Area Product Meter Research Articles

Investigation of the optimal tube voltage kV exposure parameters for general X-ray of dental cone-beam computed tomography: A cephalometric view

This study aims to investigate and optimize the effect of different exposure parameters on the reduction of noise and radiation dose and to find the optimal balance among tube voltage, tube current, and exposure time for the latest-generation cone-beam computed tomography system (CBCT) at Advanced Medical and Dental Institute, Universiti Sains Malaysia, using the dose area product (DAP) meter. The DAP meter was attached to the X-ray detector of the CBCT device to cover the entire irradiated area and then connected to a Raysafe electrometer. The DAP meter was scanned with the following exposure parameter: constant tube voltage of 70 kV with a varying tube current ranging from 5 mA – 16 mA and then at a constant tube current of 10mA and a varying tube voltage ranging from 60 kV – 80 kV. For each scanning protocol, the noise was determined. At constant tube voltage and varying tube current, the noise level ranged from 41.99 – 82.16, while at constant tube current and varying tube voltage, the noise level ranged from 50.66 – 60.76 with equal exposure time. A 0.09% increase in noise was observed when the tube voltage was varied. Therefore, low noise protocols should consist of a reduction in the tube current setting rather than a reduction in peak voltage (kVp), as this would result in a smaller level of noise and consequently less quality degradation in the image.

Influence of additional filters on radiation dose during chest radiography.

The goal of this study was to examine the impact of using additional aluminum (Al) and copper (Cu) filters on radiation dose during the adult chest x-ray examination. Adult chest phantoms without and with different slabs of animal fat were used for simulating underweight, overweight, and obese patients, respectively. Phantoms were examined without and with various levels of extra Al and Cu filtering over a range of exposure parameters. A dose area product (DAP) meter was used to measure the radiation dose. Results demonstrated that radiation doses were significantly reduced (p=0.001) when applying extra filters compared with no filters for all of the different phantom sizes. The highest reduction in radiation dosage was 38, 41, and 42 percent for underweight, overweight, and obese phantom size, respectively, by 1mm Al+0.2mm Cu. In conclusion, the use of extra filters in chest x-ray imaging provides an optimal dose reduction choice regardless of the thickness of the chest region to be radiographed. DOI: http://dx.doi.org/10.31257/2018/JKP/2022/140206

SURFACE DOSE ESTIMATION BY A KAP METER FOR KILOVOLTAGE X-RAY BEAMS.

This study aims to estimate the entrance surface dose (ESD) of a water phantom for kilovoltage x-ray beams using an air kerma area product meter (KAP meter) equipped in an x-ray unit. The KAP meter was calibrated in terms of the ESD determined by a plane-parallel ionization chamber based on a 60Co absorbed dose-to-water calibration coefficient, ${N}_{D,w}^{{}^{60}\mathrm{C}\mathrm{o}}$. The ESD measured using the KAP meter was verified by comparing it with that estimated by the air kerma calibration coefficient, NK, for x-ray beam qualities. The ratio of ESDs based on ${N}_{D,w}^{{}^{60}\mathrm{C}\mathrm{o}}$ and NK was 1.003 on average and independent of the beam quality. The ESD by the KAP meter was an agreement within ±1.5% with that measured using the plane-parallel chamber for 10×10-30×30cm2 fields with a source-surface distance of 75-150cm. It was possible to estimate the ESD directly in a water phantom for x-ray beams without correction factors compared to the existing air kerma calibration, using a KAP meter calibrated based on ${N}_{D,w}^{{}^{60}\mathrm{C}\mathrm{o}}$.

Radiation exposure during therapeutic cardiac interventional procedures

The purpose the current work were to assess the radiation exposure given to patients during percutaneous coronary interventions (PCI), pacemaker (PM) and coronary angiography (CA), procedures. In total, 419 procedures were carried out in 4 specialized hospitals. Calibrated Kerma area product meters were used to quantify the patient doses. Effective dose was extrapolated using the national radiological protection board (NRPB) software program. The mean KAP (Gy.cm2) per procedure were 8.6, 6.2 and 5.6 for PCI, PM, and CA procedures, respectively. While in that order, e mean and Entrance Surface Air Kerma (ESAK, mGy) per procedure were 705.9,509, and 464.7 for PCI, PM, and CA. Patients’ doses is below the level of the deterministic effects and the effective dose per procedure is low. Patients radiation doses is lowest compared to the previous studies.

