A new reference-type ionization chamber with direction-independent response for use in small-field photon-beam dosimetry – An experimental and Monte Carlo study

The frequently applied narrow and non-standard transverse dose profiles of intensity modulated photon-beam radiotherapy, lacking lateral secondary electron equilibrium, require the use of high-resolution dosimetry detectors, and small air-filled detectors are recommended as the reference detectors for cross-calibration of the high-resolution detectors. The present study focuses on the dosimetric properties of a novel cylindrical ionization chamber, the PTW Semiflex 3D 31021. The chamber's effective point of measurement was found to lie at (0.41 ± 0.04) r downstream the tip of the inner surface of the spherical front wall in the axial orientation and (0.46 ± 0.04) r upstream the chamber axis in the radial orientation. Due to its symmetrical design, the sigma values of its lateral dose response functions for all chamber's orientations are the same (2.10 ± 0.05 mm). The polarity correction factors obtained in this work do not exceed 0.1% and the saturation correction factor was below 1% up to a dose-per-pulse value of 0.956 mGy. The radiation quality correction factor k_Q of the chamber as a function of the tissue-phantom-ratio, TPR_20,10, has been calculated by Monte Carlo simulation and has been determined experimentally at the German Metrology Institute (Physikalisch-Technische Bundesanstalt, PTB). The values of the non-reference condition correction factor k_NR have been Monte-Carlo-calculated for use of the chamber at various depths and field sizes.     

Author affiliation addition: “Hepatitis B virus detected in paper currencies in a densely populated city of India: A plausible source of horizontal transmission?”

Addition of authors’ affiliation to "Hepatitis B virus detected in paper currencies in a densely populated city of India: A plausible source of horizontal transmission?" World J Hepatol 2020 Oct 27; 12(10): 775-791. In this article, one of the affiliations of two authors was not mentioned. Ruchi Supekar, a joint first author and Subhajit Biswas, the corresponding author are affiliated to Academy of Scientific and Innovative Research (AcSIR) Ghaziabad- 201002, India.     

扩散敏感梯度相关图像变形规律与矫正技术研究

目的用坐标变换描述不同方向扩散敏感梯度(Gb)情况下图像的变形规律,探讨不同方向Gb时扩散加权成像(DWI)的变形机制矫正方法.方法采用自制25点空间定位模具,在三个垂直方向施加b为1000 mm2/s的Gb后采集DWIR,S,P,并同时获得b为0 mm2/s的DWI0.应用数据拟合的方法建立成像平面的坐标变换方程.利用坐标变换将DWIR,S,P对DWI0进行矫正,再将DWI0对标准SE-T1WI进行矫正,定量研究其变形程度与规律.结果相对于标准SE-T1WI成像平面,DWI(0,R,S,P)成像平面的变形为平面弹性变形.相对于DWI0,DWIR,S,P的变形均为刚体的平行移动.DWIS与DWIR的变形主要表现在Y方向上的正向移动,以DWIS为重; DWIP表现为X与Y方向均有位移存在.各个坐标变换公式的方差分析P<0.001,决定系数均大于0.99.结论 EPI的梯度回波采集方式产生的电涡流对空间定位梯度产生的影响导致图像变形为平面弹性变形.而DWI中,不同Gb情况下,具有不同的变形规律.各坐标变换公式准确定量地描述了平面成像的变形规律,可以用于矫正成像变形.     

Is there an optimal degree of correction for ankle varus deformity after supramalleolar osteotomy? A systematic review

BackgroundThere is no consensus on the angle targeted for in varus ankle deformity after supramalleolar osteotomy (SMOT). The aim of this study was to investigate which obtained correction has the best clinical outcome after valgus SMOT.MethodsA systematic review according PRISMA guidelines was conducted with studies being eligible for inclusion when published in English, German or Dutch, patients older than 18 years at study entrance, primary or posttraumatic varus ankle osteoarthritis, using any valgus SMOT technique, describing radiological alignment and clinical outcome at baseline and after at least 12 months follow-up. Risk of bias was assessed using the McMaster University Occupational Therapy Evidence-Based Practice Research Group quality assessment tool. The electronical databases PubMed, EMBASE and Cinahl were used as data sources. Included cohorts were categorized according to the mean obtained medial distal tibia angle (MDTA; ranged between 87° and 100°). A linear mixed effect model was used for individual patient data to assess the association between the MDTA and the (difference in) clinical outcome.ResultsThirty studies including 33 patient cohorts with 922 ankles were identified. At a mean follow-up of 4 years no differences in clinical outcome between correction categories were found. Individual data of 34 ankles showed no relationship between obtained MDTA and clinical outcome either.ConclusionThis review could not demonstrate an optimal degree of correction after valgus SMOT. Results were hampered by biased low quality studies and the widespread use of unreliable 2D alignment measures such as the MDTA.     

