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Objective:To investigate the predictive value of thrombus enhancement (TE) and thrombus permeability in cardioembolic thrombus with acute middle cerebral artery occlusion based on CT.Methods:The clinical and image data of 93 patients with acute middle cerebral artery occlusion who were admitted to the First Affiliated Hospital of Soochow University within 12 hours after onset from January 2020 to July 2022 were retrospectively analyzed. According to the TOAST criteria, the patients were divided into the cardioembolism (CE) group (43 cases) and the large artery atherosclerosis (LAA) group (50 cases). All patients received noncontrast CT and CT angiography, and then thrombus permeability [thrombus attenuation increase (TAI), void fraction (ε)] and TE were assessed. Independent sample t-test, Mann-Whitney U test and χ2 test were used in univariable analysis between two groups. Multivariable logistic regression analysis was used to explore the independent influencing factors for cardioembolic stroke and establish a logistic model. The receiver operating characteristic (ROC) curve and the area under the curve (AUC) were used to evaluate the predictive value of TAI, ε, TE and the logistic model in cardioembolic thrombus with acute middle cerebral artery occlusion. Results:There were statistically significant differences in sex, atrial fibrillation, hypertension, diabetes mellitus, smoking, baseline National Institutes of health stroke scale (NIHSS), TAI, ε and TE between the CE group and the LAA group ( P<0.05). Binary logistics regression analysis showed that TAI (OR=1.300, 95%CI 1.147-1.473, P<0.001), hypertension (OR=0.116, 95%CI 0.025-0.535, P=0.006) and baseline NIHSS (OR=1.165, 95%CI 1.040-1.304, P=0.008) were independent influencing factors for cardioembolic thrombus. The ROC curve indicated that the logistic model predicted cardioembolic thrombus with the highest AUC of 0.907 (95%CI 0.848-0.966). TE predicted cardioembolic thrombus with the highest sensitivity of 90.7%. Conclusion:TE and thrombus permeability have application value for predicting cardioembolic thrombus with acute middle cerebral artery occlusion based on CT.
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Objective To verify the leaf positioning accuracy of multi-leaf collimator (MLC) in intensity modulated radiation therapy (IMRT) by using radiochromic films to provide references for IMRT quality control.Methods Medical linear accelerators of different designs,owned by 7 first-class hospitals at grade-3 in Hubei,were selected for this verification study.Five strip picket fence pattern was created by treatment planning system (TPS).Each strip was 0.6 cm wide with a 3 cm strip separation.MLC leaf positions,positioning bias and opening widths were then measured with EBT2 radiochromic films.Results According to IAEA standards,the film-measured and TPS planned MLC leaf position difference was ±0.5 mm.The difference of MCL strip position of No.5 and No.7 accelerator was 0.7 and-1.0 mm,respectively,not in line with the IAEA standards.The difference of film-measured MLC leaf position between each pairs and all pairs of leaves of 7 accelerators were all within ± 0.5 mm,in line with the IAEA requirements.As required by IAEA,the difference of opening width of MLC leave of each pair relative to the averaged widths of all pairs should be within ±0.75 mm.The filem-measured values from 7 accelerators ranged from-0.6 to 0.5 mm,all in line with the IAEA standards.Standard deviation of opening width of all leaves were required to be within 0.3 mm.The measured values from 7 accelerators ranged from 0.1 to 0.2 mm,in line with the IAEA standard.Conclusions The use of EBT2 radiochromic films to verify MLC leaf positioning accuracy is an important means of quality control owing to its simplicity and high measurement accuracy.It is recommended for verification use at a large scale.
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Objective To develop measurement methodology using film for the positioning accuracy of MLC leaves in IMRT.Methods The solid water phantom of 30 cm x 30 cm was scanned and the scanned images were transferred to TPS for treatment plan formulation.The five MLC strip picket fence pattern was formed by MLC leaves,each 3.0 cm long × 6.0 mm wide.The separation between strip and strip is 3.0 cm.SAD is 100 cm at dmax for 6 MV X-ray,with 250 MU per MLC strip.EBT2 radiochomic film was put on the phantom for delivery of IMRT,for each MLC strip.The present study focused on 30 accelerators of Varian,Elekta and Siemens designs at 27 hospitals with highly skilled physicists all over Jiangsu,Sichuan,Hubei and Henan provinces.The study was conducted in the same way as used in international multi-radiotherapy center (IMRC).The irradiated films were sent respectively to IAEA dosimetry laboratory and external audit group (EGA) of China for measurement,analysis and calculation.Results According to IAEA requirements,the differenc of film-measured and TPS-planned of MLC leaf position for each strip should be within ±0.5 mm.China had participated in the research of IMRC,with the result of 0.3,0.2,0.0,-0.1,and-0.2 mm,respectively.For 30 accelerators in four provinces involved in the study,the IAEA's verification results of MLC leaf position were within 0.6-1.0 mm for 5 accelerators and within ± 0.5 mm for other 25 ones.Whereas the verification results of EAG were within 0.6-1.0 mm for 6 accelerators and within ±0.5 mm for other 24 ones.According to IAEA requirements,the film-measured MLC leaf position deviation for each pair of leaves and average all pairs of leaves should be within ±0.5 mm.China had participated in IMRC's research,with the measured result being 0.04 mm.The verification result of EGA for 30 accelerators showed the measured MLC leaf position deviations were all ＜0.3 mm per strip,consistent with IAEA requirements.The IAEA's result showed the measured deviations of MLC leaf position for 29 accelerators were within ±0.5 mm,with only other one being-0.7 mm not consistent with the IAEA requirements.As required by IAEA,the difference of film-measured difference of MLC opening width should be within ±0.75 mm between each pair and average all pairs of leaves.China's result in research of IMRC showed the difference of minimum width to mean width was-0.2 mm whereas the difference of maximum width to mean width was 0.4 mm.For 30 accelerators involved in IAEA'verification study,the measured result shown that the difference between maximum and average of filmmeasured of MLC leaf width,and between minmum and average,were within ± 0.75 mm for 24 accelerators,in line with the IAEA requirements.For other 6 ones,the values were beyond ±0.75 mm,not in line with the IAEA requirements.For the verification result of EAG,the difference between maximum and average widths and between minmum and average widths for 25 accelerators were within ±0.75 mm as required by IAEA,whereas for other 5 ones the value were beyond ±0.75 mm,not consistent with IAEA requirements.The standard deviation of film-measured MLC opening width between each pair and average all pairs should be within 0.3 mm as required by IAEA.China's IMRC result was 0.12 mm.The verification result of IAEA shown the standard deviation of MLC opening position were ＜0.3 mm for 26 accelerators and ＞ 0.3 mm for other 4 accelerators.EAG verification result were the same as IAEA result.Conclusions The method using radiochromic film for measuring accuracy of MLC leaf position is convenient and practicable as a quality audit.It is suitable for quality verification in medical institutions owing to easy to post and repeated measurements.
