Carlos Ubeda de la Cerda | Universidad de Tarapacá de Arica (UTA) (original) (raw)

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Papers by Carlos Ubeda de la Cerda

Journal of Digital Imaging, 2010

Revista Chilena de Radiología

Se realizó un Levantamiento Radiométrico en dos servicios de Imaginología con un total de 7 salas... more Se realizó un Levantamiento Radiométrico en dos servicios de Imaginología con un total de 7 salas de radiodiagnóstico evaluadas. Se utilizó metodología del Protocolo de Control de Calidad en Radiodiagnóstico ARCAL (Acuerdo de Cooperación Regional para la promoción de la ciencia nuclear y tecnología en América Latina y el Caribe) XLIX del Organismo Internacional de Energía Atómica (OIEA)(1). Se calcularon las tasas de dosis efectiva en superficie en diferentes posiciones de interés desde el punto de vista de la protección radiológica. El 85% de las posiciones evaluadas presentan tasas de dosis efectivas que cumplen con los valores límites establecidos en el protocolo ARCAL XLIX. No obstante el personal ocupacionalmente expuesto (POE) ubicado a un metro del simulador (área controlada)(2) supera hasta en un factor 7 el límite propuesto en ARCAL XLIX.

Las exposiciones médicas constituyen la principal fuente de exposición a radiaciones ionizantes a... more Las exposiciones médicas constituyen la principal fuente de exposición a radiaciones ionizantes a la población mundial. Por esta razón, la Comunidad Europea ha desarrollado una serie de acuerdos, que tienen como objetivo regularizar estas actividades. En el mismo sentido España, a través de una serie de Decretos Reales estructuró un marco legal que considera aspectos amplios de Protección Radiológica,
como así también criterios de calidad de las exposiciones médicas, las cuales pueden ser usadas como referencia para desarrollar estos temas en nuestro país.

International journal of odontostomatology

Radiation Physics and Chemistry

International Journal of Morphology

Radiation protection dosimetry, Jan 11, 2018

The objective of this article is to present initial occupational dose values using digital active... more The objective of this article is to present initial occupational dose values using digital active personal dosimeters for medical staff during adult interventional cardiology procedures in a public hospital in Chile. Personal dose equivalent Hp(10) over the lead apron of physician, nurse and radiographer were measured during 59 procedures. Mean values of occupational dose Hp(10) per procedure were 47.6, 6.2 and 4.3 μSv for physician, nurse and radiographer, respectively. If no protective tools are used, physician dose can exceed the new eye lens dose limit.

Journal of radiological protection : official journal of the Society for Radiological Protection, Jan 21, 2017

The goal of the present study is to propose a set of national diagnostic reference levels (DRLs) ... more The goal of the present study is to propose a set of national diagnostic reference levels (DRLs) for paediatric interventional cardiology (IC) procedures classified by age and weight in Costa Rica and to estimate the collective dose to the paediatric population deriving from these intervention practices. The data collection period was from May 2016 to May 2017. National DRLs were set as the third quartile of patient dose data distributions for kerma area-product (KAP) values. A sample of 154 paediatric IC procedures (collected in the national paediatric hospital with a single x-ray system) was used and divided into four age ranges and five weight ranges. The national DRLs obtained for KAP by age range were from 1.79 Gy•cm2 (<1 yr) to 23.0 Gy•cm2 (10 to <16 yrs). The national DRLs obtained for KAP by weight range were from 1.0 Gy•cm2 (<10 kg) to 49.6 Gy•cm2 (50-<80 kg). The contribution to collective dose to population in Costa Rica amounted to 0.78 person.Sv.&#13.

Revista chilena de radiología

Physica medica : PM : an international journal devoted to the applications of physics to medicine and biology : official journal of the Italian Association of Biomedical Physics (AIFB), Jan 22, 2017

The aim of this study was to present the results of organ and effective doses for paediatric pati... more The aim of this study was to present the results of organ and effective doses for paediatric patients for different types of interventional cardiology procedures for age and weight groups, derived from a patient dosimetry pilot programme carried out in Chile, under the auspices of the International Atomic Energy Agency. Over seven years, a retrospective collection of demographic and patient dose data was obtained: age, gender, weight, height, number of cine series, total number of cine frames, fluoroscopy time, dose-area product (DAP) and cumulative dose at patient entrance reference point. Monte Carlo software was used to calculate organ and effective doses. 1506 procedures were divided into four age and seven weight groups. Organ doses (median values) for diagnostic and therapeutic procedures were: active bone marrow 0.90 and 0.64mGy; heart 1.99 and 1.46mGy; lungs 3.56 and 2.59mGy; thyroid 1.27 and 0.83; and breast (in the case of females) 1.78 and 1.36mGy. The ranges for effectiv...

