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21.
: A careful examination of the foundation upon which the concept of the Dose-Volume Histogram (DVH) is built, and the implications of this set of parameters on the clinical application and interpretation of the DVH concept has not been conducted since the introduction of DVHs as a tool for the quantitative evaluation of treatment plans. The purpose of the work presented herein is to illustrate problems with current methods of implementing and interpreting DVHs when applied to hollow anatomic structures such as the bladder and rectum.

: A typical treatment plan for external beam irradiation of a patient with prostate cancer was chosen to provide a data set from which DVH curves for both the bladder and rectum were calculated. The two organs share the property of being shells with contents that are of no clinical importance. DVHs for both organs were computed using a solid model and using a shell model. Typical treatment plans for prostate cancer were used to generate DVH curves for both models. The Normal Tissue Complication Probability (NTCP) for these organs is discussed in this context.

: For an eight-field conformal treatment plan of the prostate, a bladder DVH curve generated using the shell model is higher than the corresponding curve generated using the solid model. The shell model also has a higher NTCP. A six-field conformal treatment plan slo results in a higher DVH curve for the shell model. A treatment plan consisting of bilateral 120-degree arcs, results in a higher DVH curve for the shell model, as well as a higher NTCP.

: The DVH concept currently used in evaluation of treatment plans is problematic because current practices of defining exactly what constitutes “bladder” and “rectum.” Commonly used methods of tracing the bladder and rectum imply use of a solid structure model for DVHs. In reality, these organs are shells and the critical structure associated with NTCP is obviously and indisputably the shell, as opposed to its contents. Treatment planning algorithms for DVH computation should thus be modified to utilize the shell model for these organs.  相似文献   

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23.
患者,男性,9个月,因发现阴茎根部背侧有一窦口9个月入院。患儿生后即被发现其阴茎根部背侧有一窦口,无漏尿,排尿时此窦口也无尿液排出。有时有无色粘液样物从窦口排出,窦口周围皮肤一直未出现红肿。体检:阴茎阴囊发育正常,双侧睾丸大小正常,阴茎根部背侧有一窦口(见封3图1)。触  相似文献   
24.
Despite recent progress in the identification and characterization of numerous nasal biotransformation enzymes in laboratory animals, the expression of biotransformation genes in human nasal mucosa remains difficult to study. Given the potential role of nasal biotransformation enzymes in the metabolism of airborne chemicals, including fragrance compounds and therapeutic agents, as well as the potential interspecies differences between laboratory animals and humans, it would be highly desirable to identify those biotransformation genes that are expressed in human nasal mucosa. In this study, a global gene expression analysis was performed to compare biotransformation enzymes expressed in human fetal and adult nasal mucosa to those expressed in liver. The identities of a list of biotransformation genes with apparently nasal mucosa-selective expression were subsequently confirmed by RNA-polymerase chain reaction (PCR) and DNA sequencing of the PCR products. Further quantitative RNA-PCR experiments indicated that, in the fetus, aldehyde dehydrogenase 6 (ALDH6), CYP1B1, CYP2F1, CYP4B1, and UDP glucuronosyltransferase 2A1 are expressed preferentially in the nasal mucosa and that ALDH7, flavin-containing monooxygenase 1, and glutathione S-transferase P1 are at least as abundant in the nasal mucosa as in the liver. The nasal mucosal expression of CYP2E1 was also detected. These findings provide a basis for further explorations of the metabolic capacity of the human nasal mucosa for xenobiotic compounds.  相似文献   
25.
目的:探讨影像组学方法在术前预测直肠非黏液性腺癌淋巴结转移中的价值。方法:回顾性分析91例手术病理切片证实为直肠非黏液性腺癌患者的影像学资料,其中61例为训练样本,30例为验证样本。基于全瘤体积,从每个原发病灶术前高分辨T2加权成像(T2-weighted imaging,T2WI)图像中提取影像组学特征1 301个。基于训练样本,利用最小绝对收缩和选择算子(the least absolute shrinkage and selection operator,LASSO)逻辑回归方法筛选关键特征并构建影像组学分类器。采用受试者工作特征(receiver operating characteristic,ROC)曲线评价影像组学分类器的辨别效能,并将其与形态学标准进行比较。在验证样本中验证影像组学分类器的价值。结果:由5个影像组学特征构建的分类器与淋巴结转移状态有关(P<0.001)。在训练样本和验证样本中,影像组学分类器诊断淋巴结转移的曲线下面积分别为0.874(95% CI:0.787~0.960)和0.878(95% CI:0.727~1.000),形态学标准诊断淋巴结转移的曲线下面积分别为0.619(95% CI:0.487~0.752)和0.556(95% CI:0.355~0.756)。无论是训练样本还是验证样本,影像组学分类器的诊断效能均高于形态学标准(均P<0.05)。结论:影像组学分类器可术前个体化预测直肠非黏液性腺癌淋巴结转移,而且其诊断效能高于形态学标准。  相似文献   
26.
自体牙移植预后的影响因素   总被引:1,自引:0,他引:1  
自体牙移植是将自体牙在体内异位移植来修复牙列缺损的一种方法。尽管自体牙移植适用范围不广且预后受到很多因素的影响,但许多研究证实,自体牙移植可作为一种修复牙列缺损的理想选择。本文就自体牙移植预后的影响因素进行综述。  相似文献   
27.
目的了解基层医务人员对慢性阻塞性肺疾病的认知、过去一年继续教育情况及继续教育对慢性阻塞性肺疾病相关认知的影响。方法选取2019年10月1—31日2372名来自社区卫生服务中心(站)、乡镇卫生院和村卫生室的医务人员自愿在线填写了调查问卷,内容包括个人基本特征,对慢性阻塞性肺疾病危险因素和诊断的认知及继续教育情况。结果基层医务人员熟知吸烟、二手烟、长期呼吸道疾病史、室外空气污染和职业性粉尘等危险因素,但是对室内空气污染和遗传因素认知不足,并且仍有12.1%的基层医务人员知晓吸烟是危险因素,但正在吸烟或戒烟6个月以内。80%的调查对象知道肺功能是诊断慢性阻塞性肺疾病的金标准,但仅60.7%的调查对象能正确判读肺功能结果。过去一年中仅44.3%的基层医务人员接受了相关继续教育。继续教育对提升基层医务人员慢性阻塞性肺疾病危险因素和诊断相关认知的影响差异有显著性(OR=1.524,95%CI 1.289~1.802;OR=1.528,95%CI 1.289~1.812)。结论加大继续教育的惠及范围,有针对性地加强基层医务人员对室内空气污染和遗传因素的认知,同时在基层配备肺功能仪的前提下,开展以实操...  相似文献   
28.
张婷  张小猛 《国际眼科杂志》2024,24(7):1093-1097

