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1.  Diagnostic reference levels in intraoral dental radiography in Korea 
Imaging Science in Dentistry  2012;42(4):237-242.
Purpose
The objectives of this study were to survey the radiographic exposure parameters, to measure the patient doses for intraoral dental radiography nationwide, and thus to establish the diagnostic reference levels (DRLs) in intraoral dental X-ray examination in Korea.
Materials and Methods
One hundred two intraoral dental radiographic machines from all regions of South Korea were selected for this study. Radiographic exposure parameters, size of hospital, type of image receptor system, installation duration of machine, and type of dental X-ray machine were documented. Patient entrance doses (PED) and dose-area products (DAP) were measured three times at the end of the exit cone of the X-ray unit with a DAP meter (DIAMENTOR M4-KDK, PTW, Freiburg, Germany) for adult mandibular molar intraoral dental radiography, and corrections were made for room temperature and pressure. Measured PED and DAP were averaged and compared according to the size of hospital, type of image receptor system, installation duration, and type of dental X-ray machine.
Results
The mean exposure parameters were 62.6 kVp, 7.9 mA, and 0.5 second for adult mandibular molar intraoral dental radiography. The mean patient dose was 2.11 mGy (PED) and 59.4 mGycm2 (DAP) and the third quartile one 3.07 mGy (PED) and 87.4 mGycm2 (DAP). Doses at university dental hospitals were lower than those at dental clinics (p<0.05). Doses of digital radiography (DR) type were lower than those of film-based type (p<0.05).
Conclusion
We recommend 3.1 mGy (PED), 87.4 mGycm2 (DAP) as the DRLs in adult mandibular molar intraoral dental radiography in Korea.
doi:10.5624/isd.2012.42.4.237
PMCID: PMC3534178  PMID: 23301210
Radiation Protection; Radiation Dosage; Radiography, Dental
2.  Establishment of diagnostic reference levels in computed tomography for select procedures in Pudhuchery, India 
Computed tomography (CT) scanner under operating conditions has become a major source of human exposure to diagnostic X-rays. In this context, weighed CT dose index (CTDIw), volumetric CT dose index (CTDIv), and dose length product (DLP) are important parameter to assess procedures in CT imaging as surrogate dose quantities for patient dose optimization. The current work aims to estimate the existing dose level of CT scanner for head, chest, and abdomen procedures in Pudhuchery in south India and establish dose reference level (DRL) for the region. The study was carried out for six CT scanners in six different radiology departments using 100 mm long pencil ionization chamber and polymethylmethacrylate (PMMA) phantom. From each CT scanner, data pertaining to patient and machine details were collected for 50 head, 50 chest, and 50 abdomen procedures performed over a period of 1 year. The experimental work was carried out using the machine operating parameters used during the procedures. Initially, dose received in the phantom at the center and periphery was measured by five point method. Using these values CTDIw, CTDIv, and DLP were calculated. The DRL is established based on the third quartile value of CTDIv and DLP which is 32 mGy and 925 mGy.cm for head, 12 mGy and 456 mGy.cm for chest, and 16 mGy and 482 mGy.cm for abdomen procedures. These values are well below European Commission Dose Reference Level (EC DRL) and comparable with the third quartile value reported for Tamil Nadu region in India. The present study is the first of its kind to determine the DRL for scanners operating in the Pudhuchery region. Similar studies in other regions of India are necessary in order to establish a National Dose Reference Level.
doi:10.4103/0971-6203.125509
PMCID: PMC3931229  PMID: 24600173
Computed tomography; CTDIw; CTDIv; dose length product; dose reference level; pencil ionization chamber; polymethylmethacrylate phantom
3.  Establishment of local diagnostic reference levels for quality control in intraoral radiography 
Oral Radiology  2016;33(1):38-44.
Objective
To investigate the dosage and imaging conditions for patients undergoing intraoral radiography at Meikai University Hospital and establish assurance and quality control data.
Methods
Tube voltage, exposure time, and air kinetic energy released per unit mass (air kerma) of three intraoral radiography units were measured. To calculate the patient entrance dose (PED) for each radiograph using Insight film, we extracted data for 1063 patients from their exposure records. The PED was compared with the diagnostic reference level (DRL) from the European Commission and the UK.
Results
The tube voltage of the three units was maintained at 60 ± 2 kV. Differences in exposure time were less than 1.7 % for all units. The air kerma rates were well maintained within a 4.2 % error. Based on the patient data, there were no significant differences in the mean exposure times for males and females for all anatomical sites. The mean PED ranged from 1.09 ± 0.31 mGy for the mandibular incisors to 2.42 ± 0.33 mGy for the maxillary molars. The mean PED at the mandibular molars using InSight film was 1.59 ± 0.20 mGy, being less than the recommended value based on the DRL for intraoral radiography in the UK.
Conclusions
We concluded that radiographic conditions at the hospital have been properly maintained. This basic quality control data may assist other dental radiation facilities to reduce patient dosage.
doi:10.1007/s11282-016-0245-9
PMCID: PMC5216092
Patient entrance dose (PED); Diagnostic reference level (DRL); Intraoral radiography; Radiation dosage
4.  Assessment of paediatric CT dose indicators for the purpose of optimisation 
The British Journal of Radiology  2012;85(1019):1488-1498.
Objectives
To establish local diagnostic reference levels (LDRLs) at the Royal Children's Hospital (RCH) Melbourne, Parkville, Australia, for typical paediatric CT examinations and compare these with international diagnostic reference levels (DRLs) to benchmark local practice. In addition, the aim was to develop a method of analysing local scan parameters to enable identification of areas for optimisation.
