oalib

Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99

Submit

Any time

2019 ( 40 )

2018 ( 116 )

2017 ( 122 )

2016 ( 141 )

Custom range...

Search Results: 1 - 10 of 5179 matches for " Radiation Dosage "
All listed articles are free for downloading (OA Articles)
Page 1 /5179
Display every page Item
Dosimetric Comparison between Bone and Target Matching Considering Interfractional Prostate Motion in Volumetric Modulated Arc Therapy  [PDF]
Ryuta Nakahara, Kentaro Ishii, Nobuhide Wakai, Ryu Kawamorita, Wataru Okada, Shun Kishimoto, Kazuki Kubo, Toshifumi Nakajima, Masatoshi Hasegawa
International Journal of Medical Physics,Clinical Engineering and Radiation Oncology (IJMPCERO) , 2018, DOI: 10.4236/ijmpcero.2018.71005
Abstract: Adequate matching methods are critical for accurate volumetric-modulated arc therapy (VMAT). We investigated the dosimetric differences in the target and organs at risk (OARs) between bone matching and target matching in patients with prostate cancer treated with VMAT. The relationship between the dosimetric differences and interfractional motion of the prostate was also evaluated. Forty patients with prostate cancer classified as intermediate risk were enrolled in a study to assess the differences in dosimetry between two matching methods. These patients were treated with VMAT and prescribed dose was 78 Gy. The dose distribution was calculated using cone-beam computed tomography (CBCT) for this study. We selected clinical target volume (CTV) as the target, and the rectum and bladder as the OARs. The Dmean, D98, D95, and D2 to the target and V10-V70 to the OARs were calculated as different dose from target matching value minus bone matching value. Multiple regression analysis was used to evaluate the effect of interfractional motion of the prostate on the differences in dose. The CTV D95 values differed by -0.22 ± 1.01 Gy (mean ± standard deviation). Rectum and bladder V70 values differed by 4.6% ± 7.2% and -2.6% ± 7.2%, respectively. There was a correlation between interfractional motion of the prostate and the dose differences to OARs (R2 = 0.73 - 0.94). The dose differences to OARs also varied depending on the direction of the prostate’s motion. We found that bone matching resulted in an increased rectal dose and high risk of decreasing dose to the CTV.
Tempo de radia??o emitida por fluoroscopia em cirurgias ortopédicas
La Salvia, Jo?o Caron;Moraes, Pablo Reis de;Ammar, Tiago Yossef;Schwartsmann, Carlos Roberto;
Revista Brasileira de Ortopedia , 2011, DOI: 10.1590/S0102-36162011000200003
Abstract: objective: to ascertain the mean length of radiation emission from fluoroscopic devices during several types of orthopedic surgery and which of these required greater use of radiation. methods: the times taken to perform sixteen different types of surgery (total of 80 procedures) were measured. at the end of each procedure, the length of time for which fluoroscopy was used directly from the image intensifier was ascertained. results: the mean time required for fluoroscopy per operation was 61 seconds. the procedures that demanded greatest mean duration of radiation use were bilateral proximal femoral epiphysiodesis (5.1 minutes) and femoral shaft osteosynthesis using a locked intramedullary nail (3.33 min). conclusion: the mean duration of fluoroscopy use in orthopedic operations was 61 seconds. the procedures using an intramedullary device were the ones that required greatest radiation emission.
Radiación ionizante secundaria generada en equipos de cineangiografía coronaria digital y analógica: influencia de los sistemas externos de protección radiológica
Ramírez N,Alfredo; Farias Ch,Eric; Silva J,Ana María; Oyarzún C,Carlos; Leyton L,Fernando; Ugalde P,Héctor; Dussaillant N,Gastón; Cumsille G,Miguel Angel;
Revista médica de Chile , 2000, DOI: 10.4067/S0034-98872000000800004
