RESUMO
Stereotactic body radiation therapy (SBRT) is usually verified with a dynamic phantom or solid phantom, but there is a demand for phantoms that can accurately simulate tumor dynamics within an individual that would allow customized validation in every patient. We developed a new 4D dynamic target phantom (multi-cell 4D phantom) that allows simulation of tumor movement in patients. The basic quality and dynamic reproducibility of this new phantom was verified in this investigation. The newly developed multi-cell 4D phantom comprises four main components: soft tissue, bones, lungs, and tumor (target). The phantom structure was based on computed tomography (CT) data of a male. In this study, we investigated the basic performance of a multi-cell 4D phantom. All the CT numbers of the phantom were very close to those of human data. The geometric maximum amplitudes were 4.57 mm in the lateral direction, 4.59 mm in the ventrodorsal direction, and 3.68 mm in the cranio-caudal direction. Geometric errors were 0.84, 0.58, and 0.40 mm, respectively. Movements of the abdominal surface were stable for 60 s. Repeated measurements show no actual differences in target movements between multiple measurements and indicated high reproducibility (r > 0.97). End-to-end tests using Gafchromic film revealed a gamma pass rate of 98% or above (2 mm/3%). Although our phantom performed limited reproducibility in the movement of the patient tumor at present, a satisfactory level of precision was confirmed in general. This is a very promising device for use in the verification of radiation therapy for moving targets.
Assuntos
Tomografia Computadorizada Quadridimensional/instrumentação , Processamento de Imagem Assistida por Computador/métodos , Imagens de Fantasmas , Radiografia Abdominal/métodos , Planejamento da Radioterapia Assistida por Computador/métodos , Técnicas de Imagem de Sincronização Respiratória/métodos , Tomografia Computadorizada por Raios X/métodos , Tomografia Computadorizada Quadridimensional/métodos , Humanos , Pulmão/diagnóstico por imagem , Masculino , Movimento , Radiocirurgia/métodosAssuntos
Dequalínio , Compostos de Quinolínio , Cristalização , Armazenamento de Medicamentos , Óleos , Pomadas , Fatores de Tempo , ÁguaRESUMO
Since gamma-hydroxybutyric acid (GHB) is known to be an effective anesthetic adjuvant in animal and a natural metabolite of succinic semialdehyde (SSA), the effect of SSA and GHB on the convulsive action of vitamin B6 antagonists was studied using the onset of seizure as a parameter. The administration of SSA and GHB to mice protected them against the convulsive action of B6 antagonist, such as castrix (2-chloro-4-dimethyl-6-methylpyrimidine), thiosemicarbazide, or penicillamine. The anticonvulsant effect of SSA seems to be due to an increase in brain levels of GHB converted in vivo from SSA.