Methods
A retrospective audit of patient records for paediatric CT brain, chest and abdomen/pelvis examinations was undertaken. Demographic information, examination parameters and dose indicators—volumetric CT dose index (CTDIvol) and dose–length product (DLP)—were collected for 220 patients. LDRLs were derived from mean survey values and the effective dose was estimated from DLP values. The normalised CTDIvol values, mAs values and scan length were analysed to better identify parameters that could be optimised.
Results
The LDRLs across all age categories were 18–45 mGy (CTDIvol) and 250–700 mGy cm (DLP) for brain examinations; 3–23 mGy (CTDIvol) and 100–800 mGy cm (DLP) for chest examinations; and 4–15 mGy (CTDIvol) and 150–750 mGy cm (DLP) for abdomen/pelvis examinations. Effective dose estimates were 1.0–1.6 mSv, 1.8–13.0 mSv and 2.5–10.0 mSv for brain, chest and abdomen/pelvis examinations, respectively.
Conclusion
The RCH mean CTDIvol and DLP values are similar to or lower than international DRLs. Use of low-kilovoltage protocols for body imaging in younger patients reduced the dose considerably. There exists potential for optimisation in reducing body scan lengths and justifying the selection of reference mAs values. The assessment method used here proved useful for identifying specific parameters for optimisation.
Advances in knowledge
Assessment of individual CT parameters in addition to comparison with DRLs enables identification of specific areas for CT optimisation.
doi:10.1259/bjr/28015185
PMCID: PMC3500792  PMID: 22844033
5.  Dose indices in dental cone beam CT and correlation with dose–area product 
Dentomaxillofacial Radiology  2013;42(5):20120362.
Objectives:
In the 2011 project “Safety and efficacy of a new and emerging dental X-ray modality (SEDENTEXCT)”, it was suggested that dose index (DI) and dose–area product (DAP) could be easily measured and used as diagnostic reference levels (DRLs), which would help in the management of radiation doses to patients in optimum exposure settings. Such indices could be directly related to effective dose. The purposes of this study, therefore, were to measure and calculate the DI and DAP in cone beam CT (CBCT) machines and to evaluate the correlation between the two.
Methods:
Dose measurements were performed on three-dimensional cone beam CT (3D-CBCT) machines [3D Accuitomo (J. Morita Mfg. Corp., Kyoto, Japan), Veraviewepocs (J. Morita Mfg. Corp.) and CS9300 (Carestream, New York, NY)] by exposing a cylindrical poly-methyl methacrylate (PMMA) phantom using a CT ionization chamber. These dose measurements were used for the calculation of Dose Indices 1 and 2, according to the methodology suggested by SEDENTEXCT. The DAP was measured using a DAP meter that was attached to the detector to cover the entire irradiated area.
Results:
The DI1 ranged from 53.6 mR to 216.6 mR, the DI2 ranged from 77.1 mR to 325.0 mR and the DAP ranged from 101.1 mGy cm2 to 457.9 mGy cm2, depending on the machines and exposure settings. Index 2 had a better correlation with the DAP than Index 1.
Conclusions:
The DIs and DAP proposed by SEDENTEXCT may be useful for establishing DRLs for dental CBCT machines; however, further studies are necessary to determine which of these indices provide accurate dose estimates proportionally relating to the effective dose.
doi:10.1259/dmfr.20120362
PMCID: PMC3635780  PMID: 23520392
cone beam computed tomography; dose index; dose area product; diagnostic reference levels
6.  Patient Radiation Exposure During Diagnostic and Therapeutic Procedures for Intracranial Aneurysms: A Multicenter Study 
Neurointervention  2016;11(2):78-85.
Purpose
To assess patient radiation doses during cerebral angiography and embolization of intracranial aneurysms across multi-centers and propose a diagnostic reference level (DRL).
Materials and Methods
We studied a sample of 490 diagnostic and 371 therapeutic procedures for intracranial aneurysms, which were performed at 23 hospitals in Korea in 2015. Parameters including dose-area product (DAP), cumulative air kerma (CAK), fluoroscopic time and total angiographic image frames were obtained and analyzed.
Results
Total mean DAP, CAK, fluoroscopy time, and total angiographic image frames were 106.2 ± 66.4 Gy-cm2, 697.1 ± 473.7 mGy, 9.7 ± 6.5 minutes, 241.5 ± 116.6 frames for diagnostic procedures, 218.8 ± 164.3 Gy-cm2, 3365.7 ± 2205.8 mGy, 51.5 ± 31.1 minutes, 443.5 ± 270.7 frames for therapeutic procedures, respectively. For diagnostic procedure, the third quartiles for DRLs were 144.2 Gy-cm2 for DAP, 921.1 mGy for CAK, 12.2 minutes for fluoroscopy times and 286.5 for number of image frames, respectively. For therapeutic procedures, the third quartiles for DRLs were 271.0 Gy-cm2 for DAP, 4471.3 mGy for CAK, 64.7 minutes for fluoroscopy times and 567.3 for number of image frames, respectively. On average, rotational angiography was used 1.5 ± 0.7 times/session (range, 0-4; n=490) for diagnostic procedures and 1.6 ± 1.2 times/session (range, 0-4; n=368) for therapeutic procedures, respectively.
Conclusion
Radiation dose as measured by DAP, fluoroscopy time and image frames were lower in our patients compared to another study regarding cerebral angiography, and DAP was lower with fewer angiographic image frames for therapeutic procedures. Proposed DRLs can be used for quality assurance and patient safety in diagnostic and therapeutic procedures.
doi:10.5469/neuroint.2016.11.2.78
PMCID: PMC5018552  PMID: 27621943
Cerebral angiography; Cerebral embolization; Diagnostic reference levels; Radiation dose
7.  Establishment of CT diagnostic reference levels in Ireland 
The British Journal of Radiology  2012;85(1018):1390-1397.
