Assessment of Adult's Abdominopelvic Computed Tomography Radiation Doses in Amhara Region, Ethiopia

BACKGROUND: Computed Tomography plays a priceless role for diagnostic and therapeutic purpose; however,applying an optimized Computed Tomography Technique to produce qualified image while delivering minimum radiation dose to patients is the common challenge. The main objective of this study was to establish local diagnostic reference levels for adult patients who visited abdominopelvic Computed Tomography examination. METHODS: A total of 158 patients who had taken abdominopelvic Computed Tomography examination from three selectedAmhara region hospitals were investigated. Both prospective and retrospective techniques of data collection were used while collecting the data in the entire sample. Two GE - Optima Computed Tomography 540 (16 slices) and one Phillips ­ Brilliance (64slices), were employed during data collections. Data for patient demographics scan protocols, Computed Tomography dose descriptors and machine specifications were collected and analyzed by using SPSS software version 26. RESULTS: The third quartile estimated computed tomography dose index volume and dose length product, which is the local Diagnostic Reference Levels, were 12 mGy and 1904 cm.mGy respectively. The investigated local Diagnostic Reference Levels of Computed Tomography Dose index volume (mGy) was comparable to other international Diagnostic Reference Levels. However, the third quartile value of dose length product (cm.mGy) was higher than other reported international Diagnostic Reference Levels. CONCLUSION: The values of local Diagnostic Reference Levels presented in this work can be used as a baseline upon which future dose measurements can be compared in Amhara region

Optimización de la protección en radiología y cardiología intervencionista pediatrica en América Latina y el Caribe (OPRIPALC) / Optimization of protection in pediatric interventional cardiology and radiology in Latin America and the Caribbean (OPRIPALC)

El objetivo del presente artículo ha sido describir el programa "Optimización de la Protección en Radiología Intervencionista Pediátrica en América Latina y el Caribe" (OPRIPALC) que nace el año 2018 como respuesta conjunta de la Organización Panamericana de la Salud y la Organización Mundial de la Salud, en cooperación con el Organismo Internacional de Energía Atómica, para colaborar con sus Estados miembros en asegurar que las exposiciones a la radiación de los pacientes pediátricos sean las mínimas necesarias durante los procedimientos intervencionistas. Actualmente, hay 18 centros de los siguientes 10 países que participan: Argentina, Brasil, Chile, Colombia, Costa Rica, Cuba, Ecuador, México, Perú y Uruguay. Para el desarrollo del programa se plantean una serie de objetivos, productos, actividades y resultados esperados. La puesta en marcha de la WEB de OPRIPALC ha significado un instrumento muy válido para seguir la información actualizada del programa. Un programa actualizado de formación en radioprotección para los profesionales implicados en el programa, se está realizando por medio de "webinars". Se deberá seguir actuando en la aplicación del programa de control de calidad básico para los equipos de rayos X participantes y validar los valores de los Niveles de Referencia para Diagnóstico (NRDs). Se propone formar un equipo de trabajo entre los Físicos Médicos y Tecnólogos Médicos participantes de OPRIPALC para implicarse en las pruebas de control básicas que todos los centros debieran realizar. Se han presentado algunos resultados iniciales de OPRIPALC en eventos científicos internacionales. Se está avanzando en proponer unos primeros valores sobre NRDs en procedimientos de intervencionismo cardiológico pediátrico por bandas de edad y peso. OPRIPALC es una de las pocas iniciativas de carácter regional para obtener valores de NRDs en procedimientos intervencionistas pediátricos. Se espera que tanto los valores de referencia como la metodología empleada en OPRIPALC, puedan ser utilizados en otras regiones del mundo.

The objective of this article has been to describe the program "Optimization of Protection in Pediatric Interventional Radiology in Latin America and the Caribbean" (OPRIPALC) that was born in 2018 as a joint response of the Pan American Health Organization and the World Organization of the Health, in cooperation with the International Atomic Energy Agency, to collaborate with its member states in ensuring that radiation exposures of pediatric patients are the minimum necessary during interventional procedures. Currently, there are 18 centers from the following 10 countries participating: Argentina, Brazil, Chile, Colombia, Costa Rica, Cuba, Ecuador, Mexico, Peru and Uruguay. For the development of the program, a series of objectives, products, activities and expected results are proposed. The launch of the OPRIPALC WEBSITE has been a very valid instrument for following up-to-date information on the program. An updated training program in radiation protection for the professionals involved in the program is being carried out through webinars. It should continue acting in the application of the basic quality control program for the participating X-ray equipment and validate the values of the Diagnostic Reference Levels (DRLs). It is proposed to form a work team among the OPRIPALC participating medical physicists to get involved in the basic control tests that all centers should carry out. Some initial results of OPRIPALC have been presented at international scientific events. Progress is being made in proposing first values on DRLs in pediatric cardiac intervention procedures by age and weight bands. OPRIPALC is one of the few regional initiatives to obtain DRLs values in pediatric interventional procedures. It is expected that both the reference values and the methodology used in OPRIPALC can be used in other regions of the world.

