The role of high-energy computed radiography(CR)in radiotherapy

Computed radiography(CR)imaging has high irradiation tolerance and it is easy to archive CR images along with other image information by Digital Imaging and Communications in Medicine(DICOM)format,and to process them.CR can be used in radiation Quality Control(QC)task and verification of treatment setting-up.In this paper,the role of high-energy CR in radiation oncology is studied.The patients were imaged by CR system and EPID before radiotherapy.All verification images were acquired with 1–2 MU(Monitor Unit)using 6 MV X-rays.QC for a linac was done with film and high-energy CR to collect the data on daily,weekly and monthly basis.The QC included Multileaf Collimators(MLC)calibration and mechanical iso-centre check.CR was also adapted to verify patient position,the film was used to compare with digitally reconstructed radiographs(DRR)and portal image from EPID. Treatment setting-up was verified based on the result of comparison.High quality verification images could be acquired by the CR system.Comparing to EPID,the results showed that the system was suitable for practical use to acquire daily verification images,and it was useful to fulfill part of quality assurance(QA)in radiation oncology.The quality of image acquired by the high-energy CR system is comparable or even better than DRRs and portal images. The final treatment set-up for the patients could be verified more accurately with the CR system.

图像融合技术在Computed Radiography影像中的应用研究

将图像融合技术应用于CR(ComputedRadiography)技术中 ,有效改善影像的信噪比 (signal-to -noiseratio)。运用双IP(ImagePlate)技术采集人体体模影像后 ,在变换域进行图像配准。建立融合图像的数学模型 ,基于此模型对配准完成的源图像实施不同权重的加权计算得到融合图像。结果 融合图像信噪比源图像可提高 30 %左右。结论 将图像融合技术应用于CR技术可有效改善影像质量 ,有助于提高诊断的准确性。

A Derived Exposure Chart for Computed Radiography in a Negroid Population

Background: Computed radiography has a wider exposure latitude when compared with film-screen imaging system. Consequently, the risk of dose creep is high. A conscientious effort is there-fore, needed by the radiographer to keep exposure as low as reasonably achievable. Objective: To derive a computed radiography exposure chart for a negroid population using AGFA photostimulable phosphor plates and a GE static X-ray machine. Materials and Method: A static X-ray machine, a digitizer, and photostimulable phosphor plates were used for the X-ray examination. Chest examinations were done at a Focus-Film-Distance (FFD) of 150 - 180 cm while all other examinations were conducted at 90 - 100 cm FFD. The range of exposure factors (kVp, mA and mAs) used by radiog-raphers in the centre was noted and the 90th percentile calculated. Over a three-month period, the patients were examined with the 90th percentile of tube potential (kVp) while keeping other factors constant. The kVp was gradually decreased and halted if radiologists and radiographers uncon-nected with the work expressed misgivings about the quality of the image. A similar procedure was adopted for the tube current (mA). The threshold adopted as low as reasonably achievable was the factor preceding the point of observation by other personnel. Metrics for central tendency from the statistical packages for social sciences, version 17.0 was used to analyze the data. Results: 335 subjects of both gender aged 0 - 92 years were examined by the researchers. Adult exposure factors used by the radiographers (and those derived by the researchers) had a range of 45 - 130 kVp (62 - 94 kVp), 63 - 320 mA (100 - 250 mA) and 4.0 - 25.0 mAs (5.0 - 20.0 mAs) respectively. Pediatric chest (and researchers-derived) factors were 50 - 75 kVp (52 - 65 kVp), 50 - 250 mA (100 - 220 mA) and 3.20 - 10.0 mAs (3.2 - 6.5 mAs) respectively. Conclusion: Upper threshold of adult (and paediatric) exposure factors in computed radiography with comparable equipment and accessories should not exceed 94 kVp (65 kVp), 250 mA (220 mA) and 20.0 mAs (6.5 mAs) respectively. The derived exposure chart is also adequate to address motion unsharpness in chest examinations.

