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2.
Phys Med ; 60: 139-149, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31000074

RESUMO

PURPOSE: To describe a new system for scanned ion beam therapy, named RIDOS (Real-time Ion DOse planning and delivery System), which performs real time delivered dose verification integrating the information from a clinical beam monitoring system with a Graphic Processing Unit (GPU) based dose calculation in patient Computed Tomography. METHODS: A benchmarked dose computation algorithm for scanned ion beams has been parallelized and adapted to run on a GPU architecture. A workstation equipped with a NVIDIA GPU has been interfaced through a National Instruments PXI-crate with the dose delivery system of the Italian National Center of Oncological Hadrontherapy (CNAO) to receive in real-time the measured beam parameters. Data from a patient monitoring system are also collected to associate the respiratory phases with each spot during the delivery of the dose. Using both measured and planned spot properties, RIDOS evaluates during the few seconds of inter-spill time the cumulative delivered and prescribed dose distributions and compares them through a fast γ-index algorithm. RESULTS: The accuracy of the GPU-based algorithms was assessed against the CPU-based ones and the differences were found below 1‰. The cumulative planned and delivered doses are computed at the end of each spill in about 300 ms, while the dose comparison takes approximatively 400 ms. The whole operation provides the results before the next spill starts. CONCLUSIONS: RIDOS system is able to provide a fast computation of the delivered dose in the inter-spill time of the CNAO facility and allows to monitor online the dose deposition accuracy all along the treatment.


Assuntos
Algoritmos , Íons/uso terapêutico , Sistemas On-Line , Dosagem Radioterapêutica , Computadores , Humanos , Respiração , Síncrotrons , Fatores de Tempo
3.
Met Ions Life Sci ; 192019 Jan 14.
Artigo em Inglês | MEDLINE | ID: mdl-30855102

RESUMO

Metal ions are indispensable for living organisms. However, the roles of metal ions in humans is complex, and remains poorly understood. Imbalances in metal ion levels, due to genetic or environmental sources, are associated with a number of significant health issues. However, in clinical medicine, the role of metal ions and metal-based drugs is notable in three major areas: as metal-related diseases; as metal-based medicines (including drugs, imaging agents, and metal chelators); and as agents of metal-based toxicity.


Assuntos
Íons/uso terapêutico , Metais/uso terapêutico , Quelantes , Meios de Contraste , Humanos , Preparações Farmacêuticas
4.
Appl Radiat Isot ; 150: 192-198, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-30553541

RESUMO

The relative biological effectiveness (RBE) values were determined for single- and mixed-ion beams containing carbon and oxygen ions. The CHO-K1 cells were irradiated with beams with the linear energy transfer (LET) values of 236-300 and 461-470 keV/µm for 12C and 16O ions, respectively. The RBE was estimated as a function of dose, survival fraction (SF) and LET. The SF was not affected by varying contributions of the constituent ions to the total mixed dose. The RBE has the same value for single-ion exposures with ions with LET 300 (12C) and 470 keV/µm (16O).


Assuntos
Radioterapia com Íons Pesados , Íons/uso terapêutico , Eficiência Biológica Relativa , Animais , Células CHO , Sobrevivência Celular/efeitos da radiação , Cricetulus , Radioterapia com Íons Pesados/estatística & dados numéricos , Íons Pesados , Transferência Linear de Energia , Neoplasias/radioterapia , Oxigênio
5.
Radiother Oncol ; 128(1): 83-100, 2018 07.
Artigo em Inglês | MEDLINE | ID: mdl-30001932

RESUMO

Under the umbrella of the European Network for Light Ion Therapy (ENLIGHT), the project on Union of Light Ion Centers in Europe (ULICE), which was funded by the European Commission (EC/FP7), was carried out from 2009 to 2014. Besides the two pillars on Transnational Access (TNA) and Networking Activities (NA), six work packages formed the pillar on Joint Research Activities (JRA). The current manuscript focuses on the objectives and results achieved within these research work packages: "Clinical Research Infrastructure", "Biologically Based Expert System for Individualized Patient Allocation", "Ion Therapy for Intra-Fractional Moving Targets", "Adaptive Treatment Planning for Ion Radiotherapy", "Carbon Ion Gantry", "Common Database and Grid Infrastructures for Improving Access to Research Infrastructures". The objectives and main achievements are summarized. References to either publications or open access deliverables from the five year project work are given. Overall, carbon ion radiotherapy is still not as mature as photon or proton radiotherapy. Achieved results and open questions are reflected and discussed in the context of the current status of carbon ion therapy and particle and photon beam therapy. Most research topics covered in the ULICE JRA pillar are topical. Future research activities can build upon these ULICE results. Together with the continuous increase in the number of particle therapy centers in the last years ULICE results and proposals may contribute to the further growth of the overall particle therapy field as foreseen with ENLIGHT and new joint initiatives such as the European Particle Therapy Network (EPTN) within the overall radiotherapy community.


