PURPOSE: The purpose of this study is to investigate fundamental aspects of the dose response of fluorescent screen-based electronic portal imaging devices (EPIDs). MATERIALS AND METHODS: We acquired scanned signal across portal planes as we varied the radiation that entered the EPID by changing the thickness and anatomy of the phantom as well as the air gap between the phantom and the EPID. In addition, we simulated the relative contribution of the scintillation light signal in the EPID system RESULTS: We have shown that the dose profile across portal planes is a function of the air gap and phantom thickness. We have also found that depending on the density change within the phantom geometry, errors associated with dose response based on the EPID scan can be as high as 7%. We also found that scintillation light scattering within the EPID system is an important source of error. CONCLUSION: This study revealed and demonstrated fundamental characteristics of dose response of EPID, as relative to that of ion chambers. This study showed that EPID based on fluorescent screen cannot be an accurate dosimetry system

Objective: To evaluate the in vivo antischistosomal activities of the crude extracts of Echinops kebericho Mesfin (E. kebericho) root and Hagenia abyssinica (Bruce) J.F. Gmel (H. abyssinica) flower. Methods: Mice were infected with (150 ± 10) Schistosoma mansoni cercariae by paddling technique. Crude extracts were administered orally for five consecutive days at doses of 300, 600 and 1 200 mg/kg/day along with 200 mg/kg/day praziquantel and 3% tween 80 given as a control. Results: E. kebericho root extract showed a statistically significant (P < 0.05) reduction in fecal egg count of 64.44%, 42.96% & 26.82% and worm burden of 65.71%, 47.86% & 31.43% at treatment doses of 1 200 mg/kg/day, 600 mg/kg/day and 300 mg/kg/day, respectively. Similarly, H. abyssinica flower extracts showed a significant (P < 0.05) reduction in fecal egg count up to 84.57%, 77.06% & 63.89% and worm burden of 91.43%, 81.43% & 70.71% at a respective dose levels. In addition, a significant (P < 0.05) reduction in liver granuloma score was observed in all H. abyssinica administered dose groups and E. kebericho at 1 200 mg/kg/day dose group as compared to infected untreated control group. Conclusions: H. abyssinica and E. kebericho crude extracts show a promising antischistosomal activity.