Evaluating the use of higher kVp and copper filtration as a dose optimisation tool in digital planar radiography

IntroductionTo identify the potential of beam hardening techniques, specifically the use of higher kilo voltage (kV) and copper (Cu) filtration, to optimise digital planar radiographic projections. The study assessed the suitability of such techniques in radiation dose reductions while maintaining diagnostic image quality for four common radiographic projections: antero-posterior (AP) abdomen, AP-knee, AP-lumbar spine, and lateral lumbar spine.MethodsAnthropomorphic phantom radiographs were obtained at varying kVp (standard kVp, +10 kVp, and +20 kVp) and varying Cu filtration thickness (0 mm, 0.1 mm, and 0.2 mm Cu). The Dose Area Product (DAP), mAs and time (s) were recorded as an indication of the emitted radiation dose. Image quality was assessed objectively via Contrast-Noise-Ratio (CNR) calculations and subjectively via Visual Grading Analysis (VGA) performed by radiographers and radiologists.ResultsOptimised exposure protocols were established for the AP-abdomen (100 kVp with 0.2 mm Cu), AP-knee (85 kVp, and 0.1 mm Cu), AP-lumbar spine (110 kVp and 0.2 mm Cu), and lateral lumbar spine (110 kVp and 0.2 mm Cu). This strategy resulted in respective DAP reductions of 71.98%, 62.50%, 64.51% and 71.85%. While CNR values decreased as beam hardening techniques were applied, VGA demonstrated either a lack of statistical variation or improved image quality between the standard and the optimised exposure protocols.ConclusionsDAP reductions without compromising image quality can be achieved through beam hardening for the AP-abdomen, AP-knee, AP-lumbar spine, and lateral lumbar spine projections.Implications for practiceBeam hardening techniques should be considered as an optimisation strategy in medical imaging departments. Research into the applicability of this strategy for other radiographic projections is recommended.     

Acute knee trauma: analysis of multidetector computed tomography findings and comparison with conventional radiography

Purpose: To evaluate the multidetector computed tomography (MDCT) findings of acute knee trauma and to compare radiography with MDCT in patients referred to a level 1 trauma center.

Material and Methods: During a 5-year period, a total of 415 MDCT examinations were performed on 409 patients with acute knee trauma to reveal complex fracture anatomy or rule out a fracture. MDCT and primary radiographs were re-evaluated with respect to fracture location and trauma mechanism. Tibial plateau fractures were further analyzed depending on anatomical location: anterior-medial, anterior-lateral, posterior-lateral, and posterior-medial regions. Maximal depression of the tibial articular surface was measured. Findings on the primary knee radiographs were compared with MDCT findings.

Results: Of the 409 patients, 356 (87%) had a knee fracture. A total of 451 fractures were found in all anatomic regions: distal femur (n = 49), proximal tibia (n = 307), patella (n = 23), and proximal fibula (n = 72). Primary radiographs were available in 316 (76%) cases. Of these, 225 (71%) had MDCT in order to reveal the fracture anatomy better, and 91 (29%) had a subsequent MDCT after negative plain radiographs. Overall sensitivity of radiography was 83%, while negative predictive value was 49%. On radiography, tibial plateau articular depression was underestimated in all regions except when the fracture consisted of the whole half of the anterior or posterior plateau. The three main injury mechanisms were traffic accident, a simple fall, and sport. In 49 cases (15%), primary radiographs were suboptimal due to positioning.

Conclusion: In severely injured patients, diagnostically sufficient radiographs are difficult to obtain, and therefore a negative radiograph is not reliable in ruling out a fracture. In these patients, MDCT is a fast and accurate examination and is also recommended in patients with tibial plateau fractures or complex knee injuries in order to evaluate the fracture adequately.     

