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.

Analytic simulator and image generator of multiple-scattering Compton camera for prompt gamma ray imaging

For prompt gamma ray imaging for biomedical applications and environmental radiation monitoring, we propose herein a multiple-scattering Compton camera (MSCC). MSCC consists of three or more semiconductor layers with good energy resolution, and has potential for simultaneous detection and differentiation of multiple radio-isotopes based on the measured energies, as well as three-dimensional (3D) imaging of the radio-isotope distribution. In this study, we developed an analytic simulator and a 3D image generator for a MSCC, including the physical models of the radiation source emission and detection processes that can be utilized for geometry and performance prediction prior to the construction of a real system. The analytic simulator for a MSCC records coincidence detections of successive interactions in multiple detector layers. In the successive interaction processes, the emission direction of the incident gamma ray, the scattering angle, and the changed traveling path after the Compton scattering interaction in each detector, were determined by a conical surface uniform random number generator (RNG), and by a Klein-Nishina RNG. The 3D image generator has two functions: the recovery of the initial source energy spectrum and the 3D spatial distribution of the source. We evaluated the analytic simulator and image generator with two different energetic point radiation sources (Cs-137 and Co-60) and with an MSCC comprising three detector layers. The recovered initial energies of the incident radiations were well differentiated from the generated MSCC events. Correspondingly, we could obtain a multi-tracer image that combined the two differentiated images. The developed analytic simulator in this study emulated the randomness of the detection process of a multiple-scattering Compton camera, including the inherent degradation factors of the detectors, such as the limited spatial and energy resolutions. The Doppler-broadening effect owing to the momentum distribution of electrons in Compton scattering was not considered in the detection process because most interested isotopes for biomedical and environmental applications have high energies that are less sensitive to Doppler broadening. The analytic simulator and image generator for MSCC can be utilized to determine the optimal geometrical parameters, such as the distances between detectors and detector size, thus affecting the imaging performance of the Compton camera prior to the development of a real system.

¿Son reproducibles las mediciones dosimétricas a bajas dosis en cardiología intervencionista? / Are dosimetric measurements at low doses reproducible in interventional cardiology?

Abstract. There are several methods for measuring the absorbed radiation dose of occupationally exposed professionals, but it is unknown if these are reproducible at low doses. The aim of this study is to determine the level of reproducibility of thermoluminescent dosimeters (TLD) and optically stimulated luminescence dosimeters (OSL) in simulated conditions. A reproducibility study was performed using two types of dosimeters, which were placed in the location of medical interventionist work area inside the catheter laboratory. An anthropomorphic phantom was used as a patient and the same projections, collimation and radiographic techniques that were employed in the past 30 angiographies, an examination considered as low exposure in the context of interventional cardiology. Lin's concordance coefficient correlation was calculated, obtaining a value of -0.006 with a 95% CI of -0.069 to 0.056 for TLD dosimeters with OSL. The data obtained showed poor reproducibility at low doses of radiation.

Resumen. Existen varios métodos para medir la dosis de radiación absorbida por los profesionales ocupacionalmente expuestos, pero se desconoce si estos son reproducibles entre sí a bajas dosis. El objetivo del estudio fue determinar el grado de reproducibilidad entre los dosímetros termoluminiscentes (TLD) y los dosímetros luminiscentes ópticamente estimulados (OSL), en condiciones simuladas. Se realizó un estudio de reproducibilidad, empleando 2 tipos de dosímetros, los cuales se dispusieron en la ubicación de trabajo del médico intervencionista dentro del pabellón. Se empleó un fantoma antropomórfico como paciente y se replicaron las mismas proyecciones, colimación y técnicas radiológicas empleadas en las últimas 30 coronariografías, examen considerado de baja exposición en el contexto de cardiología intervencionista. Se aplicó el coeficiente de correlación de concordancia de Lin, obteniéndose un valor de -0,006 con un IC al 95% de -0,069 a 0,056 para los dosímetros TLD con OSL. Los datos obtenidos mostraron una escasa reproducibilidad a bajas dosis de radiación.