Objective
To propose Irish CT diagnostic reference levels (DRLs) by collecting radiation doses for the most commonly performed CT examinations.
Methods
A pilot study investigated the most frequent CT examinations. 40 CT sites were then asked to complete a survey booklet to allow the recording of CT parameters for each of 9 CT examinations during a 12-week period. Dose data [CT volume index (CTDIvol) and dose–length product (DLP)] on a minimum of 10 average-sized patients in each category were recorded to calculate a mean site CTDIvol and DLP value. The rounded 75th percentile was used to calculate a DRL for each site and the country by compiling all results. Results are compared with international DRL data.
Results
Data were collected for 3305 patients. 30 sites responded with data for 34 scanners, representing 54% of the national total. All equipment had multislice capability (2–128 slices). DRLs are proposed using CTDIvol (mGy) and DLP (mGy cm) for CT head (66/58 and 940, respectively), sinuses (16 and 210, respectively), cervical spine (19 and 420, respectively), thorax (9/11 and 390, respectively), high resolution CT (7 and 280, respectively), CT pulmonary angiography (13 and 430, respectively), multiphase abdomen (13 and 1120, respectively), routine abdomen/pelvis (12 and 600, respectively) and trunk examinations (10/12 and 850, respectively). These values are lower than current DRLs and comparable to other international studies. Wide variations in mean doses are noted across sites.
Conclusions
Baseline figures for Irish CT DRLs are provided on the most frequently performed CT examinations. The variations in dose between CT departments as well as between identical scanners suggest a large potential for optimisation of examinations.
doi:10.1259/bjr/15839549
PMCID: PMC3474022  PMID: 22595497
8.  Radiation Dose to Newborns in Neonatal Intensive Care Units 
Iranian Journal of Radiology  2012;9(3):145-149.
Background
With the increase of X-ray use for medical diagnostic purposes, knowing the given doses is necessary in patients for comparison with reference levels. The concept of reference doses or diagnostic reference levels (DRLs) has been developed as a practical aid in the optimization of patient protection in diagnostic radiology.
Objectives
To assess the radiation doses to neonates from diagnostic radiography (chest and abdomen). This study has been carried out in the neonatal intensive care unit of a province in Iran.
Patients and Methods
Entrance surface dose (ESD) was measured directly with thermoluminescent dosimeters (TLDs). The population included 195 neonates admitted for a diagnostic radiography, in eight NICUs of different hospital types.
Results
The mean ESD for chest and abdomen examinations were 76.3 µGy and 61.5 µGy, respectively. DRLs for neonate in NICUs of the province were 88 µGy for chest and 98 µGy for abdomen examinations that were slightly higher than other studies. Risk of death due to radiation cancer incidence of abdomens examination was equal to 1.88 × 10 -6 for male and 4.43 × 10 -6 for female. For chest X-ray, it was equal to 2.54 × 10 -6 for male and 1.17 × 10 -5 for female patients.
Conclusion
DRLs for neonates in our province were slightly higher than values reported by other studies such as European national diagnostic reference levels and the NRPB reference dose. The main reason was related to using a high mAs and a low kVp applied in most departments and also a low focus film distance (FFD). Probably lack of collimation also affected some exams in the NICUs.
doi:10.5812/iranjradiol.8065
PMCID: PMC3522370  PMID: 23329980
Intensive Care Units; Neonatal; Radiation Dosimetry
9.  Dose audit for patients undergoing two common radiography examinations with digital radiology systems 
PURPOSE
We aimed to determine the radiation doses delivered to patients undergoing general examinations using computed or digital radiography systems in Turkey.
MATERIALS AND METHODS
Radiographs of 20 patients undergoing posteroanterior chest X-ray and of 20 patients undergoing anteroposterior kidney-ureter-bladder radiography were evaluated in five X-ray rooms at four local hospitals in the Ankara region. Currently, almost all radiology departments in Turkey have switched from conventional radiography systems to computed radiography or digital radiography systems. Patient dose was measured for both systems. The results were compared with published diagnostic reference levels (DRLs) from the European Union and International Atomic Energy Agency.
RESULTS
The average entrance surface doses (ESDs) for chest examinations exceeded established international DRLs at two of the X-ray rooms in a hospital with computed radiography. All of the other ESD measurements were approximately equal to or below the DRLs for both examinations in all of the remaining hospitals. Improper adjustment of the exposure parameters, uncalibrated automatic exposure control systems, and failure of the technologists to choose exposure parameters properly were problems we noticed during the study.
CONCLUSION
This study is an initial attempt at establishing local DRL values for digital radiography systems, and will provide a benchmark so that the authorities can establish reference dose levels for diagnostic radiology in Turkey.
doi:10.5152/dir.2013.12122
PMCID: PMC4463244  PMID: 24317331
10.  Dose Assessment in Computed Tomography Examination and Establishment of Local Diagnostic Reference Levels in Mazandaran, Iran 
Background
Medical X-rays are the largest man-made source of public exposure to ionizing radiation. While the benefits of Computed Tomography (CT) are well known in accurate diagnosis, those benefits are not risk-free. CT is a device with higher patient dose in comparison with other conventional radiation procedures.
Objective
This study is aimed at evaluating radiation dose to patients from Computed Tomography (CT) examination in Mazandaran hospitals and defining diagnostic reference level (DRL).
Methods
Patient-related data on CT protocol for four common CT examinations including brain, sinus, chest and abdomen & pelvic were collected. In each center, Computed Tomography Dose Index (CTDI) measurements were performed using pencil ionization chamber and CT dosimetry phantom according to AAPM report No. 96 for those techniques. Then, Weighted Computed Tomography Dose Index (CTDIW), Volume Computed Tomography Dose Index (CTDI vol) and Dose Length Product (DLP) were calculated.