膝关节摄影中照射野大小对DDR系统影像质量的影响

目的评价在膝关节摄影中，照射野的选择对直接数字化X线摄影（DDR）系统影像质量的影响。方法随机抽取50例膝关节患者，在摄影条件相同的情况下，对左右侧膝关节用不同的照射野进行摄影，在工作站分别对膝关节影像进行灰度值测量，测量点为胫骨内外髁连线，获得连线的灰度值曲线。小照射野组使用DDR系统进行膝关节正位摄影，焦一片距100cm，摄影条件为55kV、25mAs，照射野包括软组织边缘1～2cm。大照射野组是对小照射野组相同病例的对侧膝关节使用相同的摄影条件，照射野与探测器板的大小一致。结果小照射野组的软组织灰度值曲线呈逐渐变化，显示层次增加；大照射野组的软组织灰度值曲线较平缓，接近骨骼组织时变化陡峭，显示高反差。小照射野组的骨骼组织灰度值曲线形态与大照射野组基本一致，但灰度值的大小整体增大，骨骼组织与软组织的灰度值差异减少。结论DDR系统对面积较小的部位进行摄影时，应缩小照射野，可以获得较理想的影像质量。     

Scatter dose calculation for anti-scatter linear grids in mammography

Monte Carlo simulations were used to optimize the geometry of a mammography anti-scatter linear grid to achieve minimum scatter-to-primary ratio (SPR) for different X-ray tube voltages. A single optimum design of the grid with 0.9 mm septa height, 12 μm septa thickness and 100 μm interspace thickness was found for breast phantom thicknesses between 30 and 80 mm. The optimal grid has 0.153–0.330 scatter-to-primary ratio, a Bucky factor (BF) less than 2.5 and a contrast improvement factor (CIF) of 1.3.     

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.     

An evaluation of paediatric projection radiography in Ireland

PurposeThis study investigated common paediatric radiography examinations in Ireland and analysed any potential for improvement by considering compliance with requirements for justification, the range of doses delivered and potential Diagnostic Reference Levels, and technique approaches that enhance optimisation.MethodReferral information, Dose Area Product (DAP) dose, technique details and patient data were gathered from 568 paediatric examinations performed across several hospitals. The examinations were mobile infant chest (n = 66), chest (n = 266), abdomen (n = 96), lumbar spine (n = 14), full spine (n = 5), pelvis (n = 151) and skull (n = 28). Data were analysed to allow comment on the adequacy of justification, the range of doses being delivered and possible Diagnostic Reference Levels (DRLs), and the potential for optimisation of radiographic technique.Results/conclusionsResults indicate that the principle of justification is generally applied well in paediatric practice.Dose results indicate that age-related doses are generally comparable to published data, although dose variations exist within and between hospitals. Although differences between minimum and maximum DAP values were substantial, differences between the first and third quartile values were rarely greater than a factor of three. With regard to DRLs, age-related, 75th centile DAP values are presented for five paediatric X-ray examinations. While DAP DRLs stated as a function of age are a pragmatic approach to preliminary DRL values, size related DRLs are acknowledged as a better approach and the necessity of objective paediatric patient size measurement is emphasised.With regard to potential for optimisation, small samples limited analysis of factorial influences on DAP. However, trends indicate that objective consideration of kVp and mAs, careful collimation, and matching of exposure to baby weight in neonates and to measured patient depth in children could all contribute to better optimisation. These factors are all within the radiographer's control, thus highlighting the pivotal role of the radiographer in ensuring that the principle of optimisation is attained.     

The use of radiography in forensic medicine

Forensic radiography has traditionally been carried out within imaging departments or mortuaries by radiographers on a voluntary basis. This paper presents an overview of traditional and newer techniques, together with an insight into some techniques carried out internationally, which may influence future developments in the United Kingdom, as uncovered in a search of the literature using CD-ROM and manual methods.     