A dose monitoring system for dental radiography

PURPOSE: The current study investigates the feasibility of a platform for a nationwide dose monitoring system for dental radiography. The essential elements for an unerring system are also assessed. MATERIALS AND METHODS: An intraoral radiographic machine with 14 X-ray generators and five sensors, 45 panoramic radiographic machines, and 23 cone-beam computed tomography (CBCT) models used in Korean dental clinics were surveyed to investigate the type of dose report. A main server for storing the dose data from each radiographic machine was prepared. The dose report transfer pathways from the radiographic machine to the main sever were constructed. An effective dose calculation method was created based on the machine specifications and the exposure parameters of three intraoral radiographic machines, five panoramic radiographic machines, and four CBCTs. A viewing system was developed for both dentists and patients to view the calculated effective dose. Each procedure and the main server were integrated into one system. RESULTS: The dose data from each type of radiographic machine was successfully transferred to the main server and converted into an effective dose. The effective dose stored in the main server is automatically connected to a viewing program for dentist and patient access. CONCLUSION: A patient radiation dose monitoring system is feasible for dental clinics. Future research in cooperation with clinicians, industry, and radiologists is needed to ensure format convertibility for an efficient dose monitoring system to monitor unexpected radiation dose.

Does Ad Hoc Coronary Intervention Reduce Radiation Exposure? – Analysis of 568 Patients / Intervenção Coronariana Ad Hoc Reduz a Exposição Radiológica? - Análise em 568 Pacientes

Background:Advantages and disadvantages of ad hoc percutaneous coronary intervention have been described. However little is known about the radiation exposure of that procedure as compared with the staged intervention.Objective:To compare the radiation dose of the ad hoc percutaneous coronary intervention with that of the staged procedureMethods:The dose-area product and total Kerma were measured, and the doses of the diagnostic and therapeutic procedures were added. In addition, total fluoroscopic time and number of acquisitions were evaluated.Results:A total of 568 consecutive patients were treated with ad hoc percutaneous coronary intervention (n = 320) or staged percutaneous coronary intervention (n = 248). On admission, the ad hoc group had less hypertension (74.1% vs 81.9%; p = 0.035), dyslipidemia (57.8% vs. 67.7%; p = 0.02) and three-vessel disease (38.8% vs. 50.4%; p = 0.015). The ad hoc group was exposed to significantly lower radiation doses, even after baseline characteristic adjustment between both groups. The ad hoc group was exposed to a total dose-area product of 119.7 ± 70.7 Gycm2, while the staged group, to 139.2 ± 75.3 Gycm2 (p < 0.001).Conclusion:Ad hoc percutaneous coronary intervention reduced radiation exposure as compared with diagnostic and therapeutic procedures performed at two separate times.

Fundamento:Uma série de vantagens e desvantagens tem sido descrita para a intervenção coronária percutânea ad hoc, como a realizada ao mesmo tempo que o cateterismo diagnóstico, porém pouco se sabe sobre a exposição radiológica desse procedimento, comparado com a intervenção estadiada, ou seja, em dois momentos.Objetivo:Comparar a dose de radiação utilizada na angioplastia ad hoc com a angioplastia estadiada.Métodos:O produto de dose por área e o Kerma total foram mensurados, somando-se ambas as fases de diagnóstico e terapêutica. Além disso, foram computados o tempo total de fluoroscopia e o número de filmagens.Resultados:Um total de 568 pacientes consecutivos foram tratados com intervenção coronária percutânea ad hoc (n = 320) ou estadiada (n = 248). À admissão, o grupo do ad hoc apresentava menos hipertensão (74,1% vs. 81,9%; p = 0,035), dislipidemia (57,8% vs. 67,7%; p = 0,02) e doença triarterial (38,8% vs. 50,4%; p = 0,015). O grupo ad hoc foi exposto a doses significativamente menores de radiação, mesmo após ajuste para as diferenças basais entre os grupos. O grupo ad hoc foi exposto a uma dose de produto de dose por área total de 119,7 ± 70,7 Gycm2 enquanto que os pacientes estadiados foram expostos a uma dose de 139,2 ± 75,3 Gycm2 (p < 0,001).Conclusão:A intervenção coronária percutânea ad hoc reduziu a exposição radiológica, em comparação com procedimentos diagnósticos e terapêuticos realizados em tempos separados.

