scholarly journals In Vitro Comparison of Passive and Active Clinical Proton Beams

2020 ◽  
Vol 21 (16) ◽  
pp. 5650 ◽  
Author(s):  
Anna Michaelidesová ◽  
Jana Vachelová ◽  
Jana Klementová ◽  
Tomáš Urban ◽  
Kateřina Pachnerová Brabcová ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Code ◽  
Proton Beams ◽  
Biologically Relevant ◽  
Dose Rates ◽  
Medulloblastoma Cell Line ◽  
Significant Difference ◽  
Clonogenic Cell ◽  
In Vitro Comparison

Nowadays, the irradiation methodology in proton therapy is switching from the use of passively scattered beams to active pencil beams due to the possibility of more conformal dose distributions. The dose rates of active pencil beams are much higher than those of passive beams. The purpose of this study was to investigate whether there is any difference in the biological effectiveness of these passive and active irradiation modes. The beam qualities of double scattering and pencil beam scanning were measured dosimetrically and simulated using the Monte Carlo code. Using the medulloblastoma cell line DAOY, we performed an in vitro comparison of the two modes in two positions along the dose–deposition curve plateau and inside the Bragg peak. We followed the clonogenic cell survival, apoptosis, micronuclei, and γH2AX assays as biological endpoints. The Monte Carlo simulations did not reveal any difference between the beam qualities of the two modes. Furthermore, we did not observe any statistically significant difference between the two modes in the in vitro comparison of any of the examined biological endpoints. Our results do not show any biologically relevant differences related to the different dose rates of passive and active proton beams.

scholarly journals In vitro Comparison of Accuracy of Two Scanners Used in Dental Medicine

2019 ◽  
Vol 70 (7) ◽  
pp. 2344-2346
Author(s):  
Alexandru Victor Burde ◽  
Marius Manole ◽  
Radu-Septimiu Campian ◽  
Cosmin Sinescu ◽  
Sorana Baciu
Keyword(s):  
Experimental Model ◽  
Reference Model ◽  
Direct Consequence ◽  
Intraoral Scanner ◽  
Average Deviation ◽  
Virtual Reference ◽  
Significant Difference ◽  
Industrial Ct ◽  
In Vitro Comparison

This experimental study aims to highlight and compare the resolution and accuracy (trueness and fidelity) of an intraoral scanner and a laboratory scanner. In order to achieve the aim of this study, an experimental model consisting of a die with a standard preparation for a porcelain-fused to metal crown was manufactured from a physiognomic polymethylmethacrylate resin. The experimental model was scanned with an industrial CT to obtain the virtual reference model. Then, the die was scanned 15 times with each scanner. In order to asses trueness, comparisons were made with the virtual reference model, and for fidelity, the first scan in the series was compared with the following scans. In regards to the trueness of the scanners, the average deviation for the laboratory scanner is 4.31 and 17.34 mm for the intraoral scanner. When comparing the serial scannings� of the same die, the lowest recorded deviation is 6.4 mm for the laboratory scanner and 21.57mm for the intraoral scanner. For both fidelity and trueness, the F test demonstrates that there is a statistically significant difference between the scanners and the applied T-tests confirm the lower degree of error-rate generation by the laboratory scanner. The dimensional limitations imposed for the intraoral scanners have a direct consequence on their trueness and fidelity when compared to their laboratory counterparts.

Application of a 3D Discrete Ordinates-Monte Carlo Coupling Method on CAP1400 Cavity Streaming Calculation

2017 ◽  
Author(s):  
Zheng Zheng ◽  
Hui Li ◽  
Mengqi Wang
Keyword(s):  
Monte Carlo ◽  
Reactor Core ◽  
Coupling Method ◽  
Normal Operation ◽  
Discrete Ordinates ◽  
Deep Penetration ◽  
Monte Carlo Code ◽  
Surface Source ◽  
Dose Rates ◽  
Mc Method

