Síndrome de robo de la subclavia tras tratamiento endovascular de aorta torácica / Subclavian steal syndrome after endovascular treatment of the thoracic aorta

Introducción: el síndrome de robo de la subclavia es una entidad poco habitual que se presenta en pacientes con estenosis u oclusión de la arteria subclavia, habitualmente la izquierda, y secundario a ateroesclerosis. Los síntomas derivados de esta entidad son: la isquemia del miembro superior y los síntomas neurológicos. Caso clínico: se presenta un caso de un varón que, tras cinco meses de tratamiento endovascular de úlcera de aorta torácica penetrante, presenta síntomas neurológicos. Se realizó diagnóstico del síndrome a través de eco Doppler y se confirmó con angio RM. Finalmente, y debido a la incapacidad que producían los síntomas, se decidió tratamiento quirúrgico mediante cirugía de bypass carótido subclavio izquierdo. Discusión: el síndrome del robo de la subclavia es una entidad que raramente se presenta asociada a síntomas. Debe tenerse una alta sospecha para diagnosticarlo y tratarlo si es necesario. Aunque la tendencia actual es el tratamiento endovascular, en ocasiones la cirugía de derivación tradicional es la única opción. Siempre que sea posible, debe estudiarse la dominancia de las arterias vertebrales antes de ocluir la arteria subclavia en los procedimientos. (AU)

Introduction: subclavian steal syndrome is a rare entity, occurring in patients with stenosis or occlusion of the subclavian artery, usually the left subclavian artery and secondary to atherosclerosis. The symptoms derived from this entity are: ischemia of the upper limb and neurological symptoms. Case report: we present a case of a man who, after five months of endovascular treatment of penetrating thoracic aortic ulcer, presented neurological symptoms. The syndrome was diagnosed by echo-Doppler and confirmed by MRI angiography. Finally, due to the incapacity caused by the symptoms, surgical treatment was decided by left carotid-subclavian bypass. Discussion: subclavian steal syndrome is an entity rarely presents with symptoms, it must be highly suspected in order to diagnose it and, if necessary, treat it. Although, the current trend is endovascular treatment, sometimes traditional bypass surgery is the only option. Whenever possible, the dominance of the vertebral arteries should be studied before occluding the subclavian artery in the procedures. (AU)

IS2aR, a computational tool to transform voxelized reference phantoms into patient-specific whole-body virtual CTs for peripheral dose estimation.

BACKGROUND: The risk of radiogenic cancer induction due to radiotherapy depends on the dose received by the patient's organs. Knowing the position of all organs is needed to assess this dose in a personalized way. However, radiotherapy planning computed tomography (pCT) scans contain truncated patient anatomy, limiting personalized dose evaluation. PURPOSE: To develop a simple and freely available computational tool that adapts an ICRP reference computational phantom to generate a patient-specific whole-body CT for peripheral dose computations. METHODS: Various bone-segmentation methods were explored onto fifteen pCTs, and the one with the highest Sørensen-Dice coefficient was implemented. The reference phantom is registered to the pCT, obtaining a registration transform matrix, which is then applied to create the whole-body virtual CT. Additional validation involved a comparison of absorbed doses to organs delineated on both the pCT and the virtual CT. RESULTS: A dedicated graphical user interface was designed and implemented to house the developed functions for i) selecting a registration region on which automatic bone segmentation and rigid registration will occur, ii) displaying the results of these processes under selectable views, and iii) exporting the final patient-specific whole-body CT. This software was termed IS2aR. The tested whole-body virtual CT generated by IS2aR fulfilled our requirements. CONCLUSIONS: IS2aR is a user-friendly computational software to create a personalized whole-body CT containing the original structures in the reference phantom. The personalized dose deposited in peripheral organs can be estimated further to assess second cancer induction risk in epidemiological studies.

An environmentally friendly approach for the characterization of construction materials: determination of trace, minor, and major elements by slurry sampling high-resolution continuum source graphite furnace atomic absorption spectrometry.

