[Measurement and analysis of the imaging dose with megavoltage computed tomography for helical tomotherapy].

BACKGROUND & OBJECTIVE: During the helical tomotherapy process, megavoltage computed tomography (MVCT) images are usually used for guiding the precise setup of patients before/after treatment delivery, which would certainly increase the total dose for patients. This study was to investigate the imaging dose of MVCT using the body and head phantom on a tomotherapy machine. METHODS: A set of cylindrical body and head phantoms was adopted for scanning with different pitch values (1.0/2.0/3.0), lengths (4.8/7.2/9.6/12/14.4 cm) and patient setups on the couch of tomotherapy system. The average MVCT imaging doses were measured using A1SL chambers inserted in the phantoms with preset geometry. The dose uniformity was qualitatively analyzed. RESULTS: The MVCT scanning dose for the body phantom was between 0.599 and 2.876 cGy during each treatment delivery, while the dose for the head phantom was between 0.913 and 3.231 cGy. Two major parameters, the assigned pitch numbers and scanning lengths, were the most important impacts to the dose variation. The MVCT dose was inversely proportional to the CT pitch value. With respect to the scanning length, the doses responded differently along the radial direction of the phantoms with different setup criteria. CONCLUSION: The results may provide a reliable guidance for proper planning design of the scanning region, which is valuable to help minimize the extra doses to patient.

[Endoscopic, clinicopathologic and immunohistochemical features of gastric stromal tumor].

BACKGROUND & OBJECTIVE: For gastric stromal tumor (GST), the low incidence and high diversity in endoscopic and pathologic manifestations lead to misdiagnosis. This study was to explore the features of GST in endoscopy and clinicopathology. METHODS: Clinical data of 42 GST patients, treated at the Second Affiliated Hospital of Sun Yat-sen University from Jan. 1996 to Jan. 2006, were analyzed for their clinicopathologic and endoscopic features. The expression of CD117, CD34, smooth muscle actin (SMA), Desmin and S-100 were detected by immunohistochemistry. Their correlations to clinicopathologic features of GST were analyzed. RESULTS: Of the 42 cases of GST, 21 (50.0%) were at the fundus, 14 (33.3%) at the body, and 7 (16.7%) at the antrum; 17 (40.5%) were benign, 14 (33.3%) borderline, 11 (26.2%) malignant. Endoscopically, GST presented submucosal hemispheroid or polypoid protuberant lesions with clear border. While the positive rate of gastroendoscopic biopsy was low. Of the 42 cases, 29 were spindle cell type, 5 were epithelial cell type, and 8 were mixed type. The positive rates of CD34 and CD117 were 92.86% and 78.57%. CONCLUSIONS: GST has unique morphologic features. Combined detection of CD117 and CD34 benefits the diagnosis of GST.

Photoassisted reaction of sulfur mustard under UV light irradiation.

The photoassisted reaction of sulfur mustard (HD) in both the vapor and droplet states under UV light irradiation was investigated. It was found that HD molecules in either the gas or the condensed phase could be easily converted into other chemicals under the irradiation of a germicidal lamp. The products detected upon reaction suggested that the photoassisted reaction of HD molecules in the gas phase produced a kind of nontoxic heavy polymer, and this method seemed to be applicable for decontamination of air. Nevertheless, the photoassisted reaction of HD droplets would produce a series of products containing -SCH2CH2Cl or -OCH2CH2CI groups, some of which were proven to be even more toxic than HD. Therefore, it was not an effective method forthe decontamination of HD droplets. The obtained experimental results would indicate that two possible pathways might be involved in the destruction of HD molecules: (1) HD molecules may undergo a photochemical reaction upon absorbing photons of sufficient energy, which leads to cleavage the C-S bond in HD molecules at the primary step, or (2) HD molecules could be oxidized by the photogenerated ozone.

Photoassisted reaction of chemical warfare agent VX droplets under UV light irradiation.

A photoassisted reaction of O-ethyl S-[2-(diisopropylamino) ethyl] methylphosphonothioate (VX) droplets in air was carried out. The experimental results indicated that VX droplets could be easily and chemically transformed into other compounds under irradiation of a germicidal lamp over sufficient time. Quantum chemical calculation results demonstrated that UV light less than 278 nm wavelength could possibly initiate photoreaction of VX and that both P-S and P=O bonds in the VX molecule were lengthened. The identification of reaction products by gas and liquid chromatography mass spectroscopy and NMR revealed that the VX molecule in air under UV light irradiation could undergo isomerization of S-esters to O-esters, cleavage of P-S, S-C, and C-N bonds, and ozonation of tertiary amines.

[Associated risk factors of fatty liver in the patients with type 2 diabetes mellitus].

OBJECTIVE: To analyze the associated risk factors, clinical characteristics and laboratory abnormalities of type 2 diabetes patients with fatty liver. METHODS: The data of type 2 diabetes cases with fatty liver were collected in our hospital. 63 cases of type 2 diabetes without fatty liver were selected randomly as control during the same period. The associated variables were analyzed by using logistic regression model. The clinical data and liver function were compared between two groups. RESULTS: The proportion of obesity and hyperlipidemia was higher in type 2 diabetes patients with fatty liver than without fatty liver. Body mass index (BMI) (OR: 4.392) was positive correlation to fatty liver in the patients with type 2 diabetes. In contrast, insulin sensitivity index (ISI) (OR: 0.000) and regular insulin treatment (OR: 0.058) were negative correlation to it. The abnormal frequencies of aspartate aminotransferase (AST, 16.0%), alanine aminotransferase (ALT, 25.2%), the ratio of AST/ALT less than 1 (52.8%) and gamma-glutamyltransferase (GGT, 31.9%) of type 2 diabetes patients with fatty liver were significantly higher than those without fatty liver (3.2%, 6.4%, 36.5% and 11.1% respectively). CONCLUSION: Obesity and insulin resistance might increase the risk of fatty liver in the patients with type 2 diabetes. Patients of type 2 diabetes with fatty liver show higher serum lipid level and more obvious damages of liver function than those without fatty liver