Neutrons and photons produced from reactor core during operation pass through the pressure vessel, reach the reactor cavity, and form the reactor cavity streaming. Reactor cavity streaming dose rates calculation during normal operation is important for the evaluation and control of the equipment dose rates in the nuclear power plant. Because reactor is great in dimension and complex in geometry, neutrons and photons fluence rates declined by several orders from reactor core to outside. Cavity streaming calculation is a deep penetration calculation with heavy computation load which is difficult to converge. Three dimensional Discrete Ordinates and Monte Carlo (SN-MC) coupling method combines the advantage of the SN method with high efficiency and the MC method with fine geometrical modeling. The SN-MC coupling method decreases the tally errors and increases the efficiency of the MC method effectively by using MC surface source generated by the SN fluence rates. In this paper, the theoretical model of the 3D SN-MC coupling method is presented. In order to fulfill the coupling calculation, a 3D Discrete Ordinates code is modified to output angular fluence rates, a link code DO2MC is developed to calculate cummulative distribution functions of source particle variables on surface source, and a source subroutine is written for a 3D Monte Carlo code. The 3D SN-MC coupling method is applied on the calculation of the CAP1400 cavity streaming neutron and photon dose rates. Numerical results show that the 3D SN-MC coupling codes are correct, the relative errors of the results are less than 20% compared with those of the MC bootstrapping method, and the efficiency is greatly enhanced.

scholarly journals Differential Role of Progesterone Receptor Isoforms in the Transcriptional Regulation of Human Gonadotropin-Releasing Hormone I (GnRH I) Receptor, GnRH I, and GnRH II

2005 ◽  
Vol 90 (2) ◽  
pp. 1106-1113 ◽  
Author(s):  
Beum-Soo An ◽  
Jung-Hye Choi ◽  
Kyung-Chul Choi ◽  
Peter C. K. Leung
Keyword(s):  
Promoter Activity ◽  
Control Level ◽  
Expression Level ◽  
Transcriptional Level ◽  
Mrna Levels ◽  
Dependent Manner ◽  
Progesterone Receptor Isoforms ◽  
Medulloblastoma Cell Line ◽  
Significant Difference

Hypothalamic GnRH is a decapeptide that plays a pivotal role in mammalian reproduction by stimulating the synthesis and secretion of gonadotropins via binding to the GnRH receptor on the pituitary gonadotropins. It is hypothesized that sex steroids may regulate GnRH I (a classical form of GnRH), GnRH II (a second form of GnRH), and GnRH I receptor (GnRHRI) at the transcriptional level in target tissues. Thus, in the present study a role for progesterone (P4) in the regulation of GnRH I, GnRH II, and GnRHRI was investigated using a human neuronal medulloblastoma cell line (TE671) as an in vitro model. The cells were transfected with human GnRHRI promoter-luciferase constructs, and promoter activities were analyzed after P4 treatment by luciferase and β-galactosidase assay. The mRNA levels of GnRH I and GnRH II were analyzed by RT-PCR. Treatment of TE671 cells with P4 resulted in a decrease in GnRHRI promoter activity compared with the control level in a dose- and time-dependent manner. Cotreatment of these cells with RU486, an antagonist of P4, reversed P4-induced inhibition of GnRHRI promoter activity, suggesting that the P4 effect is mediated by P4 receptor (PR). In the cells transfected with a full-length of PR A- or PR B-expressing vector, overexpression of PR A increased the sensitivity toward P4 in an inhibition of GnRHRI promoter, whereas PR B increased transcriptional activity of GnRHRI promoter in the presence of P4. However, PR B itself did not act as a transcriptional activator of GnRHRI promoter. Because TE671 cells have been recently demonstrated to express and synthesize two forms of GnRHs, we also investigated the regulation of GnRH mRNAs by P4. In the present study, P4 increased GnRH I mRNA levels in a time- and dose-dependent manner. This stimulatory effect of P4 in the regulation of GnRH I mRNAs was significantly attenuated by RU486, whereas no significant difference in the expression level of GnRH II was observed with P4 or RU496. Interestingly, although the expression level of PR B was low compared with that of PR A, P4 action on the GnRH I gene was mediated by PR B. In conclusion, these results indicate that P4 is a potent regulator of GnRHRI at the transcriptional level as well as GnRH I mRNA. This distinct effect of P4 on the GnRH system may be derived from different pathways through PR A or PR B.