[Evaluation of the natural gamma radiation level in residential zones and determination of annual effective exposure dose in the residents of Hamadan province, Iran, 2012]

Human is always exposed to natural background ionizing radiation which may have harmful effects; therefore, measurement of the natural background radiation is important. In this study, was measured the dose of effective natural background gamma radiation in indoor residential zones of Hamadan Province. In this cross-sectional study, we selected four stations along the main geographic directions and one in the center of city for measurement of the indoor dose rate in each of the cities in Hamadan Province. Based on the household numbers, some houses were selected randomly in every station and natural background indoor dose was measured by using RDS-110 survey meter. Then, using the results of our previous study about measuring the level of outdoor natural gamma radiation in this province, we determined the level of annual effective exposure dose from natural gamma radiation in Hamadan residents. In Hamadan province cities, maximum and minimum indoor natural background radiation [gamma ray] belonged to Razan City [1.41 +/- 0.079 mSv] and Asadabad City [0.955 +/- 0.044 mSv], respectively. Mean annual equivalent indoor dose in Hamadan Province was 1.20 +/- 0.070 mSv. Also the maximum indoor natural background radiation dose [gamma ray] in the buildings with the age of more and less than 25 years were 1.42 +/- 0.219 mSv and 1.44 +/- 0.149 mSv, respectively. According to the results of this study and our previous study about outdoor gamma natural background radiation, the annual effective dose in Hamadan Province residents was 0.83 mSv. According to the results of this study, it seems that annual effective equivalent dose due to indoor gamma radiation in Hamadan Province exceeded the mean external exposure amount reported by UNSCEAR [0.5 mSv]. Also the annual effective dose due to gamma background radiation in Hamadan Province residents is 0.83 mSv, which is higher than the global average [0.48 mSv] reported by UNSCEAR - 2000. Therefore epidemiological studies to assess the prevalence of chronic diseases associated with natural radiation exposure among Hamadan Province residents are recommended

Evaluación de la radiación recibida por personal y pacientes durante la CPRE en el Uruguay / [Analysis of radiation exposure to medical staff and patients during ERCP in Uruguay].

BACKGROUND: The ERCP procedure requires the use of fluoroscopy with the subsequent exposure to ionizing radiation. The doses received by patients, physicians and assistants in the endoscopy have never been recorded in our area. This analysis describes the findings of the MIRED_Uy study (measuring radiation in digestive endoscopy in Uruguay). Objective. To determine radiation exposure received by patients, physicians and assistants during ERCP. METHODS: Data were collected from 33 procedures conducted by four endoscopists, supported by endoscopy assistants. All staff took basic radiation-protection measures. The magnitudes measured were the kerma area product (KAP) for the patient and the effective dose (E) and the equivalent doses in hand (HM) and lens of the eyes (HC) for the operators. RESULTS: Mean value for PKA was 24 Gy.cm2 (range: 0.04-71) equivalent to 312 chest x-rays. The mean fluoroscopy time was 2.3 minutes (range: 0.45 a 5.70 minutes). The E mean per procedure was 3.69, 5.14 y 3.69 muSv, for physician, first and second assistant respectively. The dose in hand for the physician was 19.4 muSv and the dose in lens was 7.94 muSv. CONCLUSIONS: The first results of measuring ERCP radiation doses in Uruguay are presented These procedures expose the patient and staff to measurable radiation doses, which should be taken into account to minimize their risks.