Results
The CTDIw for brain, sinus, chest and abdomen & pelvic ranged (15.6-73), (3.8-25. 8), (4.5-16.3) and (7-16.3), respectively. Values of DLP had a range of (197.4-981), (41.8-184), (131-342.3) and (283.6-486) for brain, sinus, chest and abdomen & pelvic, respectively. The 3rd quartile of CTDIW, derived from dose distribution for each examination is the proposed quantity for DRL. The DRLs of brain, sinus, chest and abdomen & pelvic are measured 59.5, 17, 7.8 and 11 mGy, respectively.
Conclusion
Results of this study demonstrated large scales of dose for the same examination among different centers. For all examinations, our values were lower than international reference doses.
PMCID: PMC4681462  PMID: 26688796
Diagnostic Reference Levels; Computed Tomography; Mazandaran; CTDI; DLP
11.  Radiation dose in coronary angiography and intervention: initial results from the establishment of a multi-centre diagnostic reference level in Queensland public hospitals 
Introduction
Radiation dose to patients undergoing invasive coronary angiography (ICA) is relatively high. Guidelines suggest that a local benchmark or diagnostic reference level (DRL) be established for these procedures. This study sought to create a DRL for ICA procedures in Queensland public hospitals.
Methods
Data were collected for all Cardiac Catheter Laboratories in Queensland public hospitals. Data were collected for diagnostic coronary angiography (CA) and single-vessel percutaneous intervention (PCI) procedures. Dose area product (PKA), skin surface entrance dose (KAR), fluoroscopy time (FT), and patient height and weight were collected for 3 months. The DRL was set from the 75th percentile of the PKA.
Results
2590 patients were included in the CA group where the median FT was 3.5 min (inter-quartile range = 2.3–6.1). Median KAR = 581 mGy (374–876). Median PKA = 3908 uGym2 (2489–5865) DRL = 5865 uGym2. 947 patients were included in the PCI group where median FT was 11.2 min (7.7–17.4). Median KAR = 1501 mGy (928–2224). Median PKA = 8736 uGym2 (5449–12,900) DRL = 12,900 uGym2.
Conclusion
This study established a benchmark for radiation dose for diagnostic and interventional coronary angiography in Queensland public facilities.
doi:10.1002/jmrs.67
PMCID: PMC4175852
Coronary angiography; coronary intervention; diagnostic reference level; radiation dose
12.  Radiation dose to patients from X-ray radiographic examinations using computed radiography imaging system 
The screen-film system is replaced by computed radiography system for recording the images of the patients during X-ray radiography examinations. The change in imaging system requires the re-establishment of the institutional diagnostic reference levels (DRLs) for different types of X-ray examinations conducted at the hospital. For this purpose, patient specific parameters [age, height, weight, body mass index (BMI), object to image distance (OID)] and machine specific parameters (kVp, mAs, distance and field sizes) of 1875 patients during 21 different types of X-ray examinations were recorded for estimating the entrance skin dose (ESD). The ESD for each of these patients were estimated using measured X-ray beam output and the standard value of the back scatter factor. Five number summary was calculated for all the data for their presentation in the Box-Whisker plot, which provides the statistical distribution of the data. The data collected indicates that majorly performed examinations are cervical spine AP, Chest PA and Knee Lat with percentage contributions of 16.05, 16 and 8.27% respectively. The lowest contribution comes from Hip Lat which is about 1.01%. The ratio of measured ESD (maximum to minimum) for these examinations is found to be highest for the cervical spine AP with a value of 50 followed by Thoracic spine AP of 32.36. The ESD ratio for Chest PA, Knee Lat and Lumbar Spine AP are 30.75, 30.4 and 30.2 respectively. The lowest ESD ratio is for Hip Lat which is 2.68. The third quartile values of ESDs are established as the institutional DRLs. The ESD values obtained for 21 different X-ray projections are either comparable or lesser than the reported national/international values.
doi:10.4103/0971-6203.152244
PMCID: PMC4471642  PMID: 26150685
Patient dose; entrance skin dose; diagnostic reference level; computed radiography; CR imaging system; X-ray machine; X-ray imaging
13.  Evaluation of surface radiation dose to the thyroid gland and the gonads during routine full-mouth intraoral periapical and maxillary occlusal radiography 
Aim:
The quantitative aspects of radiation doses to critical organs can help the dental professionals to take the necessary radiation protective measures as deemed necessary and can help the general public to allay radiation exposure fear in dental radiography, if any. Our study determines the surface radiation dose to thyroid and gonads in full-mouth intraoral periapical (IOPA) and maxillary occlusal radiography.
Materials and Methods:
A total number of 120 subjects participated in the study. The surface radiation dose was estimated to the thyroid gland and the gonads in full-mouth IOPA radiography using 10 IOPA (E speed films) and in maxillary occlusal radiography. The measurements were calculated using a digital pocket dosimeter (PD-4507).
Results:
The average dose at the thyroid gland level during full-mouth intraoral and maxillary occlusal radiography was estimated to be 10.93 mRads (1.093 × 10-2 mGy) and 0.4 mRads (4.0 × 10-2 mGy), respectively. The average surface radiation dose at the gonadal region during a full mouth intraoral and maxillary occlusal radiography was estimated to be 1.5 mRads (1.5 × 10-2 mGy) and 0.15 mRads (1.5 × 10-3 mGy), respectively.
Conclusion:
Our results suggest that although the radiation exposure doses to critical organs namely thyroid and gonads is within the safe limits still precautionary measures for these organs are advocated.
doi:10.4103/0976-237X.68597
PMCID: PMC3220092  PMID: 22114389
Gonads; intraoral radiography; radiation dose; thyroid
14.  Evaluation of Mean Glandular Dose and Modulation Transfer Function for Different Tube Potentials and Target-Filter Combinations in Computed Radiography Mammography 
Background:
Different target-filter combinations in computed radiography have different impacts on the dose and image quality in digital radiography. This study aims to evaluate the mean glandular dose (MGD) and modulation transfer function (MTF) of various target-filter combinations by investigating the signal intensities of X-ray beams.
