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Projection X-ray Imaging
摘要： Recent advances in digital detector technology for medical radiography and fluoroscopy have resulted in improved workflow efficiency, operational flexibility, image quality, and diagnostic accuracy. This is attributed to the implementation of portable flat-panel x-ray detector devices able to provide real-time readout, processing, and display of medical images. As a result, digital radiography flat-panel detectors are rapidly replacing computed radiography passive detectors for projection imaging exams and image intensifier detectors for dynamic fluoroscopy exams. Advanced exam capabilities now include digital tomosynthesis and dual-energy radiography; the former is based on rapid acquisition of multiple angle-dependent image projections to synthesize tomographic slabs at selectable depths within the patient, and the latter is based on rapid back-to-back acquisition of the same anatomy at low and high x-ray energies to generate separate soft tissue and bone images. In both situations, superimposition of anatomy is reduced or eliminated, with the possibility of enhanced diagnostic confidence. Increased x-ray absorption efficiency and lower electronic noise of digital radiography detectors compared to computed radiography detectors enable equal image quality at lower patient dose; however, because of a disconnect between image appearance and radiation dose, lower patient dose is not always achieved. Education, training, and implementation of standards such as the International Electrotechnical Commission 62494-1 Digital Radiography Exposure Index are needed to ensure image quality at the lowest appropriate radiation dose. The National Council on Radiation Protection and Measurements can contribute to radiation responsibility in medical imaging by providing guidance on use of digital radiography, including recommendations for acquisition protocols and exposure index standards, for development of radiographic exam diagnostic reference levels, and for oversight of retake and reject analysis.
关键词： x rays,radiation dose,fluoroscopy,National Council on Radiation Protection and Measurements
更新于2025-09-23 15:23:52
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Ambient dose during intraoral radiography with current techniques: Part 1 conversion factor for scattered radiation using a rectangular collimator
摘要： The aim of this study was to establish a conversion factor for assessing the scattered radiation produced during intraoral radiography with a rectangular collimator in areas where the remnant beam is not present. The dose level in the remnant beam will be addressed in another study. A radiological phantom (Rando) in the upright position was exposed to radiation delivered by a Planmeca Intra X-ray unit over 9 exposure geometries (right side of a full mouth series). For each geometry, the scattered radiation dose was measured at 5 locations in the horizontal plane and 4 locations in the vertical plane in front of the patient. The measurements were corrected for background and leakage radiation. An inventory of the distributions of the different geometries with respect to their share of the total workload was created in order to assign the correct weightings of the total ambient scattered radiation for the different geometries. The weightings were used to construct a scattered radiation pattern for a representative mix of exposures. The maximum value found in this pattern was used to arrive at a safe conversion factor. The scattered ambient radiation dose was evenly distributed over the horizontal plane. The scattered ambient radiation dose ranged from 20 to 65% lower in the vertical plane. The conversion factor established for scattered ambient radiation was 0.05 μSv per mAs at 1 meter. This factor is 3-fold lower than the conversion factors reported previously.
关键词： radiation protection,dental radiography,radiation monitoring,Dental Equipment
更新于2025-09-23 15:23:52
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Ambient dose during intra-oral radiography with current techniques: Part 2 quantifying the remnant beam - an <i>in vivo</i> study
摘要： Objectives: (1) To find a safe reference transmission factor for the remnant beam to be used when assessing the remnant beam during intra-oral radiography. (2) To identify factors such as exposure type, side (left or right), gender and age that might significantly affect transmission. Methods: Measurements were performed in the remnant beam during 323 intra-oral exposures of 43 patients. The exposure parameters were 60 kV and 7 mA. These measurements were compared with values in the same setting, but without a patient present to arrive at a transmission value. Differences between types of exposure [bitewing (BW), incisor and canine (IC) periapical, premolar and molar (PM) periapical], exposure side (left or right), gender and age were statistically analysed. The reference value was based on the exposure yielding the highest transmission value, to which a safety margin of two standard deviations (SDs) was added, and then rounding up. Results: The respective mean transmission values (SD) for BW, IC and PM exposures were as follows: 1.78% (1.15%), 0.639% (0.63%) and 2.60% (0.98%). The differences between PM and IC and between BW and IC were significant (p > 0.01). The differences between exposure side, gender and age were not significant. The reference transmission value, which was calculated from the highest mean transmission percentage for PM (2.60%) plus twice the SD (0.98%) and rounding up, was 5%. Conclusions: A transmission factor of 5% could be used to assess the remnant beam during intra-oral radiography. Anterior exposures led to significantly lower transmission values than posterior exposures.