Economic Evaluation of Conventional Radiography with Film and Computed Radiography: Applied at BMC

Conventional radiography with film (CRF) has been in use for diagnostic purposes for a long time now. It has proved to be a great assert for the radiographers in assessing various abnormalities. With recent advances in technology it is now possible to have digital solutions for radiography problems at a very cost effective, environment friendly and also with better image quality in certain applications when compared to CRF. Rather than using a CRF a computed radiography (CR) uses imaging plates to capture the image. The imaging plate contains photosensitive phosphors which contain the latent image. Later this plate is introduced into a reader which is then converted into a digital image. The major advantage and the cost effective element of this system is the ability to reuse the imaging plates unlike the photographic film where in only a single image can be captured and cannot be reused. The computed radiography drastically reduces the cost by eliminating the use of chemicals like film developers and fixers and also the need for a storage room. It also helps to reduce the costs that are involved in the disposal of wastes due to conventional radiography. This paper investigates whether it is cost effective to use computed radiography over film based system at Al-Batnan Medical Center (BMC), Tobruk, Libya by using Cost Benefit Analysis (CBA). Apart from the initial cost of the CR System, based on the data collected from the center, from the year 2008 to 2012 (until June 2012) a total of 581,566 images were produced with the total cost incurred using film based system being USD 4,652,528. If the same number of images were produced using a CR system the total cost incurred would have been USD 82,600. Taking into consideration the cost of a new CR system to be USD 120,000 the overall cost of producing these images is USD 202,600. It is observed that an amount of USD 4,449,928 could have been saved over the period of 5 years starting from 2008 to 2012 by using the CR system at BMC. Using Cost Benefit Analysis, the average value of the net difference between the costs and benefits for the conventional film based system is ?83.38 where as for the Computed System it is 22.06. Based on the principles of Cost Benefit Analysis it can be concluded that the system with a net positive difference is more cost beneficial than the other. With the help of the above two analysis it can be concluded that the use of computed radiography is definitely more cost effective for use at BMC, when compared to the conventional x-ray radiography.

Comparative Study of Clinical Manifestation, Plain Film Radiography and Computed Tomography for Diagnosis of Maxillofacial Trauma

Objective: Maxillofacial injuries are one of the commonest injuries encountered. Roentgenographic evaluation of maxillofacial trauma is of prime importance for diagnosis and treatment of these injuries. Study Design: Forty patients were evaluated in the prospective four-year study. We studied and evaluated the demography and diagnostic efficacy of clinical, plain radiography, and computed scan in maxillofacial trauma. Result: Road traffic accidents were the commonest cause of maxillofacial injuries. Patients having multiple fractures, mandibular fractures were the commonest. Conclusion: Computed tomography proved a useful adjunct in midfacial trauma.

增材制造材料中的CR检测应用

作为近净成形的新兴制造工艺,增材制造应用广泛,其逐点融合的工艺特点,容易产生气孔、结合不良等缺陷。针对该问题,通过分析增材制造材料CR检测过程中成像板、金属屏、透照电压及曝光量等参数,并将增材制造材料CR与RT的成像结果等进行对比,得出CR的优势及适用范围,以便更好指导检测业务的开展。

CR在鼻骨骨折检查中的作用

目的 :为探讨CR在鼻骨骨折检查中的作用 ,回顾性分析了 4 0例鼻骨骨折患者的鼻骨侧位CR片及普通X线平片。结果 :4 0例鼻骨骨折在CR片上均有不同程度X线表现 ,而普通X线平片仅发现鼻骨骨折 19例。结论 :鼻骨侧位CR片对鼻骨骨折及其它面骨复合骨折的诊断敏感性高于普通X线平片 ,CR片骨折线显示清晰 ,综合信息量高 。

CR影像处理参数调节原理及优化方法

目的:研究CR影像密度、对比度、组织均衡、空间频率、LUT曲线等计算机X线摄影影像处理参数的调节原理及优化方法。方法:应用Konica REGIUS MODEL170 CR,在其控制台CS-1上调节各种影像参数。结果:可以优化人体各部位影像,提高影像质量。结论:全面掌握了计算机X线摄影处理参数的调节方法,并合理有效地组合运用,就能够获得优质医学影像。

CR、CT、MRI在脊柱结核诊断中的临床价值

[目的]评价计算机X线摄影(CR)、计算机断层成像(CT)、磁共振成像(MRI)在脊柱结核诊断中的临床价值。[方法]回顾分析经病理证实的41例脊柱结核的影像学资料。41例做了CR,22例做了CT,31例均做了MRI。[结果]41例中38例CR片清晰显示骨质改变及椎间隙狭窄或消失,30例CR片可看到软组织阴影。22例CT均清晰显示了钙化,22例CT检查附件均未见明显异常,21例CT清晰显示椎体骨质改变,20例CT显示了软组织阴影。31例MRI均显示软组织均受累,附件均未见受累,其中29例椎间隙狭窄或消失。病变T1WI均以低信号为主,T2WI均以高信号为主。[结论]CR片仍为脊柱结核的基本检查方法,CT较好显示了结核的破坏范围及细微钙化,MRI对显示结核的侵犯范围、软组织异常及椎间盘异常有明显优势。三者相结合有助于脊柱结核的诊断。