Niveles de Referencia para Diagnóstico Locales en Procedimientos Radiográficos Dentales Periapicales. Primeros valores para Chile

RESUMEN: La información que aportan los procedimientos de radiología dental, tanto en la evaluación, como en el diagnóstico y tratamiento de patologías y/o alteraciones dento maxilofaciales, hace que correspondan al tipo más frecuente de estudio radiológico. Sin embargo, existe un escaso conocimiento en nuestro país respecto de los niveles de dosis que se imparten en dichos procedimientos, haciendo necesaria su determinación para maximizar el beneficio derivado de los mismos y minimizar el riesgo radiológico para los pacientes. El presente estudio determinó el nivel de referencia para diagnóstico (NRD) local en la radiografía periapical de Molar maxilar e Incisivo, para ello se realizaron simulaciones de los procedimientos radiográficos en un maniquí antropomorfo seccional y se determinó el valor de Kerma aire en la superficie de entrada con retrodispersión mediante dosimetría termoluminiscente. Los NRD locales determinados en la radiografía periapical de Molar maxilar fueron 5,6 mGy para adultos y 4,0 mGy para niños; mientras que en la radiografía periapical de Incisivo fue de 9,2 mGy para pacientes adultos y 1,8 mGy para niños. Los resultados obtenidos buscan orientar la ejecución de futuras investigaciones en el área y aportar información del nivel de radiación en estos procedimientos, con lo que se espera promover una cultura de radioprotección y motivar la optimización de las dosis registradas.

ABSTRACT: The information provided by dental radiology procedures, both in evaluation, as well as in the diagnosis and treatment of pathologies and / or dentomaxilofacial alterations, makes them the most frequent type of radiological study. However, there is a meager knowledge in our country regarding dose levels applied in such procedures, making their determination necessary to maximize the benefits and to minimize the radiological risk to patients. The present study determined the local diagnostic reference level (LDRL) for the periapical radiography of the Maxillary molar and Incisive. Simulations of radiographic procedures were performed and the value of air Kerma at the entrance surface with backscattering, was estimated using thermo luminescent dosimetry. The LDRL determined in the maxillary molar periapical radiography was 5.6 mGy for adults and 4.0 mGy for children; while on the incisive periapical radiography it was 9.2 mGy for adult patients and 1.8 mGy for children. The results obtained seek to guide the execution of future research in the area and provide information on the radiation doses delivered in these procedures, which is expected to promote a radiation protection culture and motivate the optimization of the registered doses.

Niveles de Referencia para Diagnóstico en Procedimientos Radiológicos Dentales: Una Guía Práctica / Diagnostic Reference Levels in Dental Radiological Procedures: A Practical Guide

RESUMEN: Las exposiciones médicas con radiación ionizante son actualmente la principal fuente de exposición a la radiación artificial a nivel global, entre ellas, los exámenes dentales corresponden a uno de los más frecuentes. Para prevenir dosis innecesariamente altas a los pacientes durante estas exposiciones, la Comisión Internacional de Protección Radiológica (ICRP) recomienda la utilización de Niveles de Referencia para Diagnóstico (DRLs), como una herramienta efectiva de ayuda a la optimización de la protección radiológica en la exposición médica de pacientes. Dado que la legislación de Chile aún no ha incorporado el uso de los DRLs, el presente trabajo de revisión tuvo como objetivo analizar la publicación N° 135 de la ICRP para generar un documento que sirva de guía para los odontólogos, explicando de manera didáctica y en un lenguaje sencillo, pero técnico, los principales aspectos a tener en cuenta para establecer los DRLs en procedimientos de radiología dental.

