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Objective To investigate patient doses undergoing routine interventional cardiology procedures in China. Methods A retrospective analysis was performed on 238 adult patients who achieved one of interventional procedures including coronary angiography (CAG), percutaneous coronary angioplasty (PTCA) and radiofrequency catheter ablation (RF). According to intervention operations, all cases were divided into three groups:CAG (77), PTCA (95) and RF (66). Data of four special metrics, peak skin dose (PSD), dose-area product (DAP), cumulative dose (CD), and fluoroscopy time (FT), these parameters were measured and collected for these procedures. Frequencies of high-dose cases (PSD>2 Gy and PSD>3 Gy) were specifically recorded. Third quartile of DAP distribution was used to establish dose reference level (DRL) and then DRL values in this study were compared with ones reported in literatures. Wallis Kruskal rank-sum test was used to compare radiation dose of patients undergoing different intervention procedures. The total correlation among CD, DAP and PSD was analyzed by Spearman method. Results For patients undergoing CAG,PTCA and RF procedure, the median PSDs were 0.24, 1.05 and 0.62 Gy, respectively.The median DAPs were 34.99, 94.53 and 36.33 Gy · cm2, respectively.The median CDs were 0.39, 1.27 and 0.36 Gy, respectively.The median FTs were 4.50, 15.31 and 13.40 min, respectively. The difference among procedures was statistically significant (χ2=105.083, 92.032, 115.509, 100.883, respectively, P all cases, DAP and CD were correlative (r=0.845, P2 Gy, including 14 patients undergoing PTCA and 8 patients undergoing RF. There were 1.6% (22/238) patients with PSD>3 Gy, including 1 patients undergoing PTCA and 3 patients undergoing RF. The DRL for PTCA in this study is 133 Gy · cm2 and higher than that in literatures. The DRL for CAG in this study is 46 Gy · cm2 and slight lower than that in literatures. The DRL for RF in this study is 49 Gy·cm2. Conclusion Data from this study are in the range of most reported values for CAG and RF procedure, while higher than that obtained in some literatures for PTCA.
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Objective To analyse the CT radiation dose statistically using the standardized radiation-dose-structured report (RDSR) of digital imaging and communications in medicine (DICOM). Methods Using the self-designed software, 1230 RDSR files about CT examination were obtained searching on the picture archiving and communication system ( PACS ) . The patient dose database was established by combination of the extracted relevant information with the scanned sites. The patients were divided into adult group (over 10 years) and child groups (0-1 year, 1-5 years, 5-10 years) according to the age. The average volume CT dose index ( CTDIvol ) and dose length product ( DLP) of all scans were recorded respectively, and then the effective dose ( E) was estimated. The DLP value at 75% quantile was calculated and compared with the diagnostic reference level ( DRL) . Results In adult group, CTDIvol and DLP values were moderately and positively correlated ( r=0?41 ) , the highest E was observed in upper abdominal enhanced scan, and the DLP value at 75% quantile was 60% higher than DRL. In child group, their CTDIvol in group of 5-10 years was greater than that in groups of 0-1 and 1-5 years ( t=2?42, 2?04, P<0?05);the DLP value was slightly and positively correlated with the age (r=0?16), while E was moderately and negatively correlated with the age ( r = -0?48 ) . Conclusions It is a simple and efficient method to use RDSR to obtain the radiation doses of patients. With the popularization of the new equipment and the application of regionalized medical platform, RDSR would become the main tool for the dosimetric level surveying and individual dose recording.
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Objective To study the dosimetry parameters of 125I seed source (type Sinko BT-125-1) with thermoluminescent dosimeter (TLD) in the phantom.Methods The new type of phantom was modified to suit to measurement of a common type of 125I seed source.The AAPM TG43 protocol recommended measurements of dose-rate constant (Λ),radial dose function (gL (r)),and anisotropy function (F (r,θ)) have been performed in the phantom with TLD.Results The Λ was 0.928 cGyh-1 U-1.The gL(r) was determined at different radial distances r ranging from 1.0 to 10.0 cm with an interval of 1.0 cm ; and F (r,θ) at angles from 0° to 90° in 10° increments.The gL (r) of 125I seed source showed a difference of 9.6％ at the most in comparison to the corresponding values of 125I seed source (type Amersham 6711).The difference in F(2 cm,θ) of 125I seed source and Amersham 6711 was up to 10.2％ near the source end.With the phantom the combined standard uncertainty in the whole measurement was less than 6.0％.Conclusions The experimental results exhibit fairly small measurement uncertainties and good self-consistency.It's feasible to measure the dosimetry characters of permanent implant seeds in the modified phantom.