种植支抗非拔牙矫治成人上颌前突畸形的临床研究

目的：探讨种植支抗非拔牙矫治成人上颌前突畸形的临床疗效。方法分析50例上颌前突畸形成人患者临床资料,依据支抗不同进行临床分组,对照组(传统强支抗组)20例和观察组(种植支抗非拔牙矫治组)30例。结果观察组上颌前突患者上中切牙切缘到Y轴的距离(U1-Y)、下中切牙切缘到Y轴的距离(L1-Y)、上第一磨牙冠近中点到Y轴的距离(U6-Y)、下中切牙长轴和下颌平面所形成的后上夹角(L1-MP)、上、下中切牙长轴之间的夹角(U1-L1)优于对照组,差异均有统计学意义(P<0.05)。结论不锈钢微螺钉种植系统矫治成人上颌前突畸形效果明显,值得临床推广应用。     

Estimating the prevalence of drinking problems among physicians

Objective

Surveys assessing alcohol use among physicians have most commonly employed the Alcohol Use Disorders Identification Test (AUDIT) or the AUDIT-C, the most common short version of the AUDIT. As with other screeners, prevalence estimation is dependent on the accuracy of the test as well as choice of the cutoff value. The aim of the current study is to derive more precise prevalence estimates of alcohol problems in physicians by correcting for false-positive and false-negative results.

Method

In the context of a survey, the AUDIT was sent out via email or standard postal service to all 2484 physicians in Salzburg, Austria. A total of 456 physicians participated. A published correction formula was used to estimate the real prevalence of alcohol use problems.

Results

Applying a cutoff of 5 points for the AUDIT-C, 15.7% of female and 37.7% of male physicians screened positive. Use of a correction based on general population data and the sensitivity and specificity of the AUDIT-C resulted in much lower prevalence rates: 4.0% for female and 9.5% for male physicians. Using the full AUDIT, 19.6% of the female physicians and 48% of the male physicians were screened positive. Using the correction, the estimated prevalence rates for females and males were 6.3% and 15.5%, respectively.

Conclusions

Our findings demonstrate that uncorrected screening results may markedly overestimate the prevalence of physicians drinking problems.     

Correction osteotomy of distal radius malunion stabilised with dorsal locking plates without grafting

The purpose of this study was to evaluate the results of our correction osteotomies of distal radial malunions without a bone graft. Eleven consecutive patients (mean age 52 years, range 18–71) were treated. A dorsal approach was utilised to perform an opening-wedge osteotomy which then was stabilised with two dorsal columnar plates without filling the osteotomy gap. All patients went on to radiographic union with a filling of the osteotomy gap within a mean period of 3 months (range 2–6 months). All patients had satisfactory results in terms of function and pain. Correction osteotomy and stabilisation with bicolumnar locked plate fixation without a bone graft provides sufficient stability to allow the highly vascularised metaphysis to heal. In patients without risk factors predisposing to non-union, this procedure is safe and feasible.     

Correction of penile torsion and chordee by mobilization of urethra with spongiosum in chordee without hypospadias

ObjectiveTo investigate the feasibility of correcting coexistent penile torsion and chordee without hypospadias by mobilization of the urethra and spongiosum.Materials and MethodsA retrospective study of nine patients with simultaneous penile torsion and chordee without hypospadias was undertaken between January 2006 and December 2012. During this period, a total of 364 cases of hypospadias and 38 of chordee without hypospadias were operated on, making a total of 402 patients with hypospadias-related complexes. The same steps were used for correction of both torque and chordee. After a circumcoronal incision, the penis was fully degloved and the spongiosum with urethra was lifted up off the cavernosa. Next, mobilization of the hypoplastic urethra with spongiosum was extended into the glans. If chordee or torque persisted, urethral mobilization was performed proximally up to the bulbar urethra, as required. Spongioplasty and glansplasty were done and a per-urethral stent was kept in for three to five days.ResultsThe age of the patients ranged from 5 to 16 years (median 6 years). Penile torsion ranged from 30° to 120°, with a median of 75°. Ventral chordee ranged from 45° to 100°, with a median of 50°. A ratio of 1:9.6 was found for chordee without hypospadias compared to the total hypospadias cases, with an incidence of 9.5%. The ratio of chordee without hypospadias with torsion compared to the total hypospadias cases was 1:29. There was an incidence of chordee without hypospadias with penile torsion of 3.5% in all patients with hypospadias. The ratio of chordee without hypospadias with torsion to only chordee without hypospadias was 1:1.71, with an incidence of 37.0%. Every step contributed to the correction of curvature and torsion. Chordee was corrected in two patients by penile degloving and lifting of the spongiosa off the urethral plate; three patients required additional mobilization of the urethra into the glans. Another two patients needed proximal urethral mobilization and one required a dorsal plication. In five patients, torque was corrected by penile degloving, lifting of the spongiosa and mobilization of the urethra into the glans; four patients required further proximal urethral mobilization. All patients had excellent functional and cosmetic results. No residual chordee or torque was observed in any patient on follow-up at 12–24 months.ConclusionThe technique of distally mobilizing a hypoplastic urethra with spongiosum from the corpora into the glans, and proximally up to the bulbar region corrects moderate to severe chordee and torsion with excellent cosmetic results. The incidence of torsion with chordee without hypospadias was 3.5% of all cases of hypospadias.