Electroferotipos cortos de rotavirus detectados en adultos con diarrea en Paraguay

La presencia de rotavirus en adultos ha sido subestimada por mucho tiempo debido a que la mayor incidencia y patogenicidad se observa en niños menores de 5 años. Con el fin de determinar los electroferotipos circulantes en adultos, se empleó la técnica de PAGE para analizar23 aislados de rotavirus de individuos adultos (promedio de edad: 42,5 años; rango: 24 a 67 años), recolectados entre Septiembre de 2003 a Febrero de 2005 del Laboratorio del Hospital San Roque, Asunción. En las 23 muestras se detectaron 5 electroferotipos diferentes, 19 presentaron alguno de los 3 patrones largos detectados (denominados LA, LB y LC) y 4 presentaron algún patrón corto (SA y SB). Desde 1998 hasta la fecha, nuestro grupo de trabajo detectó un solo caso de rotavirus con patrón corto (aislado en septiembre de 1999) luego de analizar más de 1500 heces de niños con diarrea aguda. Estudios previos en población infantil, han reportado que se necesitan varios años de estudio para identificar rotavirus con patrones cortos en una comunidad, sin embargonuestros resultados sugieren que además es importante ampliar las variables demográficas de la población de estudio para encontrar más variantes de rotavirus, como en este caso es la aparición de patrones cortos en adultos sin que estos se presenten en niños

Extended calibration range for prompt photon emission in ion beam irradiation

Monitoring the dose delivered during proton and carbon ion therapy is still a matter of research. Among the possible solutions, several exploit the measurement of the single photon emission from nuclear decays induced by the irradiation. To fully characterize such emission the detectors need development, since the energy spectrum spans the range above the MeV that is not traditionally used in medical applications. On the other hand, a deeper understanding of the reactions involving gamma production is needed in order to improve the physic models of Monte Carlo codes, relevant for an accurate prediction of the prompt-gamma energy spectrum.This paper describes a calibration technique tailored for the range of energy of interest and reanalyzes the data of the interaction of a 80MeV/u fully stripped carbon ion beam with a Poly-methyl methacrylate target. By adopting the FLUKA simulation with the appropriate calibration and resolution a significant improvement in the agreement between data and simulation is reported.Comment: 4 pages, 7 figures, Submitted to JINS

Measurement of secondary particle production induced by particle therapy ion beams impinging on a PMMA target

Particle therapy is a technique that uses accelerated charged ions for cancer treatment and combines a high irradiation precision with a high biological effectiveness in killing tumor cells [1]. Informations about the secondary particles emitted in the interaction of an ion beam with the patient during a treatment can be of great interest in order to monitor the dose deposition. For this purpose an experiment at the HIT (Heidelberg Ion-Beam Therapy Center) beam facility has been performed in order to measure fluxes and emission profiles of secondary particles produced in the interaction of therapeutic beams with a PMMA target. In this contribution some preliminary results about the emission profiles and the energy spectra of the detected secondaries will be presente

First Ex-Vivo Validation of a Radioguided Surgery Technique with beta- Radiation

Purpose: A radio-guided surgery technique with beta- -emitting radio-tracers was suggested to overcome the effect of the large penetration of gamma radiation. The feasibility studies in the case of brain tumors and abdominal neuro-endocrine tumors were based on simulations starting from PET images with several underlying assumptions. This paper reports, as proof-of-principle of this technique, an ex-vivo test on a meningioma patient. This test allowed to validate the whole chain, from the evaluation of the SUV of the tumor, to the assumptions on the bio-distribution and the signal detection. Methods: A patient affected by meningioma was administered 300 MBq of 90Y-DOTATOC. Several samples extracted from the meningioma and the nearby Dura Mater were analyzed with a beta- probe designed specifically for this radio-guided surgery technique. The observed signals were compared both with the evaluation from the histology and with the Monte Carlo simulation. Results: we obtained a large signal on the bulk tumor (105 cps) and a significant signal on residuals of $\sim$0.2 ml (28 cps). We also show that simulations predict correctly the observed yields and this allows us to estimate that the healthy tissues would return negligible signals (~1 cps). This test also demonstrated that the exposure of the medical staff is negligible and that among the biological wastes only urine has a significant activity. Conclusions: This proof-of-principle test on a patient assessed that the technique is feasible with negligible background to medical personnel and confirmed that the expectations obtained with Monte Carlo simulations starting from diagnostic PET images are correct.Comment: 17 pages, 4 Figs, Accepted by Physica Medic

Characterization of a detector for β− radio-guided surgery

This paper reports a new device for the radio-guided surgery technique exploiting β− emitters. A specific intraoperative β− detecting probe based on a low-density organic crystal, the diphenylbutadiene-doped para-therphenyl, coupled by optical fibres to a photomultiplier, was developed. A portable readout electronics was designed to provide the surgeons with multi real-time feedback. The aspects related to the applicability of the device, in particular the perception of the spatial resolution of the probe and the comprehension time necessary to the operator to interpret the system response were investigated. Preliminary promising results support the possibility of using this innovative probe in cancer surgery

Secondary radiation measurements for charged particle therapy monitoring: fragmentation of therapeutic He, C and O ion beams impinging on a PMMA target

In Charged Particle Therapy (CPT), besides protons, there has been recently a growing interest in 4He, 12C and 16O beams. The secondary radiation produced in the interaction of those beams with a patient could be potentially used for on‐line monitoring of range uncertainties in order to fully exploit the advantages of those light ions resulting from increased Radio Biological Effectiveness, reduced multiple scattering and Oxygen Enhancement Ratio. The study and precise characterization of secondary radiation (beta+, prompt gamma, charged fragments) is the cornerstone of any R&D activity aiming for online monitoring development and purpose of the analysis presented here

Secondary radiation measurements for charged particle therapy monitoring: fragmentation of therapeutic He, C and O ion beams impinging on a PMMA target

In Charged Particle Therapy (CPT), besides protons, there has been recently a growing interest in 4He, 12C and 16O beams. The secondary radiation produced in the interaction of those beams with a patient could be potentially used for on‐line monitoring of range uncertainties in order to fully exploit the advantages of those light ions resulting from increased Radio Biological Effectiveness, reduced multiple scattering and Oxygen Enhancement Ratio. The study and precise characterization of secondary radiation (beta+, prompt gamma, charged fragments) is the cornerstone of any R&D activity aiming for online monitoring development and purpose of the analysis presented here

Intraoperative probe detecting β− decays in brain tumour radio-guided surgery

Abstract Radio-guided surgery (RGS) is a technique to intraoperatively detect tumour remnants, favouring a radical resection. Exploiting β − emitting tracers provides a higher signal to background ratio compared to the established technique with γ radiation, allowing the extension of the RGS applicability range. We developed and tested a detector based on para-terphenyl scintillator with high sensitivity to low energy electrons and almost transparent to γ s to be used as intraoperative probe for RGS with β − emitting tracer. Portable read out electronics was customised to match the surgeon needs. This probe was used for preclinical test on specific phantoms and a test on "ex vivo" specimens from patients affected by meningioma showing very promising results for the application of this new technique on brain tumours. In this paper, the prototype of the intraoperative probe and the tests are discussed; then, the results on meningioma are used to make predictions on the performance of the probe detecting residuals of a more challenging and more interesting brain tumour: the glioma