Revisit image control for pediatric chest radiography

Purpose The aim of this study was to analyze the fraction defectiveness and efficacy of the patient immobilization device (PID) for pediatric chest radiography. Materials and methods We examined 840 plain chest radiographs in six hospitals, including four children's hospitals and two general hospitals. The mean age of the patients was 1.9 years (range 0–5 years). Two board-qualified pediatric radiologists rated (into three grades, by consensus) the degree of inspiration, rotation, lordosis, scoliosis, and cutoff or coning as well as the quality of the chest radiographs. Results The incidence of “poor” and “very poor” quality examinations was 2/140 and 3/140 in each of two children's hospitals using PID. The corresponding figures were 9/139 and 17/140 in the two children's hospitals that did not use PID. The general hospital using PID had 14/140 “poor” and “very poor” examinations. The general hospital that did not use PID had 28/140 “poor” and “very poor” examinations. Thus, statistically better quality chest radiography was obtained with the use of PID (P < 0.001). Likewise, rotation, lordosis, and scoliosis were less frequently diagnosed as present when PID was used (P < 0.001, 0.001, 0.05). Cutoff or coning had no relation to the use of PID (P = 0.13). No significant difference was found between the degree of inspiration and the use of PID (P = 0.56). Conclusion Fraction defectiveness in the general hospital that did not use PID was as much as 14 times higher than that of the children's hospitals that used PID. The patient immobilization device is recommended for hospitals with technologists not specifically trained for pediatric examination.     

MR imaging of lung parenchyma at 0.2 T: evaluation of imaging techniques,comparative study with chest radiography and interobserver analysis

The purpose of this study was to evaluate low-field MR imaging of the lung parenchyma in comparison with postero-anterior (PA) and lateral chest radiographs (CR). One hundred one prospectively randomized patients who had received routine CR were additionally examined with magnetic resonance imaging (MRI) at 0.2 T. Utilized sequences were: constructive interference in steady state (CISS), true fast imaging in steady state precession (True-FISP) and T1-weighted spin-echo (T1SE). Consensus reading of two observers was performed for CR. Three other observers analyzed hardcopies of the MRI examinations for each sequence independently. The individual results for the comparisons between the sequences and CR were calculated using kappa coefficients with their corresponding confidence intervals. Additionally, an interobserver analysis was performed.The proportions of agreement for the three sequences compared with CR were high, with 0.93 for CISS, 0.89 for True-FISP and 0.91 for T1SE. The kappa coefficients and the corresponding confidence intervals were 0.81 [0.68; 0.95] for CISS, 0.72 [0.57; 0.88] for True-FISP and 0.78 [0.65; 0.92] for T1SE. Concerning CISS, differences between MRI and CR were mainly related to advantages resulting from cross-sectional imaging. The smallest 95% lower confidence bound of the three kappa measures for comparing the MR readers with each other was 0.97, indicating a high interobserver agreement. Low-field MRI of the lung parenchyma using the CISS sequence is well comparable with chest radiography and demonstrates slight advantages resulting from the cross-sectional imaging technique.     

Clinical evaluation of a dual-side readout technique computed radiography system in chest radiography of premature neonates

Background: Recently, the dual-side readout technique has been introduced in computed radiography, leading to an increase in detective quantum efficiency (DQE) compared with the single-side readout technique.

Purpose: To evaluate if the increase in DQE with the dual-side readout technique results in a higher clinical image quality in chest radiography of premature neonates at no increase in radiation dose.

Material and Methods: Twenty-four chest radiographs of premature neonates were collected from both a single-side readout technique system and a double-side readout technique system. The images were processed in the same image-processing station in order for the comparison to be only dependent on the difference in readout technique. Five radiologists rated the fulfillment of four image quality criteria, which were based on important anatomical landmarks. The given ratings were analyzed using visual grading characteristics (VGC) analysis.

Results: The VGC analysis showed that the reproduction of the carina with the main bronchi and the thoracic vertebrae behind the heart was better with the dual-side readout technique, whereas no significant difference for the reproduction of the central vessels or the peripheral vessels could be observed.

Conclusions: The results indicate that the higher DQE of the dual-side readout technique leads to higher clinical image quality in chest radiography of premature neonates at no increase in radiation dose.     

