Experimental determination of the recombination correction factor kS for SNC 125c,SNC 350p and SNC 600c ionization chambers in pulsed photon beams

Accurate ionization chamber measurements of the absorbed dose to water require the correction of incomplete collection of charges created within the chamber volume. According to current dosimetry protocols such as the TRS-398 or the DIN 6800-2, incomplete charge collection is accounted for by the correction factor k_s, which can be determined numerically or experimentally. The method proposed by Burns & McEwen (Phys. Med. Biol., 1998) was used in this study to determine the coefficients γ and δ used for the calculation of the correction factor k_s of three ionization chambers, the SNC 125c, the SNC 600c and the SNC 350p (all Sun Nuclear Corp., Melbourne, Florida) for an absorbed dose to water range of 0.2 mGy to 1.6 mGy per pulse in pulsed photon beams. The shift of the effective point of measurement from the reference point Δz and the correction factor k_r were determined for the SNC 350p according to the draft DIN 6800-2:2019-07.     

A method for determination mass absorption coefficient of gamma rays by Compton scattering

A method was proposed for determination mass absorption coefficient of gamma rays for compounds, alloys and mixtures. It is based on simulating interaction processes of gamma rays with target elements having atomic numbers from Z=1 to Z=92 using the MCSHAPE software. Intensities of Compton scattered gamma rays at saturation thicknesses and at a scattering angle of 90° were calculated for incident gamma rays of different energies. The obtained results showed that the intensity of Compton scattered gamma rays at saturations and mass absorption coefficients can be described by mathematical formulas. These were used to determine mass absorption coefficients for compound, alloys and mixtures with the knowledge of their Compton scattered intensities. The method was tested by calculating mass absorption coefficients for some compounds, alloys and mixtures. There is a good agreement between obtained results and calculated ones using WinXom software. The advantages and limitations of the method were discussed.     

Interstitial lung diseases in children

Interstitial lung disease (ILD) in children (chILD) is a heterogeneous group of rare respiratory disorders that are mostly chronic and associated with high morbidity and mortality. The pathogenesis of the various chILD is complex and the diseases share common features of inflammatory and fibrotic changes of the lung parenchyma that impair gas exchanges. The etiologies of chILD are numerous. In this review, we chose to classify them as ILD related to exposure/environment insults, ILD related to systemic and immunological diseases, ILD related to primary lung parenchyma dysfunctions and ILD specific to infancy. A growing part of the etiologic spectrum of chILD is being attributed to molecular defects. Currently, the main genetic mutations associated with chILD are identified in the surfactant genes SFTPA1, SFTPA2, SFTPB, SFTPC, ABCA3 and NKX2-1. Other genetic contributors include mutations in MARS, CSF2RA and CSF2RB in pulmonary alveolar proteinosis, and mutations in TMEM173 and COPA in specific auto-inflammatory forms of chILD. However, only few genotype-phenotype correlations could be identified so far. Herein, information is provided about the clinical presentation and the diagnosis approach of chILD. Despite improvements in patient management, the therapeutic strategies are still relying mostly on corticosteroids although specific therapies are emerging. Larger longitudinal cohorts of patients are being gathered through ongoing international collaborations to improve disease knowledge and targeted therapies. Thus, it is expected that children with ILD will be able to reach the adulthood transition in a better condition.     

成人阻塞性睡眠呼吸暂停综合征的局麻手术治疗

目的比较成人阻塞性睡眠呼吸暂停综合征(OSAS),全麻手术治疗即悬雍垂腭咽成形术(UPPP)与坐位局麻下行改良悬雍垂腭咽成形术优缺点。方法5年来,笔者对368例成年OSAS施行局麻坐位改良悬雍垂腭咽成形术,并对其进行术中术后并发症观察及术后效果回访。结果多导睡眠图(PSG)分析显示,术前、后血氧饱和度有明显不同(P<0.05),睡眠结构明显改变,呼吸暂停消失。无术中、术后并发症。结论坐位局麻下手术要优于传统全麻手术治疗,坐位局麻下悬雍腭成形术是可行的。     

人体血氧饱和度监测方法的研究

血氧饱和度是人体的重要参数,临床上许多场合都要对血氧饱和度进行检测,其中通过无创的方法对血氧饱和度进行检测能够为医生的临床行为提供快速、直接、有效的操作依据.其中透射式血氧饱和度监测技术已经成为较成熟的监护手段,但由于传感器使用范围的限制,在某些场合需要使用反射式血氧仪对血氧饱和度进行检测.本文对现有几种血氧饱和度的测量方法进行了讨论,重点对脉搏式血氧饱和度的测量原理进行了详细地分析,并对反射式血氧饱和度测量仪的研制进行了简单地探讨.     

磁共振压脂序列在脊柱急性损伤中的应用

目的:进一步认识MRI的T2WI压脂序列在脊柱急性损伤检查中的作用。方法:回顾性分析脊柱损伤MRI资料109例,比较常规T2WI和FST2WI对椎体骨折、骨髓水肿、脊髓损伤的检出率。结果:FS T2WI对隐匿性骨折和骨髓水肿的检出率明显高于常规T2WI,还能较准确地显示骨质损伤范围及突出损伤部位的解剖结构特征。结论:FST2WI能提高脊柱骨质损伤显示的敏感性和诊断的准确性,应作为脊柱损伤MRI检查中的常规序列。     

EARLY DIAGNOSIS OF TUMOR WITH ELECTRON SPIN RESONANCE (ESR): METHOD OF ELECTRONIC SATURATION OF ENERGY LEVEL

ESR saturation power point of the hair of healthy, lung cancer, esophageal cancer, as well as silicosis, tuberculosis and cardiovascular disease were detected. The results show that the positive rate is 1.69%, 85.42%, 90.4%, 20.00%, 27.27% and 0% respectively. There is a significant difference between lung cancer, esophageal cancer and healthy persons (P<0. 001). ESR saturation power point elevates sharply after treatment of lung cancer, 71. 43% of total cases ranged from 7. 9 to 24. 0 (mW), after treatment of esophageal cancer, 71. 23% ranged from 7.9 to 19.9 (mW). All patients with cardiovascular disease were examined to be negative, i. e. , above 10. 0 (mW).     

Apport de la saturation veineuse centrale en oxygène dans la décision transfusionnelle postopératoire

Objective

The aim of this study was to assess the value of central venous oxygen saturation (ScvO₂) for the decision of blood transfusion in comparison with the criteria of the French guidelines for blood transfusion (2003).

Study design

Prospective, observational.

Patients and methods

Sixty patients, haemodynamically stable, for whom a blood transfusion (BT) was discussed in the postoperative course of general surgery, were included. ScvO₂ (%) and haemoglobin (g/dl) were measured before and after BT. Patients were retrospectively divided into two groups according to ScvO₂ measured before BT (< or ≥ 70%). Results are expressed as median.

Results

The ScvO₂ before transfusion was greater or equal to 70% in 25 (47.2%) patients. Following BT, the ScvO₂ increased significantly (from 57.8 to 68.5%) in the group with initial ScvO₂ less than 70% whereas it was unchanged in patients with initial ScvO₂ greater or equal 70% (from 76.8 to 76.5%). Twenty patients (37.7%) did not meet the French guidelines for BT criteria. Eighteen patients out of 33 that met the criteria had ScvO₂ greater or equal 70% before BT while 13 patients with ScvO₂ less than 70% were not detected by these same criteria.

Conclusion

ScvO₂ could be a relevant biological parameter to complete the current guidelines for BT in stable patient with a central venous catheter during the postoperative period.