Assuntos
Pesquisa Biomédica/organização & administração , Íons/uso terapêutico , Neoplasias/radioterapia , Fótons/uso terapêutico , Radioterapia/métodos , Pesquisa/organização & administração , Bases de Dados Factuais , Europa (Continente) , Radioterapia com Íons Pesados/métodos , Humanos , Terapia com Prótons/métodos
6.
Cell Stress Chaperones ; 23(6): 1337-1343, 2018 11.
Artigo em Inglês | MEDLINE | ID: mdl-29876727

RESUMO

Candida albicans causes opportunistic fungal infections usually hidden among more dominant bacteria and does not exhibit high pathogenicity in vivo. Among the elderly, due to reduced host resistance to pathogens attributable to immunoscenesence, oral candidiasis is more likely to develop often leading to systemic candidiasis. Surface pre-reacted glass ionomer filler (S-PRG filler) is an ion-releasing functional bioactive glass that can release and recharge six ions which in turn strengthens tooth structure, inhibits demineralization arising from dental caries, and suppresses dental plaque accumulation. However, its effects on C. albicans have never been elucidated. Here, we evaluated the effects of ion released from S-PRG filler on C. albicans. Results show that extraction liquids containing released ions (ELIS) decreased the amount of hydrogen peroxide and catalase activity in C. albicans. Moreover, ELIS presence was found to affect C. albicans: (1) suppression of fungal growth and biofilm formation, (2) prevent adherence to denture base resin, (3) inhibit dimorphism conversion, and (4) hinder the capability to produce secreted aspartyl proteinase. Taken together, our findings suggest that ELIS induces oxidative stress in C. albicans and suppresses its growth and pathogenicity. In this regard, we propose that ELIS has the potential to be clinically used to help prevent the onset and inhibition of oral candidiasis among the elderly population.


Assuntos
Resinas Acrílicas/farmacologia , Biofilmes/efeitos dos fármacos , Candida albicans/efeitos dos fármacos , Candidíase Bucal/prevenção & controle , Cimentos de Ionômeros de Vidro/farmacologia , Dióxido de Silício/farmacologia , Resinas Acrílicas/química , Resinas Acrílicas/uso terapêutico , Idoso , Ácido Aspártico Proteases/metabolismo , Candida albicans/crescimento & desenvolvimento , Candida albicans/patogenicidade , Catalase/antagonistas & inibidores , Adesão Celular/efeitos dos fármacos , Bases de Dentadura/microbiologia , Cimentos de Ionômeros de Vidro/química , Cimentos de Ionômeros de Vidro/uso terapêutico , Humanos , Íons/química , Íons/farmacologia , Íons/uso terapêutico , Estresse Oxidativo , Dióxido de Silício/química , Dióxido de Silício/uso terapêutico
7.
Radiat Oncol ; 13(1): 120, 2018 Jun 25.
Artigo em Inglês | MEDLINE | ID: mdl-29941049

RESUMO

BACKGROUND: Uncertainties associated with the delivery of treatment to moving organs might compromise the accuracy of treatment. This study explores the impact of intra-fractional anatomical changes in pancreatic patients treated with charged particles delivered using a scanning beam. The aim of this paper is to define the potential source of uncertainties, quantify their effect, and to define clinically feasible strategies to reduce them. METHODS: The study included 14 patients treated at our facility with charged particles (protons or 12C) using intensity modulated particle therapy (IMPT). Treatment plans were optimized using the Treatment Planning System (TPS) Syngo® RT Planning. The pre-treatment dose distribution under motion (4D) was simulated using the TPS TRiP4D and the dose delivered for some of the treatment fractions was reconstructed. The volume receiving at least 95% of the prescribed dose (V95CTV) and the target dose homogeneity were evaluated. The results from the 4D dose calculations were compared with dose distributions in the static case and its variation correlated with the internal motion amplitude and plan modulation, through the Pearson correlation coefficient, as well the significant p-value. The concept of the modulation index (MI) was introduced to assess the degree of modulation of IMPT plans, through the quantification of intensity gradients between neighboring pencil beams. RESULTS: The induced breathing motion together with dynamic beam delivery results in an interplay effect, which affects the homogeneity and target coverage of the dose distribution. This effect is stronger (∆V95CTV > 10%) for patients with tumor motion amplitude above 5 mm and a highly modulated dose distribution between and within fields. The MI combined with the internal motion amplitude is shown to correlate with the target dose degradation and a lack of plan robustness against range and positioning uncertainties. CONCLUSIONS: Under internal motion the use of inhomogeneous plans results in a decrease in the dose homogeneity and target coverage of dose distributions in comparison to the static case. Plan robustness can be improved by using multiple beams and avoiding beam entrance directions susceptible to density changes. 4D dose calculations support the selection of the most suitable plan for the specific patient's anatomy.