Methods:
General Electric (GE) Senographe DMR Plus mammography unit was used for MGD and MTF evaluation. The measured MGD was compared with the dose reference level (DRL), whereas the MTF was evaluated using ImageJ 1.46o software. A modified Mammography Accreditation Phantom RMI 156 was exposed using different target-filter combinations of molybdenum-molybdenum (Mo-Mo), molybdenum-rhodium (Mo-Rh) and rhodium-rhodium (Rh-Rh) at two different tube voltages, 26 kV and 32 kV with 50 mAs.
Results:
In the MGD evaluations, all target-filters gave an MGD value of < 1.5 mGy. The one-way ANOVA test showed a highly significant interaction between the MGD and the kilovoltage and target-filter material used (26 kV: F (2,12) = 49,234, P = 0.001;32 kV: F (2,12) = 89,972, P = 0.001). A Tukey post-hoc test revealed that the MGD for 26 kV and 32 kV was highly affected by the target-filter combinations. The test of homogeneity of variances indicates that the MGD varies significantly for 26 kV and 32 kV images (0.045 and 0.030 (P < 0.05), respectively). However, the one-way ANOVA for the MTF shows that no significant difference exists between the target-filter combinations used with 26 kV and 32 kV images either in parallel or perpendicular to the chest wall side F (2,189) = 0.26, P > 0.05).
Conclusion:
Higher tube voltage and atomic number target-filter yield higher MGD values. However, the MTF is independent of the X-ray energy and the type of target-filter combinations used.
PMCID: PMC3743978  PMID: 23966821
mean glandular dose (MGD); modulation transfer function (MTF); computed radiography; spatial resolution; image processing
15.  CT chest abdomen pelvis doses in Scotland: has the DRL had its day? 
The British Journal of Radiology  2014;87(1041):20140157.
Objective:
This article reports on a pilot study designed to collect dose data representative of current CT chest abdomen pelvis (CAP) practice in Scotland, make any immediately obvious interventions and to identify if the current UK diagnostic reference level (DRL) of 940 mGy cm is still appropriate. The aims are to identify if a Scotland-wide picture archiving and communication system (PACS)–based dose audit of a number of CT examinations is likely to have value in terms of optimization of patient doses and to comment on the significance of the results in terms of future optimization strategies.
Methods:
Dose audit of CT CAP examinations at 32 different scanner sites across Scotland using accepted data collection and analysis methods. The minimum sample size was 30.
Results:
Results indicate that CT CAP doses are lower than those previously reported (median, 800 mGy cm, 75th percentile 840 mGy cm) but follow a distribution that is not in keeping with the concept of DRLs as presently understood or implemented.
Conclusion:
There is value in a PACS-based dose audit project to provide serial snapshots of patient doses as optimization efforts take place and to revise current knowledge about CT doses. In our opinion, the results call into question whether DRLs or the concept of “achievable dose” are suitable for devising optimization strategies once a certain degree of optimization has taken place.
Advances in knowledge:
The results reported here suggest that it may be time to take a different approach to optimization, concentrating on tools that are more refined than the DRL, which may have become more of a compliance tool than an aid to optimization.
doi:10.1259/bjr.20140157
PMCID: PMC4453148  PMID: 24971617
16.  The status of Spain's dental practice following the European Union directive concerning radiological installations: 11 years on (1996–2007) 
Dentomaxillofacial Radiology  2010;39(8):468-474.
Objectives
The aim of this study was to assess the influence of European Union legislation on dental radiology practice in Spain and the reduction in doses administered in dental radiological installations 11 years after its introduction.
Methods
A total of 19 079 official reports on dental surgeries from 16 Spanish autonomous regions published between 1996 and 2007 were studied. We analysed the physical characteristics of the X-ray units, anomalies, film processing, exposure times and mean radiation doses administered in clinical situations.
Results
The dose applied to obtain a radiograph of an upper second molar had decreased by 37% up until 2007, the mean dose being 2.7 mGy, with 81.1% of installations using a dose of less than 4 mGy, with a reference dose for the 3rd quartile of 3.6 mGy. Of note was the incorporation of digital systems (50.1%), which are gradually replacing manual processing systems (45.3%). There were significant differences between the systems: direct digital radiology < indirect digital radiology = Insight = Ektaspeed = Ultraspeed (P < 0.001). In installations with digital systems, 6.3% used more than 4 mGy (20.5% with direct radiology and 3.2% with indirect radiology) and 7.4% a dose of less than 0.5 mGy, with a mean dose of 1.8 mGy and a reference dose for the 3rd quartile of 2.3 mGy.
Conclusion
There has been a gradual improvement in dental radiology practices; however, the incorporation of digital systems has not resulted in all the benefits hoped for, and mistakes are frequent. Besides the physical parameters that have been established, anatomical and clinical image quality criteria should be established to convince dentists of the real benefits of incorporating quality guarantee procedures in their practices.
doi:10.1259/dmfr/20362385
PMCID: PMC3520208  PMID: 21062940
radiography, intraoral, dental; radiation dosage; radiology; dental film
17.  Radiation Doses in Consecutive CT Examinations from Five University of California Medical Centers 
Radiology  2015;277(1):134-141.
The purpose of the analysis was to provide summary data on CT dose derived from a large number of consecutive CT examinations that institutions can use as a starting point for evaluating the CT radiation doses they use in their patients.
