (1/4-1/3) are in fact bipolar disorder. A major part of MDD is in fact Bipolar Disorder and should be treated as such.

Integrated selection criteria for drought tolerance in wheat (Triticum aestivum L.) breeding programs using discriminant analysis

Secondary traits are critical in determining the production of bread wheat in drought prone environments. This study was conducted to assess the effect of 25 morpho-physiological secondary traits on grain yield of 40 bread wheat genotypes under drought stress condition. The field and glasshouse experiments were carried out during 2009–2010 and 2010–2011. Considerable genetic variation was observed for all traits. Low genetic variance (0.10) and high genetic×environment interaction (0.31) resulted in moderate heritability (0.45) for grain yield. The average broad sense heritability for secondary traits (0.65) was significantly higher than for grain yield. In this research, ten secondary traits including water use, relative ionic leakage, leaf length, root length, grain number, awn length, above ground biomass, yield potential, days to flowering, and grain filling period could significantly discriminate high and low yield genotypes under drought stress condition. This showed the importance of these ten traits in breeding program for drought tolerance. Discriminant function of these ten traits was used as a comprehensive index for selection of high yield genotypes (Eq. (11)). This index could explain 76% of grain yield variation, and had significant positive correlation with grain yield under drought stress condition in the first (r=0.88**) and second year (r=0.53**). Consequently, this criterion was proposed for integrated selection in future breeding programs. Discriminant function showed that the relative ionic leakage and root length were the most important traits, followed by water use and grain filling period. Due to high heritability of secondary traits and their correlation with grain yield, selection based on these traits could improve genetic gain for grain yield in drought prone environments.

Predicting changes in cortical electrophysiological function after in vitro traumatic brain injury.

Finite element (FE) models of traumatic brain injury (TBI) are capable of predicting injury-induced brain tissue deformation. However, current FE models are not equipped to predict the biological consequences of tissue deformation, which requires the determination of tolerance criteria relating the effects of mechanical stimuli to biologically relevant functional responses. To address this deficiency, we present functional tolerance criteria for the cortex for alterations in neuronal network electrophysiological function in response to controlled mechanical stimuli. Organotypic cortical slice cultures were mechanically injured via equibiaxial stretch with a well-characterized in vitro model of TBI at tissue strains and strain rates relevant to TBI (up to Lagrangian strain of 0.59 and strain rates up to 29 [Formula: see text]. At 4-6days post-injury, electrophysiological function was assessed simultaneously throughout the cortex using microelectrode arrays. Electrophysiological parameters associated with unstimulated spontaneous network activity (neural event rate, duration, and magnitude), stimulated evoked responses (the maximum response [Formula: see text], the stimulus current necessary for a half-maximal response [Formula: see text], and the electrophysiological parameter [Formula: see text] that is representative of firing uniformity), and evoked paired-pulse ratios at varying interstimulus intervals were quantified for each cortical slice culture. Nonlinear regression was performed between mechanical injury parameters as independent variables (tissue strain and strain rate) and each electrophysiological parameter as output. Parsimonious best-fit equations were determined from a large pool of candidate equations with tenfold cross-validation. Changes in electrophysiological parameters were dependent on strain and strain rate in a complex manner. Compared to the hippocampus, the cortex was less spontaneously active, less excitable, and less prone to significant changes in electrophysiological function in response to controlled deformation (strain or strain rate). Our study provides functional data that can be incorporated into FE models to improve their predictive capabilities of the in vivo consequences of TBI.

Variability in heat tolerance in Bambara groundnut (Vigna subterranea (L.) Verdc.)

Four Bambara groundnut landraces (Vigna subterranea (L.) Verdc.) of African origin (S-165 A, DodR, Uniswa red and SB-42), were grown at research farm of Central Arid Zone Research Institute, Regional Research Station, Bikaner to evaluate for heat tolerance based on the cell membrane thermostability of leaf tissue by using five temperature treatments (40, 45, 50, 55 and 60 °C) and four heating durations (15, 30, 45 and 60 min). Lethal temperature and lethal heating duration was used as the selection criteria for heat tolerance. Significant genotypic variations were evident for both lethal temperature and lethal heating duration. A strong relationship between lethal temperature and lethal heating duration indicates that any one of two parameters can be used as selection criteria for screening Bambara groundnut genotypes for heat tolerance. However, the range of lethal temperature was too narrow (47.5–49.4 °C), whereas the range of lethal heating duration was fairly longer (39.9–48 min) to distinguish the genotypes. Further, there was strong and significant relationship between lethal heating duration and relative injury under heat stress at 50 °C. From this study it can be concluded that lethal heating duration at 50 °C is a potential selection criterion for identifying heat tolerant genotypes in Bambara groundnut.

Three dimensional dose verification of VMAT plans using the Octavius 4D dosimetric system

The Octavius 4D dosimetric system generates a 3D dose matrix based on a measured planar dose and user supplied Percentage Depth Dose (PDD) data. The accuracy of 3D dose matrices reconstructed by the Octavius 4D dosimetric system was systematically studied for an open static field, an open arc field and clinical VMAT plans. The Octavius reconstructed 3D dose matrices were compared with the Treatment Planning System (TPS) calculated 3D dose matrices using 3D gamma (γ) analysis with 2%/2mm and 3%/3mm tolerance criteria. The larger detector size in the 2D detector array of the Octavius system resulted in failed voxels in the high dose gradient regions. For the open arc fields mean (1σ) γ pass rates of 84.5(8.9) % and 94.2(4.5) % were observed with 2%/2mm and 3%/3mm tolerance criteria respectively and for clinical VMAT plans mean (1σ) γ pass rates of 86.8(3.5) % and 96.7(1.4) % were observed.

Benchmarking the gamma pass score using ArcCHECK for routine dosimetric QA of VMAT plans

A minimum expected gamma (γ) pass rate for VMAT plan verification using ArcCHECK was established based on the RTTQA, TGI 19 test cases and 10 clinical plans with varying levels of complexity. The impact of the 'Measurement Uncertainty' parameter as available in the ArcCHECK software on γ pass rate was studied for both global and local γ analysis. Our results show that excluding measurement uncertainty adds tighter tolerance in local γ comparison. From the verification of our benchmark cases we established minimum expected γ pass rates of 85% and 88% for 2%/2mm global and 3%/3mm local tolerance criteria.