Assuntos
Íons/uso terapêutico , Movimentos dos Órgãos , Neoplasias Pancreáticas/radioterapia , Planejamento da Radioterapia Assistida por Computador , Humanos , Dosagem Radioterapêutica , Radioterapia de Intensidade Modulada , Incerteza
8.
Radiother Oncol ; 128(1): 109-114, 2018 07.
Artigo em Inglês | MEDLINE | ID: mdl-29459152

RESUMO

PURPOSE: To derive the dose-response curve for temporal lobe reactions (TLRs) after proton therapy and to compare the resulting relative biological effectiveness (RBE)-weighted tolerance doses based on an RBE of 1.1 with published values for carbon ions, which were calculated by the two versions of the local effect model (LEM I or IV). METHODS AND MATERIALS: 62 patients treated with protons for skull base tumors were analyzed for TLRs using magnetic resonance imaging. Within the mean follow-up time of 38 months, TLRs were observed in six patients. Dose-response curves based on the RBE-weighted maximum dose, excluding the 1 cm3-volume with the highest dose, were derived and compared to previously published dose-response curves for carbon ions, which were obtained using LEM I or IV, respectively. RESULTS: The dose-response curves for protons and LEM I were found to be almost identical while the curve of LEM IV was shifted toward higher doses. The resulting tolerance doses at the 5% effect level were 68.2+2.7-5.6, 68.6+3.0-3.9 and 78.3+3.8-5.0 Gy (RBE), respectively. CONCLUSIONS: The RBE-weighted dose prescription for protons leads to the same RBE-weighted dose-response curve for TLR as the one for LEM I-based carbon ions, while LEM IV predicts clinically significant higher tolerance doses.


Assuntos
Neoplasias Encefálicas/radioterapia , Radioterapia com Íons Pesados/métodos , Terapia com Prótons , Neoplasias da Base do Crânio/radioterapia , Lobo Temporal/efeitos da radiação , Adolescente , Adulto , Idoso , Neoplasias Encefálicas/diagnóstico por imagem , Carbono/uso terapêutico , Criança , Relação Dose-Resposta à Radiação , Feminino , Humanos , Íons/uso terapêutico , Imagem por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Dosagem Radioterapêutica , Planejamento da Radioterapia Assistida por Computador/métodos , Eficiência Biológica Relativa , Neoplasias da Base do Crânio/diagnóstico por imagem , Lobo Temporal/diagnóstico por imagem , Adulto Jovem
9.
Drug Discov Today ; 23(4): 879-890, 2018 04.
Artigo em Inglês | MEDLINE | ID: mdl-29407177

RESUMO

Bone scientists are actively investigating a range of methods to promote skeletal tissue regeneration. A review of recent literature has revealed that several ions are uniquely capable of inducing stem cell differentiation down desired lineages. There exists enormous promise for these ions to be used in bone regenerative medicine. Given that these ions can be released from biodegradable polymeric materials, their long-term delivery can be achieved through a variety of controlled-release strategies compared with the relatively few options available for expensive and fragile polypeptide-based growth factors. In this review, we highlight the developments in using ions in conjunction with biomaterials for bone regeneration.


