CR与非晶体硅DR胸部摄影曝光剂量优化的探讨

目的 比较CR与非晶体硅DR在胸部摄影中入射剂量的差异,探讨两者最优化曝光剂量。方法 应用CR、DR分别对胸部模体行不同入射剂量曝光成像,记录模体表面入射剂量,用CDRAD2.0评估软件计算模体影像图像质量因子反数值IQFinv。CR组、DR组图像IQFinv差异用两独立样本t 检验;CR组、DR组各自图像IQFinv与入射剂量的关系应用pearson相关;应用ROC曲线分析获取两组最佳图像IQFinv值,并换算曝光剂量。结果 CR和DR组入射剂量和图像质量IQFinv值之间呈明显的正相关(r =0.893、0.848, P<0.01),并存在线性回归。CR和DR组IQFinv值差异有统计学意义(t =5.455, P<0.05)。ROC曲线分析(曲线下面积AUC＝0.893, P<0.001),最佳IQFinv值为3.55。结论 CR、DR系统对于低对比度细节的检测能力均随着入射剂量的增加而增加。入射剂量相同时,DR系统对于低对比度细节的检测能力优于CR;在获得相同的图像质量时,与CR相比应用DR可大大降低被检者辐射剂量。     

Mobile chest imaging of neonates in incubators: Optimising DR and CR acquisitions

IntroductionNeonates are a particularly vulnerable patient group with complex medical needs requiring frequent radiographic examinations. This study aims to compare computed radiography (CR) and direct digital radiography (DDR) portable imaging systems used to acquire chest x-rays for neonates within incubators.MethodsAn anthropomorphic neonatal chest phantom was imaged under controlled conditions using one portable machine but captured using both CR and DDR technology. Other variables explored were: image receptor position (direct and incubator tray), tube current and kV. All other parameters were kept consistent. Contrast-to-noise ratio (CNR) was measured using ImageJ software and dose-area-product (DAP) was recorded. Optimisation score was calculated by dividing CNR with the DAP for each image acquisition.ResultsThe images with the highest CNR were those acquired using DDR direct exposures and the images with lowest CNR were those acquired using CR with the image receptor placed within the incubator tray. This is also supported by the optimisation scores which demonstrated DDR direct produced the optimal combination with regards to CNR and radiation dose. The CNR had a mean increase of 50.3% when comparing DDR direct with CR direct respectively. This was also evident when comparing DDR and CR for in-tray acquisitions, with CNR increasing by a mean of 43.5%. A mean increase of 20.4% was seen in CNR when comparing DDR tray exposures to CR direct.ConclusionDDR direct produced images of highest CNR, with incubator tray reducing CNR for both CR and DDR. However, DDR tray still had better image quality compared to CR direct.Implications for practiceWhere possible, DDR should be the imaging system of choice for portable examinations on neonates owing to its superior image quality at lower radiation dose.     

CR与非晶体硅DR胸部摄影曝光剂量优化的探讨

目的 比较CR与非晶体硅DR在胸部摄影中入射剂量的差异,探讨两者最优化曝光剂量.方法 应用CR、DR分别别胸部模体行不同入射剂量曝光成像,记录模体表面入射剂量,用CDRAD2.0评估软件计算模体影像图像质量因子反数值IQFinv.CR组、DR组图像IQFinv差异用两独立样本t检验;CR组、DR组各自图像IQFinv与入射剂量的关系应用pearson相关;应用ROC曲线分析获取两组最佳图像IQFinv值,并换算曝光剂量.结果 CR和DR组入射剂量和图像质量IQFinv值之间呈明显的正相关(r=0.893、0.848,P<0.01),并存在线性回归.CR和DR组IQFinv值差异有统计学意义(t=5.455,P<0.05).ROC曲线分析(曲线下面积AUC=0.893,P<0.001),最佳IQFinv值为3.55.结论 CR、DR系统对于低对比度细节的检测能力均随着入射剂量的增加而增加.入射剂量相同时,DR系统对于低对比度细节的检测能力优于CR;在获得相同的图像质量时,与CR相比应用DR可大大降低被榆者辐射剂量.     

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.     