SUMMARY: Currently exposure to ionizing radiation is currently the main source of exposure to artificial radiation worldwide, with dental examinations being one of the most frequent events. In order to prevent exposure of unnecessarily high doses in patients, the International Commission on Radiological Protection (ICRP) recommends the use of Diagnostic Reference Levels (DRLs), as an effective tool to help maximize protection from radiation during medical exposure of patients. Given that the Chilean legislation has not yet incorporated the use of DRLs, the purpose of this study was to analyze publication N° 135 of the ICRP to generate a document, to serve as a guide for dentists, didactically outlining in simple but technical language, the main aspects to consider when establishing DRLs in dental radiology procedures.

Valores típicos de dosis para tomografía computada de cerebro en pacientes adultos / Typical dose values for brain computed tomography in adult patients

Resumen: Debido al aumento en el uso de la Tomografía Computada (TC), y en consecuencia, la probabilidad de generar un incremento progresivo de la dosis recibida por los paciente y su relación en el potencial riesgo de los efectos de las radiaciones ionizantes, es importante implementar el uso de niveles de referencia diagnóstico (DRLs) en TC, como herramienta fundamental dentro de un programa de control de calidad que permita la evaluación y optimización de las dosis entregadas a los pacientes según la tarea clínica deseada. Con el objetivo de establecer valores típicos de dosis en TC de cerebro en Clínica Bupa Reñaca, se estudió una muestra de 73 informes dosimétricos generados en un equipo TC Toshiba Aquilion 64, en términos de indicadores de dosis para TC: Índice de dosis en TC por volumen (CTDIvol) y Producto dosis longitud (DLP). Con los datos obtenidos, se estimó el valor del percentil 50 (p50) para cada indicador de dosis, y se determinaron los valores típicos de dosis en cada grupo estudiado según sexo, edad e indicación clínica. Se logró definir y establecer una metodología que permitió la obtención de los valores típicos de dosis para TC de cerebro, optimizando las dosis sin producir una disminución en la calidad de la imagen necesaria para nuestro propósito clínico.

Abstract: Due to the increase in the use of Computed Tomography (CT), and consequently, the probability of generating a progressive increase in the dose received by the patient and its relationship in the potential risk of the effects of ionizing radiation, it is important to implement the use of diagnostic reference levels (DRLs) in CT, as a fundamental tool within a quality control program that allows the evaluation and optimization of the doses delivered to patients according to the desired clinical task. In order to establish typical dose values in brain CT at Bupa Reñaca Clinic, a sample of 73 dosimetric reports generated on a Toshiba Aquilion 64 CT unit was studied, in terms of dose indicators for CT: Dose rate on CT by volume (CTDIvol) and Dose Length Product (DLP). With the data obtained, the value of the 50th percentile (p50) for each dose indicator was estimated, and typical dose values were determined in each group studied according to sex, age and clinical indication. It was possible to define and establish a methodology that allowed obtaining typical dose values for brain CT, optimizing the doses without producing a decrease in the image quality necessary for our clinical purpose.

Evolution and interpretation of diagnostic reference levels for adults undergoing X-ray computed tomography in China / 中华放射医学与防护杂志

The diagnostic reference level (DRL) for adults radiation dose in CT examination based on a large-scale national survey data is released in the form of national health industry standards (WS/T 637-2018) after more than ten years of exploration by radiologists,imaging technologists,radiation protection specialists and radiographers.Its principles and method are in line with international practices and the actual situation in China,which basically cover frequently-used CT examination items for adults.Compared with DRL in several other countries or organizations,radiation exposure to the patients as a whole is at a reasonably low level.The 50th percentile (achievable dosimetry levels) and 25th percentile (indicative level of unusually low dosimetry) are given as additional tools for radiation dose optimization guidance.In daily activities of radiological diagnosis,the radiation dose should be matched with image quality and clinical diagnostic tasks,and the frequency of unjustifiable high or low radiation dose should be reduced.

Evolution and interpretation of diagnostic reference levels for adults undergoing X-ray computed tomography in China / 中华放射医学与防护杂志

The diagnostic reference level (DRL) for adults radiation dose in CT examination based on a large-scale national survey data is released in the form of national health industry standards (WS/T 637-2018) after more than ten years of exploration by radiologists, imaging technologists, radiation protection specialists and radiographers. Its principles and method are in line with international practices and the actual situation in China, which basically cover frequently-used CT examination items for adults. Compared with DRL in several other countries or organizations, radiation exposure to the patients as a whole is at a reasonably low level. The 50th percentile (achievable dosimetry levels) and 25th percentile (indicative level of unusually low dosimetry) are given as additional tools for radiation dose optimization guidance. In daily activities of radiological diagnosis, the radiation dose should be matched with image quality and clinical diagnostic tasks, and the frequency of unjustifiable high or low radiation dose should be reduced.