Abstract: background: exposure to ionizing radiation is a known hazard of radiological procedures. aim: to compare the emission of secondary ionizing radiation from two coronary angiographic equipments, one with digital and the other with analog image generation. to evaluate the effectiveness of external radiological protection devices. material and methods: environmental and fluoroscopy generated radiation in the cephalic region of the patient was measured during diagnostic coronary angiographies. ionizing radiation generated in anterior left oblique projection (alo) and in anterior right oblique projection (aro) were measured with and without leaded protections. in 19 patients (group 1), a digital equipment was used and in 21 (group 2), an analog equipment. results: header radiation for groups 1 and 2 was 1194 ± 337 and 364 ± 222 μgray/h respectively (p<0.001). during fluoroscopy and with leaded protection generated radiation for groups 1 and 2 was 612 ± 947 and 70 ± 61 μgray/h respectively (p<0.001). for alo projection, generated radiation for groups 1 and 2 was 105 ± 47 and 71 ± 192 μgray/h respectively (p<0.001). during filming the radiation for alo projection for groups 1 and 2 was 7252 ± 9569 and 1671 ± 2038 μgray/h respectively (p = 0.03). out of the protection zone, registered radiation during fluoroscopy for groups 1 and 2 was 2800 ± 1741 and 1318 ± 954 μgray/h respectively (p < 0.001); during filming, the figures were 15500 ± 5840 and 18961 ± 10599 μgray/h respectively (ns). conclusions: digital radiological equipment has a lower level of ionizing radiation emission than the analog equipment. (rev méd chile 2000; 128: 853-62).
Radiación ionizante secundaria generada en equipos de cineangiografía coronaria digital y analógica: influencia de los sistemas externos de protección radiológica Secondary ionizing radiation generated by analog and digital coronary cineangiographic equipment: Influence of external protection devices
Alfredo Ramírez N,Eric Farias Ch,Ana María Silva J,Carlos Oyarzún C
Revista médica de Chile , 2000,
Abstract: Background: Exposure to ionizing radiation is a known hazard of radiological procedures. Aim: To compare the emission of secondary ionizing radiation from two coronary angiographic equipments, one with digital and the other with analog image generation. To evaluate the effectiveness of external radiological protection devices. Material and methods: Environmental and fluoroscopy generated radiation in the cephalic region of the patient was measured during diagnostic coronary angiographies. Ionizing radiation generated in anterior left oblique projection (ALO) and in anterior right oblique projection (ARO) were measured with and without leaded protections. In 19 patients (group 1), a digital equipment was used and in 21 (group 2), an analog equipment. Results: Header radiation for groups 1 and 2 was 1194 ± 337 and 364 ± 222 μGray/h respectively (p<0.001). During fluoroscopy and with leaded protection generated radiation for groups 1 and 2 was 612 ± 947 and 70 ± 61 μGray/h respectively (p<0.001). For ALO projection, generated radiation for groups 1 and 2 was 105 ± 47 and 71 ± 192 μGray/h respectively (p<0.001). During filming the radiation for ALO projection for groups 1 and 2 was 7252 ± 9569 and 1671 ± 2038 μGray/h respectively (p = 0.03). Out of the protection zone, registered radiation during fluoroscopy for groups 1 and 2 was 2800 ± 1741 and 1318 ± 954 μGray/h respectively (p < 0.001); during filming, the figures were 15500 ± 5840 and 18961 ± 10599 μGray/h respectively (NS). Conclusions: Digital radiological equipment has a lower level of ionizing radiation emission than the analog equipment. (Rev Méd Chile 2000; 128: 853-62).
Effects of a radiation dose reduction strategy for computed tomography in severely injured trauma patients in the emergency department: an observational study
Soo Hyun Kim, Seung Eun Jung, Sang Hoon Oh, Kyu Nam Park, Chun Song Youn
Scandinavian Journal of Trauma, Resuscitation and Emergency Medicine , 2011, DOI: 10.1186/1757-7241-19-67
