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1.
IEEE Trans Radiat Plasma Med Sci ; 8(1): 15-20, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-38173701

RESUMO

Proton range verification (PRV) in proton therapy by means of prompt-gamma detection is a promising but challenging approach. High count rates, energies ranging between 1 MeV and 7 MeV, and a strong background complicate the detection of such particles. In this work, the Cherenkov light generated by prompt-gammas in the pure Cherenkov emitters TlBr, TlCl and PbF2 was studied. Cherenkov light in these crystals can provide a very fast timing signal with the potential to achieve very high count rates and to discern between prompt-gammas and background signals. Crystals of 1×1 cm2 and thicknesses of 1 cm, 2 cm, 3 cm and 4 cm were simulated. Different photodetector configurations were studied for 2.3 MeV, 4.4 MeV, and 6.1 MeV prompt-gammas. TlCl achieved the greatest number of detected Cherenkov photons for all energies, detector dimensions, and photodetector efficiency modeling. For the highest prompt-gamma energy simulated, TlCl yielded approximately 250 Cherenkov detected photons, using a hypothetical high-performance photodetector. Results show the crystal blocks of 1 cm × 1 cm × 1 cm have greater prompt-gamma detection efficiency per volume and a comparable average number of detected Cherenkov photons per event.

2.
Pediatr Radiol ; 23(7): 519-21, 1993.
Artigo em Inglês | MEDLINE | ID: mdl-8309752

RESUMO

OBJECTIVE: To determine the prevalence and clinical significance of adrenal hemorrhage in infants undergoing ECMO therapy. METHODS: Prospective US evaluation of the adrenal glands was performed in 50 consecutive infants undergoing ECMO. The infants were examined at least every other day while on bypass. Adrenal hemorrhage was diagnosed at US examination when a suprarenal mass or adrenal gland enlargement was identified. RESULTS: Adrenal hemorrhage was identified in two infants (4%); one infant with septicemia, and one with primary pulmonary hypertension. Both hemorrhages were unilateral; one was right-sided, and one left-sided. One hemorrhage occurred on the first day following the onset of ECMO and the other on the third day. The adrenal hemorrhage was not associated with an acute drop in hematocrit nor with adrenal insufficiency in either infant. CONCLUSION: Adrenal hemorrhage is uncommon in infants undergoing ECMO. When hemorrhage did occur in this series, it did not result in clinical complications.


Assuntos
Doenças das Glândulas Suprarrenais/etiologia , Oxigenação por Membrana Extracorpórea/efeitos adversos , Hemorragia/etiologia , Doenças das Glândulas Suprarrenais/diagnóstico por imagem , Feminino , Hemorragia/diagnóstico por imagem , Humanos , Recém-Nascido , Masculino , Estudos Prospectivos , Ultrassonografia
3.
Radiology ; 185(2): 549-52, 1992 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-1410371

RESUMO

One hundred eighty pediatric patients with suspected appendicitis were prospectively examined with graded compression ultrasonography (US) to assess the sensitivity, specificity, and accuracy of graded compression US in the diagnosis of appendicitis in children and to compare those results with results of clinical assessment in the diagnosis of this disorder. Patients were assigned to one of three groups prior to US based on the clinical level of confidence that appendicitis was present and on the planned management decision. Of 141 patients in the low- and intermediate-clinical risk categories, 20 (14%) had appendicitis: US had a sensitivity of 100%, specificity of 97%, and accuracy of 97% in these two groups. Of 39 patients in the high-clinical risk category, 32 (82%) had appendicitis: US had a sensitivity of 81%, specificity of 86%, and accuracy of 82%. Of 52 patients with surgically proved appendicitis, the initial management decision was to discharge to home or admit for observation and further testing in 18 (35%). Results at US were positive for appendicitis in all 18 patients in the latter two categories.


Assuntos
Apendicite/diagnóstico por imagem , Adolescente , Adulto , Apendicite/diagnóstico , Apendicite/patologia , Apêndice/diagnóstico por imagem , Apêndice/patologia , Criança , Pré-Escolar , Diagnóstico Diferencial , Técnicas de Diagnóstico por Cirurgia , Reações Falso-Positivas , Feminino , Seguimentos , Humanos , Masculino , Planejamento de Assistência ao Paciente , Probabilidade , Estudos Prospectivos , Fatores de Risco , Sensibilidade e Especificidade , Ultrassonografia
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