Xpektrin, un simulador de espectros fácil de usar y ampliamente distribuible para radiología general / Xpektrin, an easy to use and highly distributable X-Ray spectra simulator in general radiography

Resumen: Se presenta una aplicación basada en Microsoft Excel llamada Xpektrin para el cálculo de dosis en radiología general. La aplicación permite simular espectros de rayos X en radiología general utilizando el modelo TASMICS a partir de mediciones del kerma en aire (Kair) y de la capa Hemirreductora (HVL). Tiene implementado el cálculo de magnitudes radiométricas y dosimétricas, como el kerma en aire en la superficie de entrada (Ke) y la dosis en piel (Dskin), en función de la elección arbitraria de los factores de exposición, el tipo y grosor de filtro, la distancia foco-piel y el tamaño de campo. Xpektrin fue validado con la herramienta computacional SPEKTR 3.0, utilizando mediciones de dosis y de HVL de tubos de rayos X de tres recintos hospitalarios. Se encontró buena correlación en ambas aplicaciones entre las mediciones experimentales y los valores calculados de HVL y con coeficientes de Pearson R² ≥ 0.99 en todos los casos. Sin embargo, se obtuvo mejor concordancia con los valores experimentales de HVL con Xpektrin (mediana de diferencias -0.43%, -0.04% y 0.01%) que con SPEKTR 3.0 (mediana de diferencias -3.31%, 0.10% y -7.85%), en particular para el tubo con mayor filtración. Xpektrin está optimizada para ser utilizada en los departamentos de radiología para la determinación de dosis de pacientes individuales en función de los parámetros utilizados durante la exposición, por lo que puede ser utilizada como parte de un sistema de registro dosimétrico o como apoyo para el establecimiento de niveles de referencia para diagnóstico (NRD), siendo particularmente útil en servicios con equipos sin registros automáticos de dosis. Además, debido a sus características de simulador, puede ser útil como herramienta pedagógica. El uso de Excel permite que sea altamente distribuible y fácil de usar, sin necesidad de conocimientos de programación.

Abstract: Xpektrin, an easy to use and highly distributable X-Ray Spectra Simulator in General Radiography. An application based on Microsoft Excel called Xpektrin is presented for dose calculation in general radiology. The application was developed to simulate X-ray spectra in general radiography using the TASMICS model. Using as inputs air kerma (Kair) and Half-value layer (HVL) measurements, Xpektrin allows the calculation of several radiometric and dosimetric quantities, such as the entrance surface air kerma (Ke) and the skin dose (Dskin), depending on the exposure factors, filter material type, filter thickness, focus-skin distance and field size. Xpektrin was validated against the Matlab toolkit SPEKTR 3.0, using dose and HVL measurements of X-ray tubes from three different hospitals. It was found good correlation in both applications between the experimental measurements and the calculated HVL and Kair values with Pearson coefficients R² ≥ 0.99 in all cases. However, experimental and calculated HVL have better agreement with Xpektrin (median percent difference -0.43%, -0.04% and 0.01%) than SPEKTR 3.0 (median percent difference -3.31%, 0.10% and -7.85%), particularly for the tube with greater filtration thickness. Xpektrin is optimized to be used in radiology departments for patient dose determination depending on the exposure parameters and may be used as part of a dosimetric record system or as a support for the determination of Diagnostic Reference Levels, which may be useful when no automatic dose records are available. In addition, due to its simulator characteristics, it can be useful as a pedagogical tool. Using Excel allows Xpektrin to be highly distributable and easy to use, without the need for programming skills.