A Study of Patient's Dose Control at Radiography by Using a Dose Area Product Meter

The International Commission on Radiological Protection recommends adaptation of the diagnostic reference levels (DRLs). Japan DRLs 2020 apply the entrance surface dose (ESD) in radiography. However, it is difficult to measure ESD in the clinical setting. A dose area product meter has been proposed for use as a dose index in interventional radiology. We investigated the basic characteristic of a dose area product meter and the relationship of ESD and dose area product meter values in radiography. We measured calibration factors from phantom studies and estimated ESD from the dose area product meter. Subject thickness was measured from the chest clinical images for calculation of ESD. Estimated ESD from the dose area product meter was compared with that calculated from program software (Surface Dose Evaluation Code, Sdec). Relative dose (dose area product meter/ionization chamber) decreased when tube voltage was lower (60 kV) or higher (130 kV). A positive correlation was found between the estimated and calculated ESD. Dose area product meter can be used for patient's dose control in radiography.

Entrance Surface Dose (ESD) Measurement During Pediatric Chest X-Rays

Introduction Given the high radiation tissue sensitivity of pediatric patients, it is necessary to monitor their received dose in order to optimize radiation protection. The first aim of this study was to evaluate of the entrance surface dose (ESD) in pediatric patients undergoing chest x-ray at the main hospital of Dezful, Iran. The second aim was to compare our results with the established dose reference levels (DRL). Materials and Methods The studied population included 204 pediatric patients less than 15 year who were referred to chest x-ray. A calibrated dose area product meter (DAP-meter) with permanent installation on x-ray unit was used to radiation dose measurements. For each patient, the demographic data, exposure parameters and the dose read by DAP-meter were recorded and ESD was calculated using standard mathematical formula. Results The average value of ESD was 119 μGy in patients less than 15 years. This value was 51.3, 122.3, 131.5 and 171.2 μGy for the age groups less than 1 year, 1 to 5 year, 5 to 10 year and 10 to 15 year, respectively. A statistical significant difference was seen between ESD values ​​in different age groups (P<0.001), whereas no statistical difference was seen between ESD values in ​ girls and boys (P =0.993). Conclusion Pediatric patients in hospital investigated (except age group less than 1 year) are subjected to unnecessary radiation exposure, especially due to use of non-optimize x-ray protocols.

Modified Technique for the Visualization of C6/C7 in Lateral Cervical Spine Radiography

Introduction: In the Swimmer’s view, the C6 and C7 can be visualized as superimposed on the shoulders. This study aimed to explore the technique to demonstrate C1 to C7 in the lateral spine and improve the diagnostic value in that region. Material and Methods: An experimental study was carried out using a RANDO phantom to obtain images of the lateral cervical spine. Twelve radiographs were taken using different kVps at different centering points. The image quality of the radiographs was evaluated by two radiographers using the modified image quality criteria score sheet adapted from the Commission of European Communities on image quality. A dose area product meter was utilized to estimate the entrance surface dose (ESD); however, CALDose_X5 Monte Carlo software was used to estimate the effective dose. Results: The findings indicated that a higher centering point at 2 inches above the pinna of the ear can clearly visualize the lower cervical spine (C6/C7) and cervicothoracic junction (C7/T1). The results of the Kruskal-Wallis test revealed significant differences (p 0.05) in the ESD between different utilized centering points. The effective dose of the modified technique was reported to be lower, compared to that for the Swimmer’s view. Conclusion: The modified lateral technique can be used to replace the Swimmer’s view to adequately demonstrate the lower cervical spine and cervicothoracic junction with a lower radiation dose while not harming the patient due to movement during positioning.