关键词： radiation protection,dental radiography,dental equipment,radiation monitoring
更新于2025-09-23 15:23:52
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Readjustment of abdominal computed tomography protocols in a university hospital: impact on radiation dose
摘要： Objective: To assess the reduction of estimated radiation dose in abdominal computed tomography following the implementation of new scan protocols on the basis of clinical suspicion and of adjusted images acquisition parameters. Materials and Methods: Retrospective and prospective review of reports on radiation dose from abdominal CT scans performed three months before (group A – 551 studies) and three months after (group B – 788 studies) implementation of new scan protocols proposed as a function of clinical indications. Also, the images acquisition parameters were adjusted to reduce the radiation dose at each scan phase. The groups were compared for mean number of acquisition phases, mean CTDIvol per phase, mean DLP per phase, and mean DLP per scan. Results: A significant reduction was observed for group B as regards all the analyzed aspects, as follows: 33.9%, 25.0%, 27.0% and 52.5%, respectively for number of acquisition phases, CTDIvol per phase, DLP per phase and DLP per scan (p < 0.001). Conclusion: The rational use of abdominal computed tomography scan phases based on the clinical suspicion in conjunction with the adjusted images acquisition parameters allows for a 50% reduction in the radiation dose from abdominal computed tomography scans.
关键词： Contrast media,Radiation dose,Radiation protection,Computed tomography,Abdomen
更新于2025-09-23 15:23:52
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Avalia??o do conhecimento de médicos n?o radiologistas sobre aspectos relacionados à radia??o ionizante em exames de imagem
摘要： Objective: To assess the non-radiologist physicians’ knowledge on the use of ionizing radiation in imaging. Materials and Methods: Cross-sectional study utilizing an anonymous questionnaire responded by physicians in clinical and surgical specialties, divided into two parts as follows: one including questions about the physicians’ characteristics, frequency of imaging studies requests and participation in professional updating events, and another part including multiple choice questions approaching general knowledge about radiation, optimization principles and radioprotection. Results: From a total of 309 questionnaires, 120 (38.8%) were responded, 50% by physicians in surgical specialties and 50% in clinical specialties; respectively 45% and 2.5% of physicians responded that magnetic resonance imaging and ultrasonography use ionizing radiation. Overall, the average grade was higher for surgical specialists with no significant difference, except for the question about exposure in pregnant women (p = 0.047). Physicians who are professionally updated, particularly those attending clinical meetings (p = 0.050) and participating in teaching activities (p = 0.047), showed statistically superior knowledge about ionizing radiation as compared with others. Conclusion: The non-radiologist physicians’ knowledge is heterogeneous and in some points needs to be improved. Multidisciplinary clinical meetings and teaching activities are important ways to disseminate information on the subject.
关键词： Questionnaire.,Knowledge,Ionizing radiation,Imaging diagnosis,Physicians,Radiation protection
更新于2025-09-23 15:22:29
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Assessment of image quality and exposure parameters of an intraoral portable X rays device
摘要： Objective: To evaluate the exposure parameters, radiation protection, absorbed dose and radiographic image quality of the DIOX? intraoral portable radiography device. Materials and methods: The exposure parameters were measured using the Xi UNFORS detector. Operator exposure to secondary radiation was measured using the 1800cc ionization chamber coupled to the electrometer. The absorbed dose (D) in the patient was calculated using TLD-100H positioned in the Alderson RANDO anthropomorphic simulator. The quality of the radiographic digital image was assessed by comparing radiographic images obtained from two convencional devices (CS 2200- Carestream Health?; Heliodent plus- Sirona Dental Systems GMbH?) with the radiological simulator of the upper molar region (RMI) (Radiation Measurements Instruments), using three acquisition sensors : Kodak RVG 5000? and Kodak PSP?, Eastman Kodak Company, Rochester, NY, USA; EVO Micro Image?, Brazil. Results: The DIOX intraoral portable radiographic device demonstrated reliability in relation to the performance of the standard evaluated parameters, except for the diameter of the radiation field (5.8mm) less or greater. No evidence of device head radiation was detected. The Pb lead protection of the apparatus attenuates the secondary radiation, thus protecting the operator. However, it was observed that the region of the operator’s gonads was the most exposed during the measurements. In the Alderson RANDO anthropomorphic simulator, the highest value of D was in the region corresponding to the submandibular and lingual glands of the left side (0.568mGy). The image quality of the DIOX portable radiographic apparatus presented quality standards equivalent to those produced by the two conventional radiographic devices. Conclusion: The DIOX? intraoral portable radiography device demonstrated reliability in relation to the quality control and radioprotection criteria, according to international standards. Results obtained demonstrated the safe use of the DIOX? intraoral portable radiography device and indicated the need for debate and change in international sanitary oversight standards regarding the use of portable XR devices in dentistry.
关键词： Radiation Protection,Radiography, Dental, Digital,Thermoluminescent Dosimetry
更新于2025-09-23 15:21:01
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Light-Emitting Diodes (LEDS)
摘要： Since the original ICNIRP Statement was published in 2000, there have been significant improvements in the efficiency and radiance (i.e., optical radiation emission) of LEDs. The most important improvement is the development of ‘white’ LEDs that can be used as general lighting sources, which are more efficient than traditional lighting sources. LEDs emitting in the ultraviolet wavelength region have also become available and have made their way into consumer products. All these changes have led to a rise in concern for the safety of the optical radiation emissions from LEDs. Several in vitro and animal studies have been conducted, which indicate that blue and white LEDs can potentially cause retinal cell damage under high irradiance and lengthy exposure conditions. However, these studies cannot be directly extrapolated to normal exposure conditions for humans, and equivalent effects can also be caused by the optical radiation from other light sources under extreme exposure conditions. Acute damage to the human retina from typical exposure to blue or white LEDs has not been demonstrated. Concern for potential long-term effects, e.g. age-related macular degeneration (AMD), remains based on epidemiological studies indicating a link between high levels of exposure to sunlight and AMD. When evaluating the optical radiation safety of LEDs, it has now been established that published safety standards for lamps, not lasers, should be applied. Thus far, the only clear, acute adverse health effects from LEDs are those due to temporal light modulation (including flicker). Glare can also create visual disturbances when LED light fixtures are not properly designed. Further research is needed on potential health effects from short- and long-term exposure to new and emerging lighting technologies.