A slurry sampling method was developed for the fast determination of Pb, Ni, Fe, and Mn in construction materials by high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GFAAS). For sample introduction into the GF, stable slurries were prepared by sonicating 10 mg of ground solid sample in 10.0 mL of 1% (v/v) Triton X-100 and 1% (v/v) HNO3 solution for 1.0 min. The determination of the four elements was carried out in three measurement runs, with Ni and Fe being determined simultaneously. The HR-CS GFAAS measurements were performed using analytical lines with adequate sensitivity, considering the content of each element in the material: Pb at 283.306 nm (42%), Mn at 403.080 nm (6.7%), Ni at 232.003 nm (100%) and Fe at 232.036 nm (1.4%). The pyrolysis and atomization temperatures and the use of chemical modifiers were optimized using both aqueous standards and slurry samples. At optimal conditions, samples with concentrations of Pb from 1.5 to 80 µg g-1, Ni from 4.0 to 75 µg g-1, Mn from 2.0 to 600 µg g-1, and Fe from 0.15 to 60 mg g-1 could be determined using a unique sample suspension. To assess the validity of the method, a fly ash certified reference material (CRM) was analysed using the slurry sampling HR-CS GFAAS method; this CRM and the construction material samples were also analysed by HR-CS GFAAS after the digestion of the samples. The obtained results using both methods were statistically comparable (Student's paired t-test for two independent methods at a 95% confidence level) demonstrating the suitability of the proposed method.

Trombosis venosa profunda durante el periodo de vacunación frente al virus SARS-CoV-2 / Deep vein thrombosis during vaccination against SARS-CoV-2 period

Objetivos: tras el inicio de la vacunación frente al SARS-CoV-2 una de las entidades de enfermedad tromboembólica venosa (ETEV) más frecuente, la trombosis venosa profunda (TVP), apenas ha sido documentada. Analizamos los episodios de TVP durante el periodo de vacunación frente al SARS-CoV-2. Material y métodos: análisis unicéntrico retrospectivo que incluye pacientes diagnosticados de TVP (enero-septiembre de 2021). Se estratifican en dos grupos: vacunados y no vacunados frente al SARS-CoV-2 en los 28 días anteriores a iniciar la sintomatología de TVP. Variable principal: gravedad de TVP (tromboembolismo pulmonar [TEP] o necesidad de ingreso). Variables secundarias: factores de riesgo para TVP (idiopática, antecedente de ETEV, encamamiento, traumatismo, cirugía, trombofilia, hormonoterapia y neoplasia). Resultados: 192 pacientes diagnosticados de TVP, 42 (21,9 %) vacunados y 150 (78,1 %) no vacunados. Desarrollaron TEP el 52,4 % de los vacunados y el 62,7 % de los controles (p = 0,228). Necesidad de ingreso: 52,4 % de los vacunados frente al 62,4 % de los no vacunados) (p = 0,536); TVP idiopática: 28,6 % de los vacunados frente al 48 % de los no vacunados) (p = 0,025); antecedente de ETEV: 21,4 % de los vacunados frente al 17,3 % de los controles) (p = 0,543); encamamiento: 7,1 % de los vacunados frente al 12,7 % de los no vacunados (p = 0,418); traumatismo: 4,8 % de los vacunados frente al 6 % de los controles (p = 1); cirugía: 4,8 % de los vacunados frente al 1,3 % de los no vacunados (p = 0,209); trombofilia: 16,7 % de los vacunados frente al 4 % de los controles (p = 0,009); hormonoterapia: 9,5 % de los vacunados frente al 3,3 % de los no vacunados (p = 0,107); neoplasia: 28,6 % de los vacunados frente al 18,7 % de los no vacunados (p = 0,162). Se apreció un OR 6,10 (IC 95 %, 1,52-24,37) para TVP en pacientes vacunados con trombofilia en el análisis multivariante. Conclusión: la vacunación frente SARS-CoV-2 no parece aumentar la gravedad de la TVP...(AU)

