Application of phantom for dose measurement in interventional therapy for pediatric vascular anomalies / 中国辐射卫生

@#<b>Objective</b> To apply a phantom for dose measurement in interventional therapy for pediatric vascular diseases, and calculate the effective dose (<i>E</i>) and conversion coefficient of dose area product (DAP) to <i>E</i>, and to provide a dose reference for studying radiation dose and radiation protection in children. <b>Methods</b> Thermoluminescent dosimeters were placed in the organs of the phantom. Low-, medium-, and high-dose groups were set for three types of vascular anomalies based on the duration of fluoroscopy. Digital subtraction angiography was used to simulate exposure conditions at different dose levels. The organ dose was measured, and the effective dose was calculated. <b>Results</b> For the three groups of vascular anomalies in the head and face, the red bone marrow doses were 8.15, 30.34, and 43.53 mGy, respectively, the effective doses were 12.88, 47.84, and 73.12 mSv, respectively; and the average conversion coefficient of DAP to <i>E</i> was 2.16. For the three groups of vascular anomalies in the trunk, the red bone marrow doses were 2.11, 15.62, and 31.21 mGy, respectively; the effective doses were 12.39, 70.56, and 134.60 mSv, respectively, and the average conversion coefficient of DAP to <i>E</i> was 3.03. For the three groups of vascular anomalies in the lower extremities, the red bone marrow doses were 3.58, 6.50, and 12.28 mGy, respectively, the effective doses were 3.64, 7.04, and 14.85 mSv, respectively, and the average conversion coefficient of DAP to <i>E</i> was 0.73. <b>Conclusion</b> Patient dose and DAP-to-<i>E</i> conversion coefficient are in the following order: vascular anomalies in the trunk > vascular anomalies in the head and face > vascular anomalies in the lower extremities. The dose data obtained can be used to estimate children’s radiation exposure.

Practicable value of DAP (dose-area product) database in occupational radiation protection in cardiovascular interventional procedures / 中华放射医学与防护杂志

Objective To evaluate the efficacy of the DAP database in reducing radiation hazards during cardiovascular intervention.Methods The study conducted a retrospective analysis of all consecutive cardiovascular cases in the database from April 1st,2016 to June 30th,2016.Based on the imaging systems,an inage intensifier (Ⅱ) and a flat panel detector (FPD),the cases of patients undergoing coronary angiography (CAG) and percutaneous coronary interventions (PCI) were collected to observe Body Mass Index (BMI),fluoroscopy time (FT) and dose area product (DAP).Results The FT and DAP values in CAG were (3.26-±2.59) min and (1 938±1 296) μGy·m2 for the Ⅱ system and (3.00 ± 2.89) min and (3 718 ± 2 859) μGy· m2 for the FPD system,respectively,whereas,the FT and DAP values in PCI were (17.81 ± 12.71) min and (8 899 ±7 032) μGy·m2 for the Ⅱ system and (21.99 ± 15.91) min and (19 526 ± 14 134) μGy · m2 for the FPD system,respectively.The differences in DAP values (x ± s) for CAG and PCI between the angiography systems were significant(t =-10.664,11.239,P ＜ 0.05).The DAP and total DAP values during PCI for fluoroscopy from the FPD systen were 3 596 755.60 and 4 881 484.50 μGy · m2,respectively.Conclusions The DAP values in CAG and PCI using FPD system are much higher than the relevant data.The use of an FPD system resulted in higher DAP values compared to the Ⅱ system in cardiovascular interventional procedures.Reduction in fluoroscopy time may decrease radiation hazards during PCI.The DAP database allows for a fast,convenient and enough objective data to discovery timely difference and variation in dose in cardiovascular interventional procedures.

Eatimation of effective doses from a dental cone beam computed tomographic scanner / 中华放射医学与防护杂志

Objective To calculate effective dose based on the dose-area Product (DAP) measured in dental cone beam computed tomograhic (CBCT) scanning and using a conversion coefficient.Methods The method of the DAP was used to calculate the effective dose from KODAK 9500 dental CBCT scanner with fields of view (FOV) of 16 cm×15 cm and 12 cmu×8 cm.The DAP-values (mGy · cm2) were measured using a transmission ionization chamber connected to an electrometer (Doseguard 100,RTI Electronics AB,Sweden) and the chamber was placed directly on the exit of the X-ray tube.All measurements were repeated three times and averaged on each FOV data.The conversion coefficient of 0.080 μSv/mGy · cm2 was used to estimate the effective dose on the basis of DAP values,which was quoted from a literature.Results DAP values were found between the two FAOs to vary from 512 to 1 083 mGy · cm2,and the effective doses calculated with 0.080 μSv/mGy · cm2were 41 to 87 μSv.The effective doses given in this paper was lower than those reported in other literatures.Conclusions DAP measurement was found to be well defined and easy-to-use method of determining effective dose for some CBCT Units.However,determination of specific conversion coefficient in the CBCT must be further developed.