关键词： safety standards,radiation, non-ionizing,International Commission on Non Ionizing Radiation Protection,health effects
更新于2025-09-19 17:13:59
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Nrf2 played an important role in radiation protection effect of low-level laser exposed on umbilical cord mesenchymal stem cell
摘要： To investigate the protective function of low-level laser irradiation (LLLI) against ionizing irradiation and explore the molecular mechanism of photomodulation of Nrf2 protein, the impact of LLLI (635 nm, 5.7 J/cm2) before 2 Gy gamma ray radiation of radio-sensitive tissue hematopoietic stem cells was evaluated. As a result, reduced levels of reactive oxygen species and increased expression of antioxidant enzymes were detected. Moreover, increased expression of Nrf2 was observed after LLLI, whereas brusatol pretreatment before LLLI abolished this effect. In vivo, transplantation of human umbilical cord mesenchymal stem cells (hUC-MSCs) was employed for therapy of hematopoietic function in an acute radiation sickness (H-ARS) mouse model, which was induced by 6-Gy ionizing irradiation; different hUC-MSC pretreatments including LLLI and Nrf2 RNAi were accounted for during experimental grouping. LLLI treatment of cells significantly increased the erythrocyte count and number of myelopoiesis clones (P < 0.05), but such improvements were reduced by Nrf2 RNAi pretreatment compared with cells transplanted without intervention. Therefore, LLLI may improve the radiation protection effect through molecular mechanisms related to the Nrf2 antioxidant pathway.
关键词： Radiation protection,Nrf2,LLLI
更新于2025-09-19 17:13:59
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X-ray radiation protection aspects during ultrashort laser processing
摘要： Ultrashort pulse laser processing of materials allows for precise machining with high accuracy. By increasing the repetition rate to several 100 kHz, laser machining becomes quick and cost-effective. Ultrafast laser processing at high repetition rates and peak intensities above 1013 W/cm2 can cause a potential hazard by generation of unwanted x-ray radiation. Therefore, radiation protection must be considered. For 925 fs pulse duration at a center wavelength of 1030 nm, the x-ray emission in air at a repetition rate of 400 kHz was investigated up to a peak intensity of 2.6 × 1014 W/cm2. Based on the presented measurements, the properties of potential shielding materials will be discussed. By extending our previous works, a scaling of the x-ray radiation emission to higher peak intensities up to 1015 W/cm2 is described, and emitted x-ray doses are predicted.
关键词： laser-induced x-ray emission,ultrashort pulse laser processing,laser ablation,radiation protection
更新于2025-09-16 10:30:52
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Evaluation of synergistic effects of the single walled carbon nanotube and CeO2-hybrid based-nanocomposite against X-ray radiation in diagnostic radiology
摘要： Unwanted exposure during irradiation in diagnostic procedures can be very harmful to health. Researchers have done extensive studies on heavy metals and their composites to prevent or reduce this risk. However, the disadvantages, such as high weight, rigidity or toxicity, limit the use of heavy metals. So far, great efforts have been devoted to designing and manufacturing lightweight /effective protective coatings that could attenuate or absorb radiation. In this regard, polymer composites are considered as potent materials. In the present study, the protective properties of polydimethylsiloxane hybrid nanocomposites containing single wall carbon nanotube (SWCNT) and cerium oxide nanoparticles (nanoceria) have been evaluated. The exposure tests on these coatings were performed by a diagnostic X-ray machine in the radiology department of the Urmia Imam Khomeini Hospital. To evaluate the amount of attenuation, beam intensity was measured at two narrow and broad beam geometries (NBG & BBG). The measurement procedures were well chosen according to the related Standards. The Field Emission Scanning Electron Microscope (FESEM) was applied in order to investigate the nanocomposite morphology and dispersion properties of nanoparticles. Thermal stability and chemical composition of the nanocomposites were studied by thermogravimetric analysis (TGA) and Fourier-transform infrared spectroscopy (FTIR), respectively. FTSEM images and elemental analysis proved that nanoparticle showed excellent dispersion into the polymeric matrix. The attenuation improved significantly compared to the polydimethylsiloxane pure coating. The rate of attenuation increases with increasing nanoceria percentage and ultimately the hybrid sample has a better efficiency than the sample with a similar percentage of the nanoceria.
关键词： nanoceria,Radiation protection,diagnostic radiology,polydimethylsiloxane
更新于2025-09-12 10:27:22