CR与非晶体硅DR胸部摄影曝光剂量优化的探讨

目的 比较CR与非晶体硅DR在胸部摄影中入射剂量的差异,探讨两者最优化曝光剂量.方法 应用CR、DR分别别胸部模体行不同入射剂量曝光成像,记录模体表面入射剂量,用CDRAD2.0评估软件计算模体影像图像质量因子反数值IQFinv.CR组、DR组图像IQFinv差异用两独立样本t检验;CR组、DR组各自图像IQFinv与入射剂量的关系应用pearson相关;应用ROC曲线分析获取两组最佳图像IQFinv值,并换算曝光剂量.结果 CR和DR组入射剂量和图像质量IQFinv值之间呈明显的正相关(r=0.893、0.848,P<0.01),并存在线性回归.CR和DR组IQFinv值差异有统计学意义(t=5.455,P<0.05).ROC曲线分析(曲线下面积AUC=0.893,P<0.001),最佳IQFinv值为3.55.结论 CR、DR系统对于低对比度细节的检测能力均随着入射剂量的增加而增加.入射剂量相同时,DR系统对于低对比度细节的检测能力优于CR;在获得相同的图像质量时,与CR相比应用DR可大大降低被榆者辐射剂量.     

CEC analysis of radiological images produced in Europe and Asia

ObjectiveDiagnostic efficacy relies on optimised image quality and in the interest of patients this should not vary across sites for the same investigation. Previous work performed in Sweden reported variations for chest and dental images. The aim of this investigation was to establish if this problem was more widespread and involved several imaging departments (n = 20) in four countries and a range of examinations.MethodsImages produced following patient examinations of the chest, abdomen, pelvis and lumbar spine were assessed using anatomical parameters that were classified into technical and procedural criteria.ResultsMultiple measurements (n > 30,000) demonstrated variations in image quality for all examinations types across the hospitals investigated, with the lumbar spine AP projection recording the greatest degree of variation. The method of image analysis employed facilitated the differentiation of causal agents into technical or procedural categories.ConclusionsThe work demonstrates that X-ray image quality is dependent on the site of investigation and by greater adherence to published recommendations on equipment and technique these variations could be reduced. The authors recommend the method used to differentiate between technical- and procedural-based criteria, so causal agents responsible for image quality variations and corrective action can be more easily identified.     

数字X线摄影系统适宜曝光量差别的研究

目的 探讨数字X线摄影系统适宜曝光量设置方法,以确保图像质量和降低受检者受辐射剂量.方法 以树脂体模和对比度-细节测试体模(CDRAD2.0)为被照体,使用碘化铯探测器和硫氧化钆探测器的两种数字X线系统进行不同曝光参数成像.记录体模表面空气吸收剂量并进行秩和检验,用CDRAD分析软件计算图像质量因子函数(IQFinv),对相同曝光条件下的IQFinv值进行配对t检验,根据IQFinv值和系统感度确定这两种数字X线系统的适宜曝光量.结果 不同曝光条件下,两种数字X线系统体模表面空气吸收剂量差异没有统计学意义(P>0.05).碘化铯和硫氧化钆两种探测器的数字X线系统平均IQFinv值在125 kV时分别为4.89±1.01和2.47±0.25,70 kV时平均为5.10±1.05和2.38±0.43,相同曝光条件下两种数字X线系统IQFinv值差异有统计学意义(t值分别为6.509、10、158、P值均<0.05),碘化铯和硫氧化钆两种探测器的数字X线系统适宜曝光量之比约为1:2.结论 以IQFinv值为参考,可以量化不同数字X线系统最适曝光量差别,为正确设置曝光参数提供依据.     

Comparison of image quality and patient dose for chest x-ray examinations on conventional and low cost computed radiography systems

PurposeThe aims of this study were to assess if clinical chest radiographs taken at two computed radiography (CR) facilities fulfill standard quality criteria on conventional display monitor and the status of patient doses.MethodsTwenty-five adult patients were x-rayed at 102–109 kVp using Fuji type C image plates and low cost Philips PCR digitizer. Another group of 25 patients were x-rayed at 120 kVp using CRMD 4.0 image plates and conventional Agfa 75 CR digitizer. All 50 radiographs were independently assessed by four radiologists on conventional display monitor (model HP M70) with image software using six standard quality criteria. Entrance surface air kerma (ESAK) was determined using the measured incident air kerma values and exposure parameters.ResultsThe results show that the differences in visualization of anatomical structure in terms of image quality criteria were comparable (p > 0.05), with the exception of the visualisation of intervertebral disc spaces. However, the ESAK values for Philips PCR were higher than those for Agfa CR 75 (p < 0.001).ConclusionImages from a low cost CR system can display anatomic details comparably to conventional CR system but at the cost of higher radiation dose. Optimisation of variables that effect patient dose is desirable when using low cost CR systems.     

