Iterative reconstruction improves imaging quality of low er -radiation CT perfusion in patients w ith acute ischemic stroke / 国际脑血管病杂志

Objective To investigate w hether the iterative reconstruction (iDose 4 ) technique improves imaging quality of the low-radiation-dose w hole brain CT perfusion (CTP). Methods Thirty-five consecutive patients w ith clinical y suspected ischemic stroke w ere col ected. Bril iance 256 iCT w as used to perform low-radiation-dose w hole brain CTP, and the filtered back projection (FBP) and iDose 4 algorithm w ere used to conduct image reconstruction. The noise and signal to noise ratio of the 2 kinds of reconstruction algorithms, as w el as the imaging quality of each parameter map w ere compared. Results The effective dose of the w hole brain CTP w as 2.2 mSv. Compared w ith FBP, the noise of each region of interest in the iDose4 Tmax map was decreased significantly ( P<0.05) and the signal to noise ratio was increased significantly (P<0.05). The imaging quality scores (median, interquartile range) reconstructed by FPB group w ere significantly low er than by iDose 4 for cerebral blood flow (CBF) map ( 5.00 [3.00-6.00]vs. 6.00 [5.00-6.00]; Z= -2.784, P=0.005), cerebral blood volume (CBV) map ( 6.00 [5.00-6.00] vs. 6.00 [6.00-7.00]; Z= -3.674, P<0.001), and mean transit time (MTT) map (4.00 [3.00-5.00] vs. 5.00 [4.00-6.00]; Z=3.394, P=0.001). The proportions of the poor quality in CBF map ( 34.3%vs. 11.4%;χ2 =7.036, P=0.030), CBV map (11.4%vs.2.9%; χ2 =7.485, P=0.024 ) and MTT map (28.6%vs.11.4%;χ2 =5.318, P=0.070) reconstructed by FBP w ere significantly higher than by iDose 4 . Conclusions The iDose4 technique may improve imaging quality of low er-radiation-dose CTP.

Avaliação dos efeitos da radiação em procedimentos intervencionistas cardíacos / Evaluation of the effects of radiaton on cardiac interventional procedures

Objetivo - Procedimento intervencionista cardíaco é uma modalidade de exame que através de imagens em tempo real, o médico pode intervir sem que o paciente seja submetido a procedimentos cirúrgicos e riscos pós-operatórios. Esses procedimentos podem resultar em efeitos determinísticos e estocásticos para os profissionais que os realizam. O objetivo deste estudo foi avaliar se há indicativos dos efeitos causados pela radiação nos profissionais ocupacionais de uma instituição de saúde da cidade de São Paulo. Métodos - Foram analisados os dosímetros e hemogramas de dois profissionais. Resultados - As doses encontradas nos dosímetros dos dois profissionais foram 32,4 e 36,6 mSv e pequena variação nos componentes sanguíneos na análise dos hemogramas. Conclusão - Não houve indicativos de alteração causados por radiação ionizante nos profissionais analisados.

Objective - Cardiac interventional procedure is a type of exam that through real-time imaging, the physician can intervene without the patient to undergo surgical procedures and postoperative risks. These procedures can result in deterministic and stochastic effects for the professionals who perform them. The aim of this study is to assess whether there is evidence of the effects caused by radiation in a professional occupational health institution in São Paulo city. Methods - Dosimeters were analyzed and peripheral blood of two professionals. Results - Doses found in dosimeters of the two professionals were 32.4 and 36.6 mSv and a small variation in the blood components in the analysis of blood counts. Conclusion - There were no indications of change caused by ionizing radiation in occupational analyzed.

Dose-effect relationship between Q-switch ruby laser and skin pigmentation in Guinea pigs / 中华皮肤科杂志

Objective To investigate the dose-effect relationship between Q-switch ruby laser and skin pigmentation in Guinea pigs. Methods Ten Guinea pigs were included in this study, and the back of each pig was divided into 5 areas, negative control area receiving no UVB irradiation or laser treatment, positive control area receiving UVB irradiation but no laser treatment, low-, middle- and high-dose areas receiving UVB irradiation followed by the treatment with laser at an energy density of 1.5, 3.0 and 6.0 J/cm2 for 4, 2, and 1 session, respectively, with an interval of 1 week. Melanin content index (MCI) was determined, and confocal laser scanning microscopy (CLSM) and histopathology were performed to observe melanin granules and melanocytes in the skin tissue from Guinea pigs before the initial laser treatment, 2 and 4 weeks after the final laser treatment. Results The best response was observed in the low-dose areas, and there was a complete clearance of hyperpigmentation in these areas, which maintained 8 weeks without recurrence, while different degrees of skin pigmentation recurred in the middle- and high-dose areas. Moreover, the low-dose areas showed a significantly lower melanin content index (MCI) compared with the middle- and high-dose areas (F = 4.2,P < 0.05), together with a marked reduction in the extent of pigment deposition, melanin granules, melanocyte number and density. Conclusions The efficacy of Q-switched ruby laser on skin pigmentation in Guinea pigs is correlated with the energy density and treatment frequency, and, low intensity and high frequency are often associated with a better treatment outcome.

