Back pain as the initial presentation of subacute bacterial endocarditis in a patient with a complex medical history.

Infective endocarditis (IE) poses a diagnostic challenge due to its diverse clinical presentations, especially among high-risk groups. Diagnosis relies on integrating clinical presentation, blood cultures and imaging findings. Advanced imaging techniques enhance diagnostic accuracy, particularly in complex cases. Treatment involves antimicrobial therapy and surgery in complicated cases, with early intervention crucial for optimal outcomes. Coordinated care by an Endocarditis Team ensures tailored treatment plans, prompt complication management and long-term monitoring after discharge. The authors present a case of subacute IE presenting initially with back pain in a patient with a complex medical history, highlighting diagnostic and management approaches.

Comprehensive imaging analysis of intracranial atherosclerosis.

Intracranial atherosclerotic disease (ICAD) involves the build-up of atherosclerotic plaques in cerebral arteries, significantly contributing to stroke worldwide. Diagnosing ICAD entails various techniques that measure arterial stenosis severity. Digital subtraction angiography, CT angiography, and magnetic resonance angiography are established methods for assessing stenosis. High-resolution MRI offers additional insights into plaque morphology including plaque burden, hemorrhage, remodeling, and contrast enhancement. These metrics and plaque traits help identify symptomatic plaques. Techniques like transcranial Doppler, CT perfusion, computational fluid dynamics, and quantitative MRA analyze blood flow restrictions due to ICAD. Intravascular ultrasound or optical coherence tomography have a very high spatial resolution and can assess the structure of the arterial wall and the plaque from the lumen of the target vascular territory. Positron emission tomography could further detect inflammation markers. This review aims to provide a comprehensive overview of the spectrum of current modalities for atherosclerotic plaque analysis and risk stratification.

Propiedades Psicométricas de la Escala Conners-3 (SR-S) en Estudiantes Chilenos

Antecedentes En Chile, la prevalencia del Trastorno por Déficit de Atención con Hiperactividad (TDAH) se estima en un 10%. Frente a esta realidad, las políticas públicas promueven la detección oportuna de esta condición, suscitándose sin embargo problemas de sobre y sub-diagnóstico atribuibles a la falta de escalas actualizadas. Objetivo El propósito de este estudio fue evaluar las propiedades psicométricas de la escala Conners-3 en su forma abreviada de auto-reporte en niños y adolescentes chilenos. Método Se aplicó el Conners-3, y una medida de validez convergente (BRIEF-2), a una muestra no probabilística (n = 265) de estudiantes de enseñanza básica y media (8-18 años). Se efectuó un análisis de la correlación ítem-test e inter-escalar, seguido de un análisis factorial confirmatorio (AFC), finalizando con un análisis de consistencia interna. Resultados Todos los ítems presentaron una correlación ítem-escala aceptable. La estructura interna de cinco factores del AFC coincide con la original, las cuales además presentaron una consistencia interna aceptable y evidencia de validez convergente así como divergente. Conclusiones La escala Conners-3 presenta propiedades psicométricas aceptables para ser usada en la fase de detección del TDAH, recomendándose su uso como parte de una evaluación integral que incorpore otros métodos de evaluación.

Background In Chile, it is estimated that the prevalence of Attention-Deficit/Hyperactivity Disorder (ADHD) is at 10%. Faced with this reality, public policies promote the timely detection of this condition; however, this situation generates over and underdiagnosis problems attributable to the lack of updated scales. Objective The purpose of this study was to assess the psychometric properties of the Conners-3 Rating Scale in its self-report short form in Chilean children and adolescents. Method The Conners-3 Self-report Scale and a convergent validity measure (BRIEF-2) were applied to a non-probability sample (n = 265) of elementary and high school students (8 to 18 years old). A confirmatory factor analysis (CFA) was carried out, in addition to an internal consistency analysis and an item-total and inter-scale correlation analysis. Results All the items presented an acceptable item-scale correlation. The five-factor internal structure of the CFA coincides with the original. Scales also presented an acceptable internal consistency and evidence of convergent validity. Conclusions the Conners-3 Self-report Scale presents acceptable psychometric properties for use in the detection phase of ADHD; furthermore, its use is suggested as part of a comprehensive assessment that incorporates other assessment methods.