Application of Dose Area Product (DAP) to Estimate Entrance Surface Dose (ESD) in Pediatric Chest X-Rays

Introduction: Given the high radiation tissue sensitivity of pediatric patients, it is necessary to monitor their received dose to optimize radiation protection. The first aim of this study was to evaluate the entrance surface dose (ESD) in pediatric patients undergoing a chest X-ray at the main hospital of Dezful, Iran. The second aim was to compare our results with the established dose reference levels (DRLs).
 Materials and Methods: The studied population included 204 pediatric patients less than 15 years who were referred to as chest X-ray. A calibrated dose area product meter (DAP-meter) with permanent installation on the X-ray unit was used to radiation dose measurements. For each patient, the demographic data, exposure parameters and the dose read by DAP-meter were recorded and ESD was calculated using a standard mathematical formula.
 Results: The average value of ESD was 119 μGy in patients less than 15 years. This value was 51.3, 122.3, 131.5 and 171.2 μGy for the age groups for less than 1 year, 1 to 5 years, 5 to 10 years and 10 to 15 years, respectively. A statistically significant difference was seen between ESD values ​​in different age groups (P<0.001), whereas no statistical difference was seen between ESD values in ​ girls and boys (P =0.993).
 Conclusion: Pediatric patients in hospital investigated (except age group less than 1 year) are subjected to unnecessary radiation exposure, especially due to the use of non-optimize X-ray protocols.

Measurement of the average radiation dose to the local skin and thyroid gland during intracranial aneurysm coil embolization

IntroductionIntracranial aneurysm coil embolisation is a fluoroscopically guided procedure associated with high radiation dose. The increase in the number of coil embolisation procedures raises concern for the amount of radiation and the associated radiation risks to the patients. This research study was conducted to determine the average radiation dose to patients’ thyroid glands and local skin during intracranial aneurysm coil embolisation and to establish preliminary local diagnostic reference levels for this procedure. In this paper, local skin dose refers to the absorbed radiation dose on the areas of the skin exposed to radiation during intracranial aneurysm coil embolisation, namely neck, face and scalp. MethodsThis study employed air-kerma area product meters to determine the local skin dose and diagnostic reference levels during intracranial aneurysm coil embolisation. In addition, thyroid radiation doses were measured using thermo-luminescent dosimeters on a phantom during simulation of embolisation procedures. ResultsThe local skin doses as determined by air-kerma area product ranged between 33 and 125 Gy.cm2. The mean thyroid dose was 9.87 mGy. The established local diagnostic reference level was 52.1 Gy cm2, 17.8 min’ fluoroscopy time and 503 image frames. ConclusionThe average air-kerma area product values and the proposed diagnostic reference levels were lower than most published values for intracranial aneurysm coil embolisation. Implications for practiceThe established local diagnostic reference levels are recommended for use as radiation dose optimisation tool at the research site. The findings of this study cannot be generalised or applied to other hospitals. The complexity of the embolisation procedures was not classified for this study. Further research on diagnostic reference levels for intracranial aneurysm coil embolisation, taking into account the complexity of the procedures, is recommended.

Radiogenic risks to patients and staff from fluoro-assisted therapeutic cardiac catheterizations

Advances in sectional imaging have led to prolonged x-ray fluoro-assisted therapeutic cardiac catheterizations. Given the frequency of such procedures, limited data are available for patient and staff doses. For certain pediatric cardiac catheterization procedures we examine: (i) effective and organ doses, also the radiogenic and tissue reaction risks and; (ii) staff effective dose during cardiac interventions. At four cardiac catheterization centres, patient doses were measured with a calibrated kerma area product (KAP) meter; staff doses were measured using calibrated TLDs. The mean and range of age (years) and weight (kg) for patients were 4.3 (0.04–14.0) and 10.8 (3.0–46.0) respectively; the overall mean and range of fluoroscopic time (min) was 13.0 (1.4–54.8). For coronary angiography and pacemaker procedures the overall mean and range of cumulative kerma area product (CKAP, cGy.cm2) were 350 (12.0–510). The average annual staff dose of 9.0 (7.2–14.4) mSv is relatively low given the current workload. Some patients received high doses approaching the threshold for tissue reactions. Optimisation of radiation dose is required as is follow-up of patients receiving high doses to detect the possibility of tissue reactions.