Objectives: since the beginning of vaccination against SARS-CoV-2 virus one of the most frequent entities ofvenous thromboembolism (VTE), deep vein thrombosis (DVT), has been scarcely documented. We analyze DVTepisodes during vaccination against SARS-CoV-2 period.Material and methods: retrospective unicenter analysis including patients diagnosed with DVT (January -Septem-ber 2021). Patients were divided into two groups, vaccinated and unvaccinated against SARS-CoV-2 28 days priorto DVT symptoms onset. Primary endpoint: DVT severity (pulmonary embolism (PE) and/or hospital admission).Secondary endpoints: DVT risk factors (unprovoked, VTE antecedent, immobilization, trauma, surgery, thrombo-philia, hormone therapy and cancer).Results: there were 192 DVT diagnoses, 42 (21,9 %) vaccinated and 150 (78,1 %) unvaccinated. DVT severity:PE: 52,4 % vaccinated vs. 62,7 % controls (p = 0,228); hospital admission: 52,4 % vaccinated vs. 62,4 % unvac-cinated (p = 0,536); unprovoked DVT: 28,6 % vaccinated vs. 48 % unvaccinated (p = 0,025); VTE antecedent:21,4 % vaccinated vs. 17,3 % unvaccinated (p = 0,543): immobilization: 7,1 % vaccinated vs. 12,7 % unvacci-nated; trauma: 4,8 % vaccinated vs. 6 % unvaccinated (p = 1); surgery: 4,8 % vaccinated vs. 1,3 % unvaccinat-ed (p = 0,209); thrombophilia: 16,7 % vaccinated vs. 4 % unvaccinaed (p = 0,009); hormone theraphy: 9,5 %vaccinated vs. 3,3 % unvaccinated (p = 0,107); cancer: 28,6 % vaccinated vs. 18,7 % unvaccinated (p = 0,162).Multivariate analysis showed a higher risk of DVT in vaccinated patients with thrombophilia, with an OR of6,10 (95 % CI, 1,52-24,37).Conclusion: vaccination against SARS-CoV-2 doesn’t seem to increased DVT severity, although a higher incidenceof DVT in vaccinated patients with thrombophilia was observed.(AU)

A simple analytical model for a fast 3D assessment of peripheral photon dose during coplanar isocentric photon radiotherapy.

Considering that cancer survival rates have been growing and that nearly two-thirds of those survivors were exposed to clinical radiation during its treatment, the study of long-term radiation effects, especially secondary cancer induction, has become increasingly important. To correctly assess this risk, knowing the dose to out-of-field organs is essential. As it has been reported, commercial treatment planning systems do not accurately calculate the dose far away from the border of the field; analytical dose estimation models may help this purpose. In this work, the development and validation of a new three-dimensional (3D) analytical model to assess the photon peripheral dose during radiotherapy is presented. It needs only two treatment-specific input parameter values, plus information about the linac-specific leakage, when available. It is easy to use and generates 3D whole-body dose distributions and, particularly, the dose to out-of-field organs (as dose-volume histograms) outside the 5% isodose for any isocentric treatment using coplanar beams [including intensity modulated radiotherapy and volumetric modulated arc therapy (VMAT)]. The model was configured with the corresponding Monte Carlo simulation of the peripheral absorbed dose for a 6 MV abdomen treatment on the International Comission on Radiological Protection (ICRP) 110 computational phantom. It was then validated with experimental measurements using thermoluminescent dosimeters in the male ATOM anthropomorphic phantom irradiated with a VMAT treatment for prostate cancer. Additionally, its performance was challenged by applying it to a lung radiotherapy treatment very different from the one used for training. The model agreed well with measurements and simulated dose values. A graphical user interface was developed as a first step to making this work more approachable to a daily clinical application.

Peripheral Organ Equivalent Dose Estimation Procedure in Proton Therapy.

The aim of this work is to present a reproducible methodology for the evaluation of total equivalent doses in organs during proton therapy facilities. The methodology is based on measuring the dose equivalent in representative locations inside an anthropomorphic phantom where photon and neutron dosimeters were inserted. The Monte Carlo simulation was needed for obtaining neutron energy distribution inside the phantom. The methodology was implemented for a head irradiation case in the passive proton beam of iThemba Labs (South Africa). Thermoluminescent dosimeter (TLD)-600 and TLD-700 pairs were used as dosimeters inside the phantom and GEANT code for simulations. In addition, Bonner sphere spectrometry was performed inside the treatment room to obtain the neutron spectra, some relevant neutron dosimetric quantities per treatment Gy, and a percentual distribution of neutron fluence and ambient dose equivalent in four energy groups, at two locations. The neutron spectrum at one of those locations was also simulated so that a reasonable agreement between simulation and measurement allowed a validation of the simulation. Results showed that the total out-of-field dose equivalent inside the phantom ranged from 1.4 to 0.28 mSv/Gy, mainly due to the neutron contribution and with a small contribution from photons, 10% on average. The order of magnitude of the equivalent dose in organs was similar, displaying a slow reduction in values as the organ is farther from the target volume. These values were in agreement with those found by other authors in other passive beam facilities under similar irradiation and measurement conditions.