Assuntos
Regeneração Óssea/efeitos dos fármacos , Osso e Ossos/efeitos dos fármacos , Íons/farmacologia , Íons/uso terapêutico , Animais , Materiais Biocompatíveis/química , Humanos , Íons/química , Medicina Regenerativa/métodos
10.
Radiat Oncol ; 13(1): 2, 2018 Jan 09.
Artigo em Inglês | MEDLINE | ID: mdl-29316969

RESUMO

BACKGROUND: Due to their favorable physical and biological properties, helium ion beams are increasingly considered a promising alternative to proton beams for radiation therapy. Hence, this work aims at comparing in-silico the treatment of brain and ocular meningiomas with protons and helium ions, using for the first time a dedicated Monte Carlo (MC) based treatment planning engine (MCTP) thoroughly validated both in terms of physical and biological models. METHODS: Starting from clinical treatment plans of four patients undergoing proton therapy with a fixed relative biological effectiveness (RBE) of 1.1 and a fraction dose of 1.8 Gy(RBE), new treatment plans were optimized with MCTP for both protons (with variable and fixed RBE) and helium ions (with variable RBE) under the same constraints derived from the initial clinical plans. The resulting dose distributions were dosimetrically compared in terms of dose volume histograms (DVH) parameters for the planning target volume (PTV) and the organs at risk (OARs), as well as dose difference maps. RESULTS: In most of the cases helium ion plans provided a similar PTV coverage as protons with a consistent trend of superior OAR sparing. The latter finding was attributed to the ability of helium ions to offer sharper distal and lateral dose fall-offs, as well as a more favorable differential RBE variation in target and normal tissue. CONCLUSIONS: Although more studies are needed to investigate the clinical potential of helium ions for different tumour entities, the results of this work based on an experimentally validated MC engine support the promise of this modality with state-of-the-art pencil beam scanning delivery, especially in case of tumours growing in close proximity of multiple OARs such as meningiomas.


Assuntos
Hélio/uso terapêutico , Neoplasias Meníngeas/radioterapia , Meningioma/radioterapia , Terapia com Prótons/métodos , Planejamento da Radioterapia Assistida por Computador/métodos , Humanos , Íons/uso terapêutico , Método de Monte Carlo , Eficiência Biológica Relativa
11.
Med Phys ; 45(1): 352-369, 2018 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-29105791

RESUMO

PURPOSE: To describe the implementation of dosimetry equipment and phantoms into clinical practice of light ion beam therapy facilities. This work covers not only standard dosimetry equipment such as computerized water scanners, films, 2D-array, thimble, and plane parallel ionization chambers, but also dosimetry equipment specifically devoted to the pencil beam scanning delivery technique such as water columns, scintillating screens or multilayer ionization chambers. METHOD: Advanced acceptance testing procedures developed at MedAustron and complementary to the standard acceptance procedures proposed by the manufacturer are presented. Detailed commissioning plans have been implemented for each piece of dosimetry equipment and include an estimate of the overall uncertainty budget for the range of clinical use of each device. Some standard dosimetry equipment used in many facilities was evaluated in detail: for instance, the recombination of a 2D-array or the potential use of a microdiamond detector to measure reference transverse dose profiles in water in the core of the primary pencil beams and in the low-dose nuclear halo (over four orders of magnitude in dose). RESULTS: The implementation of dosimetry equipment as described in this work allowed determining absolute spot sizes and spot positions with an uncertainty better than 0.3 mm. Absolute ranges are determined with an uncertainty comprised of 0.2-0.6 mm, depending on the measured range and were reproduced with a maximum difference of 0.3 mm over a period of 12 months using three different devices. CONCLUSION: The detailed evaluation procedures of dosimetry equipment and phantoms proposed in this work could serve as a guidance for other medical physicists in ion beam therapy facilities and also in conventional radiation therapy.


Assuntos
Íons/uso terapêutico , Imagens de Fantasmas , Radiometria/instrumentação , Humanos , Pelve , Dosímetros de Radiação , Software , Incerteza
12.
Rev. lab. clín ; 10(4): 217-220, oct.-dic. 2017.
Artigo em Espanhol | IBECS | ID: ibc-166854

RESUMO

Se describen dos casos clínicos de pacientes con hipomagnesemia grave secundaria a inhibidores de la bomba de protones. Los datos de laboratorio nos pueden ayudar a diferenciar entre la hipomagnesemia producida por pérdida intestinal de magnesio y la producida por pérdidas renales de magnesio. La hipomagnesemia asociada al uso prolongado de inhibidores de la bomba de protones es un efecto adverso que suele pasar inadvertido y que puede ocasionar manifestaciones clínicas graves, siendo conveniente realizar controles periódicos de magnesemia en pacientes que precisen de tratamiento prolongado con inhibidores de la bomba de protones, fundamentalmente en el uso concomitante de antiarrítmicos o diuréticos y en aquellos pacientes con hipocalcemia y/o hipopotasemia. La posibilidad de este y de otros efectos adversos es un motivo más para valorar periódicamente el tratamiento con inhibidores de la bomba de protones a largo plazo (AU)


