scholarly journals Evaluation of stray radiation to the operator for five hand-held dental X-ray devices

2019 ◽  
Vol 48 (5) ◽  
pp. 20180301 ◽  
Author(s):  
Richard Smith ◽  
Richard Tremblay ◽  
Graeme M Wardlaw
Keyword(s):  
Digital Image ◽  
Protected Area ◽  
Ionization Chamber ◽  
Portable Devices ◽  
X Ray ◽  
Air Kerma ◽  
Tissue Equivalent ◽  
Stray Radiation ◽  
The Mean ◽  
Occupational Radiation

Objectives: Evaluate stray radiation to the operator, as represented by a plane within the significant zone of occupancy (SZO), produced by five models of hand-held intraoral dental X-ray devices (HIDXDs). Methods: The stray radiation for five models of HIDXDs was measured, using an anthropomorphic tissue-equivalent head phantom as a scattering object. An ionization chamber was used to measure the air kerma (μGy) at 63 positions in a 160 cm high by 60 cm wide plane that was 10 cm behind the X-ray device, identified as being within the SZO. Results: Based on the measured air kerma from stray radiation of five different HIDXDs, the estimated annual air kerma at all measured spatial positions was calculated. When calculated using a median air kerma of 0.8 mGy at the distal end of the cone, as typically required for digital image receptors, 1 the ranges for estimated annual air kerma in the SZO across the devices were 0.14–0.77 mGy for the median, 0.41–1.01 mGy for the mean, and 1.32–2.55 mGy for the maximum. Similarly, when calculated using a median air kerma of 1.6 mGy as typically required for D-speed film, 2 the ranges for estimated annual air kerma across the devices were 0.28–1.54 mGy for the median, 0.83–2.03 mGy for the mean, and 2.64–5.10 mGy for the maximum. Conclusions: From measured air kerma values of stray radiation in the SZO, estimated annual exposures to the operator for HIDXDs are expected to be greater than from conventional wall-mounted or portable devices activated from a protected area (at a distance or behind shielding). HIDXDs should therefore only be used when patient accessibility makes their use necessary and the use of a portable device on a stand or a wall-mounted device is not reasonably feasible. This approach would keep occupational radiation exposures of dental workers as low as reasonably achievable.

scholarly journals Comparison of entrance surface air kerma measurement with MTS-N (LiF: Mg, Ti) chips with a kilovoltage X-ray source

2021 ◽  
Vol 22 (1) ◽  
pp. 20-34
Author(s):  
Akintayo Daniel Omojola ◽  
Samuel Olaolu Adeneye ◽  
Michael Onoriode Akpochafor ◽  
Isiaka Olusola Akala ◽  
Azuka Anthonio Agboje
Keyword(s):  
Ionization Chamber ◽  
Radiation Detectors ◽  
Field Size ◽  
Peak Voltage ◽  
X Ray ◽  
Air Kerma ◽  
Image Distance ◽  
The Mean ◽  
Dose Accuracy ◽  
Entrance Surface Air Kerma

Objective: Radiation detectors are key components that ensure the accuracy and performances of dosimetry equipment. The study is aimed to compare the mean entrance surface air kerma (ESAK) between a DCT-10mm ionization chamber (IC) and MTS-N (LiF: Mg, Ti) chips when both detectors are exposed to ≤ 5mGy with a 10 by 10 field size, with an X-ray source and to determine the accuracy of the Thermoluminescent (TL) chips. Also, the dose will be compared to similar studies. Materials and Methods: A functional, Digital Radiography (DR) X-ray System was used. A DCT-10mm ionization chamber (IC) and an XR Multidetector was positioned at a Source to Image Distance (SID) of 100cm on polystyrene, about 20cm thick. An X-ray spectrum generated at a Practical Peak Voltage (PPV) of 60-107kV with Half Value Layer (HVL) of 2.4-4.3mmAl and filtration > 3mmAl was used. The same setup was used for the MTS-N chips. Results: The mean doses for 1-5 mGy with the MTS-N chips were 1.07±0.07, 1.60±0.13, 2.23±0.11, 2.58±0.07 and 3.45±0.10 mGy respectively, with accuracies of 7, 20, 26, 36 and 31%. Dose accuracy at 1and 2mGy was within 25% respectively. Dose accuracies at 3, 4 and 5mGy was within >25%. The correction factor for 1-5mGy was 0.94, 1.25, 1.35, 1.55 and 1.45 respectively. Conclusion: Validation of the MTS-N chips with the reference ionization chamber to this study was within 36%. The Radiation and Nuclear Safety Authority (STUK) recommends that ESAK be within 25% for entrance surface dose. ESAK accuracy mostly increased with dose as observed in this study.