Effect of olive leaf phytochemicals on the anti-acetylcholinesterase, anti-cyclooxygenase-2 and ferric reducing antioxidant capacity.

In this study, the phytochemical profile of fifty olive leaves (OL) extracts from Spain, Italy, Greece, Portugal, and Morocco was characterized and their anti-cholinergic, anti-inflammatory, and antioxidant activities were evaluated. Luteolin-7-O-glucoside, isoharmnentin, and apigenin were involved in the acetylcholinesterase (AChE) inhibitory activity, while oleuropein and hydroxytyrosol showed noteworthy potential. Secoiridoids contributed to the cyclooxygenase-2 inhibitory activity and antioxidant capacity. Compounds such as oleuropein, ligstroside and luteolin-7-O-glucoside, may exert an important role in the ferric reducing antioxidant capacity. It should be also highlighted the role of hydroxytyrosol, hydroxycoumarins, and verbascoside concerning the antioxidant activity. This research provides valuable insights and confirms that specific compounds within OL extracts contribute to distinct anti-cholinergic, anti-inflammatory, and anti-oxidative effects.

Tigertriever in the treatment of acute ischemic stroke with underlying intracranial atherosclerotic disease.

BACKGROUND: The Tigertriever device offers a unique feature that enables gradual control of the radial expansion. We sought to evaluate the safety and efficacy of the Tigertriever device in patients with large vessel occlusion (LVO) and underlying intracranial atherosclerotic disease (ICAD). The patients were part of the TIGER trial. METHODS: The presence of underlying ICAD was determined by a core imaging laboratory using CT angiography and digital subtraction angiography. The primary outcomes included successful reperfusion, puncture to reperfusion time, and complications associated with the use of the Tigertriever device. Patients underwent mechanical thrombectomy with the Tigertriever device for up to three passes, and alternative devices were employed for subsequent passes. RESULTS: A total of 160 patients were enrolled in the TIGER trial, and 32 patients had ICAD. Among the patients with ICAD, 78% achieved successful reperfusion within three passes of the Tigertriever device, without requiring rescue therapy. Additionally, a first pass effect was observed in 46.8%. The median time from puncture to reperfusion was 22 minutes. There were no device-related complications. The National Institutes of Health Stroke Scale (NIHSS) score at 24 hours was significantly reduced, from an average of 17 at baseline to 8. At the 3 month follow-up, 50% of patients achieved a modified Rankin Scale score of ≤2. CONCLUSION: Endovascular therapy (EVT) with the Tigertriever device for LVO in patients with underlying ICAD is effective and safe. When compared with historical data from other devices employed in similar cases, we observed a high rate of successful reperfusion, along with a shorter puncture to reperfusion time.

Workplace bullying and sexual harassment among general surgery residents in Colombia / Acoso laboral y sexual en residentes de cirugía general en Colombia

INTRODUCTION: Workplace bullying and sexual harassment are concerns among general surgery residents in Colombia. OBJETIVE: To explore the prevalence and impact of workplace bullying and sexual harassment incidents among general surgery residents in Colombia. MATERIALS AND METHODS: This nationwide study was conducted in 2020. Residents selfrated their exposure to workplace bullying and to sexual harassment in the forms of gender harassment, unwanted sexual attention, and sexual coercion. We analyzed demographic variables, perpetrator's characteristics, and differences between victims and non-victims. RESULTS: The study included 302 residents. It found that 49% of general surgery residents in Colombia suffered from workplace bullying and 14.9% experienced sexual harassment. The main forms of sexual harassment were gender harassment (47%) and unwanted sexual attention (47%). Women reported significantly higher rates of being sexually harassed. Surgeons were the main perpetrators of sexual harassment. CONCLUSIONS: Workplace bullying and sexual harassment are frequent events in general surgery residency in Colombia. These findings suggest the need for interventions to improve the educational culture of surgical departments and decrease the prevalence of these behaviors.