Two clinical cases are presented on patients with severe hypomagnesaemia induced by proton pump inhibitors. Laboratory data can help us to differentiate between hypomagnesaemia caused by intestinal loss of magnesium and the one produced by renal magnesium losses. Hypomagnesaemia associated with a prolonged use of proton pump inhibitors is an inadvertent adverse effect that can lead to severe clinical manifestations, therefore it is advisable to perform periodic monitoring of magnesium in the blood of patients who require prolonged treatment with proton pump inhibitors, especially in the concomitant use of antiarrhythmic or diuretic drugs, and in those patients with hypocalcaemia and/or hypokalaemia. The possibility of this and other adverse effects is one more reason to periodically evaluate long-term proton pump inhibitors treatment (AU)


Assuntos
Humanos , Feminino , Pessoa de Meia-Idade , Idoso , Magnésio/análise , Deficiência de Magnésio/induzido quimicamente , Deficiência de Magnésio/diagnóstico , Bombas de Próton/efeitos adversos , Bombas de Próton/análise , Instabilidade Articular/complicações , Instabilidade Articular/diagnóstico , Hipertonia Muscular/diagnóstico , Dor Lombar/complicações , Íons/uso terapêutico , Homeostase
13.
Phys Med ; 42: 116-126, 2017 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-29173904

RESUMO

Radiotherapy with protons and carbon ions enables to deliver dose distributions of high conformation to the target. Treatment with helium ions has been suggested due to their physical and biological advantages. A reliable benchmarking of the employed physics models with experimental data is required for treatment planning. However, experimental data for helium interactions is limited, in part due to the complexity and large size of conventional experimental setups. We present a novel method for the investigation of helium interactions with matter using miniaturized instrumentation based on highly integrated pixel detectors. The versatile setup consisted of a monitoring detector in front of the PMMA phantom of varying thickness and a detector stack for investigation of outgoing particles. The ion type downstream from the phantom was determined by high-resolution pattern recognition analysis of the single particle signals in the pixelated detectors. The fractions of helium and hydrogen ions behind the used targets were determined. As expected for the stable helium nucleus, only a minor decrease of the primary ion fluence along the target depth was found. E.g. the detected fraction of hydrogen ions on axis of a 220MeV/u 4He beam was below 6% behind 24.5cm of PMMA. Monte-Carlo simulations using Geant4 reproduce the experimental data on helium attenuation and yield of helium fragments qualitatively, but significant deviations were found for some combinations of target thickness and beam energy. The presented method is promising to contribute to the reduction of the uncertainty of treatment planning for helium ion radiotherapy.


Assuntos
Radioterapia com Íons Pesados/instrumentação , Radioterapia com Íons Pesados/métodos , Hélio/uso terapêutico , Íons/uso terapêutico , Miniaturização , Simulação por Computador , Desenho de Equipamento , Hidrogênio , Miniaturização/instrumentação , Método de Monte Carlo , Imagens de Fantasmas , Polimetil Metacrilato , Radiometria/instrumentação , Planejamento da Radioterapia Assistida por Computador/instrumentação , Planejamento da Radioterapia Assistida por Computador/métodos
14.
Acta Oncol ; 56(11): 1359-1366, 2017 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-28828925

RESUMO

Only few ten radiotherapy facilities worldwide provide ion beams, in spite of their physical advantage of better achievable tumor conformity of the dose compared to conventional photon beams. Since, mainly the large size and high costs hinder their wider spread, great efforts are ongoing to develop more compact ion therapy facilities. One promising approach for smaller facilities is the acceleration of ions on micrometre scale by high intensity lasers. Laser accelerators deliver pulsed beams with a low pulse repetition rate, but a high number of ions per pulse, broad energy spectra and high divergences. A clinical use of a laser based ion beam facility requires not only a laser accelerator providing beams of therapeutic quality, but also new approaches for beam transport, dosimetric control and tumor conformal dose delivery procedure together with the knowledge of the radiobiological effectiveness of laser-driven beams. Over the last decade research was mainly focused on protons and progress was achieved in all important challenges. Although currently the maximum proton energy is not yet high enough for patient irradiation, suggestions and solutions have been reported for compact beam transport and dose delivery procedures, respectively, as well as for precise dosimetric control. Radiobiological in vitro and in vivo studies show no indications of an altered biological effectiveness of laser-driven beams. Laser based facilities will hardly improve the availability of ion beams for patient treatment in the next decade. Nevertheless, there are possibilities for a need of laser based therapy facilities in future.