Niveles de referencia para diagnóstico: una herramienta efectiva para la protección radiológica de pacientes / Diagnostic reference levels: an effective tool to radiological protection of patient

Se sabe que las exposiciones médicas con radiaciones ionizantes son actualmente la principal fuente de exposición a la radiación artificial a nivel global. Para prevenir dosis innecesariamente altas durante estas exposiciones a los pacientes, la Comisión Internacional de Protección Radiológica (ICRP) recomienda la utilización de los Niveles de Referencia para Diagnóstico (DRLs), como una herramienta efectiva de ayuda a la optimización de la protección radiológica en la exposición médica de pacientes para diagnóstico y procedimientos de intervención. Dado que la legislación chilena no tiene incorporado aún su uso, el presente trabajo de revisión tiene como objetivo, elaborar un documento guía para los profesionales de la salud y áreas afines, que contenga de manera sucinta y con recomendaciones prácticas, los principales aspectos a tener en cuenta para establecer los DRLs en procedimientos de radiodiagnóstico, intervencionismo y medicina nuclear, basados esencialmente en la publicación N° 135 de la ICRP sobre DRLs.

It is known that medical exposition with ionizing radiation is currently the main exposition source to artificial radiation at global level. To prevent unnecessarily high doses during these patient expositions, the International Commission on Radiological Protection (ICRP) recommends the use of Diagnostic Reference Levels (DRLs), as an effective tool to support the optimization of radiological protection for patient medical exposure for diagnosis and interventional procedures. Since that the Chilean legislation does not have its use incorporated yet, the present revision work aims to elaborate a guiding document for health professionals and related fields, that succinctly and with practical recommendations, the main aspects to consider for establishing DRLs in procedures for radiodiagnostic, intervention, and nuclear medicine, mainly based in N° 135 ICRP publication about DRLs.

Patient Dose Assessment for Common Digital Diagnostic Radiology Examination in Hamad Medical Corporation Hospitals in the State of Qatar.

The aim of this study was to estimate radiation doses to patients undergoing standard radiographic examinations using Computed Radiography (CR) and Direct Digital Radiography (DDR) in two hospitals within Hamad Medical Corporation (HMC) in Qatar, and compare the results with regional and international Diagnostic Reference Levels (DRLs). Data on 3391 patients were recorded from different X-ray rooms in HMC hospitals. Entrance Skin Dose (ESD) was measured for 1046 patients for the most five common X-ray examinations (a total of 7 projections) namely: Skull, Chest, Abdomen, Lumbar Spine and Pelvis. Exposure factors such as kV, mAs and Focal to Skin Distance (FSD) were recorded for each patient. Tube Output was measured for a range of selected kV values. ESD for each individual patient was calculated using the tube output and the technical exposure factors for each examination. The ESD values were compared with some international DRLs for all types of examinations. HMC patient demographic data evaluated from this study were: average age of 39 years, average weight of 60-80 kg and mean height of 165 cm. The most procedure performed during the time of this study was chest PA (52%), and the least procedure performed was skull AP/LAT (1%) examination. The mean ESD values found to be generally lower than the published values. With exception of abdomen examinations at Hamad General Hospital (HGH), mean ESD values were found to be within the established IAEA (DRL). The mean ESD values at HGH were found to be much higher than that at Al Khor Hospital (AKH) for abdomen, Lumbar spine AP, Lumbar Spine LAT and pelvis, but generally lower than the published values.

Patient Radiation Exposure During Diagnostic and Therapeutic Procedures for Intracranial Aneurysms: A Multicenter Study / 신경중재치료의학

PURPOSE: To assess patient radiation doses during cerebral angiography and embolization of intracranial aneurysms across multi-centers and propose a diagnostic reference level (DRL). MATERIALS AND METHODS: We studied a sample of 490 diagnostic and 371 therapeutic procedures for intracranial aneurysms, which were performed at 23 hospitals in Korea in 2015. Parameters including dose-area product (DAP), cumulative air kerma (CAK), fluoroscopic time and total angiographic image frames were obtained and analyzed. RESULTS: Total mean DAP, CAK, fluoroscopy time, and total angiographic image frames were 106.2 ± 66.4 Gy-cm2, 697.1 ± 473.7 mGy, 9.7 ± 6.5 minutes, 241.5 ± 116.6 frames for diagnostic procedures, 218.8 ± 164.3 Gy-cm², 3365.7 ± 2205.8 mGy, 51.5 ± 31.1 minutes, 443.5 ± 270.7 frames for therapeutic procedures, respectively. For diagnostic procedure, the third quartiles for DRLs were 144.2 Gy-cm² for DAP, 921.1 mGy for CAK, 12.2 minutes for fluoroscopy times and 286.5 for number of image frames, respectively. For therapeutic procedures, the third quartiles for DRLs were 271.0 Gy-cm² for DAP, 4471.3 mGy for CAK, 64.7 minutes for fluoroscopy times and 567.3 for number of image frames, respectively. On average, rotational angiography was used 1.5 ± 0.7 times/session (range, 0-4; n=490) for diagnostic procedures and 1.6 ± 1.2 times/session (range, 0-4; n=368) for therapeutic procedures, respectively. CONCLUSION: Radiation dose as measured by DAP, fluoroscopy time and image frames were lower in our patients compared to another study regarding cerebral angiography, and DAP was lower with fewer angiographic image frames for therapeutic procedures. Proposed DRLs can be used for quality assurance and patient safety in diagnostic and therapeutic procedures.

