Case report: the occurrence of fibrillary lines in overnight orthokeratology

BACKGROUND: To report the occurrence of concentric fibrillary lines in the central corneas of a 13-year-old girl during overnight orthokeratology. METHODS: Observational case report. RESULTS: The initial refractive errors and keratometric readings (flattest/steepest meridians) of the patient were -6.00/-0.50 x 180 and 45.25/46.20 D, respectively, in the right eye and -5.50 DS and 44.90/45.80 D, respectively in the left eye. She underwent orthokeratology for myopic control, with a target reduction of 4.00 D myopia. A pair of DreimLens lenses was prescribed to be worn on a nightly basis and spectacles were worn by day. The same orthokeratology lenses were used throughout the monitoring period. Corneal topography showed well-centred treatment zones but persistent peripheral corneal staining due to trichiasis. A faint, peripheral pigmented brownish corneal arc and bundles of fine concentric fibrillary lines were observed in the central cornea about 12 months after commencing lens wear. In view of the persistent corneal staining due to trichiasis, she was advised to stop the orthokeratology treatment after 16 months of lens wear and was prescribed 1-Day Acuvue daily disposable contact lenses. The pigmented line disappeared after 2 months of hydrogel lens wear, while the fibrillary lines took 10 months to resolve. CONCLUSIONS: Fibrillary lines are a feature of the normal cornea thought to represent the arrangement of the subbasal, epithelial nerve plexus. We hypothesize that orthokeratology lens wear stimulates an altered epithelial migration pattern and a structural reorganisation of the subbasal nerve plexus in relation to this. This is assumed to account for the concentric pattern of fibrillary lines seen in our patient. The lines had no effect on vision and resolved over a period of 10 months following cessation of orthokeratology lens wear.     

弧形刀片夹持器的设计及在白内障手术中的应用

目的 探讨弧形刀片夹持器夹持剃须刀片做小切口白内障囊外摘出人工晶状体植入术的效果。方法 对312眼老年性白内障囊外摘出后房人工晶状体植入术随机分成两组。A组常规以新月形隧道刀做巩角膜隧道切口及以角膜刀穿刺前房并扩大切口；B组用特制的弧形刀片夹持器夹持剃须刀片，做隧道式切口、穿刺前房及扩大切口。其余手术步骤两组完全相同。术后观察1周及3月的视力和角膜散光情况。结果 术后1周及3月的视力和角膜散光度两组均相近，差异无统计学意义（P〉0．05），手术均无重要并发症。结论 弧形刀片夹持器夹持剃须刀片作小切口白内障摘出人工晶状体植入术安全可靠，更为经济，而且取材方便，值得在基层医院推广。     

Properties of AgSnO2 Contact Materials Doped with Different Concentrations of Cr

As an important component carrying the core function and service life of switching appliances, the selection and improvement of electrical contact materials is of great significance. AgSnO₂, which is non-toxic, environmentally friendly and has excellent performance, has become the most promising contact material to replace AgCdO. However, it has deficiencies in machinability and electrical conductivity. The property of AgSnO₂ contact material was improved by doping element Cr. The relationship between the mechanical and electrical properties of AgSnO₂ contact materials and doping concentrations were investigated and analyzed by simulation and experiment. Based on the first principle, the elastic constants of supercell models Sn_1−xCr_xO₂ (x = 0, 0.083, 0.125, 0.167, 0.25) were calculated. The results show that the material with a doping ratio of 25% is least prone to warp and crack, and the material with a doping ratio of 12.5% has the best toughness and ductility and the lowest hardness, which leads to molding and is subsequently easier to process. The Cr-doped AgSnO₂ contacts with different doping proportions were prepared by the sol–gel and powder metallurgy method. Additionally, their physical performance and electrical contact properties were measured in experiments. The results show that the doped SnO₂ powders prepared by the sol–gel method realize integration doping, which is consistent with the crystal model constructed in the simulation calculation. Sn_0.875Cr_0.125O₂ has lower hardness, which is beneficial to process and form. Doping helps to stabilize the arc root, inhibit the ablation of contact by arc, reduces arc duration and arc energy, improves the resistance to arc erosion of AgSnO₂ contact material, and makes electrical contact performance more stable. The contact material with a doping concentration of 16.7% has the best arc erosion resistance.     