Dosimetric calibration of CT pencil chamber in cobalt beams / 中国医疗器械杂志

<p><b>OBJECTIVE</b>To explore the dose-length product calibration method for pencil ionization chamber in cobalt beams.</p><p><b>METHODS</b>The PTW TM30009 ionization chamber was placed into the central hole of T40017 head phantom and irradiated 60 s in 20 cm x 20 cm cobalt beam. The charge was collected with UNIDOS electrometer. Absorbed doses were measured with TM30013 0.6 mL farmer-type chamber under the same condition. The CT chamber calibration factor was expressed in dose-length product. Dose linearity and spatial response were also investigated.</p><p><b>RESULTS</b>The calibration factor in dose-length product was derived from measured data. Dose linearity and spatial response were good in cobalt beams.</p><p><b>CONCLUSION</b>It is feasible to calibrate the CT chamber in cobalt beams for patient dose evaluation in MVCT.</p>

Intercomparison of environmental gamma doses measured with A NaI (Tl) survey meter and thermoluminescent dosimeters (TLDs) in the Poonch division of Azad Kashmir, Pakistan / 生物医学与环境科学（英文）

This study presents the intercomparison of the outdoor environmental gamma dose rates measured using a NaI (Tl) based survey meter along with thermoluminescent dosimeters (TLDs) and estimation of excess lifetime cancer risk (ELCR), for the inhabitants of Poonch division of the Azad Kashmir, Pakistan. CaF2: Dy (TLD-200) card dosimeters were installed at height of 1 m from ground at fifteen different locations covering the entire Poonch division comprising of three districts. During three distinct two month time periods within the six month study period, all the installed dosimeters were exposed to outdoor environmental gamma radiations, retrieved and read out at Radiation Dosimetry Laboratory, Health Physics Division, PINSTECH laboratory, Islamabad. The ambient outdoor gamma dose rate measurements were also taken with NaI (Tl) based portable radiometric instrument at 1 m above the ground. To estimate the annual gamma doses, NaI (Tl) based survey data were used for one complete year following the deployment of the dosimeters. The mean annual gamma dose rates measured by TLDs and survey meter were found as 1.47±0.10 and 0.862±0.003 mGy/y respectively. Taking into account a 29% outdoor occupancy factor, the annual average effective dose rate for individuals was estimated as 0.298±0.04 and 0.175±0.03 mSv/y by TLDs and survey meter, respectively. For outdoor exposure, the ELCR was calculated from the TLD and survey meter measurements. The environmental outdoor average annual effective dose obtained in present study are less than the estimated world average terrestrial and cosmic gamma ray dose rate of 0.9 mSv/y reported in UNSCEAR 2000. The possible origins of gamma doses in the area and incompatibilities of results obtained from the two different measurement techniques are also discussed.

Occupational Hazard: Radiation Exposure for the Urologist – Developing a Reference Standard

Introduction To date, there is a paucity of literature offering practicing urologists a reference for the amount of radiation exposure received while surgically managing urolithiasis. This study examines the cumulative radiation exposure of an urologist over 9 months. Materials and Methods We present a case series of fluoroscopic exposures of an experienced stone surgeon operating at an academic comprehensive stone center between April and December 2011. Radiation exposure measurements were determined by a thermoluminescent dosimeter worn on the outside of the surgeon's thyroid shield. Estimations of radiation exposure (mrem) per month were charted with fluoroscopy times, using scatter plots to estimate Spearman's rank correlation coefficients. Results The total 9-month radiation exposure was 87 mrems for deep dose equivalent (DDE), 293 mrem for lens dose equivalent (LDE), and 282 mrem for shallow dose equivalent (SDE). Total fluoroscopy time was 252.44 minutes for 64 ureteroscopies (URSs), 29 percutaneous nephrolithtomies (PNLs), 20 cystoscopies with ureteral stent placements, 9 shock wave lithotripsies (SWLs), 9 retrograde pyelograms (RPGs), 2 endoureterotomies, and 1 ureteral balloon dilation. Spearman's rank correlation coefficients examining the association between fluoroscopy time and radiation exposure were not significant for DDE (p = 0.6, Spearman's rho = 0.2), LDE (p = 0.6, Spearman's rho = 0.2), or SDE (p = 0.6, Spearman's rho = 0.2). Conclusions Over a 9-month period, total radiation exposures were well below annual accepted limits (DDE 5000 mrem, LDE 15,000 mrem and SDE 50,000 mrem). Although fluoroscopy time did not correlate with radiation exposure, future prospective studies can account for co-variates such as patient obesity and urologist distance from radiation source. .