Patient Radiation Dose in Diagnostic and Interventional Procedures for Intracranial Aneurysms: Experience at a Single Center

OBJECTIVE: To assess patient radiation doses during cerebral angiography and embolization of intracranial aneurysms in a large sample size from a single center. MATERIALS AND METHODS: We studied a sample of 439 diagnostic and 149 therapeutic procedures for intracranial aneurysms in 480 patients (331 females, 149 males; median age, 57 years; range, 21-88 years), which were performed in 2012 with a biplane unit. Parameters including fluoroscopic time, dose-area product (DAP), and total angiographic image frames were obtained and analyzed. RESULTS: Mean fluoroscopic time, total mean DAP, and total image frames were 12.6 minutes, 136.6 +/- 44.8 Gy-cm2, and 251 +/- 49 frames for diagnostic procedures, 52.9 minutes, 226.0 +/- 129.2 Gy-cm2, and 241 frames for therapeutic procedures, and 52.2 minutes, 334.5 +/- 184.6 Gy-cm2, and 408 frames for when both procedures were performed during the same session. The third quartiles for diagnostic reference levels (DRLs) were 14.0, 61.1, and 66.1 minutes for fluoroscopy time, 154.2, 272.8, and 393.8 Gy-cm2 for DAP, and 272, 276, and 535 for numbers of image frames in diagnostic, therapeutic, and both procedures in the same session, respectively. The proportions of fluoroscopy in DAP for the procedures were 11.4%, 50.5%, and 36.1%, respectively, for the three groups. The mean DAP for each 3-dimensional rotational angiographic acquisition was 19.2 +/- 3.2 Gy-cm2. On average, rotational angiography was used 1.4 +/- 0.6 times/session (range, 1-4; n = 580). CONCLUSION: Radiation dose in our study as measured by DAP, fluoroscopy time and image frames did not differ significantly from other reported DRL studies for cerebral angiography, and DAP was lower with fewer angiographic image frames for embolization. A national registry of radiation-dose data is a necessary next step to refine the dose reference level.

Disminución de la dosis de radiación en el radiodiagnóstico / Reducing the dose of radiation in diagnostic radiology

El número de procedimientos radiológicos ha tenido un incremento acelerado durante la primera década del siglo XXI, obteniendo un impacto beneficioso sobre la salud. Sin embargo, este incremento conlleva a una mayor exposición a las radiaciones ionizantes. El uso de la radiación ionizante tiene un riesgo inherente, aun cuando el riesgo asociado a un examen radiológico es menor comparado con el riesgo natural, cualquier riesgo añadido, no importa cuán pequeño sea, es inaceptable si no se beneficia el paciente. El concepto de niveles de referencia diagnósticos se debe utilizar para reducir las variaciones en la práctica entre las instituciones y promover rangos óptimos, indicadores de dosis para los protocolos específicos de las diferentes modalidades. En general, los principios básicos de la protección radiológica (justificación, optimización y límite de dosis) deben ser respetados para ayudar a contrarrestar el incremento injustificado en el número de procedimientos que se realizan.

The number of radiological procedures performed has had a rapid increase during the first decade of the 21st century, achieving a beneficial impact on healthcare. However, this increase leads to a greater exposure to ionizing radiation. The use of ionizing radiation has an inherent risk. Although the risk associated with a radiological examination is minor compared to the natural risk, any added risk, no matter how small, is unacceptable if it does not benefit the patient. The concept of diagnostic reference levels should be used to reduce variations in practice among institutions and to promote optimal dose indicator ranges for specific protocols of the different methods. In general, the basic principles of radiation protection (justification, optimization and dose limits) must be followed to reduce the unjustified increase in the number of procedures being performed.