Introducción: El acoso laboral y el acoso sexual son preocupaciones en la formación quirúrgica. Objetivo: Exploramos la magnitud de estos problemas entre los residentes de cirugía general en Colombia. Materiales y métodos: se realizó un estudio nacional en junio de 2020. Los residentes autoevaluaron su exposición a la intimidación y el acoso sexual en forma de acoso de género, atención sexual no deseada y coerción sexual. Se analizaron variables demográficas y perpetradores entre víctimas y no víctimas. Resultados: Se incluyeron un total de 302 residentes. Las tasas de acoso laboral y sexual fueron del 49% y 14,9%, respectivamente. Las principales formas de acoso sexual correspondieron al acoso de género (47%) y la atención sexual no deseada (47%). El acoso sexual fue significativamente mayor entre las mujeres. Los cirujanos fueron los principales perpetradores. Conclusiones: El acoso laboral y el acoso sexual son frecuentes en la formación quirúrgica en Colombia. Estos hallazgos conducen a intervenciones para mejorar la cultura educativa de los departamentos quirúrgicos para disminuir la prevalencia de estos comportamientos.

Diagnostic performance of contrast-enhanced ultrasound in diagnosing hepatic artery occlusion after liver transplantation: A systematic review and meta-analysis.

INTRODUCTION: Hepatic artery occlusion (HAO) is a significant complication post-liver transplantation. Doppler ultrasound (DUS) has been widely used as an initial screening test for detecting HAO; however, its performance is often not sufficient. Although other diagnostic tests such as computed tomography angiography (CTA), magnetic resonance angiography (MRA), and angiogram are more accurate, they are invasive and have several limitations. Contrast-enhanced ultrasound (CEUS) is an emerging tool for detecting HAO; however, the results from previous studies were limited due to a small number of patients. Therefore, we aimed to evaluate its performance by performing a meta-analysis. METHOD: We performed a systemic review and meta-analysis of studies evaluating the performance of CEUS for the detection of HAO in an adult population. A literature search of EMBASE, Scopus, CINAHL, and Medline was conducted through March 2022. Pooled sensitivity, specificity, log diagnostic odd ratio (LDOR), and area under summary receiver operating curve (AUC) were calculated. Publication bias was assessed by Deeks' funnel plot. RESULT: Eight studies were included, with 434 CEUS performed. Using a combination of CTA, MRA, angiography, clinical follow-up, and surgery as the gold standard, the sensitivity, specificity, and LDOR of CEUS for detection of HAO were .969 (.938, .996), .991 (.981, 1.001), and 5.732 (4.539, 6.926), respectively. AUC was .959. The heterogeneity between studies appeared universally low, and no significant publication bias was found (p = .44). CONCLUSION: CEUS appeared to have an excellent performance for the detection of HAO and could be considered as an alternative when DUS is non-diagnostic or when CTA, MRA, and angiogram are not feasible.

Workplace bullying and sexual harassment among general surgery residents in Colombia / Acoso laboral y sexual en residentes de cirugía general en Colombia

Introduction. Workplace bullying and sexual harassment are concerns among general surgery residents in Colombia. Objective. To explore the prevalence and impact of workplace bullying and sexual harassment incidents among general surgery residents in Colombia. Materials and methods. This nationwide study was conducted in 2020. Residents selfrated their exposure to workplace bullying and to sexual harassment in the forms of gender harassment, unwanted sexual attention, and sexual coercion. We analyzed demographic variables, perpetrator's characteristics, and differences between victims and non-victims. Results. The study included 302 residents. It found that 49% of general surgery residents in Colombia suffered from workplace bullying and 14.9% experienced sexual harassment. The main forms of sexual harassment were gender harassment (47%) and unwanted sexual attention (47%). Women reported significantly higher rates of being sexually harassed. Surgeons were the main perpetrators of sexual harassment. Conclusions. Workplace bullying and sexual harassment are frequent events in general surgery residency in Colombia. These findings suggest the need for interventions to improve the educational culture of surgical departments and decrease the prevalence of these behaviors.