Comparison of dosiology between three dimensional conformal and intensity-modulated radiotherapies (5 and 7 fields) in gastric cancer post-surgery / 华中科技大学学报（医学）（英德文版）

The purpose of this study was to compare the dose distribution of intensity-modulated radiotherapy (IMRT) in 7 and 5 fields as well as 3-D conformal radiotherapy (3D-CRT) plans for gastric cancer using dosimetric analysis. In 15 patients with gastric cancer after D1 resection, dosimetric parameters for IMRT (7 and 5 fields) and 3D-CRT were calculated with a total dose of 45 Gy (1.8 Gy/day). These parameters included the conformal index (CI), homogeneity index (HI), maximum dose spot for the planned target volume (PTV), dose-volume histogram (DVH) and dose distribution in the organs at risk (OAR), mean dose (Dmean), maximal dose (Dmax) in the spinal cord, percentage of the normal liver volume receiving more than 30 Gy (V30) and percentage of the normal kidney volume receiving more than 20 Gy (V20). IMRT (7 and 5 fields) and 3D-CRT achieved the PTV coverage. However, IMRT presented significantly higher CI and HI values and lower maximum dose spot distribution than 3D-CRT (P=0.001). For dose distribution of OAR, IMRT had a significantly lower Dmean and Dmax in spinal cord than 3D-CRT (P=0.009). There was no obvious difference in V30 of liver and V20 of kidney between IMRT and 3D-CRT, but 5-field IMRT showed lower Dmean in the normal liver than other two plans (P=0.001). IMRT revealed favorable tumor coverage as compared to 3D-CRT and IMRT plans. Specifically, 5-field IMRT plan was superior to 3D-CRT in protecting the spinal cord and liver, but this superiority was not observed in the kidney. Further studies are needed to compare differences among the three approaches.

Radiation Safety and Education in the Applicants of the Final Test for the Expert of Pain Medicine

BACKGROUND: The C-arm fluoroscope is known as the most important equipment in pain interventions. This study was conducted to investigate the completion rate of education on radiation safety, the knowledge of radiation exposure, the use of radiation protection, and so on. METHODS: Unsigned questionnaires were collected from the 27 pain physicians who applied for the final test to become an expert in pain medicine in 2011. The survey was composed of 12 questions about the position of the hospital, the kind of hospital, the use of C-arm fluoroscopy, radiation safety education, knowledge of annual permissible radiation dose, use of radiation protection, and efforts to reduce radiation exposure. RESULTS: In this study, although most respondents (93%) had used C-arm fluoroscopy, only 33% of the physicians completed radiation safety education. Even though nine (33%) had received education on radiation safety, none of the physicians knew the annual permissible radiation dose. In comparing the radiation safety education group and the no-education group, the rate of wearing radiation-protective glasses or goggles and the use of radiation badges or dosimeters were significantly higher in the education group. However, in the use of other protective equipment, knowledge of radiation safety, and efforts to reduce radiation exposure, there were no statistical differences between the two groups. CONCLUSIONS: The respondents knew very little about radiation safety and had low interest in their radiation exposure. To make the use of fluoroscopy safer, additional education, as well as attention to and knowledge of practices of radiation safety are required for pain physicians.