Abstract: We implemented the radiation dose reduction strategy in May 2009. A prospective observational study design was used to collect data from patients who met the inclusion criteria during this one year study (intervention group) from May 2009 to April 2010. The prospective data were compared with data collected retrospectively for one year prior to the implementation of the radiation dose reduction strategy (control group). By comparison of the cumulative effective dose and the number of CT examinations in the two groups, we evaluated effects of a radiation dose reduction strategy. All the patients met the institutional adult trauma team activation criteria. The radiation doses calculated by the CT scanner were converted to effective doses by multiplication by a conversion coefficient.A total of 118 patients were included in this study. Among them, 33 were admitted before May 2009 (control group), and 85 were admitted after May 2009 (intervention group). There were no significant differences between the two groups regarding baseline characteristics, such as injury severity and mortality. Additionally, there was no difference between the two groups in the mean number of total CT examinations per patient (4.8 vs. 4.5, respectively; p = 0.227). However, the mean effective dose of the total CT examinations per patient significantly decreased from 78.71 mSv to 29.50 mSv (p < 0.001).The radiation dose reduction strategy for CT in severely injured trauma patients effectively decreased the cumulative effective dose of the total CT examinations in the emergency department. But not effectively decreased the number of CT examinations.Over the last decade, the use of computed tomography (CT) scanning has approximately doubled, and CT scanning represents approximately two thirds of the total effective radiation dose in the United States [1]. Particularly in trauma patients, CT has become an essential diagnostic tool for treatment. Accordingly, the utilization of CT has increased ove
Angiografía coronaria por tomografía computarizada multidetector con gatillado electrocardiográfico prospectivo: análisis de la calidad de imagen y de la dosis de radiación
Carrascosa,Patricia; Capu?ay,Carlos; Deviggiano,Alejandro; Tajer,Carlos D.; Vallejos,Javier; Goldsmit,Alejandro; García,Mario J.;
Revista argentina de cardiolog?-a , 2009,
Abstract: background multidetector row computed tomography coronary angiography (mdct-ca) has become a useful diagnostic tool for the direct quantification of coronary stenosis, for identifying coronary anomalies and for the assessment of coronary artery bypass grafts. despite its clinical value has been questioned due to the effective radiation dose (erd) received by each patient, radiation exposure is similar to other studies. however, different strategies are permanently tested in order to reduce the erd maintaining adequate and diagnostic image quality. objectives to determine the image quality and effective radiation dose (erd) of prospective electrocardiogram-gated multidetector row computed tomography coronary angiography (pmdctca) (the x-ray beam is turned on for only a short portion of diastole) compared to retrospective ecg gating (rmdctca) (the x-ray beam is turned on throughout the cardiac cycle) and a preliminary approach of its diagnostic accuracy compared to digital invasive coronary angiography (ca). material and methods fifty consecutive patients with suspected coronary artery disease and sinus rhythm were evaluated with pmdct-ca and compared to a control group who underwent rmdctca. image quality was analyzed by two reviewers. interobserver concordance and erd were determined. the diagnostic accuracy of pmdct-ca compared to ca to detect coronary artery stenosis > 50% was assessed in 30 patients. results there were no significant differences in the image quality between both groups. agreement between the reviewers for segment image quality scores was k = 0.92. mean erd was 3.5 msv for pmdct-ca compared to 9.7 and 12.9 msv for rmdct-ca with and without tube current modulation, respectively. individual analysis including all segments showed that the sensitivity, specificity, positive predictive value and negative predictive value of pmdct-ca for the detection of coronary stenosis were 94.74%, 81.82%, 90% and 90%, respectively. conclusion our initial experience
Es suficiente la protección otorgada por gafas plomadas en cardiología intervencionista? Protection against ionizing radiation by leaded glass googles during interventional cardiology
Claudio Zett-Lobos,Felipe Vera-Mu?oz,Katerina Arriola-Alvarez,Oscar Díaz-Ramos
Revista médica de Chile , 2013,