Multi-facility Survey on Accuracy and Calibration Method for Dose Area Product Meter of Angiography Systems

In many facilities, the displayed dose of dose-area product (DAP) is used for the dose management of interventional radiology. In this study, we investigated the measured dose at the patient entrance reference point (interventional reference point) and the displayed dose on each angiography systems. Also, we investigated the calibration method of each DAP. The errors of the measured dose and the displayed dose were less than 35%, but that dispersion was wide between the systems. The calibration methods varies according to a system. And even in the same manufacturer, the calibration methods were different. Therefore, to use the displayed dose of DAP for patient dose management, we need to compare that with the measured dose regularly. The differences of calibration methods induce the wide dispersion of the errors of the measured and the displayed dose. So the standardization of the calibration method in each manufacturer is expected.

284. Protocol of verification of dose indicators of radiological equipment for the correct archiving and recording of dosimetric data

Purpose Dose report in radiological examination will be an issue soon with the Euratom directive 2013/59 [ [1] European Commission. Councile Directive 2013/59Euratom. Google Scholar ]. Our purpose is to analyze our results on approximately 10 years of dose control activity in our Hospital as required by the current regulations D.Lvo 187/00. The aim of the work is to analyze the measurement methods implemented on the installed radiological equipment DAP, KAP, CTDI, ESD, and compare them with our reference measurement. Methods During the acceptance tests and the annual constancy tests of all radiological equipment installed since 2007, we have set up a verification protocol of dose indicator through direct measurements with calibrated instruments [ [2] CEI EN 60580 Dose area product meter; 2001. Google Scholar ]. For DAP/KAP direct digital X-ray equipment, angiography systems radiography e fluoroscopy systems our adopted protocol controls the following parameters: accuracy, reproducibility, dependence on the field, dependence on the quality of the beam with an external calibrated DAP meter: Dose guard 100 (RTI electron ics). For CTDI vol values provided from CT scanners: Pencil ionization camera (Victoreen Instruments) and PMMA phantoms. For mammography (ESD and AGD displayed dose): measurements with calibrated dosimeter and phantoms in mammography. Results Conclusions Calibrations were requested on dose display devices in direct digital equipment (DAP) in 4% of equipments with a discrepancy of more than 20%, [Fig. 1] due to the loss of calibration due to the drop in tube efficiency. For the remaining equipment the discrepancies detected are within the limits. The verification protocol is reliable and compliant with the guidelines, useful in the preliminary phase to the registration of the dosimetric data protocol [ [3] AIFM Report: Radiation dose index monitoring (RDIM); 2016. Google Scholar ]. Dose report in radiological examination will be an issue soon with the Euratom directive 2013/59 [ [1] European Commission. Councile Directive 2013/59Euratom. Google Scholar ]. Our purpose is to analyze our results on approximately 10 years of dose control activity in our Hospital as required by the current regulations D.Lvo 187/00. The aim of the work is to analyze the measurement methods implemented on the installed radiological equipment DAP, KAP, CTDI, ESD, and compare them with our reference measurement. During the acceptance tests and the annual constancy tests of all radiological equipment installed since 2007, we have set up a verification protocol of dose indicator through direct measurements with calibrated instruments [ [2] CEI EN 60580 Dose area product meter; 2001. Google Scholar ]. For DAP/KAP direct digital X-ray equipment, angiography systems radiography e fluoroscopy systems our adopted protocol controls the following parameters: accuracy, reproducibility, dependence on the field, dependence on the quality of the beam with an external calibrated DAP meter: Dose guard 100 (RTI electron ics). For CTDI vol values provided from CT scanners: Pencil ionization camera (Victoreen Instruments) and PMMA phantoms. For mammography (ESD and AGD displayed dose): measurements with calibrated dosimeter and phantoms in mammography. Calibrations were requested on dose display devices in direct digital equipment (DAP) in 4% of equipments with a discrepancy of more than 20%, [Fig. 1] due to the loss of calibration due to the drop in tube efficiency. For the remaining equipment the discrepancies detected are within the limits. The verification protocol is reliable and compliant with the guidelines, useful in the preliminary phase to the registration of the dosimetric data protocol [ [3] AIFM Report: Radiation dose index monitoring (RDIM); 2016. Google Scholar ].