老年肺结核的X线、CT征象（附260例分析）

目的了解老年肺结核的影像特征,进一步提高诊断准确率。方法260例临床及病理证实的老年性肺结核患者均经胸部x线平片检查,其中157例经CT平扫,对所有患者X线、CT表现进行了回顾性分析,对X线与CT诊断肺结核的能力进行了比较,以及观察分析病变的部位、范围、形态、类型。结果本组260例肺结核中,X线平片正确诊断191例（73.5％）,漏诊及不能确诊69例（26.5％）。老年性肺结核的主要X线征象：空洞及纤维性空洞性病变175例,增殖性病变142例,纤维病变及钙化81例,渗出性病变52例。CT正确诊断146例（93％）,漏误诊11例（7％）。肺结核主要CT表现：纤维空洞性病变,片状渗出性病变,增殖性病变,纤维及钙化,淋巴结增大,结核球。本组X线漏诊69例,后经CT明确诊断。被CT漏诊的2例由X线胸片明确诊断。结论CT对老年肺结核的诊断准确率明显高于x线平片。老年肺结核具有临床症状不典型,影像表现多样,典型征象少,病变部位不固定等特点,只有综合分析才能做出正确的诊断。     

Direct detector radiography versus dual reading computed radiography: feasibility of dose reduction in chest radiography

The image quality of dual-reading computed radiography and dose-reduced direct radiography of the chest was compared in a clinical setting. The study group consisted of 50 patients that underwent three posteroanterior chest radiographs within minutes, one image obtained with a dual read-out computed radiography system (CR; Fuji 5501) at regular dose and two images with a flat panel direct detector unit (DR; Diagnost, Philips). The DR images were obtained with the same and with 50% of the dose used for the CR images. Images were evaluated in a blinded side-by-side comparison. Eight radiologists ranked the visually perceivable difference in image quality using a three-point scale. Then, three radiologists scored the visibility of anatomic landmarks in low and high attenuation areas and image noise. Statistical analysis was based on Friedman tests and Wilcoxon rank sum tests at a significance level of P<0.05. DR was judged superior to CR for the delineation of structures in high attenuation areas of the mediastinum even when obtained with 50% less dose (P<0.001). The visibility of most pulmonary structures was judged equivalent with both techniques, regardless of acquisition dose and speed level. Scores for image noise were lower for DR compared with CR, with the exception of DR obtained at a reduced dose. Thus, in this clinical preference study, DR was equivalent or even superior to the most modern dual read-out CR, even when obtained with 50% dose. A further dose reduction does not appear to be feasible for DR without significant loss of image quality.     

Dose and perceived image quality in chest radiography

Chest radiography is the most commonly performed diagnostic X-ray examination. The radiation dose to the patient for this examination is relatively low but because of its frequent use, the contribution to the collective dose is considerable. Consequently, optimization of dose and image quality offers a challenging area of research. In this article studies on dose reduction, different detector technologies, optimization of image acquisition and new technical developments in image acquisition and post processing will be reviewed.Studies indicate that dose reduction in PA chest images to at least 50% of commonly applied dose levels does not affect diagnosis in the lung fields; however, dose reduction in the mediastinum, upper abdomen and retrocardiac areas appears to directly deteriorate diagnosis. In addition to patient dose, also the design of the various digital detectors seems to have an effect on image quality. With respect to image acquisition, studies showed that using a lower tube voltage improves visibility of anatomical structures and lesions in digital chest radiographs but also increases the disturbing appearance of ribs.New techniques that are currently being evaluated are dual energy, tomosynthesis, temporal subtraction and rib suppression. These technologies may improve diagnostic chest X-ray further. They may for example reduce the negative influence of over projection of ribs, referred to as anatomic noise. In chest X-ray this type of noise may be the dominating factor in the detection of nodules. In conclusion, optimization and new developments will enlarge the value of chest X-ray as a mainstay in the diagnosis of chest diseases.     

