23,578 research outputs found
Application of CT in Diagnosing Carcinoma of the Maxillary Sinuses : PART 2: An Experimental Study of Pitfalls Encountered when Diagnosing Carcinoma of the Maxillary Sinuses with CT
Full text link1982-03A phantom simulating the transverse section of the maxillary sinuses was constructed for experimentation with various CT scanners to study the following: (1) the occasional inability to image the very thin posterior-lateral walls which have no real bone defects, and (2) to verify whether or not the bony walls surrounding the maxillary sinuses are actually as thick as they appear on CT. The phantom was made of an acrylic cylinder containing three cavities simulating the maxillary sinuses and the nasal cavity and filled with water. The walls, made of thin aluminum and acrylic plates and placed between water and air, disappeared in some CT images. The thickness of the walls calculated from CT values was greater than the true thickness imaged by each CT scanner. The author stresses that in CT images, either experimentally or clinically, thin bony walls placed between water and air or fat tend to disappear, and that bony walls tend to appear thicker than their true thickenss.departmental bulletin pape
Pilot-test scale affinity chromatographic purification of trypsin and chymotrypsin from hog pancreas.
No full textCytochrome C release induces apoptosis of nasopharyngeal carcinoma by antitumor glyfoline
No full textOPTIMIZATION OF ITERATIVE CT RECONSTRUCTION TO REDUCE PATIENT ABSORBED DOSE IN PET/CT EXAMINATIONS
No full textreservedL’apporto dosimetrico di un esame PET/CT deriva dalla dosimetria del radiofarmaco e dalla dosimetria della componente CT. Con la presente tesi si è cercato di ridurre il carico dosimetrico al paziente ottimizzando la ricostruzione iterativa CT e utilizzandola al posto della ricostruzione FBP attualmente in uso.
I dati sperimentali sono stati raccolti presso la UOC di Medicina Nucleare dell’Ospedale Santa Maria della Misericordia di Rovigo con il tomografo PET/CT Siemens Biograph mCT.
È stata eseguita una prima analisi quantitativa su fantoccio antropomorfo (Alderson Rando) per valutare la qualità d’immagine CT al variare della dose erogata e dell’algoritmo di ricostruzione iterativo rispetto a FBP; quindi un’analisi quantitativa su fantoccio PET NEMA IQ per valutare l’accuratezza del SUV delle immagini PET. In base ai dati ottenuti si sono stabiliti i parametri di acquisizione e ricostruzione ottimizzati che sono stati successivamente verificati qualitativamente dalla valutazione clinica di 25 indagini PET/CT.
L’uso dell’algoritmo SAFIRE a livello 3 ha permesso di ridurre la dose CT al 70%, mantenendo la stessa qualità d’immagine finale, dati che sono stati confermati anche dall’analisi qualitativa delle immagini PET/CT.
L’applicazione della ricostruzione iterativa secondo i dati raccolti permette di ridurre la dose complessiva assorbita dal paziente in media di 1,7 mSv (-18%), portando l’esposizione dalla classe IV alla classe III (come definita nell’ art.161 D.Lgs 101/2020) nell’ 86% dei casi.The dosimetric contribution of a PET/CT exam derives from the dosimetry of the radiopharmaceutical and the dosimetry of the CT component. With this thesis we attempted to reduce the dosimetric burden on the patient by optimizing the iterative CT reconstruction instead of the FBP reconstruction currently used.
The experimental data were collected at the Nuclear Medicine Unit of the Santa Maria della Misericordia Hospital in Rovigo with the Siemens Biograph mCT PET/CT tomograph.
A first quantitative analysis was performed on an anthropomorphic phantom (Alderson Rando) to evaluate the CT image quality by varying the dose delivered and the iterative reconstruction algorithm compared to FBP; then a quantitative analysis on a NEMA IQ PET phantom to evaluate the SUV accuracy of the PET images. Based on the data obtained, the optimized acquisition and reconstruction parameters were established which were subsequently qualitatively verified by the clinical evaluation of 25 PET/CT examinations.
The use of the SAFIRE algorithm at level 3 allowed the CT dose to be reduced to 70%, while maintaining the same final image quality, data that were also confirmed by the qualitative analysis of PET/CT images.
The application of the iterative reconstruction according to the data collected makes it possible to reduce the overall dose absorbed by the patient by an average of 1,7 mSv (-18%), bringing the exposure from class IV to class III (as defined in art.161 D. Lgs. 101/2020) in 86% of cases
Differential control of sympathetic-nerve activities during combined asphyxia and paramedian reticular nucleus stimulation in cats.
No full textPresence of perikaryon in the sympathetic pressor areas of dorsal and ventrolateral medulla inhibiting phrenic nerve discharge in cats.
No full textNeurons in the medullary gigantocellular reticular nculeus mediate cardioinhibition in cats.
No full textMagnetic resonance cholangiography for evaluation of cholestatic jaundice in neonates and infants.
No full textSchistosome skin testing and intestinal parasite survey among inhabitants of Yuan-Shan, Ilan County, Taiwan.
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