Sensitivity enhancement of methacrylic acid gel dosimeters by incorporating iodine for computed tomography scans.

PURPOSE: Polymer gel dosimeters provide three-dimensional absorbed dose information and have gradually become a popular tool for quality assurance in radiotherapy. This study aims to incorporate iodine into the MAGAT-based gel as radiation sensitizer and investigate whether it can be used to measure the radiation dose and slice thickness for CT scans. METHODS: The nMAGAT(I) gel was doped with 0.03, 0.05, and 0.07-M iodine. The absorbed dose was delivered using a CT scanner (Alexion 16, Toshiba Medical Systems, Japan) with tube voltages of 80, 100, 120, and 135 kVp. The irradiated nMAGAT(I) gel was read using a cone beam optical CT scanner to produce dose-response curves. The nMAGAT(I) gel was used to obtain the slice sensitivity profile (SSP) and the CT dose index (CTDI) for quality assurance of CT scans. RESULTS: The 0.07-M iodine-doped nMAGAT(I) gel exhibited maximum sensitivity with the dose enhancement ratio of 2.12. The gel was chemically stable 24 h after its preparation, and the polymerization process was completed 24-48 h after the irradiation. For CT quality assurance, the full width at half maximum measured by the nMAGAT(I) gel matched the nominal slice thickness of CT. The CTDI at center, CTDI at peripheral, and weighted CTDI obtained by the nMAGAT(I) gel differed from those obtained by the ionization chamber by -4.2%, 3.1%, and 0.7%, respectively. CONCLUSIONS: The nMAGAT(I) gel can be used to assess radiation doses and slice thickness in CT scans, thus rendering it a potential quality assurance tool for CT and other radiological diagnostic applications.

Colon Visualization on Bone Scan Due to Recto-abscess Fistula From Urinoma.

The accumulation of the bone-seeking agent in the bowel during a bone scan is rare. A 68-year-old man with colon cancer underwent bone scintigraphy for staging. Whole-body images revealed an abnormal accumulation of hot radioactivity in the abdominal cavity and the colon. Abdominal CT showed a recto-abscess fistula between the rectum and the urinoma. Incidental visualization of colonic radioactivity suggested the presence of a fistula between the bowel and the urinoma, explaining the peculiar finding of the bone-seeking agent in the bowel.

Amentoflavone Induces Apoptosis and Inhibits NF-ĸB-modulated Anti-apoptotic Signaling in Glioblastoma Cells.

The goal of the present study was to investigate anticancer effect of amentoflavone on glioblastoma cells in vitro. Our results demonstrated that amentoflavone not only significantly reduced cell viability, nuclear factor-ĸappa B (NF-ĸB) activation, and protein expression of cellular Fas-associated protein with death domain-like interleukin 1 beta-converting enzyme inhibitory protein (C-FLIP) and myeloid cell leukemia 1 (MCL1), but significantly triggered cell accumulation at the sub-G1 phase, loss of mitochondrial membrane potential, and expression of active caspase-3 and -8. In order to verify the effect of NF-ĸB inhibitor on expression of anti-apoptotic proteins, we performed western blotting. We found that the of NF-ĸB inhibitor or amentoflavone markedly diminished protein levels of MCL1 and C-FLIP. Taken all together, our findings show that amentoflavone induces intrinsic and extrinsic apoptosis and inhibits NF-ĸB-modulated anti-apoptotic signaling in U-87 MG cells in vitro.

Characterization of a murine xenograft model for contrast agent development in breast lesion malignancy assessment.

BACKGROUND: The aim of the study was to develop a nude mouse xenograft model implanted with both benign and malignant xenografts as the preliminary candidate screening tool for contrast agent development in lesion malignancy indication. RESULTS: A malignant xenograft (either MCF-7 cell/matrigel™ or MDA-MB 231 cell/matrigel) and a benign xenograft (culture medium/matrigel) with cleft and slit-like features of intracanaliculer fibroadenoma were implanted subcutaneously into flanks of individual nu/nu nude mouse with >90 % successful inoculation rate. Both malignant and benign xenografts with volume up to 4 cm(3) and (size up to 2 cm) after 5(th) week were characterized in vivo by sonogram (exhibiting endogenous morphological contrast features between benign and malignant xenografts), dynamic contrast enhanced multi-detector computed tomography (presenting non-targeting exogenous morphological and dynamic contrast features between benign and malignant xenografts), and then were harvested for histological and immunohistochemistry (revealing example of targeting/molecular contrast features, such as expression of cancer vascular markers of malignant xenografts). Malignant xenografts appeared morphologically taller than wide (axis parallel to skin) with angular/ill-defined margin under sonogram observations, revealed more evident rim enhancement, angular margin and washout pattern in the time-density curve from dynamic contrast enhance multi-detector computed tomography images, and had more visible cancer vascular markers (CD31 and VEGF) expression. With limited number of subjects (5-27 for each group of a specific imaging contrast feature), those imaging contrast features of the xenograft model had larger than 85 % sensitivity, specificity, accuracy, positive and negative prediction values in indicating xenograft malignancy except for results from color Doppler detections. CONCLUSIONS: The murine xenograft model might provide an earlier efficacy evaluation of new contrast agent candidate for lesion malignancy interrogation with qualitative and quantitative indication before a human study to reduce the risk and conserve the resources (time, finance and manpower).