Abstract: Background: It is not known whether leaded glass goggles with 0.25 mm Pb equivalency, used in interventional cardiology procedures, attenuate radiation below the levels established by the latest recommendation of the International Commission on Radiological Protection (ICRP). Aim: To assess ifthe degree of attenuation of the secondary ionizing radiation achieved by the use of 0.25 mm Pb leaded glass goggles, in occupationally exposed workers in interventional cardiology procedures, meets the latest ICRP recommendations. Material and Methods: A prospective investigation was carried out to compare the eye exposure to secondary ionizing radiation received by occupationally exposed personnel in a 9 months period. A set of two thermo luminescent dosimeters was arranged in the front and back of leaded glass goggles in a cohort ofseven members of an interventional cardiology service, exposed to 1057 consecutive procedures. Results: The monthly dose equivalent measurement performed in front ofthe goggles ranged between 1.1 and 6.5 mSv, for paramedics and interventional cardiologists. The radiation measured in the back of the glass varied between 0.66 and 2.75 mSv, respectively. The degree of attenuation of the dose at eye level ranged from 40% to 57.7%, respectively. The projected annual exposure would reach 33 mSvfor the interventional cardiologist. Conclusions: With a similar load ofwork and wearing 0.25 mm Pb equivalent glass goggles, interventional cardiologists will exceed the crystalline equivalent dose limit recommended by the ICRP (20 mSv/year averaged over the past 5 years).
Rotational Angiography for 3D Roadmapping of Catheter Interventions in Congenital Heart Disease: Comparison of a Diagnostic and a Low Dose Program  [PDF]
Carolina Thoenes, Robert Cesnjevar, Sven Dittrich, Martin Gl?ckler
Open Journal of Radiology (OJRad) , 2016, DOI: 10.4236/ojrad.2016.63028
Abstract: Objectives: To compare the image quality, accuracy and effective dose of the default diagnostic pro-gram with the low dose program. Methods: The diagnostic and low dose programs of three-dimen-sional rotational angiography were compared considering their signal to noise ratio, their carrier to noise ratio and their actual radiation dose in μGym2/kg. An anthropomorphic phantom underwent both types of scans to evaluate the effective dose. Comparative measurements of vessel diameters were taken in the diagnostic and the low dose program and compared to the angiography as exact basis. The image quality of the scans using the different programs was rated by a specialist physician. Results: The low dose scan does use significantly less radiation and still provides images, which are adequate for 3D navigation of catheter-based interventions. Conclusion: Three-dimensional rotational angiography can be applied with the low dose program and is sufficient for 3D navigation.
Clinicians’ justification of imaging: do radiation issues play a role?
Lars Borgen,Erling Stranden,Ansgar Espeland
Insights into Imaging , 2010, DOI: 10.1007/s13244-010-0029-4
Abstract: Limited radiation knowledge and guideline use indicate suboptimal justification of referrals. When justifying imaging, weighting of radiation dose may play a larger role than detailed radiation knowledge.
The Role of Ionizing Radiation in the Etiology of Cancer
Cem UZAL,Murat CALOGLU
Trakya Universitesi Tip Fakultesi Dergisi , 2002,
Abstract: Every biological organism on earth is exposed to both ionizing and non-ionizing radiation and to their effects. The main sources of radiation are present in nature (sun, earth), but radiation can also be produced artificially. Ionizing radiation causes brakes in the chemical bonds of molecules in the cell and also in chromosomes, resulting in DNA strand brakes called mutations. These mutations may result in cell death or, in the long term, transformation into a cancer cell. However, as a cause of cancer, ionizing radiation comes after smoking and bad nutritional habits. An important reduction in cancer incidence can be achieved by elimination of smoking, improved nutritional habits, and avoidance of cancerogens and excessive exposure to sunlight.
Page 1 /5179
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.