Assuntos
Radioterapia com Íons Pesados/instrumentação , Íons/uso terapêutico , Lasers , Neoplasias/radioterapia , Aceleradores de Partículas , Humanos
15.
Rev. esp. anestesiol. reanim ; 64(6): 306-312, jun.-jul. 2017. tab, graf
Artigo em Espanhol | IBECS | ID: ibc-162580

RESUMO

Objetivos. Evaluar el tipo de «fluidos/sueros» de mantenimiento administrados en nuestro hospital, y comparar como se ajustan a las recomendaciones actuales, tanto en volumen como en composición. Material y métodos. Estudio observacional y transversal. Se registró el volumen y tipo de fluidoterapia de mantenimiento que se pautaba durante 24h a pacientes ingresados en diferentes servicios del hospital. Se excluyeron aquellos en los que la administración de líquidos estuviese condicionada por un exceso o déficit de líquidos y electrólitos. Resultados. Se recogieron los datos de 198 pacientes, de los cuales 74 (37,4%) fueron excluidos por no cumplir los criterios de inclusión. El volumen medio administrado fue de 2.500cc/día. La dosis media de glucosa fue de 36g cada 24h (DE: 31,4). La combinación más frecuente incluyó suero salino fisiológico (SSF) con glucosado 5% (64,4% de los casos). La cantidad media de sodio administrada en 24h fue de 173mEq (DE: 74,8) y la de cloro de 168mEq (DE: 75), lo que supone superávit de +87,4mEq y +85mEq, respectivamente. En relación con el potasio, magnesio y calcio, el déficit fue de -50mEq, -22mEq y -21mEq día, respectivamente. La administración de sustancias buffer fue excepcional, siendo las más frecuentemente utilizadas el bicarbonato (2,29%), acetato (1,29%), lactato (1,15%) y gluconato (1,10%). Conclusión. El SSF es la solución más frecuentemente utilizada. En contraste con el exceso de sodio y cloro habitualmente pautado, la cantidad de otros iones, como potasio, magnesio, sustancias buffer y aporte calórico, es muy deficitaria (AU)


Objective. To assess the types of maintenance fluids used in our hospital, comparing their volume and composition to the standards recommended by the guidelines. Material and methods. Observational, cross-sectional study. Volume and type of fluid therapy administered during 24h to patients admitted to various hospital departments were recorded. Patients receiving fluid therapy because of water-electrolyte imbalance were excluded. Results. Out of 198 patients registered, 74 (37.4%) were excluded because they did not meet the criteria for inclusion. Mean administered volume was 2,500cc/day. Mean daily glucose dose was 36g per 24h (SD: 31.4). The most frequent combination included normal saline solution (NSS) and glucose 5% (64.4%). Mean daily dose of sodium and chlorine was, respectively, 173mEq (SD: 74.8) and 168mEq (SD: 75), representing a surplus daily dose of +87.4mEq and +85mEq. Potassium, magnesium and calcium daily deficit was, respectively, -50mEq, -22mEq and -21mEq per day. Buffer administration was exceptional, bicarbonate (2.29%), acetate (1.29%), lactate (1.15%) and gluconate (1.10%) being the buffering agents most frequently used. Conclusion. NNS is the most frequently used solution. In contrast to excess doses of sodium and chlorine, there is a great deficit of other ions, buffering agents and caloric intake in the fluid therapy regimens that are usually prescribed (AU)


Assuntos
Humanos , Masculino , Feminino , Hidratação/métodos , Íons/uso terapêutico , Concentração Osmolar , Eletrólitos/uso terapêutico , Estudos Transversais/métodos
16.
Biomed Res Int ; 2017: 3726029, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28373980

