The Practice of Chest Radiography Using Different Digital Imaging Systems: Dose and Image Quality (original) (raw)
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Optimization of Image Quality and Patient Dose in Digital Radiography of the Chest
Journal of Babol University of Medical Sciences, 2017
BACKGROUND AND OBJECTIVE: Digital systems have been replacing with screen-film analogue systems in diagnostic radiology departments, rapidly. Despite the differences in the properties of new x-ray imaging detectors, the same radiographic protocols that had been used for radiographic film-screen are used for digital imaging systems, without any review yet. In this study, the image quality and the patient dose in digital imaging of the chest are evaluated and optimized. METHODS: Two digital radiography machines, Shimadzu RDA Speed and Siemens G2107 have been used in this experimental research. Imaging and dose measurement are carried out at different source to phantom distances and kilo-voltages. For measurement of the image quality, a contrast-detail radiography (CDRAD) phantom is used. For evaluation of optimization, the Inverse Image Quality Figure per patient dose squared (IQFinv/E 2) is used. FINDINGS: Evaluation of measured data for optimization shows that for both of these two digital radiography machines, despite of increasing in patent dose, with reducing of kilo-voltage, the IQFinv/E 2 is increased. The maximum values of this parameter for Imam Khomeini and Bu Ali Hospitals are measured 0.0180 and 0.0083, respectively. CONCLUSION: The results of this study indicate that despite the traditional notion of using higher kilo-voltages for chest radiography, with increasing kilo-voltage, the ratio of image quality per patient dose is reduced. So, for optimization of chest radiography, as much as possible the kilo-voltage should be reduced based on the size of patient and clinical purpose.
Clinical Imaging, 2012
We studied the performance of three computed radiography and three direct radiography systems with regard to the image noise and entrance skin dose based on a chest phantom. Images were obtained with kVp of 100, 110, and 120 and mA settings of 1, 2, 4, 8, and 10. Significant differences of image noise were found in these digital chest radiography systems (Pb.0001). Standard deviation was significantly different when the mAs were changed (Pb.001), but it was independent of the kVp values (P=.08-.85). Up to 44% of radiation dose could be saved when kVp was reduced from 120 to 100 kVp without compromising image quality.
Shehu, Mohammed Ahmed, 2020
ABSTRACT In radiography, a dose to patients primarily depends on the Entrance surface Dose (ESD) and the sensitivity of organs which are irradiated during treatment plan. The main goal of this study is to assess and compare adult patient doses to digital and conventional radiographic X-ray examinations chest (PA/AP) in Adama city special zone of oromiya region. Assessment of ESD for patients in conventional and digital diagnostic radiology examinations should be made as a means for the optimization of the radiation protection of the patients. This estimated the entrance skin dose received by patients undergoing diagnostic X-ray examinations, including the entrance skin doses for 400 patients in chest PA/AP of X-ray examinations. The entrance surface dose was determined indirectly via measurements and from knowledge of X-ray output factors and in this study entered the measurements parameters such as X-ray dose output, back scatter factor, and focus to skin distance and used physical parameters such as mAs and kV in mathematical model. The mean ESD (mGy) value calculated in to four hospitals. The mean ESD (mGy) estimated range from 0.113 -1.92 for chest PA, 0.107-1.935 for chest PA. The results obtained were compared with the diagnostic reference levels of the International Atomic Energy Agency (IAEA) 1996, European Commission (EC) 1999 and national radiological protection board (NRPB) 2000. Further studies are required for minimization of radiation doses to sensitive organs. ESDs were estimated in the present study for patients undergoing selected chest X-ray examinations in major hospitals in Adama city special zone of Oromiya region. It was observed that in some of the cases specially Adama hospital medical college