床旁DR与CR胸部摄影质量的对比研究

目的通过床旁数字化X线摄影(digitalradiography,DR)系统与计算机X线摄影(computedradiography,CR)系统胸部摄影图像质量的对比分析,探讨床旁DR摄影的优势。方法随机抽取2010年拍摄的DR床旁X线胸片1000份和既往CR床旁X线胸片1000份进行对比分析。结果床旁DR摄影的应用提供了更加优良的图像质量,明显减少了放射技师的工作量,同时还降低了患者接受的辐射剂量。结论床旁DR胸部摄影比CR胸部摄影有着明显的优势,对手术患者和危重患者的诊治起到了积极作用。     

Improvement of lung abnormality detection in computed radiography using multi-objective frequency processing: Evaluation by receiver operating characteristics (ROC) analysis

Computed radiography (CR) has been shown to have relatively low sensitivity for detection of pulmonary nodules. This poor sensitivity precludes its use as a screening modality despite the low cost, low dose and wide distribution of devices. The purpose of this study was to apply multi-objective frequency processing (MFP) to CR images and to evaluate its usefulness for diagnosing subtle lung abnormalities. Fifty CR images with simulated subtle lung abnormalities were obtained from 50 volunteers. Each image was processed with MFP. We cut chest images. The chest image was divided into two rights and left. A total of 200 half-chest images (100 MFP-processed images and 100 MFP-unprocessed images) were prepared. Five radiologists participated in this study. ROC analyses demonstrated that the detection rate of simulated subtle lung abnormalities on the CR images was significantly better with MFP (Az=0.8508) than without MFP (Az=0.7925). The CR images processed with MFP could be useful for diagnosing subtle lung abnormalities. In conclusion, MFP appears to be useful for increasing the sensitivity and specificity in the detection of pulmonary nodules, ground-glass opacity (GGO) and reticular shadow.     

Digital imaging of the chest in newborns: influence of radiation exposure on image quality

In order to evaluate the influence of radiation exposure on image quality in digital storage phosphor radiography, 200 digital storage phosphor chest radiographs, obtained on a neonatal Intensive Care Unit, and the same number of conventional screen-film radiographs (speed 250) were assessed for the visibility of anatomical structures and catheters. The same exposure parameters were used in both groups. Normal variations of radiation exposure under free exposure conditions were estimated in all digital images using a formula calculating radiation dose in the screen-plane from image sensitivity, latitude and average grey value of the right lung. There was already a significant (P < 0.001) decline in image quality in the digital images with a 30–50% reduction in radiation exposure, which was most severe for structures such as trachea, retrocardiac space, lung texture and low-contrast catheters. Compared with optimally exposed conventional images, only those digital images with a slightly higher than normal dose had an equivalent image quality. Correspondence to: U. Bick     

DR胸部X线摄影技术在临床的应用

目的评价直接数字X线摄影系统在胸部疾病诊断与筛查中的实用意义。方法自2005年9月以来,应用西门子FX直接数字X线摄影系统对我院门诊、急诊、住院患者及来院体检者进行了胸部检查。DR影像经激光打印机打印后,以数字化形式传入我院PACS供实时共享。DR影像显示病变的能力与常规X线平片进行了比较。结果自2005年9月应用西门子FX直接数字X线摄影系统以来,基本满足了我院门诊、急诊、住院患者胸部疾病诊断和来院体检者胸部疾病筛查的实际需要。与常规X线平片比较,DR影像能更清晰、准确地显示病灶。结论DR是诊断和筛查胸部疾病的重要影像技术,尤其与PACS联合应用是医院数字化管理的重要标志。     

Image quality of supine chest radiographs: intra-individual comparison of computed radiography and low-dose linear-slit digital radiography

The purpose of this retrospective study was to intra-individually compare the image quality of computed radiography (CR) and low-dose linear-slit digital radiography (LSDR) for supine chest radiographs. A total of 90 patients (28 female, 62 male; mean age, 55.1 years) imaged with CR and LSDR within a mean time interval of 2.8 days ± 3.0 were included in this study. Two independent readers evaluated the image quality of CR and LSDR based on modified European Guidelines for Quality Criteria for chest X-ray. The Wilcoxon test was used to analyse differences between the techniques. The overall image quality of LSDR was significantly better than the quality of CR (9.75 vs 8.16 of a maximum score of 10; p < 0.001). LSDR performed significantly better than CR for delineation of anatomical structures in the mediastinum and the retrocardiac lung (p < 0.001). CR was superior to LSDR for visually sharp delineation of the lung vessels and the thin linear structures in the lungs. We conclude that LSDR yields better image quality and may be more suitable for excluding significant pathological features of the chest in areas with high attenuation compared with CR.     