Rotura aórtica masiva secundaria a espondilodiscitis por Staphylococcus aureus / Massive aortic rupture secondary to Staphylococcus aureus spondylodiscitis

Introducción: presentamos un caso inusual de rotura aórtica múltiple secundaria a espondilodiscitis por Staphylococcus aureus sensible a meticilina. Caso clínico: varón de 71 años que ingresa en nuestro hospital para el estudio programado de una espondilodiscitis T7-T8 refractaria a tratamiento empírico antibiótico. El decimoquinto día de su ingreso el paciente presenta una hematemesis masiva con dos paradas cardiorrespiratorias. Tras ser reanimado en dos ocasiones, se realiza una endoscopia en el quirófano que sugiere la presencia de una fístula aortoentérica primaria. A su vez, en una tomografía computarizada de seguimiento se evidencia sangrado activo en la aorta torácica. Realizamos una angiografía diagnóstica en la que apreciamos tres puntos de ruptura aórtica. Se precisa la implantación de endoprótesis cubiertas para el control del sangrado: un dispositivo en la aorta torácica (Gore C-TAG®) y otro a nivel abdominal (Aortic Begraft®). Discusión: la aortitis es una complicación poco común de la espondilodiscitis con una tasa alta de mortalidad. Un alto índice de sospecha es clave para su temprano diagnóstico y tratamiento. La antibioterapia es obligatoria y el tratamiento endovascular puede usarse como terapia puente en emergencias. Es un procedimiento rápido que permite la estabilización hemodinámica del paciente antes de una cirugía abierta aórtica definitiva.(AU)

Introduction: we present an unusual case with multiple aortic ruptures secondary to methicillin-sensitive Staphylococcus aureus thoracic spondylodiscitis. Case report: the patient was a 71-year-old man admitted to our hospital for scheduled study of an infectious spondylodiscitis D7-D8 refractory to empirical antibiotic therapy. Fifteen days after admission, the patient began with massive hematemesis. After being resuscitated from two cardiac arrests, an endoscopy was carried out in the operating room suggesting presence of a primary aortoenteric fistula and, at the same time, in a follow-up computed tomography an active bleeding in thoracic aorta was shown. We performed a diagnostic angiography; three different sites of rupture were observed and two covered endogfrats were placed for bleeding control of thoracic and abdominal aorta: one device in thoracic aorta (Gore C-TAG®) and another one in abdominal aorta (Aortic Begraft®). Discussion: aortitis is an uncommon complication of spondylodiscitis, with a high mortality rate. A high index of suspicion is key to its diagnosis and prompt treatment. Antibiotherapy is mandatory and endovascular treatment can be used as a bridge therapy in emergency, it is a fast procedure that can secure hemodynamical stabilization prior to definitive aortic open repair.(AU)

Direct solid sampling of biological species for the rapid determination of selenium by high-resolution continuum source graphite furnace atomic absorption spectrometry.

A direct solid sampling method based on high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GFAAS) for the determination of selenium (Se) in biological tissues was optimized. The main analytical line of Se at 196.0267 nm was used to carry out all HR-CS AAS measurements. Different chemical modifiers were evaluated to prevent the loss of Se during the application of the GFAAS temperature program and avoid the interferences due to the presence of phosphorus compounds in sample matrix. The best results were achieved using ruthenium coated platforms and a palladium nanoparticle suspension (Pd NP) as co-injected modifier. Calibration was performed using aqueous standard solutions of Se(IV). For solid sampling, the optimal range of sample mass was between 0.2 and 0.8 mg. The limit of detection (LOD) was 0.06 ng (0.075 µg g-1 using a sample mass of 0.8 mg). The developed solid sampling HR-CS GFAAS method was used for Se determination in two certified reference materials of dogfish tissues and lyophilized and powdered real samples of fish tissues and chicken liver. The precision obtained in these analyses, expressed as relative standard deviation (RSD), was between 5.5 and 8.6% (n = 6). For validation purposes, the results obtained by the solid sampling HR-CS GFAAS method were compared with those found performing the analysis by HR-CS hydride generation AAS (HR-CS HGAAS) after microwave acid digestion of the samples. The Se concentrations obtained for both methods agreed at a 95% confidence level (Student's t-test), indicating the suitability of the proposed solid sampling HR-CS GFAAS method to determine Se in biological samples.