scholarly journals In Vitro Comparison of Root Surface Treatment Effect between Root Scaling with Ultrasonic Inserts and Gracey Curette and Polishing with Different Cleaning Pastes

2021 ◽  
Vol 11 (13) ◽  
pp. 5967
Author(s):  
Angelica Bertacci ◽  
Daniele Moro ◽  
Gianfranco Ulian ◽  
Giovanni Valdrè
Keyword(s):  
Single Dose ◽  
Root Surface ◽  
Grain Sizes ◽  
Morphological Evaluation ◽  
Significant Difference ◽  
Polishing Procedures ◽  
Root Surfaces ◽  
Standard Steel ◽  
In Vitro Comparison

The aim of this study was the morphological evaluation of root surfaces subjected to manual (curette) and ultrasonic (conventional and diamond tips) scaling. The surface was then polished with a rubber cup and three medium-sized pastes. Ninety teeth were randomly divided into three groups of 30 and subjected to three different root instrumentation: (1) manual instrumentation with a Gracey® curette; (2) ultrasonic instrumentation with a standard steel tip (Universal Perio S-SERIES: USU, Hu-Friedy, Chicago, IL, USA) at a power equal to 50%; and (3) with a diamond tip (Punta Piezo Serie E Scaling, Hu-Friedy, Chicago, IL, USA) at a power of 20%. Each group of the instrumented teeth was then divided in three subgroups of 10 and subjected to 30 s of rubber polishing with three different polishing pastes with medium grain sizes in single-dose cups: (1) Ultrapro Tx cool mint medium®; (2) Stomyprox media®; and (3) Nupro medium orange®. Polyether root surface replicas were then taken from all 90 samples and analyzed by SEM to evaluate surface morphology after scaling and polishing procedures. All scaling techniques caused an alteration of the root surface without statistically significant difference, whereas polishing resulted in maintenance or improvement of the surface texture.

A Biomechanical Comparison of Composite Fixation and Veterinary Acetabular Plates for Stabilization of Acetabular Osteotomies in Dogs Loaded in Three-Point-Bending Fashion

1998 ◽  
Vol 11 (03) ◽  
pp. 152-157 ◽  
Author(s):  
D. D. Lewis ◽  
J. B. Madison ◽  
L. L. Blaeser ◽  
O. I. Ianz
Keyword(s):  
Yield Point ◽  
In Vitro Study ◽  
Maximum Load ◽  
Fixation Method ◽  
Three Point Bending ◽  
Mixed Breed ◽  
Significant Difference ◽  
Biomechanical Comparison ◽  
In Vitro Comparison

SummaryAn in vitro study comparing the biomechanical performance and accuracy of reduction for two methods of acetabular osteotomy repair in the dog is presented. Pelves were harvested from five adult mixed breed dogs weighing 25-30 kg. On e hemipelvis from each dog was repaired with the composite fixation and the contralateral hemipelvis was repaired with a 2.0 mm six hole veterinary acetabular plate. Eac h hemipelvis was loaded in a threepoint- bending fashion at a rate of 5 mm/min. An extensometer was placed over the dorso-medial surface of the acetabular osteotomy during loading. Reduction was significantly better for hemipelves stabilized with the composite fixation when compared to hemipelves stabilized with the 2.0 mm six hole veterinary acetabular plate. There was not a significant difference in bending stiffness, distractional stiffness, yield point and maximum load between repair groups.An in vitro comparison was made between a composite fixation method and acetabular plates for the stabilisation of acetabular osteotomies.