Measurement of scattered and transmitted x-rays from intra-oral and panoramic dental x-ray equipment

The aim of this study was to quantify the levels of transmitted radiation arising from the use of intra-oral dental x-ray equipment and scattered radiation arising from the use of both intra-oral and panoramic x-ray equipment. Levels of scattered radiation were measured at 1 m from a phantom, using an ion chamber with a volume of 1800 cm3. Transmitted radiation was measured using both (i) a phantom and dose–area product (DAP) meter and (ii) a patient and a 1800 cm3 ion chamber. For intra-oral radiography the patient study gave a maximum transmission of 1.80% (range 0.04–1.80%, mean 0.26%) and the phantom study gave a maximum transmission of 6% (range 2–6%, mean 5%). The maximum scattered radiation, per unit DAP, was 5.5 nGy (mGy cm2)−1 at 70 kVp and a distance of 1 m. For panoramic radiography the maximum scattered radiation was 9.3 nGy (mGy cm2)−1 at 80 kVp and a distance of 1 m. Dose values are presented to enable the calculation of adequate protective measures for dental radiography rooms. Previous studies have used a phantom and measured radiation doses at 1 m from the phantom to determine the radiation dose transmitted through a patient, whereas this study uses both patient and phantom measurements together with a large-area dosemeter, positioned to capture the entire x-ray beam, to ensure that more realistic dose measurements can be made.

The Practice of Chest Radiography Using Different Digital Imaging Systems: Dose and Image Quality

Introduction: The study was undertaken to evaluate the practice of chest radiography using different digital imaging systems and its influence on dose and image quality. Materials and Methods: The study was carried out in two hospitals from March 2016 to June 2016. Sixty ambulatory patients aged 21 to 60 years who were able to cooperate without difficulty and weighed between 60 to 80 kg were selected randomly. The active matrix flat panel imagers technology was employed in the direct radiography (DR) system for Hospital A, whilst Hospital B used the single read out computed radiography (CR) system. The dose area product (DAP) meter was utilized in measuring the entrance surface air kerma. The chest radiographs were evaluated by two radiologists. Results: The mean entrance surface doses (ESDs) for posteroanterior chest in Hospital A (0.098 mGy) was lower than that obtained in Hospital B (0.161 mGy). However, the ESDs at both centres were lower than the recommended value by the International Atomic Energy Agency (IAEA; 0.3 mGy). The quality of the images for chest radiography in both hospitals was adequate to make a diagnosis with ESDs and effective doses lower than those recommended by IAEA and United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR). Conclusion: The study serves to highlight the practice of chest radiography with two different systems and its influence on image quality and dose. It can be concluded that there were significant differences in image quality and radiation dose for chest radiography practice using CR and DR.

A Comparison of Patients Absorption Doses with Bone Deformity Due to the EOS Imaging and Digital Radiology.

This study has aimed to measure the patient dose in entire spine radiography by EOS system in comparison with the digital radiography. EOS stereo-radiography was used for frontal and lateral view spine imaging in 41 patients in a prospective analytical study. A calibrated dose area product (DAP) meter was used for calibration of the DAP in EOS system. The accuracy and precision of the system was confirmed according to the acceptance testing. The same procedure was used for 18 patients referred for lumbar spine digital radiology (overall 36 images). Although radiation fields in the EOS were almost twice of that in digital radiology, and the average peak tube voltage (kVp), current supply to the tube (mA), and the average size and age of the patients referred for EOS imaging were greater than digital radiology, however, the average DAP in EOS was 1/5 of that in digital radiology system. Also, the average dose in the EOS was about 1/20 of that in digital radiology. The patient dose in EOS imaging system was lower in comparison with digital radiology (1/20).

X선을 이용한 면적선량계의 교정 연구

X선을 이용한 면적선량계의 교정 연구

Investigation of Scattered Radiation Reduction Effect by Use of Collimator Cover Covered with Leaded Sheet in Angiography Equipment.

The purpose of this study was to investigate the effect of scattered radiation reduction to medical staff by attaching the leaded sheet on the collimator cover of the angiography equipment. Ambient dose equivalent was measured to compare the rate of scattered radiation reduction between with and without the leaded sheet. Shielding effect was confirmed for scattered radiation in all directions, especially 27% of shielding ratio in the head and neck area when angiography equipment installed with small detector, and more than 40% of shielding ratio when adjusting a cut portion of leaded sheet to the field size. However, it decreased when the dose area product meter was not attached. Therefore, our proposed leaded sheet can reduce radiation dose to medical staff during angiographic and interventional procedures.