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Purpose To compare radiation dose and image quality of different scan modes for CT pulmonary angiography (CTPA) including high-pitch flash mode, dual energy CT (DECT) mode, 128-slice mode of dual source CT and 64-slice CT mode. Materials and Methods One hundred and sixty-seven patients with suspected pulmonary embolism were retrospectively studied. All the patients underwent CTPA. Twenty patients were selected randomly from the patients scanned by high-pitch flash mode. Patients who were scanned by the other three modes were selected with body mass index and age matched those in high-pitch flash mode, with 20 patients in each group. Two radiologists assessed signal-to-noise ratio (SNR) and image quality with 5-piont scale. Dose parameters of volume CT dose index (CTDIvol), dose length product (DLP), and effective dose (ED) were compared among the four groups. Results Mean CTDIvol, DLP and ED were (3.72±0.74) mGy, (137.5±28.7) mGy · cm, and (2.34±0.41) mSv for Flash mode;(5.31±1.21) mGy, (181.6±34.5) mGy· cm and (3.24±0.57) mSv for DECT mode;(5.66±1.47) mGy, (198.7±42.1) mGy·cm and (3.58±0.63) mSv for 128-CT mode;and (6.75±1.68) mGy, (231.5±54.2) mGy·cm and (4.21±0.89) mSv for 64-CT mode. There was no significant difference of SNR and image quality among the four modes (P>0.05). Conclusion There are no significant difference of image quality among the four groups. Flash mode allows for minimum radiation dose compared to other modes. DECT mode and 128-CT mode get higher radiation dose with no difference between them. 64-CT mode gets the highest radiation dose.
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Objective To explore the computed tomography (CT)manifestations of adrenocortical oncocytoma (ACO)for better understanding the disease and improving its diagnosis accuracy.Methods The CT manifestations of 9 cases with adrenocortical onco-cytomas confirmed by surgery were retrospectively reviewed and compared with pathological results.Results Five of cases were lo-cated in left side while 4 cases were in right side.Well defined and round or oval border could be found in all the cases.Of all the ca-ses,3 cases were solid lesions with equal density, 3 cm in diameter.The mixed cystic and solid components with polycystic changes could be found on CT image,and remarkable intensification on solid lesion while no intensification on cystic lesion after the enhancement. Moreover,patchy or cotton-like shape could be found on solid lesion in 4 cases and 1 case with island like intensification;reticular pattern could be found in the central of lesion in 3 cases and 1 case with stellate shape.Pathological observation showed that the on-cotytomas were comprised of cells with abundant eosinophilic cytoplasm and necrotic and fibrous capsule without pathological mitosis could be found in some of lesion.Conclusion The characteristic CT features of adrenocortical oncotytoma has a worse specificity,its diagnosis was dependent on pathologic examination.
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Objective To verify the reliability of TLD-based quality audit for radiotherapy dosimetry of medical electron accelerator in non-reference condition by monitoring the dose variations from electron beams with different field sizes and 45° wedge and the dose variations from photon beams with different field sizes and source-skin distance.Methods Both TLDs and finger ionization chambers were placed at a depth of 10 cm in water to measure the absorbed dose from photon beams,and also placed at the depth of maximum dose from electron beams under non-reference condition.TLDs were then mailed to National Institute for Radiological Protection,China CDC for further measurement.Results Among the 70 measuring points for photon beams,58 points showed the results with a relative error less than ± 7.0％ (IAEA's acceptable deviation:± 7.0％) between TLDs and finger ionization chambers measurements,and the percentage of qualified point numbers was 82.8％.After corrected by P,value,62 points were qualified and the percentage was up to 88.6％.All of the measuring points for electron beams,with the total number of 24,presented a relative error within ± 5.0％ (IAEA's acceptable deviation:± 5.0％) between TLDs and finger ioization cylindrical chambers measurements.Conclusions TLD-based quality audit is convenient for determining radiotherapy dosimetric parameters of electron beams in non-reference condition and can improve the accuracy of the measuring parameters in connection with finger chambers.For electron beams of 5 MeV ＜ E0 ＜ 10 MeV,the absorbed dose parameters measured by finger ionization chambers,combined with TLD audit,can help obtain the precise and reliable results.