Fixed-flexion radiography of the knee provides reproducible joint space width measurements in osteoarthritis

The validity of a non-fluoroscopic fixed-flexion radiographic acquisition and analysis protocol for measurement of joint space width (JSW) in knee osteoarthritis is determined. A cross-sectional study of 165 patients with documented knee osteoarthritis participating in a multicenter, prospective study of chondroprotective agents was performed. All patients had posteroanterior, weight-bearing, fixed-flexion radiography with 10° caudal beam angulation. A specially designed frame (SynaFlexer) was used to standardize the positioning. Minimum medial and lateral JSW were measured manually and twice by an automated analysis system to determine inter-technique and intra-reader concordance and reliability. A random subsample of 30 patients had repeat knee radiographs 2 weeks apart to estimate short-term reproducibility using automated analysis. Concordance between manual and automated medial JSW measurements was high (ICC=0.90); lateral compartment measurements showed somewhat less concordance (ICC=0.72). There was excellent concordance between repeated automated JSW measurements performed 6 months apart for the medial (ICC=0.94) and lateral (ICC=0.86) compartments. Short-term reproducibility for the subsample of 30 cases with repeat acquisitions demonstrated an average SD of 0.14 mm for medial JSW (CV=4.3%) and 0.23 mm for lateral JSW (CV=4.0%). Fixed-flexion radiography of the knee using a positioning device provides consistent, reliable and reproducible measurement of minimum JSW in knee osteoarthritis without the need for concurrent fluoroscopic guidance.     

高频超声和X线对膝骨性关节炎的临床应用价值比较

目的：比较高频超声和 X 线对膝骨性关节炎的临床应用价值。方法：对比高频超声和 X 线两种检查方法对膝骨性关节炎的诊断符合率,观察膝骨性关节炎的高频超声图像特征。结果：高频超声对膝骨性关节炎的诊断符合率显著高于 X 线（χ2＝7．365,P ＝0．007）。与治疗前相比髌上囊积液、滑膜厚度经治疗后显著降低（t ＝47．655,19．199;P ＝0．000,0．000）;治疗前滑膜血流信号分布比例为0级48．2％、Ⅰ级32．1％、Ⅱ级12．5％,出现窝囊肿、软骨破坏、骨质破坏的比例分别为17．9％、100％、100％。治疗后滑膜血流信号分布比例为0级64．3％、Ⅰ级12．5％、Ⅱ级7．1％,出现窝囊肿、软骨破坏、骨质破坏的比例分别为3．6％、100％、100％;治疗前 X 线显示患者发生关节间隙狭窄、骨质增生、关节面囊肿、关节内游离体和半脱位的比例分别为50．0％、42．9％、33．9％、8．9％和10．7％,而治疗后 X 线显示患者发生关节间隙狭窄、骨质增生、关节面囊肿、关节内游离体和半脱位的比例分别为12．5％、5．4％、8．9％、1．8％和0％。结论：高频超声和 X 线在临床上均可用于诊断膝骨性关节炎,且高频超声对膝骨性关节炎的诊断符合率显著高于 X 线。     

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.     

The application of anatomical side markers during abdominal and IVU examinations: An investigation of practice prior to and post-installation of computed radiography (CR)

Professionally, radiographers are accountable for their practice. Available literature highlights the ramifications of not using anatomical side markers within the primary beam. It was thought by the authors that the installation of a computed radiography (CR) system could potentially cause a change in practice due to the ease of adding anatomical side markers manually/electronically during post-processing. This study assessed anatomical marker use within the primary beam at a district general hospital in East Anglia, one-year pre-CR installation and one-year post-CR installation. 100 abdominal images were evaluated from each time period and the presence of anatomical side markers was recorded and compared to establish any significant change. The study showed that although there was a decline in use of anatomical side markers used within the primary beam post-CR installation (from 32% to 25%), the changes were not statistically significant (p > 0.05). However, the agreed standard of 100% images having the primary beam side marker present was not met. There is a conflict of opinion about the necessity for anatomical side markers to be used within the primary beam. However, the researchers believe there is a case for recommending alterations and improvements to practice to comply with ‘best practice’ requirements.     