Introducción. El acoso laboral y el acoso sexual son preocupaciones en la formación quirúrgica. Objetivo. Exploramos la magnitud de estos problemas entre los residentes de cirugía general en Colombia. Materiales y métodos. Se realizó un estudio nacional en junio de 2020. Los residentes autoevaluaron su exposición a la intimidación y el acoso sexual en forma de acoso de género, atención sexual no deseada y coerción sexual. Se analizaron variables demográficas y perpetradores entre víctimas y no víctimas. Resultados. Se incluyeron un total de 302 residentes. Las tasas de acoso laboral y sexual fueron del 49% y 14,9%, respectivamente. Las principales formas de acoso sexual correspondieron al acoso de género (47%) y la atención sexual no deseada (47%). El acoso sexual fue significativamente mayor entre las mujeres. Los cirujanos fueron los principales perpetradores. Conclusiones. El acoso laboral y el acoso sexual son frecuentes en la formación quirúrgica en Colombia. Estos hallazgos conducen a intervenciones para mejorar la cultura educativa de los departamentos quirúrgicos para disminuir la prevalencia de estos comportamientos.

Utility of repeat colonoscopy within 1 year: a patient-level analysis.

Patients undergo colonoscopies for colorectal cancer screening and for the evaluation of gastrointestinal symptoms. Analysis of large administrative databases has demonstrated that some patients undergo repeat colonoscopies at intervals inconsistent with current recommendations, but these studies do not provide patient-level details. The medical records of 110 patients undergoing repeat colonoscopies within 1 year of their index colonoscopies at a tertiary care hospital-based endoscopy center were retrospectively reviewed to determine patient demographics, gastrointestinal symptoms, and endoscopic findings. Thirty-five patients had poor bowel preparations, and 11 patients had a history of colorectal cancer. Thirty-four patients had polyps identified during their index colonoscopies, and 28 patients had no polyps identified during their index colonoscopies. Eleven patients in the nonpolyp group had new endoscopic findings identified during the repeat colonoscopies. Twenty patients who had polyps identified on their index colonoscopies had 44 polyps identified on repeat colonoscopies. Repeat colonoscopies within 1 year occurred relatively infrequently in this endoscopy center. Indications included poor bowel preparation with incomplete studies, colonic polyps with incomplete resection, multiple polyps resulting in the possibility of missed polyps, and new gastrointestinal symptoms.

Transgastric laparoscopic polypectomy in giant gastric polyps not susceptible of endoscopic management: novel surgical technique and case series.

BACKGROUND: The identification of gastric polyps incidentally in endoscopies of the upper digestive tract has increased its incidence, varying between 0.5% and 23%. 10% of these polyps have symptoms, 40% are hyperplastic. We allow ourselves to propose a laparoscopic technique for the management of giant hyperplastic polyps associated with a pyloric syndrome, not susceptible to endoscopic resection. METHOD: A series of patients approached by laparoscopic transgastric polypectomy due to the giant gastric polyps associated with pyloric syndrome, in Bogotá, Colombia, from January 2015 to December 2018. RESULTS: Seven patients, 85% female, with an average age of 51 years, who were admitted for pyloric syndrome and were taken to laparoscopic management, with an average surgical time of 42 min, intraoperative bleeding 7-8 cc, tolerance to the oral route 24 hours, no conversion, without mortality. CONCLUSIONS: Transgastric polypectomy for the management of benign giant gastric polyps that cannot be resected endoscopically turns out to be a feasible method, with a low rate of complications and without mortality.