糖尿病视网膜病变(DR)早期视野改变往往比视力更能及时反映病情进展。而全视网膜光凝(PRP)治疗DR在延缓病情进展的同时也造成了患眼视力下降和视野缩小等副作用。有研究表明,PRP治疗后的DR患者可因中心20°范围内的视野缺损而导致驾驶测试失败。为保证PRP疗效同时达到降低并发症的目的,激光技术不断改进与发展,通过调整激光参数、使用新型激光系统、与抗血管内皮生长因子(VEGF)药物联合、中西医结合治疗等方式可一定程度改善患眼视野,实现更佳疗效。未来可考虑在缺血指数(ISI)量化分析下,对视网膜缺血程度进行分级,依据ISI指标和视网膜无灌注区分布探索PRP治疗建议的最佳阈值及光凝范围,从而为DR患者提供更及时、更合理的个性化治疗方案。文章就PRP治疗DR对视野的影响进行简要综述。  相似文献   

29.
Breast surgery is an important treatment for women with malignant breast diseases. In addition to breast appearance, the integrity of breast function is increasing in patients with breast diseases. As the basis of breast physiological function, breast skin sensitivity is important to the quality of life of patients after surgery. Breast skin sensitivity gives the patient a “real” breast feeling. The sensory recovery after breast surgery has also become one of the important goals of breast surgery. In this review, we aim to discuss the research progress on recovery of breast skin sensitivity after different treatment modalities for breast disease.  相似文献   
30.
IntroductionTo investigate the incidence and causes of intraoperative choroidal detachment (CD) during small-gauge vitrectomy, as well as the anatomic and visual outcomes.MethodsWe retrospectively reviewed the medical records of 1026 consecutive patients who underwent small-gauge vitrectomy from June 2017 to December 2018 at Zhongshan Ophthalmic Centre, Guangzhou, China. Data on the presence, location, and extent of intraoperative CD and its relationship to the infusion cannula were collected. Patient demographic characteristics and postoperative anatomic and visual outcomes were also assessed.ResultsA total of six cases were found to have intraoperative CD, including two with serous CD, three with limited haemorrhagic CD, and one with CD caused by inadvertent perfusion of gas during air/fluid exchange. Retraction of the infusion cannula and acute ocular hypotony were found to be the main causes of intraoperative CD in five out of the six cases. The best-corrected visual acuity of all cases significantly improved after the surgery.ConclusionThe incidence of intraoperative CD during small-gauge vitrectomy is low; the predominant causes are retraction of the infusion cannula and acute ocular hypotony. Immediate awareness and timely closure of the incision may contribute to a better surgical prognosis.Subject terms: Uveal diseases, Diseases  相似文献   
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