[Effective dose rate of radon gas in Jooshan hot spring of Kerman Province]

Human beings are constantly exposed to different radiations that have always been recognized as a health hazard. Radon-222 and its daughter products are major sources of natural radiations and a significant total inhalation dose is related to them. Hence, the measurement of radon activity in the environment has gained an increasing importance. In this study, with the measurement of radon concentration, the indoor radon activity level and radon effective dose rate in Jooshan hot spring were determined. Concentration of radon gas inside the pool of Jooshan hot spring was measured using the active detector Rad7 type and the annual effective dose was estimated for individuals inhaling the indoor air of this pool for a specified period of time. Concentration of indoor air radon gas was 98.3 +/- 4.9 Bq/m3 and for a person staying in the pool twice a week and each time for two hours, the annual effective dose rate, due to the inhalation of radon, equals to 0.06 +/- 0.003 mSv/y. Comparison of the obtained effective dose with the standards of Environmental protection Agency and Health physics Society, it can be concluded that for individuals that normally use Jooshan hot spring pool, the resulted dose is in the recommended range

Radiation exposure and its reduction in the fluoroscopic examination and fluoroscopy-guided interventional radiology

Radiation exposure during fluoroscopy has been of consistent interest because fluoroscopy is used not only for diagnostic purposes such as upper gastrointestinal series but for many minimally-invasive treatments in various clinical fields. In 2000, the International Commission on Radiological Protection published the important report about the avoidance of radiation injuries from medical interventional procedures, and this report defined harm during fluoroscopic-guided interventional procedure and how to reduce the radiation dose of patients and staff. Two aspects of fluoroscopy exposure differ from other types of medical radiation exposure, including computed tomography. One is that the entrance surface dose during an interventional procedure may be very high, so the deterministic effects of radiation such as skin or corneal injury should be emphasized more than stochastic effects such as cancer risk. The other is that the variation in radiation exposure is great for the same kind of procedure, so it is very difficult to generate a reference level for the radiation dose. Therefore, it is necessary to develop a guideline for the use of fluoroscopy through a nationwide survey about irradiation during fluoroscopic examinations and fluoroscopy-guided intervention procedures. In conclusion, radiation exposure by fluoroscopic guided intervention is not negligible, and the practitioner should always aim to reduce radiation exposure during interventional procedures.

Ground-based observations of ultraviolet and total solar radiation in Shenyang, northeast China / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>This work explores the diurnal variation of Solar ultraviolet radiation (UVR) and total solar radiation (TSR) in northeast China, using daily observations of UVR and TSR in Shenyang.</p><p><b>METHODS</b>UVR and TSR measurements were carried out from March 1st, 2006 to December 31st, 2009 in Shenyang, Liaoning province, China (41°51' N, 123°27' E).</p><p><b>RESULTS</b>Both TSR and UVR showed seasonal variation, reaching the highest levels in summer and the lowest in winter. They showed the greatest fluctuation in summer and autumn. The irradiance of TSR and UVR on clear days around the equinoxes and solstices increased substantially compared with the mean seasonal irradiance, especially in autumn. The whole day accumulated dose of UVR in winter was far less than that during the middle part of a summer day (i.e. between 10:00 and 14:00). It was also less than the accumulated summer dose of morning and afternoon (i.e. between 8:00 and 10:00 and 14:00 and 16:00).</p><p><b>CONCLUSION</b>The instant irradiance and daily accumulated amount of UVR are low in Shenyang, especially in autumn and winter. Thus concern about the health effects arising because shortage of UVR in northeast China is warranted.</p>

Lack of Radiation Protection for Endoscopists Performing Endoscopic Retrograde Cholangiopancreatography / 대한소화기학회지

BACKGROUND/AIMS: ERCP using fluoroscopy should be practiced with an adequate radiation protection. However, the awareness of gastrointestinal endoscopists to radiation protection was considered insufficient. In Korea, a country with a rapid increase the number of ERCP procedures, there is no data about radiation protection practices for gastrointestinal endoscopists. The purpose of this study was to investigate current clinical practices and the awareness on radiation protection in ERCP performing physicians in Korea. METHODS: An anonymous questionnaire regarding radiation protection practices was mailed to 100 members of Korean Pancreatobiliary Association who was porforming ERCP. The questionnaire included ERCP volume of each endoscopist, use of protection devices such as apron, thyroid shield, lead glasses and any mobile shield for scattered radiation, and whether they monitored their own radiation exposure dosage. RESULTS: All respondents wore lead aprons during ERCP. While 52.5% of endoscopists answered that they always wear thyroid guards, 26.9% rarely or never wore it. Only 14% wore lead glasses during the procedure and 69% never wore it. The preparation rates of mobile shields or lead curtains were only 14% and 24%, respectively. Only 10% of endoscopists attached an X-ray badge and 66.7% never used it. Moreover, 75% of endoscopists responded that they did not monitor their own exposure dose to radiation during ERCP. CONCLUSIONS: The lack of radiation protection of ERCP endoscopists in Korea was seemed serious. Awareness of radiation hazard should be more concerned and educated in parallel with the preparation of radiation protection equipments.