Image quality in conventional chest radiography. Evaluation using the postprocessing tool Diamond View

The objective of this work was to evaluate the influence of the postprocessing tool Diamond View^® (Siemens AG Medical Solutions, Germany) on image quality in conventional chest radiography. Evaluation of image quality remains a challenge in conventional radiography. Based on the European Commission quality criteria we evaluated the improvement of image quality when applying the new postprocessing tool Diamond View^® (Siemens AG Medical solutions, Germany) to conventional chest radiographs. Three different readers prospectively evaluated 102 digital image pairs of chest radiographs. Statistical analysis was performed with a p value <0.05 considered as significant. Images were evaluated on basis of the modified imaging Quality Criteria by the Commission of the European Communities. Each of the 11 image quality criteria was evaluated separately using a five point classification. Statistical analysis showed an overall tendency for improved image quality for Diamond View^® (DV) for all criteria. Significant differences could be found in most of the criteria. In conclusion DV improves image quality in conventional chest radiographs.     

Routine chest radiography using a flat-panel detector: image quality at standard detector dose and 33% dose reduction.

OBJECTIVE: The purpose of this study was to evaluate the effectiveness of a large-area, flat-panel X-ray detector for performing routine chest radiography at two different detector doses. MATERIALS AND METHODS: The chest radiographs of 50 patients (age range, 16-79 years; mean age, 57 years) were obtained at two different detector dose levels. Digital images were taken from the same patients in posteroanterior and lateral views with detector doses of 2.5 microGy and 1.8 microGy, respectively, at 125 kVp tube voltage. The cesium iodide-amorphous silicon active-matrix imager had a panel size of 43 x 43 cm, a matrix of 3000 x 3000, and a pixel pitch of 143 microm. Images were presented in a random order to three independent radiologists who were unaware of the dose level at which the images had been obtained. They subjectively rated image quality on a 4-point scale, according to six criteria (presentation of obscured lung, unobscured lung, airways, mediastinum and hilum, bony thorax, and overall impression). Statistical significance of differences was evaluated with Student's t test for paired samples (confidence level, 95%). RESULTS: Digital radiographs obtained at 2.5 and 1.8 microGy were equivalent on all quality criteria. No statistically significant differences and no tendency toward a preference for images obtained at one or the other dose level were observed. According to the registered mAs values, the average difference in patient dose was 33%. CONCLUSION: Use of flat-panel digital imagers based on the cesium iodide-amorphous silicon technique allows a considerable dose reduction during routine chest radiography without loss of image quality.     

Optimising image quality and radiation dose for neonatal incubator imaging

IntroductionNeonates often require imaging within incubators however limited evidence exists as to the optimal method and acquisition parameters to achieve these examinations. This study aims to standardise and optimise neonatal chest radiography within incubators.MethodsA neonatal anthropomorphic phantom was imaged on two different incubators under controlled conditions using a DR system. Exposure factors, SID and placement of image receptor (direct v tray) were explored whilst keeping all other parameters consistent. Image quality was evaluated using absolute visual grading analysis (VGA) with contrast-to-noise ratio (CNR) also calculated for comparison. Effective dose was established using Monte Carlo simulation using entrance surface dose within its calculations.ResultsVGA and CNR reduced significantly (p < 0.05) whilst effective dose increased significantly (p < 0.05) for images acquired using the incubator tray. The optimal combinations of parameters for incubator imaging were: image receptor directly behind neonate, 0.5 mAs, 60 kV at 100 cm SID, however, if tray needs to be used then these need to be adapted to: 1 mAs at maximum achievable SID. Effective dose was highest for images acquired using both incubator tray and 100 cm SID owing to a decrease in focus to skin distance. There is significant increase (p < 0.01) in VGA between using 0.5 mAs and 1 mAs but an apparent lack of increase between 1 and 1.5 mAs.ConclusionUsing the incubator tray has an adverse effect on both image quality and radiation dose for incubator imaging. Direct exposure is optimal for this type of examination but if tray needs to be used, both mAs and SID need to be increased slightly to compensate.Implications for practiceThis study can help inform practice in order to both standardise and optimise chest imaging for neonates in incubators.     