The effect of knee position on the reproducibility of measurements taken from stress films: a comparison of four measurement methods

We evaluated the accuracy of four different means of radiographic measurement of anteroposterior translation in the knee joint. The tests were performed in normal knees, in knees lacking the anterior cruciate ligament, and in knees lacking both anterior and posterior cruciate ligaments; the knees were obtained from cadavers. It is difficult to define landmarks and to perform exact measurements, and we sought to determine which of the four methods is the most accurate. In particular, we examined the effect of various degrees of rotation and flexion on the positional relationships of the landmarks of the tibia and the femur. Received: 25 July 1998/Accepted: 17 December 1999     

Use of radiographic projections of knee

A study of determine the routine radiography practice for the investigation of acute trauma cases and those with suspected arthritis of the knee was carried out by questionnaires sent to radiologists in 41 countries. The role of radiology in the investigation of chondromalacia patellae was also ascertained. Some of the reasons for the diversities of practice are discussed.The necessity for further views of the knee to supplement the two standard projections was assessed for various diagnostic entities. It became clear that if occult fractures were not to be missed, patients with knee effusions following acute trauma required additional views if a lesion was not shown by the anteroposterior (AP) and lateral views. In contrast, two views of the knee sufficed for examination of most entities affecting the knee.     

Computed radiography versus indirect digital radiography for the detection of glass soft-tissue foreign bodies

AimThe principle aim of this study was to compare computed radiography (CR) and indirect, flat-panel, digital radiography (DR) for the visibility of radio-opaque glass foreign bodies.MethodsAn image-quality study was undertaken using a chicken thigh, as the soft-tissue model, implanted with varying sizes of glass particles (1 mm, 2 mm and 3 mm) which were imaged using CR and DR. Observers rated the acquired images based on the presence or absence and conspicuity of the foreign body. Ratings were then analysed in order to identify significance of any findings.ResultsCR (median = 4, interquartile range (IQR) = 1.0, n = 240) was found to be superior to DR (median = 3, IQR = 3.0, n = 240) in the detection of glass foreign bodies in soft-tissue (p = 0.001). Decreasing size of foreign bodies did not affect the performance of CR (p = 0.298), but did for DR with x² (2, n = 240) = 12.22, p = 0.002. The selected exposure factors were a limiting factor for DR but not for CR.ConclusionFor the systems used in the current study, CR should be considered ahead of DR for glass particles less than 3 mm while for the larger glass particles either CR or DR is appropriate. Finally, careful consideration should be taken when selecting exposure factors for imaging foreign bodies.     

Direct digital radiography versus storage phosphor radiography in the detection of wrist fractures

AIM: To define the value of digital radiography with a clinical flat panel detector system for evaluation of wrist fractures in comparison with state of the art storage phosphor radiography. MATERIAL AND METHODS: Hard copy images of 26 fractured wrist specimens were acquired with the same exposure dose on a state of the art storage phosphor radiography system and a clinical flat panel detector. Image features like cortical bone surface, trabecular bone, soft tissues and fracture delineation were independently analysed by 4 observers using a standardised protocol. Image quality ratings were evaluated with an analysis of variance (ANOVA). RESULTS: Flat panel detector radiographs were rated superior with respect to cortical and trabecular bone representation as well as fracture evaluation, while storage phosphor radiographs produced better soft tissue detail. CONCLUSION: In some of the observed image quality aspects, the performance of caesium iodide/amorphous silicon flat panel detector exceeds state of the art storage phosphor radiography. This makes it well suited for skeletal imaging particularly in trauma as seen in the detection of wrist fractures.     