Impact of considering non-occupational radiation exposure on the association between occupational dose and solid cancer among French nuclear workers

2017 ◽  
Vol 75 (3) ◽  
pp. 199-204 ◽  
Author(s):  
Lucie Fournier ◽  
Enora Cléro ◽  
Eric Samson ◽  
Sylvaine Caër-Lorho ◽  
Dominique Laurier ◽  
...  
Keyword(s):  
Occupational Exposure ◽  
Cancer Risk ◽  
Radiation Exposure ◽  
Cancer Mortality ◽  
Environmental Radiation ◽  
Occupational Radiation Exposure ◽  
X Ray ◽  
Work Related ◽  
The Mean ◽  
Occupational Radiation

ObjectivesThe French nuclear worker cohort allows for the assessment of cancer risk associated with occupational radiation exposure, but workers are also exposed to medical and environmental radiation which can be of the same order of magnitude. This study aims to examine the impact of non-occupational radiation exposures on the dose-risk analysis between occupational radiation exposure and cancer mortality.MethodsThe cohort included workers employed before 1995 for at least one year by CEA, AREVA NC or EDF and badge-monitored for external radiation exposure. Monitoring results were used to calculate occupational individual doses. Scenarios of work-related X-ray and environmental exposures were simulated. Poisson regression was used to quantify associations between occupational exposure and cancer mortality adjusting for non-occupational radiation exposure.ResultsThe mean cumulative dose of external occupational radiation was 18.4 mSv among 59 004 workers. Depending on the hypotheses made, the mean cumulative work-related X-ray dose varied between 3.1 and 9.2 mSv and the mean cumulative environmental dose was around 130 mSv. The unadjusted excess relative rate of cancer per Sievert (ERR/Sv) was 0.34 (90% CI −0.44 to 1.24). Adjusting for environmental radiation exposure did not substantially modify this risk coefficient, but it was attenuated by medical exposure (ERR/Sv point estimate between 0.15 and 0.23).ConclusionsOccupational radiation risk estimates were lower when adjusted for work-related X-ray exposures. Environmental exposures had a very slight impact on the occupational exposure risk estimates. In any scenario of non-occupational exposure considered, a positive but insignificant excess cancer risk associated with occupational exposure was observed.

The empirical formula for calculating the incident air Kerma in intraoral radiographic imaging

2021 ◽  
pp. 20210117
Author(s):  
Zoran Mirkov ◽  
Katarina M Rajković ◽  
Jovan B Stanković ◽  
Dario Faj
Keyword(s):  
Empirical Formula ◽  
Measurement Data ◽  
Radiographic Imaging ◽  
Relative Percentage ◽  
X Ray ◽  
Air Kerma ◽  
Final Formula ◽  
Average Patient ◽  
The Mean ◽  
Fitted Function

Objectives: The aim of this paper is to determine the empirical formula for calculating the incident air kerma (Ki), used as a patient dose descriptor in the intraoral radiographic imaging. Methods: The data for the formula were collected during the regular annual inspection of intraoral dental X-ray units in 2018, 2019 and early 2020. The measurement data of 50 X-ray units were processed to develop the formula. Exposure factors for imaging molars of the upper jaw of an average patient in a clinical setting were used in the measurement. The formula validity was statistically evaluated using coefficient of correlation, standard error of the fitted function and the mean relative percentage deviation. Results: measurement values of the radiation doses and calculated values obtained by using the final formula showed good agreement - the mean relative percentage deviation values less than ±15%. Conclusions: Although there are differences in X-ray units, voltages, manufacturers and device architectures (single-phase and high-frequency), the measurement data comply well with computed ones in all cases.

Practical method for determination of air kerma by use of an ionization chamber toward construction of a secondary X-ray field to be used in clinical examination rooms

2016 ◽  
Vol 9 (2) ◽  
pp. 193-201 ◽  
Author(s):  
Itsumi Maehata ◽  
Hiroaki Hayashi ◽  
Natsumi Kimoto ◽  
Kazuki Takegami ◽  
Hiroki Okino ◽  
...  
Keyword(s):  
Clinical Examination ◽  
Ionization Chamber ◽  
Practical Method ◽  
X Ray ◽  
Air Kerma

scholarly journals A Study of Entrance Surface Air Kerma for Patients Undergoing Chest and Abdomen from Digital Radiography at Chulabhorn Hospital

2019 ◽  
Vol 37 (1) ◽  
pp. 51
Author(s):  
Atchara Promduang ◽  
Napapong Pongnapang ◽  
Napat Ritlumlert ◽  
Sutthirak Tangruangkiat ◽  
Monchai Phonlakrai
Keyword(s):  
Digital Radiography ◽  
Computed Radiography ◽  
Energy Agency ◽  
X Ray ◽  
Code Of Practice ◽  
Air Kerma ◽  
Technical Report Series ◽  
Male Patients ◽  
The Mean ◽  
Entrance Surface Air Kerma