the ESD values higher than the recommended value from IAEA, NRPB and EC. Similarly the S.Aklisiya hospital and Medin Beza hospitals shows ESD (mGy) value for all types of projection examinations are similarity with that reported by IAEA [42] and European Committee (EC, 1999) [41] as well as NRPB -2000 [43]. But Rift valley hospital has the minimum value of ESD (mGy) because of the low dose output of the machine combined with high tube filtration. This could be attributed to the relatively low tube output dose and exposure parameters used in these hospitals. And also potential advantage of digital x ray from conventional is minimizes unnecessary patient dose and keeps the dose “as low as reasonably achievable” (ALARA) principle. Keywords: Ionizing Radiation; X-Ray; Conventional, digital, Radiography; Entrance Surface Dose
Patient effective dose evaluation for chest X-ray examination in three digital radiography centers
Iranian Journal of Radiation Research, 2012
Background: The radiation doses resulting from diagnostic X-ray examinations are routinely measured in terms of entrance surface dose (ESD) and effective dose (ED). In this study, for the purpose of radiation protection, the radiation doses received from Digital chest X-ray examination were evaluated in terms of ESD and ED. Material and Methods: The ED was calculated by using the MCNP Monte Carlo code and an adult hermaphrodite mathematical phantom. The effects of both operating high voltage and projection geometry on the effective dose were investigated. The absolute values of the ED were calculated for digital and conventional Posterior-Anterior (PA) and Lateral (LAT) projections of chest radiography. Results: The results show ED for PA projection in digital chest radiography in some major hospitals is higher than National Diagnostic Reference Level (NDRL). Conclusion: Therefore optimization process should be considered seriously at national level to reduce patient exposure in digital chest radiography in Iran. Iran.
Evaluation of dose–image-quality optimization in digital chest radiography
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2007
In this study, we aimed to evaluate the operation conditions and reduce patient doses while maintaining acceptable image quality in digital chest radiography. A geometric chest phantom with built-in regional test objects for quantitative assessment of image quality was used to produce images that simulate a chest projection. Images of the chest phantom were obtained using a GE Revolution XR/d digital X-ray system operated at tube potentials from 62 to 132 kVp with the grid and a distance of 180 cm between the source and image system. The X-ray images were obtained with the automatic exposure control (AEC) mode. Raw data of the acquired images were used for image-quality analysis. The signal-to-noise ratio (SNR) was used as an image-quality indicator and a figure of merit (FOM) computed by dividing the SNR 2 by the effective dose was used to estimate the optimization of the chest radiography. The routine operation tube potential of 112 kVp seems optimal for subdiaphragm examinations but not for lung and heart examinations.
Image quality and its related entrance surface dose to adult patients undergoing computed radiography (CR) examinations have been assessed using ImageJ software version 1.48 in two hospitals H-1 and H-2. In all 70 radiographs of adult patients were examined in the study consisting of 10 each for chest PA, cervical spine AP and LAT, lumbar spine AP and LAT and skull AP and LAT. Image quality of the radiographic images was assessed in terms of contrast-to-noise ratio (CNR) and signal-to-noise ratio (SNR). The CNR for all examinations were between 3.54 3.27 and 20.63 8.65 for the two hospitals involved in this study. A maximum difference 17.09 in CNR was found between hospital 1 (H-1) and 2 (H-2). The results obtained for SNR for both hospitals showed that 92.86% of all the images assessed were at least 1.22 higher than the Rose Model of the threshold value of 5. The images were of good quality and hence, they provided useful clinical information. The relationship between CNR and the entrance surface dose (ESD) to patients for all the examinations showed that there is a potential to reduce doses to patients while keeping images of diagnostic quality.
