Venous thromboembolism(VTE)is a common disease with high morbidity and mortality.The incidence and mortality of VTE are higher in elderly patients and increased level of D-dimer,a thrombosis marker is positively related with age.Therefore,the diagnostic threshold needs to be adjusted to screen VTE with D-dimer level.Elderly patients may still have VTE after implementation of anticoagulant prevention,and increasing age is a high risk factor for bleeding after anticoagulant prevention.Whether elderly patients need to be monitored for anticoagulant prevention of VTE,and the relationship between age and VTE recurrence remains to be determined.In-depth re-search on the prevention of VTE in elderly patients and exploration of innovative VTE prevention strategies may ori-ent future research.

Objective:To optimize the scheme and process of chest CT scanning and control the dose level to the examined individuals by establishing the diagnostic reference level (DRL) and warning dose value from chest CT examinations in our hospital.Methods:The medical records for 205 511 examined individuals, who had undergone chest CT scans in the Second Affiliated Hospital of Zhejiang University Medical College from January 1, 2018 to December 31, 2019, were reviewed consecutively. For the two-year examination periods, these examined individuals were divided into two groups, one for 2018 totalling 90 507 and another for 2019 with a total of 115 004. The mean value of doses from chest CT scans in 2018 was set as the DRL for the hospital, with the 75th and 25th percentiles as the upper and lower limits of diagnostic reference range (DRR) and the 97.5th percentiles as the warning dose values. The doses above the upper limit of DRR were considered to be relatively-high whearas the ones exceeding the warning dose value to be over-high. Based on the analysis of the over high dose in 2018, the scanning scheme and inspection process of the chest CT scans were improved in 2019. The number of examinations were estimated for the 2018 period for chest plain CT scans, chest enhancement CT scans, lung cancer screening low-dose CT scans, and relatively-high and over-high dose CT scans, as well as the single scanning doses to the examined in the two groups. The number of examinations resulting in high dose to the examined due to different reasons before and after the improvement were studied. The various parameters on the examined in the two groups were compared statistically.Results:After the improvement, the average dose from chest plain CT scans decreased by 8.67 %, with the statistically significant difference as compared with before improvement ( t=55.71, P<0.05). The average dose from low-dose chest CT scans fell by 20.13% with statistically significant difference ( t=81.99, P<0.05). The fraction of the examinations with slightly-high doses arising from chest plain CT scans and low dose chest CT scans dropped by 3.66% and 17.15%, respectively. The fraction of the examinations with slightly-high dose from chest enhanced CT increased by 1.7%. The fraction of the examinations with over-high dose from chest plain CT scans, enhanced CT scans and low-dose CT scans decreased by 0.55%, 1.06% and 1.74%, respectively. After improvement, the optimized fraction of the examinations with over-high dose, dropped by 4.72%, 31.49% and 19.18% respectively. Conclusions:The establishment of the DRL and the warming dose value of for chest CT examinations in our hospital is helpful to find out the cause of high dose scanning, promote the optimization of dose, reduce the average dose to the examinedes, and avoid using excessive dose during scanning.

To report a case of onychocytic carcinoma in China. A 76-year-old female patient presented with a subnail mass on her left thumb for 3 years. Skin examination showed thickening of the left thumb plate whose surface was partially yellow and black in color, slight curving of the distal plate, obvious telangiectasia under the nail plate, and verrucous hyperplasia under the nail plate and at the lateral edge of the nail plate. Histopathological examination showed that the tumor grew and infiltrated downward in clumps, with obvious keratosis and necrosis in the center of the mass, and many "squamous vortex" structures, atypical cells, and pathological mitotic figures could be seen. Immunohistochemical study revealed that HK31 and HK85 were positively expressed in the squamous vortex region, K6/K16 was positively expressed in the basal part of the tumor, and HK75 was strongly expressed in the whole tumor region. The diagnosis of onychocytic carcinoma was confirmed. The patient received surgical excision combined with 3 sessions of photodynamic therapy, and no recurrence was observed during 18 months of follow-up.

The incidence and mortality of venous thromboembolism (VTE) are high in critically ill patients, and there is still a risk of VTE and bleeding after the use of fixed-dose low molecular weight heparin (LMWH) for prophylaxis. The level of anti-factor Ⅹa is not up to standard after LMWH prophylaxis in patients with surgery or trauma. The condition of critically ill patients is complicated, and the proportion of patients with low antithrombin Ⅲ is high, which can affect the prophylactic efficacy of LMWH and contribute to VTE occurrence. There is currently no consensus on whether adjusting LMWH dose according to anti-factor Ⅹa levels can reduce VTE occurrence in critically ill patients. High-quality multicenter randomized controlled studies are needed in the future to establish new approaches for precise prevention of VTE in critically ill patients.