The Efficiency of Applying the Radiology Technologist of the Radiation Dose Monitoring Technique During the Fluoroscopy Procedures for Oncology in Paediatrics Care Aged Between 4 to 7 Years

Fluoroscopy is one of the radiation sources used in diagnostic processes in radiology. Owing to the diagnostic approach that entails observation of the affected anatomy using radiation in real time, harmful effects may potentially occur. Therefore, safety measures in the radiographer's use of equipment and effective monitoring and management are essential in diagnostic processes. Additionally, patients in the age group of four to seven years have less anatomy and tissue development, which presents higher levels of health risks. The study will focus on analyzing the pre-procedure requirements and the set of guidelines, which enable the enforcement of the safety of the concerned patients within the paediatric practice. For example, the study will observe the potency of undertaking the reduction of the fluoroscopic times and improving the communications between the health specialists. The study will also evaluate methods and techniques employed in achieving efficiency in fluoroscopy radiation dose management. Direct and indirect methods will be employed to monitor the dosage effects. Direct methods would entail performing a skin dose test on the target area of fluoroscopic radiation. Detectors would be employed, for example the photographic films and thermo-luminescent dosimeters. The indirect methods will employ the use of the dose area product meter to ascertain the effects of radiation on the patients. Some of the dose reduction techniques involve the manipulation of equipment operation, for example beam quality adjustment, dose level setting, and dose spreading. The results used to evaluate the dosage level will entail analyzing measurements of the skin exposure unit of the fluoroscopic equipment. These results will be achieved through the use of different operational voltage levels on the fluoroscopic equipment. Skin dose will be determined through a combination of several measurable factors in fluoroscopic equipment operation.

Local diagnostic reference levels for intraoral dental radiography in the public hospitals of Cyprus

PurposeThe purpose of this study was to determine local DRLs for children and adults undergoing intraoral dental examinations at the intraoral radiology units of the public hospitals in Cyprus. MethodsMeasurements were made on all the twenty intraoral X-ray units of the public hospitals in Cyprus with the intention to establish the local DRLs for all the possible intraoral X-ray examinations for children and adults. All units are film based. The measurements were made by a Dose Area Product (DAP) meter (GAMMEX RMI 841-RD) placed at the surface of the dental unit’s X-ray shaping cone (FSD 20cm). A diagnostic radiology dosimeter (Dosimax Plus A) was also placed at an FSD of 100cm to compare the dose reading between the two dosimeters. ResultsDRLs were established at the 3rd quartile for 7 exposure settings corresponding to 12 types of teeth (Adult and children mandibular and maxillary incisor, premolar and molar) with values of 197, 163, 128, 102, 81, 65 and 49mGycm−2 and 7.23, 5.94, 4.75, 3.68, 3.10, 2.41 and 1.88mGy for benchmark nominal exposure times of 1000, 800, 640, 500, 400, 320 and 250ms respectively, at a nominal exposure voltage of 70kVp. ConclusionsThe local DRLs of the present study compare well with other similar published DRLs.

Transition from image intensifier to flat panel detector in interventional cardiology: Impact of radiation dose

Flat panel detector (FPD) technology in interventional cardiology is on the increase due to its varied advantages compared to the conventional image intensifier (II) systems. It is not clear whether FPD imparts lower radiation doses compared to II systems though a few studies support this finding. This study intends to compare radiation doses from II and FPD systems for coronaryangiography (CAG) and Percutaneous Transluminal Coronary Angioplasty (PTCA) performed in a tertiary referral center. Radiation doses were measured using dose area product (DAP) meter from patients who underwent CAG (n = 222) and PTCA (n = 75) performed using FPD angiography system. The DAP values from FPD were compared with earlier reported data using II systems from the same referral center where the study was conducted. The mean DAP values from FPD system for CAG and PTCA were 24.35 and 63.64 Gycm2 and those from II system were 27.71 and 65.44 Gycm2. Transition from II to FPD system requires stringent dose optimization strategies right from the initial period of installation.