Dose-Decreasing Effect of the First Reversed Laser Beam Collimator for C-Arm Type Angiographic Equipment

This is a study on the dose-decreasing effect of the first reversed laser beam collimator (RLBC) for C-arm type angiographic equipment. A laser beam was located at the center of each plane at an oblique angle to the angiographic equipment detector. A field of view, which could be seen with the naked eye, was made by focusing the laser beam in the direction of the X-ray source. The height of the table was fixed at 75 cm and the iron balls were located within 2 mm of the top, bottom, left, and right edges of the output image. The time needed for location fixing, fluoroscopy, and measurement of dose area product (DAP) were compared by having 30 radiologists perform location fixing by looking at the fluoroscopic image while performing location fixing (no radiation) and while the RLBC was turned on. In the next test, the time needed for location fixing, fluoroscopy, and DAP were compared when varying the location of the iron balls from 2 to 10 mm from the edges of the output image. The results showed that the time needed for location fixing, the time needed for fluoroscopy, and DAP decreased, both in the first test and the second test. This study confirmed that the use of a RLBC for C-arm type angiographic equipment decreases both the time needed to perform the procedure and the radiation dose received. It is expected that continuous advancement of RLBC technology will contribute greatly to decreasing the dose of radiation needed and improving convenience during angiography.

Study on the relationship between body mass index and dose area product as well as fluoroscopy time in Han nationality during coronary angiography / 介入放射学杂志

Objective To investigate the relationship between body mass index (BMI) and dose area product (DAP) as well as fluoroscopy time during coronary angiography (CAG) in Han nationality subjects in order to improve early judging and reducing high radiation risk. Methods CAG materials of 451 Han nationality subjects were retrospectively analyzed. The patients included 276 males (age 32-87 years) and 175 females (age 42-84 years), and the BMI values ranged from 17.30 to 35.42 kg/m2. According to BMI values, the patients were divided into group A(BMI30 kg/m2,n=30). The mean DAP and fluoroscopy time of each group were calculated; the DAP values were compared between each other among the four groups by using nonparametric Kruskal-Wallis test, while the fluoroscopy time was compared between each other among the four groups by using single factor analysis of variance or LSD-t test. Results The mean DAP of group A, B, C and D was(1 070.07±541.33) μGym2,(1 326.82±606.91) μGym2,(1 937.99±1 030.31) μGym2 and (2 654.53±1 296.69) μGym2 respectively. The mean fluoroscopy time of group A, B, C and D was (3.53± 2.08) min, (2.70 ±1.80) min, (2.75 ±1.88) min and (2.71 ±1.69) min respectively. Statistically significant difference in DAP values existed between each other among the four groups (P0.05). Conclusion The DAP values of adult Han subjects receiving CAG are increased with the increase of BMI values; the fluoroscopy time is significantly prolonged in patients with BMI<20 kg/m2. In performing interventional procedure, the operator should not only understand that the increase of BMI can cause the increase of DAP, but also need to pay special attention to the increase of DAP value caused by operation difficulty when the patient’s BMI is <20 kg/m2.

Comparison of Radiation Exposure during Fluoroscopy-Guided Transforaminal Epidural Steroid Injections at Different Vertebral Levels

OBJECTIVE: To estimate and compare radiation exposure during transforaminal fluoroscopy-guided epidural steroid injection (TFESI) at different vertebral levels. MATERIALS AND METHODS: Fluoroscopy-guided TFESI was performed in 181 patients. The patients were categorized into three groups according to the injected lumbosacral nerve level of L2-4, L5, or S1. Fluoroscopy time (FT) and dose area product (DAP) were recorded for all patients; correlations between FT and DAP were determined at each level, and both FT and DAP were compared between the different vertebral levels. RESULTS: The numbers of patients who received ESI at L2-4, L5, and S1 were 29, 123, and 29. Mean FT was 44 seconds at L2-4, 33.5 seconds at L5, and 37.7 seconds at S1. Mean DAP was 138.6 microGy.m2 at L2-4, 100.6 microGy.m2 at L5, and 72.1 microGy.m2 at S1. FT and DAP were positively correlated in each group (p values < 0.001). FT was significantly shorter at L5 than that at L2-4 (p = 0.004) but was not significantly different between S1 and L2-4 or L5 (p values = 0.286 and 0.532, respectively). DAP was significantly smaller at L5 and S1 than that at L2-4, but L5 and S1 were not significantly different. After correcting for FT, DAP was significantly smaller at S1 than that at either L2-4 or L5 (p values = 0.001 and 0.010). CONCLUSION: The radiation dose was small during a single procedure of ESI and showed differences between different lumbosacral spine levels.