Optimisation of radiation dose and image quality in mobile neonatal chest radiography

PurposeTo optimise the radiation dose and image quality for chest radiography in the neonatal intensive care unit (NICU) by increasing the mean beam energy.MethodsTwo techniques for the acquisition of NICU AP chest X-ray images were compared for image quality and radiation dose. 73 images were acquired using a standard technique (56 kV, 3.2 mAs and no additional filtration) and 90 images with a new technique (62 kV, 2 mAs and 2 mm Al filtration). The entrance surface air kerma (ESAK) was measured using a phantom and compared between the techniques and against established diagnostic reference levels (DRL). Images were evaluated using seven image quality criteria independently by three radiologists. Images quality and radiation dose were compared statistically between the standard and new techniques.ResultsThe maximum ESAK for the new technique was 40.20 μGy, 43.7% of the ESAK of the standard technique. Statistical evaluation demonstrated no significant differences in image quality between the two acquisition techniques.ConclusionsBased on the techniques and acquisition factors investigated within this study, it is possible to lower the radiation dose without any significant effects on image quality by adding filtration (2 mm Al) and increasing the tube potential. Such steps are relatively simple to undertake and as such, other departments should consider testing and implementing this dose reduction strategy within clinical practice where appropriate.     

A method to optimize the processing algorithm of a computed radiography system for chest radiography

A test methodology using an anthropomorphic-equivalent chest phantom is described for the optimization of the Agfa computed radiography "MUSICA" processing algorithm for chest radiography. The contrast-to-noise ratio (CNR) in the lung, heart and diaphragm regions of the phantom, and the "system modulation transfer function" (sMTF) in the lung region, were measured using test tools embedded in the phantom. Using these parameters the MUSICA processing algorithm was optimized with respect to low-contrast detectability and spatial resolution. Two optimum "MUSICA parameter sets" were derived respectively for maximizing the CNR and sMTF in each region of the phantom. Further work is required to find the relative importance of low-contrast detectability and spatial resolution in chest images, from which the definitive optimum MUSICA parameter set can then be derived. Prior to this further work, a compromised optimum MUSICA parameter set was applied to a range of clinical images. A group of experienced image evaluators scored these images alongside images produced from the same radiographs using the MUSICA parameter set in clinical use at the time. The compromised optimum MUSICA parameter set was shown to produce measurably better images.     

Digital radiography of the chest: state of the art

Digital image acquisition possesses a number of advantages over conventional systems in radiographic examination of the chest, the most important of which is its greater dynamic range. In addition, one digital images are acquired, they can be processed by computer in ways that cannot be rivalled by conventional analog techniques. Finally, digital images can be stored, retrieved and transmitted to local or remote sites. Here the status of the different digital systems employed in chest radiology and commonly used image processing techniques are reviewed. Also discussed are the current clinical applications of integrating digital chest radiography with a picture archiving and communication system (PACS) along with the difficulties typically encountered. Studies with a variety of digital techniques have been carried out on several fronts. Computer radiography based on photostimulabe phosphor (CR) has replaced screen-film imaging in certain applications (i.e. bedside imaging). However, CR has limitations, namely its poor X-ray utilisation efficiency at high X-ray tube voltages and sensitivity to scatter; therefore, it is not ideal for all applications. Recently, a dedicated digital chest unit with excellent X-ray utilisation efficiency at high X-ray tube potentials has been introduced. On the basis during the past decade, recommendations are made regarding the most desirable equipment specifications for dedicated and bedside digital chest radiography.     

癌性肺纹理对肺癌X线早期诊断的价值

目的为了提高对早期肺癌癌性肺纹理的认识，减少早期肺癌的误漏诊。方法对32例误漏为其它疾病及确诊为肺癌经治疗后肺纹理有改变者的X线胸片进行回顾性分析。结果肺癌早期可出现增粗、连续性差或分支细小增多、僵硬，走行失常之肺纹理。结论早期肺癌X线胸片上未见明显瘤体时，其癌性肺纹理的形态特点有助于肺癌的早期诊断。