Radiography of the knee joint: A comparative study of the standing partial flexion PA projection and the standing fully extended AP projection using visual grading characteristics (VGC)

ObjectivesTo compare the diagnostic information in detection and assessment of knee pathology from knee radiographs using either the PA standing with partial flexion projection or AP fully extended standing projection.MethodA set of 32 knee radiographs was retrospectively compiled from 16 adult patients imaged using both projections over a 2-year period (PA: n = 16 and AP: n = 16). Repeat radiographs (n = 6) were added to the image set facilitating inter and intra observer reliability. Image evaluation was performed by 5 orthopaedic surgeons performing Absolute Visual Grading Analysis assessing image quality based on 6 anatomical image quality criteria specifically developed to evaluate and compare the two projections. The resulting image quality scores were analysed using Visual Grading Characteristics.ResultsImage quality scores were higher for the PA projection but variation between the two projections was not significant (p > 0.05). The PA projection was significantly (p < 0.05) better in the visualization of 2 anatomical image quality criteria involving the joint space width and tibial spines.ConclusionBoth projections can be used for general evaluation of the knee joint, however the PA partial flexion projection is preferred for the investigation of specific knee pathology. Recommendations for minimizing variations in radiographic positioning technique are also highlighted.     

CR与DR系统胸部摄影参数对比的实验研究

目的：比较CR、DR在胸部摄影中的最优化摄影参数。方法：CR、DR系统分别对胸部等效衰减模体行不同参数曝光成像,记录每次曝光的模体表面剂量,并计算模体影像图像质量因子反数值IQFinv。应用统计学软件分析获取CR组、DR组最佳图像的IQFinv值,并换算成摄影参数。结果：CR组、DR组摄影剂量和图像质量IQFinv值之间的线性回归方程为DR：IQFinv=0.005D＋3.359,CR：IQFinv=0.005D＋1.651,D为辐射剂量。ROC曲线分析（曲线下面积AUC=0.893,P〈0.001）,最佳IQFinv值为3.55,获得DR、CR最佳图像摄影参数分别为125 kV、1.6 mAs,125 kV、16 mAs。结论：要得到满足诊断要求且一致的图像质量,CR的摄影剂量大致是DR的4倍。     

Comparing the supine and erect pelvis radiographic examinations: an evaluation of anatomy,image quality and radiation dose

Objectives:Pelvis radiographs are usually acquired supine despite standing imaging reflecting functional anatomy. We compared supine and erect radiographic examinations for anatomical features, radiation dose and image quality.Methods:60 patients underwent pelvis radiography in both supine and erect positions at the same examination appointment. Measures of body mass index and sagittal diameter were obtained. Images were evaluated using visual grading analysis and pelvic tilt was compared. Dose–area product values were recorded and inputted into the CalDose_X software to estimate effective dose (ED). The CalDose_X software allowed comparisons using data from the erect and supine sex-specific phantoms (MAX06 & FAX06).Results:Patient sagittal diameter was greater on standing with an average 20.6% increase at the iliac crest (median 30.0, interquartile range [26.0 to 34.0] cm), in comparison to the supine position [24.0 (22.3 to 28.0) cm; p < 0.001]. 57 (95%) patients had posterior pelvic tilt on weight-bearing. Erect image quality was significantly decreased with median image quality scores of 78% (69 to 85) compared to 87% for the supine position [81 to 91] (p < 0.001). In the erect position, the ED was 47% higher [0.17 (0.13 to 0.33) mSv vs 0.12 (0.08 to 0.18) mSv (p < 0.001)], influenced by the increased sagittal diameter. 42 (70%) patients preferred the standing examination.Conclusion:Patient diameter and pelvic tilt were altered on weightbearing. Erect images demonstrated an overall decrease in image quality with a higher radiation dose. Optimal acquisition parameters are required for erect pelvis radiography as the supine technique is not directly transferable.     