Bragg peak characteristics of proton beams within therapeutic energy range and the comparison of stopping power using the GATE Monte Carlo simulation and the NIST data

2019 ◽  
Vol 19 (2) ◽  
pp. 173-181 ◽  
Author(s):  
Shiva Zarifi ◽  
Hadi Taleshi Ahangari ◽  
Sayyed Bijan Jia ◽  
Mohammad Ali Tajik-Mansoury ◽  
Milad Najafzadeh ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Energy Range ◽  
Bragg Peak ◽  
Stopping Power ◽  
Reference Database ◽  
Monte Carlo Code ◽  
Proton Beams ◽  
Depth Dose ◽  
Entrance Dose ◽  
Study Results

AbstractPurpose:To examine detail depth dose characteristics of ideal proton beams using the GATE Monte Carlo technique.Methods:In this study, in order to improve simulation efficiency, we used pencil beam geometry instead of parallel broad-field geometry. Depth dose distributions for beam energies from 5 to 250 MeV in a water phantom were obtained. This study used parameters named Rpeak, R90, R80, R73, R50, full width at half maximum (FWHM), width of 80–20% distal fall-off (W(80–20)) and peak-to-entrance ratio to represent Bragg peak characteristics. The obtained energy–range relationships were fitted into third-order polynomial formulae. The present study also used the GATE Monte Carlo code to calculate the stopping power of proton pencil beams in a water cubic phantom and compared results with the National Institute of Standards and Technology (NIST) standard reference database.Results:The study results revealed deeper penetration, broader FWHM and distal fall-off and decreased peak-to-entrance dose ratio with increasing beam energy. Study results for monoenergetic proton beams showed that R73 can be a good indicator to characterise a range of incident beams. These also suggest FWHM is more sensitive than W(80–20) distal fall-off in finding initial energy spread. Furthermore, the difference between the obtained stopping power from simulation and NIST data almost in all energies was lower than 1%.Conclusion:Detail depth dose characteristics for monoenergetic proton beams within therapeutic energy ranges were reported. These results can serve as a good reference for clinical practitioners in their daily practice.

scholarly journals An in vitro comparison of Antimicrobial Efficacy of Three Root Canal Irrigants—BioPure MTAD, 2% Chlorhexidine Gluconate and 5.25% Sodium Hypochlorite as a Final Rinse against E. faecalis

2013 ◽  
Vol 14 (5) ◽  
pp. 842-847 ◽  
Author(s):  
MS Rama Rao ◽  
Vinod Agrawal ◽  
Kanupriya Dhingra ◽  
V Rajesh Gopal ◽  
Abhijita Mohapatra
Keyword(s):  
Sodium Hypochlorite ◽  
Root Canal ◽  
Antibacterial Activities ◽  
Chlorhexidine Gluconate ◽  
Antimicrobial Efficacy ◽  
Pulp Tissue ◽  
Root Canal Irrigants ◽  
Significant Difference ◽  
In Vitro Comparison

ABSTRACT Aim This study was conducted to evaluate the antimicrobial activity of 5.25% sodium hypochlorite (NaOCl), 2% chlorhexidine (CHX) and BioPure MTAD when used as a final rinse against Enterococcus faecalis. Materials and methods Sixty single-rooted premolars were biomechanically prepared, inoculated with E. faecalis and divided into various groups. These were then irrigated with the test irrigants and tested microbiologically for growth of E. faecalis immediately after irrigation and after 48 hours. Results Statistical analysis showed that there was a significant difference between the antibacterial activities of BioPure MTAD, 2% CHX and 5.25% NaOCl at 5 minutes; however, the antibacterial activities of the three irrigants were comparable after 2 days of irrigation Conclusion The present study concludes that BioPure MTAD is as effective against E. faecalis as 5.25% NaOCl and more effective than 2% CHX. Clinical significance E. faecalis is one of the most resistant intracanal species and a possible cause of root canal failure. Many authors have stressed the importance of using antimicrobial irrigants during chemomechanical preparation to ensure complete disinfection. Therefore, various irrigating solutions have been used during and immediately after root canal preparation to remove debris and necrotic pulp tissue and to eliminate microorganisms that cannot be reached by mechanical instrumentation. How to cite this article Agrawal V, Rao MSR, Dhingra K, Gopal VR, Mohapatra A, Mohapatra A. An in vitro comparison of Antimicrobial Efficacy of Three Root Canal Irrigants—BioPure MTAD, 2% Chlorhexidine Gluconate and 5.25% Sodium Hypochlorite as a Final Rinse against E. faecalis. J Contemp Dent Pract 2013;14(5):842-847.

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