ANTECEDENTES: La identificación de pólipos gástricos de manera incidental en endoscopias de vías digestivas altas ha aumentado su incidencia, que varía entre el 0.5% y el 23%. El 10% de estos pólipos presentan síntomas y el 40% son hiperplásicos. Nos permitimos proponer una técnica laparoscópica para el manejo de los pólipos hiperplásicos gigantes asociados a síndrome pilórico no susceptibles de resección endoscópica. MÉTODO: Serie de pacientes llevados a polipectomía transgástrica laparoscópica por hallazgo de pólipos gástricos gigantes asociados a síndrome pilórico, en Bogotá, Colombia, de enero de 2015 a diciembre de 2018. RESULTADOS: Un total de siete pacientes, el 85% de sexo femenino, con edad promedio de 51 años, ingresaron por síndrome pilórico y fueron llevados a manejo laparoscópico, con un tiempo quirúrgico promedio de 42 minutos, sangrado intraoperatorio de 7-8 cc, tolerancia a la vía oral a las 24 horas, no conversión, sin mortalidad. CONCLUSIONES: La polipectomía transgástrica para el manejo de pólipos gástricos gigantes benignos que no pueden ser resecados por vía endoscópica resulta ser un método factible, con una baja tasa de complicaciones y sin mortalidad.

Cerebral arteriopathy and ischemic stroke in a pediatric MYH11 patient.

OBJECTIVES: Mutations in the MYH11 gene result in smooth muscle cell dysfunction and are associated with familial thoracic aortic aneurysms and dissection. We describe a pediatric patient with a stroke and a pathogenic MYH11 IVS32G>A mutation, and a phenotype similar to ACTA2. METHODS: A proband girl with an acute ischemic stroke underwent genetic analysis and 7T high-resolution MRI. RESULTS: A 12-year-old girl presented with a right middle cerebral artery occlusion. She received thrombolysis and underwent mechanical thrombectomy. An extensive stroke work-up was negative. A three-generation pedigree showed a splice site mutation of MYH11 IVS32G>A of the proband and three more family members. A 7T-MRI showed "broomstick-like" straightening of distal arterial segments, a V-shaped anterior corpus callosum and a post-stroke cystic area of encephalomalacia. This vascular appearance and parenchymal abnormalities typically present in patients with an ACTA2 phenotype. 7T-MRI also demonstrated thickening of the right middle cerebral arterial wall. DISCUSSION: This case suggests that MYH11 patients may have a similar angiographic and brain parenchymal phenotype to patients with ACTA2 mutations. This is the first report of arterial wall thickening in a MYH11 stroke patient using 7T-MRI. Patients with MYH11 mutations may display a focal cerebral steno-occlusive arteriopathy that may lead to stroke.

Natural history, angiographic presentation and outcomes of anterior cranial fossa dural arteriovenous fistulas.

BACKGROUND: Anterior cranial fossa dural arteriovenous fistulas (ACF-dAVFs) are aggressive vascular lesions. The pattern of venous drainage is the most important determinant of symptoms. Due to the absence of a venous sinus in the anterior cranial fossa, most ACF-dAVFs have some degree of drainage through small cortical veins. We describe the natural history, angiographic presentation and outcomes of the largest cohort of ACF-dAVFs. METHODS: The CONDOR consortium includes data from 12 international centers. Patients included in the study were diagnosed with an arteriovenous fistula between 1990-2017. ACF-dAVFs were selected from a cohort of 1077 arteriovenous fistulas. The presentation, angioarchitecture and treatment outcomes of ACF-dAVF were extracted and analyzed. RESULTS: 60 ACF-dAVFs were included in the analysis. Most ACF-dAVFs were symptomatic (38/60, 63%). The most common symptomatic presentation was intracranial hemorrhage (22/38, 57%). Most ACF-dAVFs drained through cortical veins (85%, 51/60), which in most instances drained into the superior sagittal sinus (63%, 32/51). The presence of cortical venous drainage predicted symptomatic presentation (OR 9.4, CI 1.98 to 69.1, p=0.01). Microsurgery was the most effective modality of treatment. 56% (19/34) of symptomatic patients who were treated had complete resolution of symptoms. Improvement of symptoms was not observed in untreated symptomatic ACF-dAVFs. CONCLUSION: Most ACF-dAVFs have a symptomatic presentation. Drainage through cortical veins is a key angiographic feature of ACF-dAVFs that accounts for their malignant course. Microsurgery is the most effective treatment. Due to the high risk of bleeding, closure of ACF-dAVFs is indicated regardless of presentation.