RESUMO

Background. Increased metal ion levels following total hip arthroplasty (THA) with metal-on-metal bearings are a highly debated topic. Local soft tissue reactions with chronic pain and systemic side effects such as neuropathy are described. The aim of the current study was to determine the serum metal ion concentrations of Cobalt (Co) and Chrome (Cr) after THA with a ceramic-on-metal (CoM) bearing. Patients and Methods. Between 2008 and 2010, 20 patients underwent THA using a CoM bearing. Clinical function was evaluated by standardized scores systems (Harris Hip Score and WOMAC Score) and radiological examination included X-rays. Patient's blood samples were obtained for metal ion analysis and correlation analysis was done between these results and implant position. Results. Overall, 13 patients with 14 CoM devices were available for the current series. The mean age at time of surgery was 61 years (range, 41 to 85). The postoperative follow-up ranged from 49 to 68 months (mean, 58). Metal ion determination showed mean concentrations of 3,1 µg/L (range, 0,3-15,2 µg/L) for Co and 1,6 µg/L (range, 0,1-5,5 µg/L) for Cr, respectively. A correlation between cup anteversion and Co and Cr concentrations was shown. Conclusion. The current series showed increments for Co and Cr following CoM THA. However, these levels are lower compared to metal ion concentrations in patients with metal-on-metal bearings and the international accepted threshold for revision of MoM devices. We recommend routine follow-up including at least one obligatory evaluation of serum metal ion concentrations and an MRI once to exclude local soft tissue reactions.


Assuntos
Artroplastia de Quadril/efeitos adversos , Anteversão Óssea/sangue , Prótese de Quadril/efeitos adversos , Adulto , Idoso , Idoso de 80 Anos ou mais , Anteversão Óssea/induzido quimicamente , Anteversão Óssea/patologia , Cerâmica/efeitos adversos , Cerâmica/uso terapêutico , Cromo/efeitos adversos , Cromo/sangue , Cromo/uso terapêutico , Cobalto/efeitos adversos , Cobalto/sangue , Cobalto/uso terapêutico , Feminino , Seguimentos , Humanos , Íons/efeitos adversos , Íons/sangue , Íons/uso terapêutico , Masculino , Pessoa de Meia-Idade , Desenho de Prótese
17.
Radiat Oncol ; 11(1): 134, 2016 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-27717378

RESUMO

INTRODUCTION: The efficacy of radiation therapy treatments for pancreatic cancer is compromised by abdominal motion which limits the spatial accuracy for dose delivery - especially for particles. In this work we investigate the potential of worst case optimization for interfractional offline motion mitigation in carbon ion treatments of pancreatic cancer. METHODS: We implement a worst case optimization algorithm that explicitly models the relative biological effectiveness of carbon ions during inverse planning. We perform a comparative treatment planning study for seven pancreatic cancer patients. Treatment plans that have been generated using worst case optimization are compared against (1) conventional intensity-modulated carbon ion therapy, (2) single field uniform dose carbon ion therapy, and (3) an ideal yet impractical scenario relying on daily re-planning. The dosimetric quality and robustness of the resulting treatment plans is evaluated using reconstructions of the daily delivered dose distributions on fractional control CTs. RESULTS: Idealized daily re-planning consistently gives the best dosimetric results with regard to both target coverage and organ at risk sparing. The absolute reduction of D 95 within the gross tumor volume during fractional dose reconstruction is most pronounced for conventional intensity-modulated carbon ion therapy. Single field uniform dose optimization exhibits no substantial reduction for six of seven patients and values for D 95 for worst case optimization fall in between. The treated volume (D>95 % prescription dose) outside of the gross tumor volume is reduced by a factor of two by worst case optimization compared to conventional optimization and single field uniform dose optimization. Single field uniform dose optimization comes at an increased radiation exposure of normal tissues, e.g. ≈2 Gy (RBE) in the mean dose in the kidneys compared to conventional and worst case optimization and ≈4 Gy (RBE) in D 1 in the spinal cord compared to worst case optimization. CONCLUSION: Interfractional motion substantially deteriorates dose distributions for carbon ion treatments of pancreatic cancer patients. Single field uniform dose optimization mitigates the negative influence of motion on target coverage at an increased radiation exposure of normal tissue. Worst case optimization enables an exploration of the trade-off between robust target coverage and organ at risk sparing during inverse treatment planning beyond margin concepts.