Estudo experimental da aplicação retiniana do laser infravermelho via transescleral sob condições de baixa visibilidade / Transscleral infrared laser retinal photocoagulation experimental study under low visibility conditions

OBJETIVOS: Pesquisa experimental, com laser de diodo infravermelho, para estimar a segurança, a reprodutibilidade e a permeabilidade da parede ocular à sua atuação clínica, quando aplicado via transescleral, em condições de baixa visibilidade. MÉTODOS: Submetemos olhos de coelhos pigmentados da raça Nova Zelândia à fotocoagulação retiniana por laser de diodo infravermelho. No olho direito, realizamos fotocoagulação via transescleral sob parâmetros de potência e tempo pré-determinados clinicamente. No olho esquerdo, foram repetidos os mesmos valores da potência e tempo usados no olho direito, desta vez, via transpupilar. Imediatamente e após 2 meses, estudos clínicos baseados na retinografia e histopatológicos foram realizados. RESULTADOS: A permeabilidade da parede ocular, quando da aplicação do laser de diodo infravermelho via transescleral, variou entre 58,95 e 63,87 por cento. A média da permeabilidade da parede ocular a 300 mW (63,14 por cento) mostrou-se significativamente superior àquela da permeabilidade da parede ocular encontrada a 500 mW (59,11 por cento), (P<0,05). CONCLUSÕES: Este estudo sugere a existência da relação dose-resposta em relação aos parâmetros empregados na aplicação do laser de diodo infravermelho via transescleral, com permeabilidade da parede ocular mensurável e reprodutível. Nenhuma rotura, hemorragia ou descolamento da retina ou vítreo foi constatado aos exames subseqüentes às aplicações do laser de diodo infravermelho, o que torna o uso da fotocoagulação via transescleral, no modelo experimental, seguro, mesmo sob condições de baixa visibilidade dos meios.

PURPOSE: Retinal photocoagulation under poor visualization condition is often required. Transscleral infrared laser can be used as an alternative to regular transpupillary treatment. Based upon retinographic measurements, we proposed to estimate the reproducibility as well as ocular wall permeability rate for this treatment. Our primary goal was to evaluate whether this technique can deliver adequate photocoagulation at predetermined parameters without direct retinal visualization. METHODS: In New Zealand pigmented rabbits, optimal transscleral infrared diode laser settings were administered to the right eye. With the same parameters, transpupillary photocoagulation was repeated in the left eye. Retinographic and clinical examinations were performed immediately and two months later. RESULTS: Ocular wall permeability rate varied between 58.95 and 63.87 percent. Average permeability using a power of 300 mW (63.14 percent) was found to be higher than that encountered before its enhancement up to 500 mW (59.11 percent), (P<0.05). CONCLUSIONS: Setting parameters showed dose-response effect. No retinal hole or retinal detachment was noticed in any rabbit. Transscleral infrared photocoagulation appeared to be a reproducible and secure method in the experimental model.

The study of the effect on the image quality in low-dose CT of the paranasal sinuses / 中华放射学杂志

Objective To determine the effect of reducing mA on the diagnostic quality of images and the radiation dose to the lens in patients undergoing paranasal sinus CT. Methods Fifty patients undergoing paranasal sinus CT at 200 mA or 50 mA. The lens dose was measured using thermoluminescent dosemeters [LiF(Mg?Cu?P)]. Image quality was evaluated for six anatomical structures, including middle turbinate, uncinate process, maxillary ostium, ethmoid infundibulum, frontal recess, and cribriform plate. These anatomical structures were assessed as: not seen (0 points), demonstrated but not clearly visualized (1 points), or clearly demonstrated (2 points). Results Mean radiation dose to the lens was significantly reduced from 7.339 mGy (200 mA) to 1.108 mGy (50 mA). No significant difference of image quality between the two mA protocols was found in either rhinosinusitis group or non-rhinosinusitis group. And for rhinosinusitis the image quality showed no significant difference between high-resolution arithmetic and soft arithmetic. Conclusion CT scanning of the sinuses can be performed at greatly reduced mA without loss of diagnostic quality of the images. As far as the rhinosinusitis is concerned, high-resolution arithmetic can not improve the image quality and soft arithmetic is enough.