Efficacy of a Self-designed Protective Lead Shield in Reduction of Radiation Exposure Dose During Endoscopic Retrograde Cholangiopancreatography / 대한소화기학회지

BACKGROUND/AIMS: The increasing use of diagnostic and therapeutic endoscopic retrograde cholangiopancreatography (ERCP) calls for greater consideration of radiation exposure risk to endoscopists and assistants, and emphasizes the proper system of radiation protection. This study was designed to assess the effect of a newly developed, self-designed, protective lead shield. METHODS: A curtain-shaped protective shield composed of seven movable lead plates was developed, each with the following dimensions: depth, 0.1 cm; width, 15 cm; length, 70 cm. The curtain-shaped protective shield was designed to be located between the patient and the endoscopist. Twenty-nine patients (11 men and 18 women) undergoing ERCP between January 2010 and March 2010 were selected for this study. The dose of radiation exposure was recorded with or without the protective lead shield at the level of the head, chest, and pelvis. The measurement was made at 50 cm and 150 cm from the radiation source. RESULTS: The mean patient age was 64 years. The mean patient height and weight was 161.7+/-6.9 cm and 58.9+/-9.9 kg, respectively. The mean body mass index (BMI) was 22.5+/-3.0 kg/m2. Endoscopists received 1522.2+/-537.0 mR/hr without the protective lead shield. At the same distance, radiation exposure was significantly reduced to 68.8+/-88.0 mR/hr with the protective lead shield (p-value<0.0001). The radiation exposure to endoscopists and assistants was significantly reduced by the use of a protective lead shield (p value<0.0001). The amount of radiation exposure during ERCP was related to the patient's BMI (r=0.749, p=0.001). CONCLUSIONS: This self-designed, protective lead shield is effective in protecting endoscopists and assistants from radiation exposure.

Desigualdade social e exposição a campos magnéticos na região metropolitana de São Paulo / Desigualdad social y exposición a campos magnéticos en la región metropolitana de Sao Paulo / Social inequality and exposure to magnetic fields in the metropolitan region of São Paulo, Southeastern Brazil

OBJETIVO: Estimar a prevalência de exposição aos campos magnéticos gerados por linhas de transmissão (LT) e caracterizar a população exposta. MÉTODOS: Informações sobre LT da Região Metropolitana de São Paulo foram fornecidas pelas concessionárias de energia e mapeadas usando sistema de informação geográfica (SIG). Dados demográficos e socioeconômicos foram obtidos por meio do Censo 2000 e incluídos no SIG em outra camada. Foram considerados expostos os domicílios e seus habitantes localizados a uma distância da LT suficiente para gerar um campo magnético 0,3 µT (microteslas). A prevalência foi estimada por meio da área de corredores de exposição ao longo das LT. A largura dos corredores de exposição se baseou em duas abordagens: uma consistiu em larguras pré-definidas pela tensão da LT e a outra por meio de cálculo do campo magnético. As informações socioeconômicas entre expostos e não expostos foram comparadas pela aplicação do teste de duas proporções (α= 5 por cento)...