Applied IrO2 Buffer Layer as a Great Promoter on Ti-Doping V2O5 Electrode to Enhance Electrochromic Device Properties

Electrochromic devices (ECDs) are a promising material for smart windows that are capable of transmittance variation. However, ECDs are still too expensive to achieve a wide market reach. Reducing fabrication cost remains a challenge. In this study, we inserted an IrO₂ buffer layer on Ti-doped V₂O₅ (Ti:V₂O₅) as a counter electrode using various Ar/O₂ gas flow ratios (1/2, 1/2.5, 1/3 and 1/3.5) in the fabrication process. The buffered-ECD resulted in a larger cyclic voltammetry (CV) area and the best surface average roughness (Ra = 3.91 nm) to promote electrochromic performance. It was fabricated using the low-cost, fast deposition process of vacuum cathodic arc plasma (CAP). This study investigates the influence of the IrO₂ buffer/Ti:V₂O₅ electrode on ECD electrochemical and optical properties, in terms of color efficiency (CE) and cycle durability. The buffered ECD (glass/ITO/WO₃/liquid electrolyte/IrO₂ buffer/Ti:V₂O₅/ITO/glass) demonstrated excellent optical transmittance modulation; ∆T = 57% (from T_bleaching (67%) to T_coloring (10%)) at 633 nm, which was higher than without the buffer (ITO/WO₃/liquid electrolyte/Ti:V₂O₅/ITO) (∆T = 36%). In addition, by means of an IrO₂ buffer, the ECD exhibited high coloration efficiency of 96.1 cm²/mC and good durability, which decayed by only 2% after 1000 cycles.     

脑转移瘤局部病灶加量容积旋转调强放疗海马体剂量学研究

目的 在脑转移瘤放射治疗中,对海马体的保护得到了越来越多的重视和研究.本研究探讨容积旋转调强放疗在脑转移瘤局部病灶加量对海马体保护的剂量学特点.方法 随机选取2013-12-01-2015-12-01在秦皇岛市第一医院放疗科治疗的15例脑转移患者,每例患者分别设计两种治疗计划,剂量体积约束条件相同,容积旋转调强放疗(volume-modulated arc therapy,VMAT)计划使用2个全弧,固定野调强放疗(fixed-field intensity modulated radiation theraPY,ff-IMRT)计划使用9个共面射野.在处方剂量要求相同情况下,比较两种计划的靶区和海马体的剂量学参数、机器跳数差异.结果 靶区剂量学参数中,VMAT计划的计划靶区体积(planning tumor volume,PTV)适形指数(0.82±0.07)好于ff-IMRT计划(0.78±0.08),t=2.457,P=0.028;对于海马体,左侧海马体最大值两计划差异无统计学意义,t=-1.175,P=0.260;VMAT计划的左侧海马体平均值为(1 186.43±1 358.29) cGy,右侧海马体最大值为(1 209.14±498.22) cGy,右侧海马体平均值为(738.16±422.70) cGy,双侧海马体最大值为(2 037.12±1 771.21) cGy,双侧海马体平均值为(940.68±765.00) cGy,低于ff-IMRT计划,差异有统计学意义,P＜0.05;对于正常组织(全身减计划靶体积,即B-P),VMAT计划的Vs(36.69±15.39)％,V15(18.61±9.87)％,V20(13.09±7.45)％小于ff-IMRT计划,差异有统计学意义,P＜0.05,其他正常组织指标无差异;VMAT计划的机器跳数(426±74)显著低于ff-IMRT计划(1 122±317),t=-8.446,P＜0.001.结论 VMAT在脑转移瘤局部病灶加量与ff-IMRT相比,明显的减少了海马体的受量和机器跳数,靶区适形度较好,并部分减少了周围正常组织的低剂量区受量,具有一定的剂量学优势.     

摆位稳健性对IMRT与VMAT剂量学影响研究

目的 比较摆位稳健性对头颈部肿瘤IMRT与VMAT剂量分布的影响程度,评价两者对图像引导需求。方法 纳入30例IMRT鼻咽癌患者按临床上剂量要求设计VMAT计划,AAA法计算剂量。每患者两计划分别沿原始x、y、z轴各移动等中心±1.0、±3.0、±5.0 mm模拟左右、上下、前后方向摆位误差对剂量分布影响,分析60个参考计划与1080个再计划DVH参数。配对t检验差异。结果 误差为1 mm时,GTV D₉₈、CTV D₉₅、HI、PGTV V₉₅平均偏差<0.5%;误差为3 mm时,GTV与CTV剂量平均变化<1.0%,且VMAT高于IMRT (GTV D₉₈,P=0.00;CTV D₉₅,P=0.00),PGTV剂量偏差要大,IMRT与VAMT中PGTV_nx与PGTV_nd V₉₅平均偏差分别为[1.64% 比1.95%(P=0.01)]、[1.73% 比2.63%(P=0.00)]。误差增大各指标偏差变大,且VMAT高于IMRT (GTV D₉₈,P=0.00;CTV D₉₅,P=0.00;CTV HI,P=0.00;PGTV V₉₅,P=0.01)。相比靶区,脊髓、脑干D_max变化更大,但IMRT与VMAT间差异不明显。结论 误差较小时(<3 mm),IMRT与VMAT计划均较稳健。VMAT对摆位误差更敏感,主要体现在靶区剂量,随摆位误差增加两者间差异变大。建议行VMAT患者增加图像引导频次。     