3D aneurysm wall enhancement is associated with symptomatic presentation.

BACKGROUND: Aneurysm wall enhancement (AWE) is a potential surrogate biomarker for aneurysm instability. Previous studies have assessed AWE using 2D multiplanar methods, most of which were conducted qualitatively. OBJECTIVE: To use a new quantitative tool to analyze a large cohort of saccular aneurysms with 3D-AWE maps METHODS: Saccular aneurysms were imaged prospectively with 3T high resolution MRI. 3D-AWE maps of symptomatic (defined as ruptured or presentation with sentinel headache/cranial nerve neuropathy) and asymptomatic aneurysms were created by extending orthogonal probes from the aneurysm lumen into the wall. Three metrics were used to characterize enhancement: 3D circumferential AWE (3D-CAWE), aneurysm-specific contrast uptake (SAWE), and focal AWE (FAWE). Aneurysms with a circumferential AWE higher than the corpus callosum (3D-CAWE ≥1) were classified as 3D-CAWE+. Symptomatic presentation was analyzed with univariate and multivariate logistic models. Aneurysm size, size ratio, aspect ratio, irregular morphology, and PHASES and ELAPSS scores were compared with the new AWE metrics. Bleb and microhemorrhage analyses were also performed. RESULTS: Ninety-three aneurysms were analyzed. 3D-CAWE, SAWE, and FAWE were associated with symptomatic status (OR=1.34, 1.25, and 1.08, respectively). A multivariate model including aneurysm size, 3D-CAWE+, age, female gender, and FAWE detected symptomatic status with 80% specificity and 90% sensitivity (area under the curve=0.914, =0.967). FAWE was also associated with irregular morphology and high-risk location (p=0.043 and p=0.001, respectively). In general, blebs enhanced 56% more than the aneurysm body. Areas of microhemorrhage co-localized with areas of increased SAWE (p=0.047). CONCLUSIONS: 3D-AWE mapping provides a new set of metrics that could potentially improve the identification of symptomatic aneurysms.

A New Methodology to Estimate Drug Cost Avoidance in Clinical Trials: Development and Application.

Background: Oncology clinical trials can lead to relevant financial savings in drug acquisition for healthcare providers. Considerable methodological heterogeneity is observed among previous studies estimating these savings. Methods: We developed a methodology to estimate the economic benefit obtained from the enrollment of patients into clinical trials through the analysis of drug cost avoidance. We designed a decision algorithm to determine if a clinical trial is associated with drug cost avoidance. This algorithm is based on five scenarios according to the availability or not of standard treatment, the presence or absence of a control arm (placebo or active treatment), and the provider of the medication. We considered as reference the cost of the standard treatment that the patient would have received in routine clinical practice. We standardized drug doses and treatment durations according to the literature. Costs were considered from a National Health System perspective. We applied this methodology at a single, research-active University Hospital in 2019. A cost avoidance analysis per trial and patient was carried out on cancer patients. Results: We analyzed 140 trials in which 198 patients were recruited. Drug cost avoidance was found in 120 trials (85.7%). The estimated total drug cost avoidance amounted to over €3,200,000. Melanoma and genitourinary tumors were the tumor types associated with the highest cost avoidance. The average drug cost avoidance per patient was €16,245. Conclusion: We describe a standardized method to estimate drug cost avoidance in clinical trials. We have applied it to all ongoing oncology clinical trials in our center. This methodology could be valuable for other centers to analyze the potential saving of clinical trials.

Reversible bilateral optic tract edema following pipeline-assisted coiling of a large ophthalmic aneurysm: A case report.