Assuntos
Carbono/química , Fracionamento da Dose de Radiação , Radioterapia com Íons Pesados/métodos , Íons/uso terapêutico , Neoplasias Pancreáticas/radioterapia , Radiometria/métodos , Algoritmos , Estudos de Coortes , Humanos , Movimento (Física) , Dosagem Radioterapêutica , Planejamento da Radioterapia Assistida por Computador/métodos , Eficiência Biológica Relativa
18.
Med Phys ; 43(7): 4198, 2016 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-27370139

RESUMO

PURPOSE: In this work, ion recombination is studied as a function of energy and depth in carbon ion beams. METHODS: Measurements were performed in three different passively scattered carbon ion beams with energies of 62 MeV/n, 135 MeV/n, and 290 MeV/n using various types of plane-parallel ionization chambers. Experimental results were compared with two analytical models for initial recombination. One model is generally used for photon beams and the other model, developed by Jaffé, takes into account the ionization density along the ion track. An investigation was carried out to ascertain the effect on the ion recombination correction with varying ionization chamber orientation with respect to the direction of the ion tracks. The variation of the ion recombination correction factors as a function of depth was studied for a Markus ionization chamber in the 62 MeV/n nonmodulated carbon ion beam. This variation can be related to the depth distribution of linear energy transfer. RESULTS: Results show that the theory for photon beams is not applicable to carbon ion beams. On the other hand, by optimizing the value of the ionization density and the initial mean-square radius, good agreement is found between Jaffé's theory and the experimental results. As predicted by Jaffé's theory, the results confirm that ion recombination corrections strongly decrease with an increasing angle between the ion tracks and the electric field lines. For the Markus ionization chamber, the variation of the ion recombination correction factor with depth was modeled adequately by a sigmoid function, which is approximately constant in the plateau and strongly increasing in the Bragg peak region to values of up to 1.06. Except in the distal edge region, all experimental results are accurately described by Jaffé's theory. CONCLUSIONS: Experimental results confirm that ion recombination in the investigated carbon ion beams is dominated by initial recombination. Ion recombination corrections are found to be significant and cannot be neglected for reference dosimetry and for the determination of depth dose curves in carbon ion beams.


Assuntos
Carbono/uso terapêutico , Íons/uso terapêutico , Radioterapia/métodos , Algoritmos , Simulação por Computador , Ciclotrons , Modelos Teóricos , Método de Monte Carlo , Radioterapia/instrumentação , Síncrotrons
19.
In Vivo ; 30(2): 119-21, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-26912822

RESUMO

Cancer therapy by means of high-energy ions is very efficient. As a consequence of the linear-energy-transfer effect only a negligible part of the produced free radicals can escape combination processes to form molecular products and to cause undesired side processes. Positrons (e⁺) and γ-rays, generated by the nuclear interaction of high-energy ions in the medium, serve in monitoring the radiation dose absorbed by the tumor. However, due to the dipole nature of water molecules a small proportion of thermalized positrons (e⁺th) can become solvated (e⁺aq). Hence, they are stabilized, live longer and can initiate side reactions. In addition, positronium (Ps), besides solvated electrons (e⁺aq), can be generated and involved in the reaction mechanisms. For a better understanding of the reaction mechanisms involved and to improve cancer therapy, a time-resolved pulse radiolysis instrument using high-energy particles is discussed here. The proposed method is examined and recommended by CERN experts. It is planned to be realized at the MedAustron Radiation Therapy and Research Centre in Wiener Neustadt, Austria.


Assuntos
Elétrons , Raios gama , Íons/uso terapêutico , Neoplasias/radioterapia , Radiólise de Impulso/métodos , Humanos , Radiólise de Impulso/instrumentação
20.
Conf Proc IEEE Eng Med Biol Soc ; 2016: 2578-2581, 2016 08.
Artigo em Inglês | MEDLINE | ID: mdl-28268849

RESUMO

In spot-scanning particle therapy, inverse treatment planning is usually limited to finding the optimal beam fluences given the beam trajectories and energies. We address the much more challenging problem of jointly optimizing the beam fluences, trajectories and energies. For this purpose, we design a simulated annealing algorithm with an exploration mechanism that balances the conflicting demands of a small mixing time at high temperatures and a reasonable acceptance rate at low temperatures. Numerical experiments substantiate the relevance of our approach and open new horizons to spot-scanning particle therapy.


Assuntos
Carbono/uso terapêutico , Íons/uso terapêutico , Dosagem Radioterapêutica , Planejamento da Radioterapia Assistida por Computador , Radioterapia Conformacional/métodos , Processos Estocásticos , Algoritmos , Simulação por Computador , Humanos , Modelos Estatísticos , Imagens de Fantasmas , Probabilidade , Cintilografia , Temperatura
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