中药熏洗配合经络导推对中风恢复期患者肢体肌张力的影响

目的 探讨中药熏洗联合经络导推在改善中风恢复期肌张力方面的作用。方法 将100例中风恢复期肌张力增高的患者,按照Minimize分层软件分为对照组、观察组各50例,对照组采用经络导推,观察组在经络导推的基础上配合中药熏洗,8周为一个疗程。于治疗前、治疗2周、4周、8周后,进行FMA、MAS、MBI的评价。结果 两组患者治疗8周后FMA、MBI评分均有所升高,两组患者使用Ashworth评定肌张力改善情况,观察组有效率88%,对照组有效率66%。结论 中风恢复期肌张力增高患者在经络导推的基础上,再联合活血通络方中药熏洗,肌张力改善明显,值得临床应用。     

乳腺癌根治术后 VMAT技术对心脏受照剂量风险评估

目的：分析乳腺癌根治术后VMAT技术对心脏的物理剂量学和生物学的指标,评估心脏的受照风险。方法随机选取10例左侧乳腺癌根治术后患者,设计4种常用计划：①改良野中野调强计划FIF（8～10个子野）;②四野调强计划4F-IMRT;③五野（增加正对心脏射野）计划5F-IMRT;④包含心脏正对弧双弧VMAT计划。统计每个患者靶区、心脏和冠状动脉左前降支区LAD剂量体积参数,用NTCP-RSM模型计算放射性心脏病死亡率。统计分析VMAT技术的结果与其余技术之间的差异。结果患者心脏Dmean和V25在4种计划下平均值分别是：7．7 Gy,6．9 Gy,9．7 cGy,6．4 Gy;9．1％,7．9％,9．7％,4．9％;LAD的平均剂量分别是29．0 Gy,27．6 Gy,32．8 Gy,26．1 Gy;NTCP的平均值分别为2．7％,1．1％,1．3％,0．86％。靶区CI四套计划平均值为：0．44、0．56、0．61、0．71,HI为0．82、0．78、0．70、0．53,VMAT技术的CI和HI结果与另外3种的结果有统计学差异（ P＜0．05）。结论与常规调强技术相比,包含心脏正对弧的VMAT计划不会显著影响心脏的并发症概率（ NTCP）,同时VMAT计划靶区的CI、HI要优于静态IMRT计划,VMAT技术可以在提高靶区剂量的同时不明显增加心脏的受照风险。     

Dosimetric comparison between volumetric modulated arc therapy planning techniques for prostate cancer in the presence of intrafractional organ deformation

The purpose of this study was to compare single-arc (SA) and double-arc (DA) treatment plans, which are planning techniques often used in prostate cancer volumetric modulated arc therapy (VMAT), in the presence of intrafractional deformation (ID) to determine which technique is superior in terms of target dose coverage and sparing of the organs at risk (OARs). SA and DA plans were created for 27 patients with localized prostate cancer. ID was introduced to the clinical target volume (CTV), rectum and bladder to obtain blurred dose distributions using an in-house software. ID was based on the motion probability function of each structure voxel and the intrafractional motion of the respective organs. From the resultant blurred dose distributions of SA and DA plans, various parameters, including the tumor control probability, normal tissue complication probability, homogeneity index, conformity index, modulation complexity score for VMAT, dose–volume indices and monitor units (MUs), were evaluated to compare the two techniques. Statistical analysis showed that most CTV and rectum parameters were significantly larger for SA plans than for DA plans (P < 0.05). Furthermore, SA plans had fewer MUs and were less complex (P < 0.05). The significant differences observed had no clinical significance, indicating that both plans are comparable in terms of target and OAR dosimetry when ID is considered. The use of SA plans is recommended for prostate cancer VMAT because they can be delivered in shorter treatment times than DA plans, and therefore benefit the patients.