Purpose
To summarize data on computed tomographic (CT) radiation doses collected from consecutive CT examinations performed at 12 facilities that can contribute to the creation of reference levels.
Materials and Methods
The study was approved by the institutional review boards of the collaborating institutions and was compliant with HIPAA. Radiation dose metrics were prospectively and electronically collected from 199 656 consecutive CT examinations in 83 181 adults and 3871 consecutive CT examinations in 2609 children at the five University of California medical centers during 2013. The median volume CT dose index (CTDIvol), dose-length product (DLP), and effective dose, along with the interquartile range (IQR), were calculated separately for adults and children and stratified according to anatomic region. Distributions for DLP and effective dose are reported for single-phase examinations, multiphase examinations, and all examinations.
Results
For adults, the median CTDIvol was 50 mGy (IQR, 37–62 mGy) for the head, 12 mGy (IQR, 7–17 mGy) for the chest, and 12 mGy (IQR, 8–17 mGy) for the abdomen. The median DLPs for single-phase, multiphase, and all examinations, respectively, were as follows: head, 880 mGy · cm (IQR, 640–1120 mGy · cm), 1550 mGy · cm (IQR, 1150–2130 mGy · cm), and 960 mGy · cm (IQR, 690–1300 mGy · cm); chest, 420 mGy · cm (IQR, 260–610 mGy · cm), 880 mGy · cm (IQR, 570–1430 mGy · cm), and 550 mGy · cm (IQR 320–830 mGy · cm); and abdomen, 580 mGy · cm (IQR, 360–860 mGy · cm), 1220 mGy · cm (IQR, 850–1790 mGy · cm), and 960 mGy · cm (IQR, 600–1460 mGy · cm). Median effective doses for single-phase, multiphase, and all examinations, respectively, were as follows: head, 2 mSv (IQR, 1–3 mSv), 4 mSv (IQR, 3–8 mSv), and 2 mSv (IQR, 2–3 mSv); chest, 9 mSv (IQR, 5–13 mSv), 18 mSv (IQR, 12–29 mSv), and 11 mSv (IQR, 6–18 mSv); and abdomen, 10 mSv (IQR, 6–16 mSv), 22 mSv (IQR, 15–32 mSv), and 17 mSv (IQR, 11–26 mSv). In general, values for children were approximately 50% those for adults in the head and 25% those for adults in the chest and abdomen.
Conclusion
These summary dose data provide a starting point for institutional evaluation of CT radiation doses.
© RSNA, 2015
doi:10.1148/radiol.2015142728
PMCID: PMC4613871  PMID: 25988262
18.  Cephalometric characterization of an adult Emirati sample with Class I malocclusion 
Background:
A review of literature indicates the Arab cephalometric pattern compared to the Caucasian cephalometric pattern is skeletally bimaxillary retrusive, dentally bimaxillary protrusive, and more divergent palatal and mandibular planes.
Objective:
The aim of this study was to clarify the cephalometric features of Emirates adults with Class I malocclusion and pleasing soft tissue profile and to evaluate for gender differences. The null hypothesis tested was no differences in lateral cephalometric measurements as a function of gender.
Materials and Methods:
The lateral cephalometric radiographs of adult Emirati nationals with Class I malocclusion were analyzed in order to characterize an indigenous Class I malocclusion population in the United Arab Emirates. Lateral cephalometric radiographs of 30 males with average age of 24.52±6.09 years and 31 females averaging 23.57±5.52 years were analyzed using Dolphin Imaging software. Twenty-two hard and soft tissue measurements comprised the cephalometric analysis.
Results:
Only one gender difference was demonstrated out of the 22 cephalometric analysis measurements used in the study; SN-PP mean for females (10.74±3.44 degrees) subjects averaged a 2.3 degree higher mean value than the males (8.43±3.95 degrees, P=0.018). The cephalometric study results were compared to published norms from Steiner and Eastman.
Conclusions:
Based upon the conditions of the present study, it may be concluded that adult Emirati males and females seeking orthodontic treatment with Class I malocclusion present similar cephalometric profiles with the exception that measurement SN-PP may be steeper in females than males. Moreover, Emiratis are likely to present greater incisor proclination and protrusion than Caucasians and may be generally considered as more bimaxillary protrusive.
doi:10.4103/2278-0203.94772
PMCID: PMC4072350  PMID: 24987619
Cephalometric norm; Class I malocclusion; orthodontics
19.  Evaluation of radiation doses delivered in different chest CT protocols 
Summary
Background
There are differences in the reference diagnostic levels for the computed tomography (CT) of the chest as cited in different literature sources. The doses are expressed either in weighted CT dose index (CTDIVOL) used to express the dose per slice, dose-length product (DLP), and effective dose (E). The purpose of this study was to assess the radiation dose used in Low Dose Computer Tomography (LDCT) of the chest in comparison with routine chest CT examinations as well as to compare doses delivered in low dose chest CT with chest X-ray doses.
Material/Methods
CTDIVOL and DLP doses were taken to analysis from routine CT chest examinations (64 MDCT TK LIGHT SPEED GE Medical System) performed in 202 adult patients with FBP reconstruction: 51 low dose, 106 helical, 20 angio CT, and 25 high resolution CT protocols, as well as 19 helical protocols with iterative ASIR reconstruction. The analysis of chest X-ray doses was made on the basis of reports from 44 examinations.
Results
Mean values of CTDIVOL and DLP were, respectively: 2.1 mGy and 85.1 mGy·cm, for low dose, 9.7 mGy and 392.3 mGy·cm for helical, 18.2 mGy and 813.9 mGy·cm for angio CT, 2.3 mGy and 64.4 mGy·cm for high resolution CT, 8.9 mGy. and 317.6 mGy·cm for helical ASIR protocols. Significantly lower CTDIVOL and DLP values were observed for low dose and high resolution CT versus the remaining CT protocols; doses delivered in CT ASIR protocols were also lower (80–81%). The ratio between medial doses in low dose CT and chest X-ray was 11.56.