Edema coursing the optic apparatus has traditionally been associated with sellar and para-sellar tumors. However, postoperative aneurysmal volume expansion following endovascular treatment has been reported to induce cranial neuropathies, such as vision loss in rare instances. Here, we present a case report of worsening optic tract edema associated with bilateral visual acuity deficit following treatment of a large left paraophthalmic aneurysm with pipeline-assisted coiling. Rapid resolution of visual deficit was observed following administration of corticosteroids. A 42-year-old female with a 6-month history of worsening left eye vision and sentinel headache presented with left visual field cut and decreased left visual acuity. She was found to have a large paraophthalmic aneurysm which was treated with pipeline-assisted coiling. Within one week post-treatment, the patient presented to the emergency department with worsening right visual complaints. On magnetic resonance imaging, T2 hyperintensities coursing the right posterior optic nerve, optic chiasm, and bilateral optic tracts were noted. Angiography demonstrated an expanding neck remnant. The patient was treated with oral corticosteroids and repeat pipeline stenting. At four week follow up, she demonstrated significant improvement of symptoms and reduced T2 hyperintensities. With the advancement in endovascular technique for the treatment of large aneurysms, more patients are electing endovascular treatment over microsurgical clipping. Given the possibility of continued growth following endovascular treatment, patient counseling regarding risks and side effects is paramount.

Characterization of Geiger-Müller radiation detectors response at the University of Costa Rica's Cyclotron Facilities / Caracterización de la respuesta de detectores de radiación Geiger-Müller en el Ciclotrón de la Universidad de Costa Rica

To ensure a reliable verification of a radiation detector, the right parameters for this response verification must be determined and a specific characterization on the detectors of interest must be performed. These were the main pillars of this study, where four Geiger-Müller at the University of Costa Rica's Cyclotron Facilities' main laboratories were studied and characterized using a 137Cs source. First, a verification of the inverse-square law was performed to corroborate the correct measurement by the detectors as the distance from a 137Cs source to the detectors was varied using a new design for a positioner support to ensure repeatability. This verification yielded a potential fit curve with and equation D=670635 x-1.961 (error percentage of 1.95%) and an R2 value of 0.9836. Then, using combinations of copper plates of widths 1.0 mm and 2.0 mm as attenuators between the source and the detectors, the mass attenuation coefficient for copper was obtained only as a reference value for future calibrations of the detectors. The result for this value was 0.040 cm2 /g. The results obtained in this study and the method developed to achieve these results will serve as a base for calibrations of the detectors at these facilities, which will ensure the safety of the patients and personnel in this building.

Para asegurar respuesta correcta de un detector de radiación, se deben determinar los parámetros correctos para esta verificación y debe realizarse una caracterización específica de los detectores de interés. Estos fueron los pilares principales de este estudio, donde se estudiaron y caracterizaron 4 detectores Geiger-Müller en los laboratorios principales del Ciclotrón de la Universidad de Costa Rica utilizando una fuente radiactiva de 137Cs. Primero, se realizó una verificación de la ley del inverso-cuadrado para corroborar la medición correcta de los detectores según se varía la distancia entre la fuente de 137Cs al detector utilizando un diseño nuevo de un soporte posicionador para la fuente que asegura la repetibilidad entre experimentos. Esta verificación resultó en una curva de ajuste potencial de ecuación D=670635x-1,961 (porcentaje de error de 1,95%) y un valor de R2 de 0,9836. Luego, utilizando combinaciones de placas de cobre de espesores 1,0 mm y 2,0 mm como atenuadores entre la fuente y los detectores, se obtuvo el coeficiente de atenuación másico para el cobre como un valor de referencia para futuras calibraciones de los detectores. Este resultado fue de 0,040 cm2/g. Los resultados obtenidos en esta investigación y el método desarrollado para lograr estos resultados servirán como una base para una futura confirmación metrológica calibraciones de los detectores en estos laboratorios, lo cual colaborará con la seguridad y protección radiológica de pacientes y trabajadores en este edificio.