OBJECTIVE: To estimate the prevalence of exposure to magnetic fields generated by transmission lines (TL) and characterize the exposed population. METHODS: Information about TL in the metropolitan region of São Paulo, Southeastern Brazil, was provided by the electricity companies and mapped out using geographic information system (GIS). Demographic and socioeconomic data were obtained from the 2000 Census and added to the GIS in another layer. Households and their inhabitants that were located at a distance from the TL that was sufficient to generate a magnetic field 0.3 µT (microteslas) were deemed to be exposed. The prevalence was estimated according to the area of the corridors of exposure along the TL. Two approaches were used to delimit the corridor width: one consisted of widths that were predefined by the TL voltage, and the other consisted of calculation of the magnetic field. The socioeconomic information on the exposed and non-exposed populations were compared by applying the two-proportion test (α= 5 percent)...

OBJETIVO: Estimar la prevalencia de exposición a los campos magnéticos generados por líneas de transmisión (LT) y caracterizar la población expuesta. MÉTODOS: Informaciones sobre LT de la Región Metropolitana de São Paulo (Sureste de Brasil) fueron providenciadas por las concesionarias de energía y mapeadas usando el sistema de información geográfica (SIG). Datos demográficos y socioeconómicos fueron obtenidos por medio del Censo 2000 e incluidos en el SIG en otra camada. Fueron considerados expuestos los domicilios y sus habitantes localizados a una distancia de la LT suficiente para generar un campo magnético 0,3 μT (microteslas). La prevalencia fue estimada por medio del área de corredores de exposición a lo largo de las LT. El ancho de los corredores de exposición se basó en dos abordajes: uno consistió en anchos pre-definidos por la tensión de la LT y la otra por medio del cálculo del campo magnético. Las informaciones socioeconómicas entre expuestos y no expuestos fueron comparadas por la aplicación de la prueba de dos proporciones (α=5 por ciento)...

The role of intensity-modulated radiotherapy in head and neck cancer.

Intensity-modulated radiotherapy (IMRT) has been a significant technological advance in the field of radiotherapy in recent years. IMRT allows sparing of normal tissue while delivering radical radiation doses to the target volumes. The role of IMRT for parotid salivary gland sparing in head and neck cancer is well established. The utility of IMRT for pharyngeal constrictor muscle and cochlear sparing requires investigation in clinical trials. The current evidence supporting the use of IMRT in various head and neck subsites has been summarized. Sparing of organs at risk allows for dose-escalation to the target volumes, taking advantage of the steep dose-response relationship for squamous cell carcinomas to improve treatment outcomes in advanced head and neck cancers. However, dose-escalation could result in increased radiation toxicity (acute and late), which has to be studied in detail. The future of IMRT in head and neck cancers lies in exploring the use of biological imaging for dose-escalation using targeted dose painting.

Radiation Exposure and Cancer Mortality Among Nuclear Power Plant Workers: a Meta-analysis / 예방의학회지

OBJECTIVES: We conducted a meta-analysis to investigate the relationship between low external doses of ionizing radiation exposure and the risk of cancer mortality among nuclear power plant workers. METHODS: We searched MEDLINE using key words related to low dose and cancer risk. The selected articles were restricted to those written in English from 1990 to January 2009. We excluded those studies with no fit to the selection criteria and we included the cited references in published articles to minimize publication bias. Through this process, a total of 11 epidemiologic studies were finally included. RESULTS: We found significant decreased deaths from all cancers (SMR = 0.75, 95% CI = 0.62 - 0.90), all cancers excluding leukemia, solid cancer, mouth and pharynx, esophagus, stomach, rectum, liver and gallbladder, pancreas, lung, prostate, lymphopoietic and hematopoitic cancer. The findings of this meta-analysis were similar with those of the 15 Country Collaborative Study conducted by the International Agency for Research on Cancer. A publication bias was found only for liver and gallbladder cancer (p = 0.015). Heterogeneity was observed for all cancers, all cancers excluding leukemia, solid cancer, esophagus, colon and lung cancer. CONCLUSIONS: Our findings of low mortality for stomach, rectum, liver and gallbladder cancers may explained by the health worker effect. Yet further studies are needed to clarify the low SMR of cancers, for which there is no useful screening tool, in nuclear power plant workers.