Conclusions
Radiation dose in extended chest LDCT with parameters allowing for identification of mediastinal structures and adrenal glands is still much lower than that in standard CT protocols. Effective doses predicted for LDCT may exceed those used in chest X-ray examinations by a factor of 4 to 12, depending on LDCT scan parameters. Our results, as well as results from other authors, suggest a possibility of reducing the dose by means of iterative reconstruction. Efforts towards further dose reduction which would permit replacing chest X-ray with low dose CT in certain research screening projects should be encouraged.
doi:10.12659/PJR.889952
PMCID: PMC3894921  PMID: 24454417
radiation safety; radiation protection; computed tomography (CT); chest CT; lung CT; low dose CT
20.  Estimating the population dose from nuclear medicine examinations towards establishing diagnostic reference levels 
Purpose of the Study:
This study conducted a review on nuclear medicine (NM) services in Mazandaran Province with a view to establish adult diagnostic reference levels (DRLs) and provide updated data on population radiation exposure resulting from diagnostic NM procedures.
Materials and Methods:
The data were collected from all centers in all cities of Mazandaran Province in the North of Iran from March 2014 to February 2015. The 75th percentile of the distribution and the average administered activity (AAA) were calculated and the average effective dose per examination, collective effective dose to the population and annual effective dose per capita were estimated using dose conversion factors. The gathered data were analyzed via SPSS (version 18) software using descriptive statistics.
Results:
Based on the data of this study, the collective effective dose was 95.628 manSv, leading to a mean effective dose of 0.03 mSv per capita. It was also observed that the myocardial perfusion was the most common procedure (50%). The 75th percentile of the distribution of administered activity (AA) represents the DRL. The AAA and the 75th percentile of the distribution of AA are slightly higher than DRL of most European countries.
Conclusions:
Myocardial perfusion is responsible for most of the collective effective dose and it is better to establish national DRLs for myocardial perfusion and review some DRL values through the participation of NM specialists in the future.
doi:10.4103/0972-3919.172353
PMCID: PMC4746838  PMID: 26917891
Collective effective dose; diagnostic reference levels; nuclear medicine; radiation exposure
21.  Lateral cephalometric diagnosis of asymmetry in Angle Class II subdivision compared to Class I and II 
Introduction
Lateral cephalometric radiographs are traditionally required for orthodontic treatment, yet rarely used to assess asymmetries.
Objective
The objective of the present study was to use lateral cephalometric radiographs to identify existing skeletal and dentoalveolar morphological alterations in Class II subdivision and to compare them with the existing morphology in Class I and II relationship.
Material and Methods
Ninety initial lateral cephalometric radiographs of male and female Brazilian children aged between 12 to 15 years old were randomly and proportionally divided into three groups: Group 1 (Class I), Group 2 (Class II) and Group 3 (Class II subdivision). Analysis of lateral cephalometric radiographs included angular measurements, horizontal linear measurements and two indexes of asymmetry that were prepared for this study.
Results
In accordance with an Index of Dental Asymmetry (IDA), greater mandibular dental asymmetry was identified in Group 3. An Index of Mandibular Asymmetry (IMA) revealed less skeletal and dental mandibular asymmetry in Group 2, greater skeletal mandibular asymmetry in Group 1, and greater mandibular dental asymmetry in Group 3.
Conclusion
Both IDA and IMA revealed greater mandibular dental asymmetry for Group 3 in comparison to Groups 1 and 2. These results are in accordance with those found by other diagnostic methods, showing that lateral cephalometric radiography is an acceptable method to identify existing skeletal and dentoalveolar morphological alterations in malocclusions.
doi:10.1590/2176-9451.19.4.080-088.oar
PMCID: PMC4296639  PMID: 25279525
Facial asymmetry; Malocclusions; Radiography; Cephalometry
22.  Radiation safety concerns and diagnostic reference levels for computed tomography scanners in Tamil Nadu 
Radiation safety in computed tomography (CT) scanners is of concern due its widespread use in the field of radiological imaging. This study intends to evaluate radiation doses imparted to patients undergoing thorax, abdomen and pelvic CT examinations and formulate regional diagnostic reference levels (DRL) in Tamil Nadu, South India. In-site CT dose measurement was performed in 127 CT scanners in Tamil Nadu for a period of 2 years as a part of the Atomic Energy Regulatory Board (AERB)-funded project. Out of the 127 CT scanners,13 were conventional; 53 single-slice helical scanners (SSHS); 44 multislice CT (MSCT) scanners; and 17 refurbished scanners. CT dose index (CTDI) was measured using a 32-cm polymethyl methacrylate (PMMA)-body phantom in each CT scanner. Dose length product (DLP) for different anatomical regions was generated using CTDI values. The regional DRLs for thorax, abdomen and pelvis examinations were 557, 521 and 294 mGy cm, respectively. The mean effective dose was estimated using the DLP values and was found to be 8.04, 6.69 and 4.79 mSv for thorax, abdomen and pelvic CT examinations, respectively. The establishment of DRLs in this study is the first step towards optimization of CT doses in the Indian context.
doi:10.4103/0971-6203.75471
PMCID: PMC3048954  PMID: 21430858
Computed tomography; diagnostic reference level; effective dose
23.  Main clinical, therapeutic and technical factors related to patient's maximum skin dose in interventional cardiology procedures 
The British Journal of Radiology  2012;85(1012):433-442.
Objective
The study aimed to characterise the factors related to the X-ray dose delivered to the patient's skin during interventional cardiology procedures.