Objective: The main purpose of this study was to investigate the typical dose for standard-sized patients in chest (posteroanterior; PA) and abdomen (anteroposterior; AP) digital radiography.Material and Methods: The air kerma was measured by the ionization chamber (Radical Corporation, model 10X6-6) in X-ray equipment manufactured by General Electric Healthcare Definium 8000 System for different kilovoltage peak (kVp) settings in each X-ray examination. The entrance surface air kerma (ESAK) was determined in 422 mediumsized patients in different projections: chest (PA) and abdomen (AP), according to the recommended protocol of the International Atomic Energy Agency Technical Report Series Number 457 (Technical Reports Series No. 457 “Dosimetry in Diagnostic Radiology: An International Code of Practice).Results: The mean entrance surface air kerma values for chest (PA) radiography in female and male patients were 0.08 milligray (mGy) and 0.09 mGy, respectively and for abdomen (AP) radiography for both genders were 0.98 mGy and 1.06 mGy, respectively.Conclusion: The mean entrance surface air kerma values of this study were less than the diagnostic reference levels from the IAEA 1996, Korea 2007, United Kingdom 2010 and Japan 2015, in all projections. Patient doses (ESAK) in chest (PA) and abdomen (AP) digital radiography at Chulabhorn Hospital were less than the other guidelines, because of the use of a high kVp technique for the chest and the automatic exposure control for the abdomen. Furthermore, Thai people are smaller than Westerners. We studied in digital radiography only that literally provides lowest radiation dose compares with screen film and computed radiography.

PROPOSED NATIONAL DIAGNOSTIC REFERENCE LEVELS FOR STANDARD RADIOGRAPHIC X-RAY PROCEDURES IN SUDAN

2020 ◽  
Vol 190 (4) ◽  
pp. 419-426
Author(s):  
Nada A Ahmed ◽  
E H Basheir ◽  
A B Farah ◽  
T S Mohammedzein ◽  
I I Suliman
Keyword(s):  
Lumbar Spine ◽  
Dose Optimization ◽  
Radiation Doses ◽  
Diagnostic Reference Levels ◽  
Reference Levels ◽  
X Ray ◽  
Air Kerma ◽  
Tube Output ◽  
The Mean ◽  
Entrance Surface Air Kerma

Abstract This study aimed to calculate patient radiation doses for adults during the seven most commonly performed conventional X-ray procedures, and to propose national diagnostic reference levels (DRLs). A representative sample of patients from 29 hospitals was included. The entrance surface air kerma (ESAK) was calculated by measuring X-ray tube output and the corresponding technical and exposure factors for each patient. Third-quartile values of the mean ESAK distributions were proposed as DRL values. The DRLs in mGy were as follows: 0.6 for chest postero–anterior (PA), 3.5 for skull AP, 1.7 for skull lateral (LAT), 2.7 for abdominal, 2.6 for pelvic AP, 3.7 for lumbar spine AP and 8 for lumbar spine LAT. Compared with literature, the maximum percentages increase were in chest PA (329%) and skull AP (187%). Since the suggested DRL for chest PA was higher than literature values, dose optimization and a review of its value is recommended.

INTRAORAL DENTAL X-RAY RADIOGRAPHY IN BOSNIA AND HERZEGOVINA: STUDY FOR REVISING DIAGNOSTIC REFERENCE LEVEL VALUE

2020 ◽  
Vol 190 (1) ◽  
pp. 90-99
Author(s):  
Jovica Praskalo ◽  
Adnan Beganović ◽  
Jovana Milanović ◽  
Koviljka Stanković
Keyword(s):  
Bosnia And Herzegovina ◽  
Digital Image ◽  
Reference Level ◽  
Diagnostic Reference Level ◽  
X Ray ◽  
The Third ◽  
Air Kerma ◽  
Dental Procedures ◽  
Maxilla And Mandible ◽  
Area Product

Abstract This paper presents the study that would allow a revision of the currently valid diagnostic reference level in intraoral dental X-ray radiography in Bosnia and Herzegovina. The study was conducted for six procedures that are used to capture incisor, premolar and molar teeth, of both maxilla and mandible, in adults. Measurements were performed on 41 intraoral X-ray devices, 20 of which were systems with digital image receptor and 21 film-based X-ray systems. In this study, incident air kerma (Ki) and air kerma-area product (PKA) were used as patient dose descriptors. The third quartile (Q3) of the measured incident air-kerma values was used to compare with the current national diagnostic reference level (DRL) for intraoral dental procedures. The obtained results of Q3 for both types of devices, with film-based and digital image receptors, have shown that the third quartile values are lower (3.5 and 1.2 mGy, respectively) than the current national DRL (7.0 mGy). Hence, new data can be used to re-establish the diagnostic reference levels in intraoral dental X-ray examinations in Bosnia and Herzegovina.