Low dose radiation therapy for COVID-19: Effective dose and estimation of cancer risk.

BACKGROUND AND PURPOSE: The objective of this work is to evaluate the risk of carcinogenesis of low dose ionizing radiation therapy (LDRT), for treatment of immune-related pneumonia following COVID-19 infection, through the estimation of effective dose and the lifetime attributable risk of cancer (LAR). MATERIAL AND METHODS: LDRT treatment was planned in male and female computational phantoms. Equivalent doses in organs were estimated using both treatment planning system calculations and a peripheral dose model (based on ionization chamber measurements). Skin dose was estimated using radiochromic films. Later, effective dose and LAR were calculated following radiation protection procedures. RESULTS: Equivalent doses to organs per unit of prescription dose range from 10 mSv/cGy to 0.0051 mSv/cGy. Effective doses range from 204 mSv to 426 mSv, for prescription doses ranging from 50 cGy to 100 cGy. Total LAR for a prescription dose of 50 cGy ranges from 1.7 to 0.29% for male and from 4.9 to 0.54% for female, for ages ranging from 20 to 80 years old. CONCLUSIONS: The organs that mainly contribute to risk are lung and breast. Risk for out-of-field organs is low, less than 0.06 cases per 10000. Female LAR is on average 2.2 times that of a male of the same age. Effective doses are of the same order of magnitude as the higher-dose interventional radiology techniques. For a 60 year-old male, LAR is 8 times that from a cardiac CT, when prescription dose is 50 cGy.

PERIPHERAL SURFACE DOSE FROM A LINEAR ACCELERATOR: RADIOCHROMIC FILM EXPERIMENTAL MEASUREMENTS OF FLATTENING FILTER FREE VERSUS FLATTENED BEAMS.

There is a growing interest in the use of flattening filter free (FFF) beams due to the shorter treatment times. The reduction of head scatter suggests a better radiation protection to radiotherapy patients, considering the expected decrease in peripheral surface dose (PSD). In this work, PSD of flattened (FF) and FFF-photon beams was compared. A radiochromic film calibration method to reduce energy dependence was used. PSD was measured at distances from 2 to 50 cm to the field border for different square field sizes, modifying relevant clinical parameters. Also, clinical breast and prostate stereotactic body radiotherapy (SBRT) plans were studied. For square beams, FFF PSD is lower compared with FF PSD (differences ranging from 3 to 64%) and 10 MV FFF yields to the lowest value, for distances greater than 5 cm. For SBRT plans, near and far away from the field border, there is a reduction of PSD for FFF-beams, but the behavior at intermediate distances should be checked depending on the case.

Incorporation of Dosimetric Gradients and Parotid Gland Migration Into Xerostomia Prediction.

Purpose: Due to the sharp gradients of intensity-modulated radiotherapy (IMRT) dose distributions, treatment uncertainties may induce substantial deviations from the planned dose during irradiation. Here, we investigate if the planned mean dose to parotid glands in combination with the dose gradient and information about anatomical changes during the treatment improves xerostomia prediction in head and neck cancer patients. Materials and methods: Eighty eight patients were retrospectively analyzed. Three features of the contralateral parotid gland were studied in terms of their association with the outcome, i.e., grade ≥ 2 (G2) xerostomia between 6 months and 2 years after radiotherapy (RT): planned mean dose (MD), average lateral dose gradient (GRADX), and parotid gland migration toward medial (PGM). PGM was estimated using daily megavoltage computed tomography (MVCT) images. Three logistic regression models where analyzed: based on (1) MD only, (2) MD and GRADX, and (3) MD, GRADX, and PGM. Additionally, the cohort was stratified based on the median value of GRADX, and a univariate analysis was performed to study the association of the MD with the outcome for patients in low- and high-GRADX domains. Results: The planned MD failed to recognize G2 xerostomia patients (AUC = 0.57). By adding the information of GRADX (second model), the model performance increased to AUC = 0.72. The addition of PGM (third model) led to further improvement in the recognition of the outcome (AUC = 0.79). Remarkably, xerostomia patients in the low-GRADX domain were successfully identified (AUC = 0.88) by the MD alone. Conclusions: Our results indicate that GRADX and PGM, which together serve as a proxy of dosimetric changes, provide valuable information for xerostomia prediction.

