Enfermedad de Creutzfeldt-Jakob: experiencia de 5 años en un hospital terciario de Chile / Creutzfeldt-Jakob disease, experience in 17 patients

Background: Creutzfeldt-Jakob disease (CJD) is a prion affection that typically produces a rapidly progressive dementia with different neurologic and extra-neurologic manifestations. Aim: To characterize clinical, imaging and electroencephalography findings in patients with a probable CJD. Patients and Methods: A case series study of patients admitted in the Neurology department at a public hospital, between 2014 and 2019. Demographic, clinical, imaging, and electroencephalographic data of patients with probable CJD were analyzed. Results: Seventeen patients aged 63 ± 11 years (53% women) with a probable CJD were gathered. The incidence was 4.7 cases/year per million inhabitants. Twenty four percent of patients had a family history of CJD. The median time between the onset of symptoms and the hospital admission was three months with a survival of four months. The most common clinical manifestations were an amnesic syndrome in 88%, myoclonus in 76%, frontal syndrome and ataxia in 71%. Brain MRI was abnormal in all patients. The preponderant finding was the involvement of the caudate nucleus in 82% of cases. In the EEG, 94% of patients had abnormalities. All had a theta-delta slowing as a base rhythm. The pseudo-periodic pattern was observed in the 29% and status epilepticus in 18%. Conclusions: In this group of patients we observed the heterogeneity of the clinical manifestations of the disease, the frequent imaging and electroencephalographic alterations and the short evolution time leading to death.

A benchmarking study of Geant4 for Auger electrons emitted by medical radioisotopes.

Auger emitting radioisotopes are of great interest in targeted radiotherapy because, once internalised in the tumour cells, they can deliver dose locally to the radiation sensitive targets, while not affecting surrounding cells. Geant4 is a Monte Carlo code widely used to characterise the physics mechanism at the basis of targeted radiotherapy. In this work, we benchmarked the modelling of the emission of Auger electrons in Geant4 deriving from the decay of 123I, 124I, 125I radionuclides against existing theoretical approaches. We also compared Geant4 against reference data in the case of 131Cs, which is of interest for brachytherapy. In the case of 125I and 131Cs, the simulation results are compared to experimental measurements as well. Good agreement was found between Geant4 and the reference data. As far as we know, this is the first study aimed to benchmark against experimental measurements the emission of Auger electrons in Geant4 for radiotherapy applications.

[Creutzfeldt-Jakob disease, experience in 17 patients]. / Enfermedad de Creutzfeldt-Jakob: experiencia de 5 años en un hospital terciario de Chile.

BACKGROUND: Creutzfeldt-Jakob disease (CJD) is a prion affection that typically produces a rapidly progressive dementia with different neurologic and extra-neurologic manifestations. AIM: To characterize clinical, imaging and electroencephalography findings in patients with a probable CJD. PATIENTS AND METHODS: A case series study of patients admitted in the Neurology department at a public hospital, between 2014 and 2019. Demographic, clinical, imaging, and electroencephalographic data of patients with probable CJD were analyzed. RESULTS: Seventeen patients aged 63 ± 11 years (53% women) with a probable CJD were gathered. The incidence was 4.7 cases/year per million inhabitants. Twenty four percent of patients had a family history of CJD. The median time between the onset of symptoms and the hospital admission was three months with a survival of four months. The most common clinical manifestations were an amnesic syndrome in 88%, myoclonus in 76%, frontal syndrome and ataxia in 71%. Brain MRI was abnormal in all patients. The preponderant finding was the involvement of the caudate nucleus in 82% of cases. In the EEG, 94% of patients had abnormalities. All had a theta-delta slowing as a base rhythm. The pseudo-periodic pattern was observed in the 29% and status epilepticus in 18%. CONCLUSIONS: In this group of patients we observed the heterogeneity of the clinical manifestations of the disease, the frequent imaging and electroencephalographic alterations and the short evolution time leading to death.

Measuring and interpreting X-ray fluorescence from planetary surfaces.

As part of a comprehensive study of X-ray emission from planetary surfaces and in particular the planet Mercury, we have measured fluorescent radiation from a number of planetary analog rock samples using monochromatized synchrotron radiation provided by the BESSY II electron storage ring. The experiments were carried out using a purpose built X-ray fluorescence (XRF) spectrometer chamber developed by the Physikalisch-Technische Bundesanstalt, Germany's national metrology institute. The XRF instrumentation is absolutely calibrated and allows for reference-free quantitation of rock sample composition, taking into account secondary photon- and electron-induced enhancement effects. The fluorescence data, in turn, have been used to validate a planetary fluorescence simulation tool based on the GEANT4 transport code. This simulation can be used as a mission analysis tool to predict the time-dependent orbital XRF spectral distributions from planetary surfaces throughout the mapping phase.