CR、CT、MRI在骨肿瘤诊断中的临床价值

[目的]评价计算机X线摄影(CR)、CT、磁共振成像(MR l)在骨肿瘤诊断中的临床价值。[方法]回顾分析55例经病理证实的影像学资料,其中55例均有CR平片,21例CT扫描,20例做了MR I检查。[结果]55例中51例CR片清晰显示骨质改变,40例CR片清晰显示病灶边界,20例CR片清晰显示骨膜反应,19例CR片清晰显示病灶内有大小不一钙化。21例行CT扫描病例均清晰显示骨质改变、病灶边界、病灶内有大小不一钙化,8例清晰显示骨膜反应。20例做了MR I检查病例均清晰显示病灶边界及软组织肿块,8例显示相应骨髓水肿。[结论]CR片仍为骨肿瘤的首选检查方法,CT较好显示了肿瘤的范围及细微结构,MR I对显示肿瘤的范围、软组织肿块及相应骨髓水肿有明显优势。三者相结合有助于骨肿瘤的诊断。

CR与屏(铜)-片成像在头颈部肿瘤放疗射野影像验证中的比较应用

目的评价计算机X线摄影(CR)与屏(铜)-片成像在头颈部肿瘤放疗射野影像验证中的应用价值。资料与方法40张验证片中,20张采用传统屏(铜)-片摄影,20张采用CR摄影。由4名观察者分别对其进行评价,评价标准参照欧共体提供的影像标准,分“可见”、“再现”及“清晰再现”三级,取其平均百分比。采用SPSS11.0统计软件包对观察者之间的一致性作方差分析。结果CR的“可见”率为18.75%,“再现”率为71.25%,“清晰再现”率为10%;屏(铜)-片的“可见”率为71.25%,“再现”率为28.75%,“清晰再现”率为0。对比分析有意义的“再现”率与“清晰再现”率之和,CR组为81.25%,而屏(铜)-片组仅为28.75%。单因素方差分析结果显示观察者之间的一致性无统计学意义(P>0.05)。结论CR成像在头颈部肿瘤放疗射野影像验证中较屏(铜)-片成像具有更好的显示效果。

移动CR与移动DR在床旁胸部摄影中的应用比较

目的对比研究移动计算机X射线摄影(CR)与移动数字化X射线摄影(DR)在床旁胸部摄影中的临床应用价值。方法随机抽取移动CR与移动DR床旁胸部摄影胸片各200张,对2种摄影方式所摄胸片的图像质量及胸内各结构的显示进行对比研究。移动CR和移动DR各200张床旁胸部摄影胸片,以其CT检查为"金标准"进行对照,将两组床旁胸片显示的病灶清晰程度分为清晰、可见、模糊、隐约可见、未见5类。统计2组的例数,绘制接受者操作特征(ROC)曲线。结果图像质量:移动CR床旁胸部摄影所得胸片的甲级片率69.0%,乙级片率24.5%,丙级片率5.0%,废片率1.5%。移动DR床旁胸部摄影所得胸片的甲级片率83%,乙级片率16%,丙级片率1%,废片率0。对胸内各结构的显示:移动CR与移动DR床旁胸部摄影所得胸片对胸内各结构的显示率移动CR低于移动DR。对病灶的显示能力:200张移动CR胸片中,126例行CT检查,67例CT所显示的病灶中,移动CR能显示64例,3例未见病灶。200张移动DR胸片中,108例行CT检查,53例CT所显示的病灶中,移动DR能显示52例,1例未见病灶。移动CR与移动DR床旁胸部摄影ROC曲线下的面积分别为0.833和0.918。结论移动CR与移动DR床旁胸部摄影,移动DR摄影的影像质量、对胸内结构的显示及对病灶的显示能力均优于移动CR,在床旁胸部摄影中移动DR具有更高的应用价值。

16层螺旋CT泌尿系成像与CR静脉肾盂造影效果对比

目的:探讨16层螺旋CT泌尿系成像的临床应用价值。方法:将行CR静脉肾盂造影的26例患者行16层螺旋CT泌尿系成像,CR图像与CT轴位以及在工作站进行MPR、VR等后处理图像进行对比。结果:通过对比,发现16层螺旋CT泌尿系成像比CR静脉肾盂造影图像好,能充分显示肾实质、肾盂、输尿管、膀胱以及泌尿器官与周围组织的关系。结论:16层螺旋CT扫描速度快,重建功能强大,后处理图像清晰,比CR静脉肾盂造影效果好,显示了CR静脉肾盂造影无法显示的细节病变,只是费用相对较高,若不考虑费用问题的话可取代CR静脉肾盂造影。