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Objective To identify the necessity to carry out optimization procedure in routine digital radiography (DR) by evaluating changes of patient radiation dose and image waste ratio before and after optimization.Methods Two hundred patients with near-standard body build were enrolled in the study.Half of them undertook routine examination,and the others undertook the examination with bestlyoptimized protocol.The dose-area product (DAP) and entrance surface dose (ESD) were recorded.The image waste ratios in 2 groups were calculated and the reasons for image waste were analyzed.The radiation dose and image waste ratio before and after optimization were compared.Results The ESD,DAP and image waste ratio in bestly-optimized radiography were significantly lower than those in non-optimized radiography (z =9.31,16.22,P＜0.05; x2 =36.5,P ＜ 0.05).Conclusion Using the bestlyoptimized digital radiography,the patient radiation dose and image waste ratio are effectively reduced.
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Objective To compare the efficiency of computed radiography energy subtraction (ES-CR) with direct digital radiography (DR) in detecting the pulmonary soft-tissue signals.Methods The adult chest phantom including TRG was imaged by ES-CR and DR separately and was estimated by 6 radiologists with 5-value-differentiation method. ROC was used to analyze the performance of two systems. Images of DR and ES-CR of 28 patients with small lung cancer were diagnosed by 3 radiologists. Results The area under the ROC curves was 0. 727 in ES-CR and 0.827 in DR (Z= 2.96,P ＜ 0. 05). 28 small lung cancer patients were significantly different between two systems (x2 = 5.14,P ＜0. 05). Conclusions The true positive proportion of DR might be higher than that of ES-CR. ES-CR is inferior to DR in detecting pulmonary soft-tissue signals.
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Objective To perform thermoluminescent measurements of radial dose function and anisotropy function of a newly designed 192Ir microSelectron-HDR source, and establish evaluation methods for HDR dosimetry.Methods A polystyrene phantom with sylindrical holes in different measure positions was designed to accommodate thermo luminescent dosimeter (TLD) rods and radiation source.TLD rods with similar sensitivity were placed on a semicircle around the source center which had been precisely localized by either radiographic means or dose measurement.Dose-rates were measured at θ = 90° and r = 1-14 cm to calculate radial dose function (gL (r)), while measured along polar angles θ = 0° -165°(interval 15°) at radial distances r = 1 cm, 3 cm and 5 cm to calculate anisotropy function (F(r,θ)).All data were compared with those calculated by Monte Carlo (MC) method.The t-test was used for the statistics.Results The values of gL (r) were 1.007 -0.681 by calculation and 1.007 -0.598 by measurement with r = 1 - 14 cm(t = 0.00 - 2.89, all P > 0.05).The values of F (r,θ) were 0.631 - 1,0.660 - 1 and 0.696 - 1 by calculation, while 0.701 - 1, 0.668 - 1 and 0.629 - 1 by measurement at 1 cm, 3 cm and 5 cm with θ=0° -165°(t=0.40 -1.63, 0.02 -2.10, 0.08 -2.03, all P>0.05).Conclusions The results of radial dose function and anisotropy function measured by TLD measurement are in consistent with those calculated by MC calculations, which can be applied in treatment planning system as original input.
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Objective To evaluate the parallactic unsharpness caused by flat panel detector in digital radiography using different incident angle of central ray. Methods R-1 square-wave phantom was exposed by Kodak DR3000 system with X-ray tube angled 0°, 10°, 20°, 30°, and 40° respectively. Then,presampled modulation transfer function (MTF) was calculated for each case above. Subsequently,experimental data were processed and Wilcoxon signed ranks test were performed by statistic software SPSS 10. 0, in which P ＜ 0. 05 was considered as statistically significant difference. Results The presampled MTF curves of incident angle of 0°-40° degree, were presented orderly from top to bottom, especially the incident angle of 40° was obviously the lowest. The incident angle of 0° was considered as a control group and other groups were compared against it. There was no statistically significant difference for MTF of incident angle of 10°( Z = - 1. 893 ,P = 0. 058 ), while there were significant difference for MTF of incident angle of 20°, 30°, and 40° ( Z = - 2. 547, - 2. 666, - 2. 666, P ＜ 0. 05 ). Conclusions For flat panel detector in digital radiography, the bigger the incident angle of central ray, the larger the parallactic unsharpness. In addition, this effect has less influence on structures of low spatial frequency than those of high spatial frequency.