Effects of tube potential and scatter rejection on image quality and effective dose in digital chest X-ray examination: An anthropomorphic phantom study

ObjectivesThe purpose of this study was to investigate the effects of tube potential and scatter rejection techniques on image quality of digital posteroanterior (PA) chest radiographs.Methods: An anthropomorphic phantom was imaged using a range of tube potentials (81–125 kV_p) without scatter rejection, with an anti-scatter grid, and using a 10 cm air gap. Images were anonymised and randomised before being evaluated using a visual graded analysis (VGA) method.ResultsThe effects of tube potential on image quality were found to be negligible (p > 0.63) for the flat panel detector (FPD). Decreased image quality (p = 0.031) was noted for 125 kV_p relative to 109 kV_p, though no difference was noted for any of the other potentials (p > 0.398) for computed radiography (CR). Both scatter rejection techniques improved image quality (p < 0.01). For FPD imaging the anti-scatter grid offered slightly improved image quality relative to the air gap (p = 0.038) but this was not seen for CR (p = 0.404).ConclusionsFor FPD chest imaging of the anthropomorphic phantom there was no dependence of image quality on tube potential. Scatter rejection improved image quality, with the anti-scatter grid giving greater improvements than an air-gap, but at the expense of increased effective dose.CR imaging of the chest phantom demonstrated negligible dependence on tube potential except at 125 kV_p. Scatter rejection improved image quality, but with no difference found between techniques. The air-gap resulted in a smaller increase in effective dose than the anti-scatter grid and would be the preferred scatter rejection technique.     

Comparison of image quality in chest,hip and pelvis examinations between mobile equipment in nursing homes and static indirect radiography equipment in the hospital

IntroductionA hospital environment can be a significant burden and a health risk especially for dementia patients. Mobile x-ray equipment (ME) is used to enable imaging of these patients at home. The aim was to compare image quality (IQ) of chest, hip and pelvis images from ME to the stationary equipment (SE) used in a hospital department.MethodsWe analysed examinations of the chest (n = 20), hip (n = 64) and pelvis (n = 32). Images were equally obtained from each setting of ME and SE. All images were graded using Visual Grading Analysis (VGA) by three radiographers (hip and pelvis) and three radiologists (chest). Technical IQ assessment was done by 80 additional images of a Contrast-Detail Radiography phantom (CDRAD).ResultsAll chest images were approved for diagnostic use, as well as the hip AP and pelvis images from SE. ‘Approved proportion of ME images was for HIP antero-posterior (AP) and pelvis, 78% [95% CI: 52–94%] and 81% [95% CI: 54–96%] respectively. Hip axial had an overall low, but not significant different approval rate. Ordered logistic regression indicated higher IQ of HIP AP and pelvic images from SE. This contrasts that the CDRAD substudy indicated better IQ, expressed as IQF_inv, from ME.ConclusionThe VGA showed higher IQ for the SE system, while the CDRAD showed higher IQ for the ME system.Implications for practiceDementia patients can be examined at their home if the acquisition is optimised according to image quality in conjunct to radiation dose. Performing imaging out of the hospital and coordinating the patients’ further treatment are new work areas for radiographers and requires excellent communication skills.     

Coronary artery stent imaging with CT using an integrated electronics detector and iterative reconstructions: First in vitro experience

BackgroundDespite continuous improvements in CT technology, accurate stent lumen delineation remains challenging.PurposeThe aim was to evaluate the quality of coronary stent lumen delineation with CT using a detector with integrated electronics.MethodsTwelve coronary stents placed in plastic tubes and filled with contrast agent (CT number 250 HU) were imaged with either a 128-section dual-source CT machine equipped with conventional detector or with integrated electronics. On both scanners, images were reconstructed with filtered back projection (slice thickness 0.6 mm; increment 0.4 mm) and sinogram-affirmed iterative reconstruction (slice thickness 0.6 mm; increment 0.4 mm), and with iterative reconstruction (slice thickness 0.5 mm; increment 0.3 mm) on the integrated scanner. Two blinded, independent readers assessed image quality, noise, in-stent diameter, in-stent attenuation, and image sharpness by using signal intensity profiles across stents.ResultsInterreader agreement for image quality assessment was substantial (κ = 0.798). Both readers rated best image quality in data sets from integrated detector at highest spatial resolution (86 or 72% of stents rated best quality). Image noise was significantly lower in data sets scanned with integrated detector, being lowest at 0.6 mm slice thickness (14.3 vs 21.0 HU; P < .001). Differences between measured and true in-stent diameters and differences in attenuation across stents were smallest, and average/maximum image sharpness was highest in data sets from the integrated detector using iterative reconstructions.ConclusionCT coronary stent imaging is significantly improved by using a detector with integrated electronics combined with iterative reconstructions.     

