Determining the Feasibility of Dose Reduction Strategies on Radiation Dose: An Experimental Phantom Study

@#Introduction: Radiation exposure during the CT examination has always been a concern due to its associated cancer risk. The guidelines suggest the optimization of radiation dose reduction. Therefore, this study aims to determine the feasibility of dose reduction strategies on radiation dose reduction using a phantom. Methods: Head and body phantoms of 16 cm and 32 cm, respectively, were used to calculate the radiation dose and measure the quantitative image quality. The phantoms were positioned and scanned with the standard protocol and low dose protocol. For dose reduction strategies, scan length was reduced in head phantom, and tube voltage and tube current were manipulated individually and by combining both and tested in both head and body phantoms. Also, the influence of rotation time was investigated in body phantom. Quantitative image quality was determined by drawing a region of interest on the obtained image. Results: Reducing scan length showed 41% reduction of radiation dose and reducing tube current, and tube voltage showed up to 75% reduction of radiation dose in head phantom and 70% reduction of radiation dose in body phantom compared to the standard protocol. The reduction of the rotation time, however, reduced the scan time and the radiation dose but the maximum mAs or tube current allowed was limited. Quantitative image quality was reduced when using a lower dose protocol. Conclusion: The dose reduction strategies showed a reduced dose, but the quantitative image quality score was reduced when scanned with low dose protocol. Further manipulation can be performed to maintain image quality.

Long-term effects of human amniotic membrane in a rat model of biliary fibrosis

Liver fibrosis is the most common outcome of chronic liver diseases, and its progression to cirrhosis can only be effectively treated with liver transplantation. The amniotic membrane (AM) has been studied as an alternative therapy for fibrosis diseases mainly for its favorable properties, including anti-inflammatory, anti-scaring and immunomodulatory properties. It was recently demonstrated that the AM reduces the progression of biliary fibrosis to its advanced stage, cirrhosis, when applied on the liver for 6 weeks after fibrosis induction. Here, we investigated the effects of AM on rat fibrotic liver, during a prolonged period of time. Fibrosis was induced by bile duct ligation (BDL), and at the same time, a fragment of AM was applied around the liver. After 1, 3, 6, and 9 weeks, the degree of fibrosis was assessed by qualitative Knodell scoring, and by quantitative image analysis to quantify the area of collagen deposition in hepatic tissue. While fibrosis progressed rapidly in untreated BDL animals, leading to cirrhosis within 6 weeks, AM-treated livers showed confined fibrosis at the periportal area with few and thin fibrotic septa, but without cirrhosis. In addition, collagen deposition was reduced to about 36 and 55% of levels observed in BDL at 6 and 9 weeks after BDL, respectively, which shows that the longer the period of AM application, the lower the collagen deposition. These results suggested that AM applied as a patch onto the liver surface for longer periods attenuated the severity of biliary fibrosis and protected against liver degeneration caused by excessive collagen deposition.

Quantitative analysis of periapical lesions on cone beam computed tomograph and periapical radiograph / 대한구강악안면방사선학회지

PURPOSE: To detect the progression of experimentally induced periapical lesions on periapical radiograph and cone beam computed tomograph (CBCT) by quantitative analysis. MATERIALS AND METHODS: After the removal of coronal pulps from premolars of two Beagle dogs, the root canals of premolars were exposed to oral environment during one week and then sealed for 70 days. Digital periapical radiographs and CBCTs were taken at baseline and every 7 days for 77 days after pulp exposure. We examined occurrence and areas of periapical bone resorption. Three comparative groups of CBCT radiographs were prepared by average projection of thin slabs with different bucco-lingual thicknesses (0.1, 3.0, and 8.0 mm) using a 3D visualization software. Radiographic densities were compensated by image normalization. Digital images were processed with mathematical morphology operations. The radiographic density and morphological features of periapical lesions were compared among three groups of CBCT in different time points. RESULTS: In the CBCT group with 0.1 mm thickness, radiographic density (p<0.05) and trabecular bone area (p<0.01) were significantly decreased at the fifth week. However, in the CBCT groups with 3 mm and 8 mm thickness and periapical radiographs, none of densitometric and morphological features showed any significant differences in different time points. Radiographic density of periapical lesion showed increasing tendency at the eleventh week after pulp exposure. CONCLUSION: Radiographic detection of periapical lesions was possible at the fifth week after pulp contamination by quantitative method and was affected by buccolingual bone thickness.

The Assessment on the Characteristics of Quantitative image in Digora(R) / 대한구강악안면방사선학회지

PURPOSE: To clarify the usefulness and the limitation of Digora system(R) by evaluating the characteristics as the quantitative image on Image Plate(IP). MATERIALS AND METHODS: Radiograms were taken by Heliodent MD(Siemens Co., Germany) with the image plate for adult, Cu-step wedge as reference material, and three pieces of dry mandibular bone. Image analysis was performed by single color enhancement, density measurement with histogram. The relationship between the exposure conditions and the distribution of the pixel values of the image, the variation of pixel values of each step of Cu-step wedge at two different area and Cu-equivalent value of three pieces of dry mandibular bone measure by conversion equation. RESULTS: There was no linear relationship between the exposure condition and the average pixel value of the image, of which the distribution was not even. The pixel value differences between the center portion and the periphery were ranged from 60 to 70 in vertical plane and from 15 to 26 in horizontal plane. Two curves formed at two different areas of the Cu-step wedge were different. The measured Cu-equivalent values showed the discrepancy among the times of measurement. CONCLUSION: As above results, Image Plate(IP) of Digora system(R) showed the limitation as the quantitative image. The physical property of IP was expected to need to be compensated for the quantitative evaluation of the bone or others.

Effects of Anti Idiotypic Antibody NP30 on Modulation of Egg Granuloma Formation and Hepatic Fibrosis of Schistosomiasis * / 中国寄生虫学与寄生虫病杂志

Objective To study the effects of the monoclonal anti idiotypic antibody NP30 active immunization on egg granuloma formation and hepatic fibrosis in Schistosoma japonicum infection. Methods ICR mice were actively immunized with NP30 100 ?g ?3 ip. every 10 days while the mice in control group were injected with SP2/0 ascites ip. simultaneously. After cercariae challenging,the mice were killed at the 4th, 8th,12th, 16th, 20th and 24th week, respectively.Mouse livers were removed and stained histochemically with VG and subjected to immunohistochemical assay of collagen type Ⅰ,Ⅲ and fibronectin(FN).The volume of egg granulomas and the content of collagen type Ⅰ,Ⅲ and FN were determined quantitatively by NYD 1000 Image Analysis System. Results The volume of egg granulomas in NP30 immunized group was much smaller than that of control group from the 12th week after cercariae challenge. The cellular components of egg granulomas in NP30 immunized group were significantly different from those of the control group,exhibiting two types of atypical egg granulomas were found.VG stain revealed that the average optical density of collagen in hepatic granulomas of experimental group was lower than that of control group.Immunohistochemical assay revealed that the contents of collagen type Ⅰ,Ⅲ and fibronectin in egg granulomas of experimental group were lower than those of control group. Conclusion NP30 vaccination may induce both cellular and humoral protective immunity to modulate egg granulomas and suppress liver fibrosis of schistosomiasis japonica.