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Objective To get the maximum information from computed radiography (CR) output images by changing post-processing parameters. Methods Six experimental photos of polypropylene balls of 2.0 mm in diameter were taken by means of one time X-ray exposing on an imaging plate (IP) with different post-processing parameters including rotation amount (GA), gray gradation type (GT), rotation center (GC), shifting amount (GS), frequency rank (RN), frequency type (RT), and degree of enhancement (RE). 6 photos were viewed by three students and one radiologist on a 6 000 lx illuminance viewbox. Receiver operating characteristic (ROC) curves were made by means of 5-value-differentiation method. Results The largest mean area value (Az) below ROC curves of a low contrast experimental photo with post-processing parameters GA=1.0,GT=A, GC=1.6, GS=0.3, RN=4.0, RT=R and RE=3.0 was 0.96, and the maximum information was obtained. The smallest mean area value (Az) was 0.78 with changed post-processing parameters GA=0.8, GS=-0.2 and RE=0.5 while other parameters were not changed. The minimum information was obtained from this photo. Conclusion In order to get the maximum information from a CR output image, the post-processing parameters should be suitably selected.
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Objective To study the effect of image processing on overall Wiener spectrum (WS) in a computed radiography system. Methods Imaging plate was exposed using conventional X-ray equipment. Overall WS sampling films were made by changing 3 parameters of spatial frequency processing, including frequency rang(RN), frequency type(RT), and degree of enhancement(RE), and by changing 1 of 4 parameters of gradation processing(rotation amount,GA).WS values were calculated by scanning on micro-densimeter for every film proceeded as discrete signal using fast Fourier transform. Results (1) The WS value of subscan direction was 7.26?10 -5 mm 2 when the spatial frequency was 1.0 LP/mm, it was 1.57 times larger than that of scan direction. The WS had peaks under high spatial frequency at sunscan direction. (2) The WS value of RN with 0 at scan direction was 7.90?10 -5 mm 2 when the spatial frequency was 1.0 LP/mm, it was 1.70 times larger than that of RN with 5, and 3.30 times larger than that of RN with 9. (3) The WS value of RE with 1.5 at scan direction was 1.05?10 -4 mm 2when the spatial frequency was 1.0 LP/mm, it was 2.27 times larger than that of RE with 1.0, and 2.92 times larger than that of RE with 0.5. (4) The WS value of GA with 1.5 at scan direction was 1.25?10 -4 mm 2 when the spatial frequency is 1.0 LP/mm, it was 2.70 times larger than that of GA with 0.8. (5) The WS value of RT with T at subscan direction was 9.80?10 -5 mm 2 when the spatial frequency was 1.0 LP/mm, it was 1.02 times larger than that of RT with F, and 1.35 times larger than that of RT with R, and also 1.55 times larger than that of RT with P. Conclusions RN, RE, and GA contributed strongly to Wiener spectra, but the contribution of RT was small. When processing the clinical images, adequate processing parameters should be chosen to reduce the image noise, so as to meet the clinical diagnostic need.
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Objective To test the overall characteristic curve on a computed radiography system. Methods Imaging plate was exposed by scale-time expose using conventional X-ray equipment. It was processed by CR system. Density of different optical density wedge on CR film was measured by using densimeter. Then, characteristic curve was plotted. Results (1) Overall characteristic curve of CR system was affected by gradation processing. (2) Average gradient of overall characteristic curve was 1.98, 3.10, and 3.75 when GA was 0.8,1.4, and 2.4. (3) Overall characteristic curve rotated around rotation center when rotation amount was changed. Conclusion According to the diagnostic purpose and different body position, rotation amount can be selected, and different contrast imaging can be acquired.