Patient Radiation Dose in Diagnostic and Interventional Procedures for Intracranial Aneurysms: Experience at a Single Center

OBJECTIVE: To assess patient radiation doses during cerebral angiography and embolization of intracranial aneurysms in a large sample size from a single center. MATERIALS AND METHODS: We studied a sample of 439 diagnostic and 149 therapeutic procedures for intracranial aneurysms in 480 patients (331 females, 149 males; median age, 57 years; range, 21-88 years), which were performed in 2012 with a biplane unit. Parameters including fluoroscopic time, dose-area product (DAP), and total angiographic image frames were obtained and analyzed. RESULTS: Mean fluoroscopic time, total mean DAP, and total image frames were 12.6 minutes, 136.6 +/- 44.8 Gy-cm2, and 251 +/- 49 frames for diagnostic procedures, 52.9 minutes, 226.0 +/- 129.2 Gy-cm2, and 241 frames for therapeutic procedures, and 52.2 minutes, 334.5 +/- 184.6 Gy-cm2, and 408 frames for when both procedures were performed during the same session. The third quartiles for diagnostic reference levels (DRLs) were 14.0, 61.1, and 66.1 minutes for fluoroscopy time, 154.2, 272.8, and 393.8 Gy-cm2 for DAP, and 272, 276, and 535 for numbers of image frames in diagnostic, therapeutic, and both procedures in the same session, respectively. The proportions of fluoroscopy in DAP for the procedures were 11.4%, 50.5%, and 36.1%, respectively, for the three groups. The mean DAP for each 3-dimensional rotational angiographic acquisition was 19.2 +/- 3.2 Gy-cm2. On average, rotational angiography was used 1.4 +/- 0.6 times/session (range, 1-4; n = 580). CONCLUSION: Radiation dose in our study as measured by DAP, fluoroscopy time and image frames did not differ significantly from other reported DRL studies for cerebral angiography, and DAP was lower with fewer angiographic image frames for embolization. A national registry of radiation-dose data is a necessary next step to refine the dose reference level.

Optimizing Imaging Quality and Radiation Dose by the Age-Dependent Setting of Tube Voltage in Pediatric Chest Digital Radiography

OBJECTIVE: The quality and radiation dose of different tube voltage sets for chest digital radiography (DR) were compared in a series of pediatric age groups. MATERIALS AND METHODS: Forty-five hundred children aged 0-14 years (yr) were randomly divided into four groups according to the tube voltage protocols for chest DR: lower kilovoltage potential (kVp) (A), intermediate kVp (B), and higher kVp (C) groups, and the fixed high kVp group (controls). The results were analyzed among five different age groups (0-1 yr, 1-3 yr, 3-7 yr, 7-11 yr and 11-14 yr). The dose area product (DAP) and visual grading analysis score (VGAS) were determined and compared by using one-way analysis of variance. RESULTS: The mean DAP of protocol C was significantly lower as compared with protocols A, B and controls (p < 0.05). DAP was higher in protocol A than the controls (p <0.001), but it was not statistically significantly different between B and the controls (p = 0.976). Mean VGAS was lower in the controls than all three protocols (p < 0.001 for all). Mean VGAS did not differ between protocols A and B (p = 0.334), but was lower in protocol C than A (p = 0.008) and B (p = 0.049). CONCLUSION: Protocol C (higher kVp) may help optimize the trade-off between radiation dose and image quality, and it may be acceptable for use in a pediatric age group from these results.

Analysis of X-ray radiation doses from different types of intervention for cardiovascular patients / 中华放射医学与防护杂志