Consenso 2018 de la Sociedad Española de Anatomía Patológica y la Sociedad Española de Oncología Médica sobre el diagnóstico y tratamiento del cáncer de origen desconocido / 2018 Consensus statement by the Spanish Society of Pathology and the Spanish Society of Medical Oncology on the diagnosis and treatment of cancer of unknown primary

El cáncer de origen desconocido se define como un grupo heterogéneo de tumores que se manifiestan con metástasis y para los que no se ha conseguido identificar su localización original. Sus características biológicas y forma de diseminación difieren del resto de tumores primarios, lo que hace que puedan considerarse como una entidad independiente. Aunque se han planteado varias hipótesis sobre su origen, la explicación más plausible sobre su agresividad y quimiorresistencia parece estar relacionada con la inestabilidad cromosómica. Dependiendo del tipo de estudio llevado a cabo, el cáncer de origen desconocido puede llegar a suponer entre el 2-9% de todos los pacientes con cáncer, principalmente entre los 60-75 años. En este artículo se revisan los principales estudios clínicos, patológicos y moleculares llevados a cabo para el análisis y determinación del origen del cáncer de origen desconocido, así como las principales estrategias terapéuticas y de manejo del paciente, tanto a nivel clínico como de anatomía patológica

Cancer of unknown primary is defined as a heterogeneous group of tumours that present with metastasis, and in which attempts to identify the original site have failed. They differ from other primary tumours in their biological features and how they spread, which means they can be considered a separate entity. There are several hypotheses regarding their origin, but the most plausible explanation for their aggressiveness and chemoresistance seems to involve chromosomal instability. Depending on the type of study done, cancer of unknown primary can account for 2-9% of all cancer patients, mostly 60-75 years old. This article reviews the main clinical, pathological and molecular studies conducted to analyse and determine the origin of cancer of unknown primary. The main strategies for patient management and treatment, by both clinicians and pathologists, are also addressed

[2018 Consensus statement by the Spanish Society of Pathology and the Spanish Society of Medical Oncology on the diagnosis and treatment of cancer of unknown primary]. / Consenso 2018 de la Sociedad Española de Anatomía Patológica y la Sociedad Española de Oncología Médica sobre el diagnóstico y tratamiento del cáncer de origen desconocido.

Cancer of unknown primary is defined as a heterogeneous group of tumours that present with metastasis, and in which attempts to identify the original site have failed. They differ from other primary tumours in their biological features and how they spread, which means they can be considered a separate entity. There are several hypotheses regarding their origin, but the most plausible explanation for their aggressiveness and chemoresistance seems to involve chromosomal instability. Depending on the type of study done, cancer of unknown primary can account for 2-9% of all cancer patients, mostly 60-75 years old. This article reviews the main clinical, pathological and molecular studies conducted to analyse and determine the origin of cancer of unknown primary. The main strategies for patient management and treatment, by both clinicians and pathologists, are also addressed.

Intensity-modulated radiation therapy and volumetric modulated arc therapy versus conventional conformal techniques at high energy: Dose assessment and impact on second primary cancer in the out-of-field region.

The aim of this work was to estimate peripheral neutron and photon doses associated with the conventional 3D conformal radiotherapy techniques in comparison to modern ones such as Intensity modulated radiation therapy and volumetric modulated arc therapy. Assessment in terms of second cancer incidence ought to peripheral doses was also considered. For that, a dosimetric methodology proposed by the authors has been applied beyond the region where there is no CT information and, thus, treatment planning systems do not calculate and where, nonetheless, about one third of second primary cancers occurs.

Impact of different biologically-adapted radiotherapy strategies on tumor control evaluated with a tumor response model.

Motivated by the capabilities of modern radiotherapy techniques and by the recent developments of functional imaging techniques, dose painting by numbers (DPBN) was proposed to treat tumors with heterogeneous biological characteristics. This work studies different DPBN optimization techniques for virtual head and neck tumors assessing tumor response in terms of cell survival and tumor control probability with a previously published tumor response model (TRM). Uniform doses of 2 Gy are redistributed according to the microscopic oxygen distribution and the density distribution of tumor cells in four virtual tumors with different biological characteristics. In addition, two different optimization objective functions are investigated, which: i) minimize tumor cell survival (OFsurv) or; ii) maximize the homogeneity of the density of surviving tumor cells (OFstd). Several adaptive schemes, ranging from single to daily dose optimization, are studied and the treatment response is compared to that of the uniform dose. The results show that the benefit of DPBN treatments depends on the tumor reoxygenation capability, which strongly differed among the set of virtual tumors investigated. The difference between daily (fraction by fraction) and three weekly optimizations (at the beginning of weeks 1, 3 and 4) was found to be small, and higher benefit was observed for the treatments optimized using OFsurv. This in silico study corroborates the hypothesis that DPBN may be beneficial for treatments of tumors which show reoxygenation during treatment, and that a few optimizations may be sufficient to achieve this therapeutic benefit.