双下肢全长负重位与非负重位摄影在全膝关节置换术前评估的研究

目的分析负重位与非负重位下肢力线的差异,探讨双下肢全长摄影在全膝关节置换术中的应用价值。方法回顾性分析我院41例接受全膝关节置换术的患者资料,术前所有患者均行双下肢全长负重位与非负重位x线片,测量负重和非负重位下肢力线（膝内翻角）、股骨力线、关节间隙夹角及胫骨平台内侧夹角。结果．负重位膝内翻角、股骨力线、关节间隙夹角均大于非负重位,差异有统计学意义（P〈O．01）;负重、非负重位膝内翻角及其差值均呈正相关（r=0．569～0．992,P〈O．01）;负重、非负重位膝内翻角及其差值与关节间隙夹角呈正相关（r=-0．567～0．632,P〈0．01）;负重、非负重位膝内翻角和关节间隙夹角及其各自差值分别与胫骨平台内侧夹角均呈负相关（r=-0．751～-0．491,P〈O．01）;负重与非负重位股骨力线呈正相关（r=0．989,P〈0．01）,但与其差值不相关（r=0．199,P〉0．01）;负重、非负重位股骨力线及其差值与胫骨平台内侧夹角不相关（r=-0．123～O．104,P〉0．01）。结论全膝关节置换术前评估,负重位比非负重位片更准确,具有重要的临床价值;非负重位对了解韧带松弛程度,平衡周围软组织有意义,建议作为参考。     

髋关节改良侧位摄影的实际应用

目的 设计一种既操作简便又与常规髋关节侧位同样拍摄效果的新体位.方法 采用不同摄影角度对骨骼模型进行X线摄影,测量股骨头、颈充分显示时中心线倾斜角度和骨骼模型倾斜角度,并对头、颈显示情况评分;对30例髋关节X线摄影患者加照新侧位,并与常规侧位的实际可操作性和图像质量进行对比.结果 模拟摄影得出中心线向头侧倾斜35°~45°,身体冠状面与探测器角度60°~70°,评分为3分;新侧位具有可行性,对关节面、间隙显示率均为96.7%,股骨头、颈均为100%,大粗隆为80%,小粗隆为100%.结论 改良髋关节侧位摄影方法同样可以显示股骨头、颈和其余诸组成骨情况.     

Radiation dose and image information in computed radiography. A phantom study of angle measurements in the weight-bearing knee

Purpose: To establish a correlation between radiation dose and diagnostic accuracy when employing a new digital method for angle determinations. The specific intention was to determine how far the radiation dose can be reduced without losing measuring accuracy and to compare this radiation dose with that employed with our conventional method.Material and Methods: An image succession of an anthropomorphic phantom was generated with a computed radiography (CR) system, by reducing the exposure stepwise. The images were archived and transferred to a workstation for evaluation. The intraobserver variation of two angle determinations was used as an indicator of the evaluation accuracy. Patient radiation doses were measured with thermoluminescent dosimeters. The energy imparted, indicating the relative risk associated with exposure to ionising radiation, and the effective dose, which determines the absolute risk, were calculated.Results and Conclusion: No significant correlation was found between patient dose and measuring accuracy within the evaluated exposure interval. At the lowest exposure of the CR system, the energy imparted to the patient was 30 μJ. Compared with our conventional analogue method this is a reduction by 98%. The effective dose was as low as 1.5 μSv. The CR technique creates possibilities to adapt exposure parameters, and thus the radiation dose to the patient, according to the purpose of the investigation.     

计算机X线摄影能量减影与直接数字摄影对胸部软组织病变检测能力比较

目的 比较计算机X线摄影能量减影技术(ES-CR)与直接数字摄影技术(DR)对肺内软组织信号的探测能力。方法 应用胸部放射学体模和X线摄影统计学体模摄取ES-CR和DR影像,由6位放射科医师用5等级判别法各自独立阅读影像,编写程序对观察结果进行受试者操作特性曲线(ROC)分析。收集28例病理证实小肺癌患者的胸部DR影像和ES-CR影像,由3位放射科医师一起做出诊断,分析其真阳性率的差异性。结果 体模影像的ROC分析,ES-CR和DR的 Az 值分别为0.727和0.827,差异有统计学意义( Z =2.96, P<0.05)。28例小肺癌两成像系统的差异也有统计学意义(χ²=5.14, P<0.05)。结论 用DR诊断的真阳性率要高于ES-CR。ES-CR对胸部软组织信号的检出能力尚不如DR。