乳腺筛查X射线成像参数与辐射剂量和影像质量的相关性研究

目的 探讨乳腺筛查X射线摄影参数对辐射剂量与影像质量的影响,以获取辐射剂量与影像质量的最佳匹配。 方法 回顾性分析接受数字乳腺X射线筛查摄影的507例受检者的曝光参数与平均腺体剂量的相关性。对不同厚度的亚克力板进行曝光,获取乳腺压迫厚度对辐射剂量的影响。通过对比度细节测试模体(CDMAM3.4)与不同厚度亚克力板的组合测试,分析其与影像质量的相关性。 结果 在507例受检者中,30~49岁为乳腺筛查影像受检者的主体人群,占67.06%。3种曝光模式下,平均腺体剂量(AGD)的均值以对比度优先模式最高,为标准模式的137.5%。 标准模式靶物质/滤过板组合是Mo/Mo、Mo/Rh、Rh/Rh共3种,各占1/3;剂量优先模式选择的是Mo/Rh、Rh/Rh 2种组合,各占50%;对比度优先模式则以选择Mo/Mo组合为主,占52%。乳腺压迫厚度与平均腺体剂量之间均呈正相关。3种曝光模式的逆影像质量指数(IQFinv)分别为98.32、95.41和107.02,其中对比度优先模式的IQFinv值最高;但当亚克力板增加到≥5 cm时,3种曝光模式下的IQFinv值很接近。结论 当受检者乳腺属于致密型乳腺且压迫厚度<4 cm时,应选择剂量优先曝光模式;>4 cm而<6 cm时,选择标准曝光模式;>6 cm选择手动。     

Does software optimization influence the radiologists' perception in low dose paediatric pelvic examinations?

Purpose

To investigate whether software optimisation can improve an observers’ perception of image quality in low dose paediatric pelvic examinations.

Evaluating the use of anti-scatter grids in adult knee radiography

IntroductionAnti-scatter grids efficiently reduce scatter radiation from reaching the imaging receptor, enhancing image quality; however, the patient radiation dose increases in the process. There is disagreement regarding the thickness thresholds for which anti-scatter grids are beneficial. This study aims to establish a thickness threshold for the use of anti-scatter grids to optimise adult knee radiography.MethodsThe study consisted of two phases. In Phase 1 phantom knee radiographs were acquired at varying thicknesses (10–16 cm) and tube voltages (60–80 kV). For each thickness and tube voltage, images with and without an anti-scatter grid were obtained. In Phase 2, two radiologists and three radiographers, evaluated the image quality of these images. Visual Grading Analysis (VGA) scores were analysed using Visual Grading Characteristics (VGC) based on the visualisation of five anatomic criteria.ResultsThe average DAP decreased by 72.1% and mAs by 73.1% when removing the anti-scatter grid. The VGC revealed that overall images taken with an anti-scatter grid have better image quality (AUC ≥0.5 for all comparisons). However, the anti-scatter grids could be removed for thicknesses 10, 12 and 14 cm in conjunction with using 80 kVp,.ConclusionAnti-scatter grids can be removed when imaging adult knees between 10 and 12 cm using any kVp setting since the radiation dose is reduced without significantly affecting image quality. For thicknesses >12 cm, the use of anti-scatter grids significantly improves image quality; however, the radiation dose to the patient is increased. The exception is at 14 cm used with 80 kVp, where changes in image quality were insignificant.Implications for practiceOptimisation by removing anti-scatter grids in adult knee radiography seems beneficial below 12 cm thickness with any kVp value. Since the average knee thickness ranges between 10 and 13 cm, anti-scatter grid can be removed for most patients. Nevertheless, further studies are recommended to test if this phantom-based threshold applies to human subjects.