scholarly journals Update on Hand-Held X-Ray Devices in Dentistry: a Literature Review

2021 ◽  
pp. 190-197
Author(s):  
Lucía Barba Ramírez ◽  
Deivi Cascante-Sequeira
Keyword(s):  
Radiation Dose ◽  
Literature Review ◽  
Protected Area ◽  
Portable Devices ◽  
X Rays ◽  
Portable Equipment ◽  
X Ray ◽  
Inherent Risk ◽  
Lower Radiation Dose ◽  
Improper Use

In the last two decades, the use of portable intraoral X-ray devices, stabilized by the operator, has increased. While all radiographic devices present an inherent risk from ionizing radiation, improper use of portable devices can increase operator exposure. Use of portable devices on a tripod or powered from a protected area is recommended. However, in highly justified cases, for using without these accessories, recommendations should be followed to reduce operator exposure. Because radioprotection is essential when using X-rays, fixed dental radiographic devices should be favored over portable equipment since the first provides a lower radiation dose to the operator.

scholarly journals Dosimetry of Occupational Radiation around Panoramic X-ray Apparatus

2017 ◽  
Author(s):  
A H Pakravan ◽  
S M R Aghamiri ◽  
T Bamdadian ◽  
M Gholami ◽  
M Moshfeghi
Keyword(s):  
Side Effects ◽  
Occupational Exposure ◽  
Ionizing Radiation ◽  
Absorbed Dose ◽  
Atomic Energy ◽  
X Ray ◽  
Panoramic Imaging ◽  
Significant Difference ◽  
The Mean ◽  
Occupational Radiation

Background: Panoramic imaging is one of the most common imaging methods in dentistry. Regarding the side-effects of ionizing radiation, it is necessary to survey different aspects and details of panoramic imaging. In this study, we compared the absorbed x-ray dose around two panoramic x-ray units: PM 2002 CC Proline (Planmeca, Helsinki, Finland) and Cranex Tome (Soredex, Helsinki, Finland).Materials and Methods: In order to estimate x-ray dose, 15 thermoluminescet dosemeters (TLD-100) were placed in 3 semi-circles of 40cm, 80cm and 120cm radii. Around each unit, the number of TLDs in each semi-circle was 5 with equal intervals. The center of semicircles accords with the patient’s position. Each TLD was exposed 40 times. These dosemeters were read out with a Harshaw Model 4000 TLD Reader (USA). The calibration processing and the reading of dosemeters were performed by the Atomic Energy Organization of Iran.Results: The mean absorbed dose in three lines of PM 2002 CC Proline was 123.2±15.1, 118.0±11.0 and 108.0±9.1 µSv, (p=0.013). The results were 140.4±15.2, 120.2±10.4 and 111.6±11.2 µSv in Cranex Tome (p=0.208), which reveals no significant difference between two systems.Conclusion: There are no significant differences between the mean absorbed dose of surveyed models in panoramic imaging by two units (PM 2002 CC Proline and Cranex Tome). These results were less than occupational exposure recommended by ICRP, even at the highest calculated doses.

Isomorphous replacement in electron diffraction of wet crystals of rat hemoglobin

1983 ◽  
Vol 41 ◽  
pp. 446-447
Author(s):  
William F. Tivol ◽  
Murray Vernon King ◽  
D. F. Parsons
Keyword(s):  
Electron Diffraction ◽  
Heavy Atom ◽  
Isomorphous Substitution ◽  
X Ray Diffraction ◽  
Salt Solutions ◽  
X Ray ◽  
Isomorphous Replacement ◽  
Structure Factors ◽  
Diffraction Structure ◽  
The Mean

Feasibility of isomorphous substitution in electron diffraction is supported by a calculation of the mean alteration of the electron-diffraction structure factors for hemoglobin crystals caused by substituting two mercury atoms per molecule, following Green, Ingram & Perutz, but with allowance for the proportionality of f to Z3/4 for electron diffraction. This yields a mean net change in F of 12.5%, as contrasted with 22.8% for x-ray diffraction.Use of the hydration chamber in electron diffraction opens prospects for examining many proteins that yield only very thin crystals not suitable for x-ray diffraction. Examination in the wet state avoids treatments that could cause translocation of the heavy-atom labels or distortion of the crystal. Combined with low-fluence techniques, it enables study of the protein in a state as close to native as possible.We have undertaken a study of crystals of rat hemoglobin by electron diffraction in the wet state. Rat hemoglobin offers a certain advantage for hydration-chamber work over other hemoglobins in that it can be crystallized from distilled water instead of salt solutions.

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