Micro-sampling method based on high-resolution continuum source graphite furnace atomic absorption spectrometry for calcium determination in blood and mitochondrial suspensions.

A micro-sampling and straightforward method based on high resolution continuum source atomic absorption spectrometry (HR-CS AAS) was developed to determine extracellular and intracellular Ca in samples of interest in clinical and biomedical analysis. Solid sampling platforms were used to introduce the micro-samples into the graphite furnace atomizer. The secondary absorption line for Ca, located at 239.856nm, was selected to carry out the measurements. Experimental parameters such as pyrolysis and atomization temperatures and the amount of sample introduced for the measurements were optimized. Calibration was performed using aqueous standards and the approach to measure at the wings of the absorption lines was employed for the expansion of the linear response range. The limit of detection was of 0.02mgL-1 Ca (0.39ng Ca) and the upper limit of linear range was increased up to 8.0mgL-1 Ca (160ng Ca). The proposed method was used to determine Ca in mitochondrial suspensions and whole blood samples with successful results. Adequate recoveries (within 91-107%) were obtained in the tests performed for validation purposes.

Uncomplicated and Cancer-Free Control Probability (UCFCP): A new integral approach to treatment plan optimization in photon radiation therapy.

PURPOSE: Biological treatment plan evaluation does not currently consider second cancer induction from peripheral doses associated to photon radiotherapy. The aim is to propose a methodology to characterize the therapeutic window by means of an integral radiobiological approach, which considers not only Tumour Control Probability (TCP) and Normal Tissue Complication Probability (NTCP) but also Secondary Cancer Probability (SCP). METHODS: Uncomplicated and Cancer-Free Control Probability (UCFCP) function has been proposed assuming a statistically uncorrelated response for tumour and normal tissues. The Poisson's and Lyman's models were chosen for TCP and NTCP calculations, respectively. SCP was modelled as the summation of risks associated to photon and neutron irradiation of radiosensitive organs. For the medium (>4Gy) and low dose regions, mechanistic and linear secondary cancer risks models were used, respectively. Two conformal and intensity-modulated prostate plans at 15MV (same prescription dose) were selected to illustrate the UCFCP features. RESULTS: UCFCP exhibits a bell-shaped behaviour with its maximum inside the therapeutic window. SCP values were not different for the plans analysed (∼2.4%) and agreed with published epidemiological results. Therefore, main differences in UCFCP came from differences in rectal NTCP (18% vs 9% for 3D-CRT and IMRT, respectively). According to UCFCP values, the evaluated IMRT plan ranked first. CONCLUSIONS: The level of SCP was found to be similar to that of NTCP complications which reinforces the importance of considering second cancer risks as part of the possible late sequelae due to treatment. Previous concerns about the effect of peripheral radiation, especially neutrons, in the induction of secondary cancers can be evaluated by quantifying the UCFCP.

Determination of essential elements in beverages, herbal infusions and dietary supplements using a new straightforward sequential approach based on flame atomic absorption spectrometry.

A simple method based on FAAS was developed for the sequential multi-element determination of Cu, Zn, Mn, Mg and Si in beverages and food supplements with successful results. The main absorption lines for Cu, Zn and Si and secondary lines for Mn and Mg were selected to carry out the measurements. The sample introduction was performed using a flow injection system. Using the choice of the absorption line wings, the upper limit of the linear range increased up to 110mgL-1 for Mg, 200mgL-1 for Si and 13mgL-1 for Zn. The determination of the five elements was carried out, in triplicate, without the need of additional sample dilutions and/or re-measurements, using less than 3.5mL of sample to perform the complete analysis. The LODs were 0.008mgL-1 for Cu, 0.017mgL-1 for Zn, 0.011mgL-1 for Mn, 0.16mgL-1 for Si and 0.11mgL-1 for Mg.