Patient doses and image quality in chest radiography: The influence of different beam qualities
Nuclear Technology and Radiation Protection, 2007
A simple method of assessing optimal X-ray beam quality in respect to patient exposure and image quality in chest screen-film radiography is presented here. Different beam qualities were generated by the use of various combinations of tube voltages (70 kV to 110 kV) and Al and Cu filter thick nesses. Patient doses were assessed by kerma-area product measurements. Simultaneously, image quality was evaluated by a twofold method: a clinical study applying European quality criteria for the radiographic technique of image on image of 126 patients and a multifunctional home-made dosimetric phantom with embedded test objects. The quantification of image quality criteria yields a simpler method of optimizing image quality and patient dose relationships. Modifications of radiographic practice, based on image quality assessment and dose measurements, resulted in significant dose reductions and preservation of image quality. Through the use of harder beam quality, dose reduction of up to a val...
Image quality and its related entrance surface dose to adult patients undergoing computed radiography (CR) examinations have been assessed using ImageJ software version 1.48 in two hospitals H-1 and H-2. In all 70 radiographs of adult patients were examined in the study consisting of 10 each for chest PA, cervical spine AP and LAT, lumbar spine AP and LAT and skull AP and LAT. Image quality of the radiographic images was assessed in terms of contrast-to-noise ratio (CNR) and signal-to-noise ratio (SNR). The CNR for all examinations were between 3.54 3.27 and 20.63 8.65 for the two hospitals involved in this study. A maximum difference 17.09 in CNR was found between hospital 1 (H-1) and 2 (H-2). The results obtained for SNR for both hospitals showed that 92.86% of all the images assessed were at least 1.22 higher than the Rose Model of the threshold value of 5. The images were of good quality and hence, they provided useful clinical information. The relationship between CNR and the entrance surface dose (ESD) to patients for all the examinations showed that there is a potential to reduce doses to patients while keeping images of diagnostic quality.
European Radiology, 2008
The introduction of digital radiography not only has revolutionized communication between radiologists and clinicians, but also has improved image quality and allowed for further reduction of patient exposure. However, digital radiography also poses risks, such as unnoticed increases in patient dose and suboptimum image processing that may lead to suppression of diagnostic information. Advanced processing techniques, such as temporal subtraction, dual-energy subtraction and computer-aided detection (CAD) will play an increasing role in the future and are all targeted to decrease the influence of distracting anatomic background structures and to ease the detection of focal and subtle lesions. This review summarizes the most recent technical developments with regard to new detector techniques, options for dose reduction and optimized image processing. It explains the meaning of the exposure indicator or the dose reference level as tools for the radiologist to control the dose. It also provides an overview over the multitude of studies conducted in recent years to evaluate the options of these new developments to realize the principle of ALARA. The focus of the review is hereby on adult applications, the relationship between dose and image quality and the differences between the various detector systems.
British Journal of Radiology, 2009
The purpose of this study was to investigate whether the exposure (speed) class (EC) of an Agfa computed radiography (CR) system could be used to optimise chest radiography. The frequency-dependent normalised noise-power spectra (NNPS(f)) were determined for a range of EC settings (25-1200) for a receptor dose of 4 mGy. Signal-tonoise ratios (SNRs) were measured in the lung, heart and diaphragm areas of a chest phantom with ECs of 400 and 600 at four tube voltages (60, 75, 90 and 125 kVp). As anatomical background can be a factor in detection of lung nodules, a tissue to rib ratio (TRR), which measures the ratio of pixel values in the nodule to that of rib, was measured in the lung region of the phantom to assess the suppression of the rib at ECs of 400 and 600. The NNPS(f) at ECs lower than 400 was relatively high. The NNPS(f) at EC 600 was found to be 7% lower when averaged over all frequencies than that at EC 400. The statistical significance of this difference was verified. The EC 800 and EC 1200 settings offered no extra advantages in terms of lowering frequency-dependent noise. The EC 600 setting offered improvements in SNR of between 10% and 18% in the lung, 11% and 16% in the heart, and 15% and 20% in the diaphragm compared with EC 400. Statistical analysis verified the significant difference. The EC 600 setting increased the TRR, thereby helping to suppress rib. This work indicates that an exposure class setting of 600 is the most appropriate for standard chest radiography, but clinical verification is required.