Objective To explore the X-ray radiation dose to patients from different cardiovascular interventional procedures and analyze the dose-affecting factors.Methods In accordance with the A,B,C operators,442 patients undergoing cardiovascular interventional procedures were collected,including single coronary angiography (CAG),percutaneous coronary intervention ( PCI ),radiofrequency catheter ablation (RFCA),congenital heart disease intervention (CHD) and permanent cardiac pacemaker implantation (PCPI),to observe dose area product (DAP),cumulative radiation dose (CD),fluoroscopy time.Results CD values of patients in groups of CAG,PCI,RFCA,CHD,PCPI were (0.34 ±0.23),(1.33 ±0.76),(0.71 ±0.43),(0.27 ±0.22) and (0.92±0.42) Gy and DAP values were (34.18 ±23.33),(135.92 ±81.14),(79.79 ±50.66),(27.93 ±23.66),and (94.60 ±48.11 ) Gy·cm2,respectively.Fluoroscopy time were (4.82 ±3.73),( 16.64 ±9.01 ),( 17.04 ± 15.29),(9.60 ±5.97)and (7.31 ±6.45) min.DAP values and fluoroscopy time were highly correlated (r =0.84,P ＜ 0.05 ).Conclusions There is significant difference in radiation dose for cardiovascular interventional procedures.Radiation dose and fluoroscopy time are directly related to surgeons' proficiency in operations.Improvement of operation proficiency should be carried out to reduce the patients' radiation dose.

Radiation doses in interventional radiology procedures / 中华放射医学与防护杂志

Objective To investigate the radiation doses for the patients undergoing interventional radiology and to analyze the dose - influencing factors.MethodsThe clinical data of 461 patients undergoing interventional radiology,including cerebral angiography ( CEA ),cerebral aneurysm embolism ( CAE ),superselective hepatic arterial chemoembolization ( SHAG ),coronary angiography ( COA ),percutaneous intracoronary stent implantation ( PIS1 ),cardiac radiofrequency catheter ablation ( RFCA ),and permanent cardiac pacemaker implantation(PCPI) were collected to observe the cumulative air kerma (CAK),dose area product (DAP),and fluoroscopy time,and effective dose was estimated using the conversion factors.Results The effective doses for CEA,CAE,SHAG,COA,PISI,RFCA,and PCPI were (0.33 ±0.20),(0.49 ±0.35),(6.92 ±4.19),(0.76 ±0.91),(2.35 ± 1.47),(0.50 ±0.74),and (0.67 ±0.70) Sv,respectively.In 126 of the 416 patients (26%),the effective doses were greater than 1 Sv,and the effective doses of 10 person-times were greater than 10 Sv,all of which were observed in the patients undergoing SHAG.The CAK values for CEA,CAE,SHAG,COA,PISI,RFCA,and PCPIwere (0.55 ±0.43),(1.34 ± 1.11),(0.95 ±0.57),(0.32 ±0.31),(0.91 ±0.33),(0.16 ±0.22),and (0.15 ±0.14) Gy,respectively.The CAK values were greater than 1 Gy in 59 of the 461 patients ( 12.8% ),greater than 2 Gy in 11 cases (2.4%) ,and greater than 3 Gy in 1 CEA cases and 1 CEA case,respectively.Conclusions There is a wide variation range in radiation dose for different procedures.As most interventional radiology procedure can result in clinically significant radiation dose to the patient,stricter dose control should be carried out.

Survey on patient dose in cardiac intervention / 介入放射学杂志

Objective To collect information of patient doses of interventional radiology in Beijing Xuanwu Hospital,and investigate correlation between the peak skin dose(PSD) and dose-area product(DAP).Methods Radiation doses from 135 patients have been studied including 84 coronary angiographies(CAG) and 51 percutaneous transluminal coronary angioplasties(PCI).Dose-area product(DAP) values,cumulative dose(CD) at interventional reference points,fluoroscopy times,total number of cine frames were collected for each patient.Skin dose measurements were made with thermoluminescent dosimeters(TLD) placed as a 10 ? 9 arrays of TLDs on the body.The grid of TLDs arrays was 5 ? 4 cm.Results Mean values for dose-area product were 2690.84 ?Gym2 for CAG and 7946.91 ?Gym2 for PCI.Mean values for CD were 431.6 mGy cm2 for CAG and 1395.3 mGy for PCI.Mean fluoroscopy times were 2.9 min for CAG and 10.9 min for PCI and mean number of frames were 544 and 945 for CAG and PCI,respectively.PSD values ranged from 26.18 to 120.37 mGy for CAG and 38.91 to 184.79 mGy for PCI.The relationship between DAP and PSD was r = 0.52 for CAG and r = 0.54 for PCI.The correlation of PSD with CD was r = 0.45 for CAG and r = 0.53 for PCI.Conclusion Comparison shows that patients DAP,CD and fluoroscopy time values were comparable with other publications.Skin dose values of investigated patients are below the threshold dose for radiation skin injury(2 Gy).There is no good relationship between DAP and PSD.So calculation of individual maximum skin dose based on DAP data is not reliable and needs to find a new reference value for skin dose.(J Intervent Radiol,2007,16:222-225)