CR在新生儿胸部床旁摄影中的应用价值

目的:探讨CR在新生儿胸部床旁摄影中的应用价值。方法:回顾分析160人的210张新生儿胸部床旁CR片图像并进行评价。结果:210张新生儿胸部床旁CR片中,甲类片201张,甲片率95.7%;乙类片9张,乙片率4.3%;废片0张,废片率为0。结论:CR系统在新生儿床边摄影中具有更高的应用价值,实现了影像的数字化并直接进入PACS,阅片速度快,X线照射剂量低,图像质量高,成功率高,为临床提供了影像诊断依据。

曝光条件、IP尺寸等与CR照片影像的空间分辨力

目的 :探讨曝光条件、IP尺寸等与CR照片影像空间分辨力的关系。方法 :依据Siemens点数法曝光条件表 ,在点数不变的情况下换算出摄影部位手的数组曝光条件 ,选用四种不同尺寸的IP及大小焦点 ,分别对矩形波测试卡进行摄影。采用无放大和放大 2倍的后处理技术 ,视读并记录CR照片影像的空间分辨力数值 ,分析其影响CR照片影像空间分辨力的条件。结果 :①摄影部位、曝光条件相同 ,CR照片影像的空间分辨力 ,小焦点大于大焦点 ;②摄影部位、曝光条件及焦点大小相同 ,CR照片影像的空间分辨力随IP尺寸的增加而减小 ;③CR照片影像的空间分辨力 ,放大 2倍的照片影像明显高于无放大处理的照片影像 ;④适宜的曝光条件可提高CR照片影像的空间分辨力。结论 :影响CR照片影像空间分辨力的条件 :小尺寸IP大于大尺寸IP ;小焦点大于大焦点 ;适宜的后处理放大倍数大于无放大处理 ;适宜的曝光条件组合大于其它组合。

环境照度对用显示器视读CR影像信息的影响

目的 测试环境照度对用显示器视读CR影像信息的影响。方法 请 6名有经验的医学影像诊断医师 ,在不同环境照度下用显示器视读标准体模TRG的CR影像 ,获得制作ROC曲线的原始数据 ,以比较影像信息量多少的ROC曲线面积值Az。结果 在环境照度为 10 0Lx、显示器亮度为 60cd/m2 时视读的CR影像上获得ROC曲线面积Az =0 .8661,分别比环境照度为 12Lx、40Lx、180Lx时的多 8%、3 %和 11% ;在环境照度为 10 0Lx、显示器亮度为 10 0cd/m2 时视读的CR影像上获得的ROC曲线面积Az =0 .82 5 0 ,分别比环境照度为 12Lx、40Lx、180Lx时的多 13 %、1%和 8%。结论 在同一显示器亮度下视读 ,环境照度为 10 0Lx时获得的ROC曲线面积Az值最大。

CR在早期诊断股骨头坏死中的作用

目的 为探讨CR检查在股骨头缺血性坏死早期诊断中的作用。方法 我们对 1 1例 1 3髋股骨头缺血性坏死病人进行了CR检查 ,并与常规X线平片对照。结果 结果发现两髋Ficat法分期Ⅰ期、一髋Ficat法分期Ⅱa期 ,以上三髋常规X线平片均不能显示出股骨头异常。其它 1 0髋Ficat法分期Ⅱb Ⅳ期 ,CR与常规X线平片相比检出率无差异。结论 CR检查对股骨头缺血性坏死的早期诊断优于常规X线平片 。

X线管倾斜摄影时CR、DR成像质量对比研究

目的:探讨计算机X线摄影(computedradiography ,CR)和数字X线摄影(digitalradiography ,DR)在X线管倾斜摄影时是否存在X线斜射效应。方法:对于屏-片组合、CR、a Si型DR和a Se型DR四种X线成像方式,分别在X线管倾斜0°、15°、30°、4 5°时对矩形波测试卡摄影。结果:在X线管倾斜0°～4 5°角范围内摄影时,CR影像分辨力无变化;a SiDR和a SeDR影像分辨力略下降;屏-片组合影像分辨力下降明显。结论:在X线摄影常用的倾斜角度范围内,屏-片组合存在X线斜射效应,CR基本上不存在X线斜射效应。