Methods
We studied 177 coronary angiographies (CAs) and/or percutaneous transluminal coronary angioplasties (PTCAs) carried out in a French clinic on the same radiography table. The clinical and therapeutic characteristics, and the technical parameters of the procedures, were collected. The dose area product (DAP) and the maximum skin dose (MSD) were measured by an ionisation chamber (Diamentor; Philips, Amsterdam, The Netherlands) and radiosensitive film (Gafchromic; International Specialty Products Advanced Materials Group, Wayne, NJ). Multivariate analyses were used to assess the effects of the factors of interest on dose.
Results
The mean MSD and DAP were respectively 389 mGy and 65 Gy cm−2 for CAs, and 916 mGy and 69 Gy cm−2 for PTCAs. For 8% of the procedures, the MSD exceeded 2 Gy. Although a linear relationship between the MSD and the DAP was observed for CAs (r=0.93), a simple extrapolation of such a model to PTCAs would lead to an inadequate assessment of the risk, especially for the highest dose values. For PTCAs, the body mass index, the therapeutic complexity, the fluoroscopy time and the number of cine frames were independent explanatory factors of the MSD, whoever the practitioner was. Moreover, the effect of technical factors such as collimation, cinematography settings and X-ray tube orientations on the DAP was shown.
Conclusion
Optimising the technical options for interventional procedures and training staff on radiation protection might notably reduce the dose and ultimately avoid patient skin lesions.
doi:10.1259/bjr/30010948
PMCID: PMC3486680  PMID: 22457404
24.  Local-Reference Patient Dose Evaluation in Conventional Radiography Examinations in Mazandaran, Iran 
Background
The most efficient application of ionizing radiation is serving medical purposes and using this radiation has caused people to learn that artificial sources of radiation exposure among these resources can be of highest exposure rate.
Obiective
The present study is aimed at initially establishing a baseline for local-reference dose level in Mazandaran, Iran in 12 projections of the most conventional x-ray examination.
Methods
In this study, 13 public hospitals in Mazandaran province were selected for review and required data collected for ten adult patients with mean weight of 70±10kg in each projection. Then, information of each center was separately analyzed. Next, in order to measure x-ray output tube, the dosimeter RTI model Barracuda calibrated has been applied for measuring air karma within energy rage of 40-150kvp. ESAK and ESD parameters, usually used for monitoring DRL in conventional radiography, were calculated.
Results
Mean ESDs in this study has been obtained to 1.47±0.98 for skull (PA/AP), 1.01±0.79 for skull (LAT), 0.67±0.38 for cervical spine (AP), 0.79±0.37 for cervical (LAT), 0.49±0.38 for chest (PA/AP), 1.06±0.44 for chest (LAT), 2.15±0.73 for thoracic spine (AP), 3±0.87 for thoracic spine (LAT), 2.81 ±0.82 for lumbar spine (AP), 4.28±0.78 for lumbar (LAT), 2.07±1.17 for abdomen and 1.90±0.99 for pelvis, respectively. The ESDs calculated for chest examination in both projections, PA and LAT are more than values recommended by the UK (2000), Brazil and Slovenia.
Conclusion
The present study has determined wide variations in radiation dose of x-ray examinations among hospitals in Mazandaran, Iran. In order to reduce skin dose, an optimization procedure should be considered. Application of a reference dose (DRL) could be a practical method for this purpose. The role of optimization of radiography parameters for reducing patient dose is a significant issue. Through optimizing parameters, it would be possible to preserve image quality while reduction of patient dose.
PMCID: PMC5022756  PMID: 27672626
Conventional Radiography; Dosimeter; Patient Dose; Mazandaran; ESAK; ESD
25.  Characterization of MOSFET dosimeter angular dependence in three rotational axes measured free-in-air and in soft-tissue equivalent material 
Journal of Radiation Research  2013;54(5):943-949.
When performing dose measurements on an X-ray device with multiple angles of irradiation, it is necessary to take the angular dependence of metal-oxide-semiconductor field-effect transistor (MOSFET) dosimeters into account. The objective of this study was to investigate the angular sensitivity dependence of MOSFET dosimeters in three rotational axes measured free-in-air and in soft-tissue equivalent material using dental photon energy. Free-in-air dose measurements were performed with three MOSFET dosimeters attached to a carbon fibre holder. Soft tissue measurements were performed with three MOSFET dosimeters placed in a polymethylmethacrylate (PMMA) phantom. All measurements were made in the isocenter of a dental cone-beam computed tomography (CBCT) scanner using 5º angular increments in the three rotational axes: axial, normal-to-axial and tangent-to-axial. The measurements were referenced to a RADCAL 1015 dosimeter. The angular sensitivity free-in-air (1 SD) was 3.7 ± 0.5 mV/mGy for axial, 3.8 ± 0.6 mV/mGy for normal-to-axial and 3.6 ± 0.6 mV/mGy for tangent-to-axial rotation. The angular sensitivity in the PMMA phantom was 3.1 ± 0.1 mV/mGy for axial, 3.3 ± 0.2 mV/mGy for normal-to-axial and 3.4 ± 0.2 mV/mGy for tangent-to-axial rotation. The angular sensitivity variations are considerably smaller in PMMA due to the smoothing effect of the scattered radiation. The largest decreases from the isotropic response were observed free-in-air at 90° (distal tip) and 270° (wire base) in the normal-to-axial and tangent-to-axial rotations, respectively. MOSFET dosimeters provide us with a versatile dosimetric method for dental radiology. However, due to the observed variation in angular sensitivity, MOSFET dosimeters should always be calibrated in the actual clinical settings for the beam geometry and angular range of the CBCT exposure.
doi:10.1093/jrr/rrt015
PMCID: PMC3766287  PMID: 23520268
dosimetry; X-ray radiation exposure; MOSFET dosimeter; angular dependence

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