Radiation protection dosimetry, Jan 21, 2017

This paper presents the results of the first characterization and experimental measurements of sc... more This paper presents the results of the first characterization and experimental measurements of scatter dose at cardiologist's eyes for the only X-ray system that performs all paediatric Interventional cardiology procedures in Costa Rica. Entrance surface air kerma (ESAK) and the scatter dose values were measured on phantoms of 4-20 cm thicknesses of polymethyl methacrylate slabs. Image quality was evaluated using DICOM images of a test object Leeds TOR 18-FG, through the numerical parameters signal-to-noise ratio (SNR), high-contrast spatial resolution (HCSR) and figure of merit (FOM). When PMMA thickness is increased and during a move from low fluoroscopy to cine modes, ESAK, SNR, HCSR and FOM values range from 0.44 to 391.0 μGy fr-1; 2.8 to 14.89; 3.17 to 15.54 and 0.51 to 79.94, respectively. The highest scattered dose rates recorded during the simulations were 1.79 and 8.04 mSv h-1 for the high fluoroscopy and cine modes, respectively.

Radiation protection dosimetry, Jan 23, 2016

The aim of this study was to determine experimentally the scatter dose at the cardiologist's ... more The aim of this study was to determine experimentally the scatter dose at the cardiologist's lower extremities in 10 common types of paediatric interventional cardiology procedures and categorised in four age groups of simulated patients, on the basis of measurements taken from characterisation of X-ray systems together with average fluoroscopy time values and the number of cine frames used as references. The highest scattered dose rates recorded during the simulations were 700 and 4000 µSv h(-1)for the low fluoroscopy and cine modes, respectively. Scattered dose at cardiologist's lower extremities for the four age groups of simulated patients and procedures ranged from 1 to 28 µSv (aged below 1 y), 6 to 58 µSv (below 5 y), 13 to 155 µSv (below 10 y) and 29 to 375 µSv (below 15 y). The present study showed a maximum annual dose that may reach the cardiologist's lower extremities of 90 mSv.

Radiation Protection Dosimetry, 2016

Under International Atomic Energy Agency regional programmeTSA3 Radiological Protection of Patien... more Under International Atomic Energy Agency regional programmeTSA3 Radiological Protection of Patients in Medical Exposures, Latin American countries evaluated the image quality and glandular doses for digital mammography equipment with the purpose of seeing the performance and compliance with international recommendations. Totally, 24 institutions participated from Brazil, Chile, Costa Rica, El Salvador, Mexico, Paraguay and Venezuela. Signal difference noise ratio results showed for CR poor compliance with tolerances; better results were obtained for full-field digital mammography equipment. Mean glandular dose results showed that the majority of units have values below the acceptable dose levels. This joint Latin American project identified common problems: difficulty in working with digital images and lack of specific training by medical physicists from the region. Image quality is a main issue not being satisfied in accordance with international recommendations; optimisation processes in which the doses are increased should be very carefully done in order to improve early detection of any cancer signs.

Applied radiation and isotopes : including data, instrumentation and methods for use in agriculture, industry and medicine, Jan 19, 2016

Studies have reported cases of radiation-induced cataract among cardiology professionals. In view... more Studies have reported cases of radiation-induced cataract among cardiology professionals. In view of the evidence of epidemiological studies, the ICRP recommends a new threshold for opacities and a new radiation dose to eye lens limit of 20mSv per year for occupational exposure. The aim of this paper is to report scattered radiation doses at the height of the operator's eye in an interventional cardiology facility without considering radiation protection devices and to correlate these values with different angiographic projections and operational modes. Measurements were taken in a cardiac laboratory with an angiography X-ray system equipped with flat-panel detector. PMMA plates of 30×30×5cm were used with a thickness of 20cm. Measurements were taken in two fluoroscopy modes (low and normal, 15pulses/s) and in cine mode (15frames/s). Four angiographic projections were used: anterior posterior; lateral; left anterior oblique caudal (spider); and left anterior oblique cranial, wit...