The impact of a magnetic field on the dose distribution using the Bebig 60Co HDR sources / 中华放射肿瘤学杂志

Objective To evaluate the impact of an external magnetic field on the dose distribution and electronic disequilibrium region around a Bebig type 60Co HDR brachytherapy source and to judge the feasibility of applying MRI scanner during brachytherapy.Methods The source model was established based on the Monte Carlo package Geant4 software.The simulated geometries consisted of the 60Co source inside a water phantom of 10.0cm× 10.0cm× 10.0cm in size.The magnetic field strength of the 0T,1.5T and 3.0T was considered,respectively.The voxels with a size of 0.2 mm,0.5 mm and 0.5 mm were established along the x-,y-and z-axis.The influence of the magnetic field on the Kerma (kinetic energy released to matter) distribution and dose distribution within the 10.0mm region from the source center was evaluated.Furthermore,the ratio of the Kerma to dose as a function of the distance to the center source was acquired.Results The 1.5T magnetic field exerted no effect on the dose distribution adjacent to 60Co HDR brachytherapy source,whereas3.0T magnetic field caused significant increase in the dose distribution within r＜6 mm from the source center.The dose distribution was increased by 40％ at r=5.4 mm from the source center.The ratio of Kerma to dose was less than 1 within the region of 1.2 mm＜r＜6.0 mm,suggesting that 3.0T magnetic field can lead to electronic disequilibrium within a larger region from the source center.Conclusions For Bebig 60Co HDR brachytherapy source,it is safe and reliable to apply1.5T external magnetic field.Nevertheless,3.0T magnetic field can cause high dose risk.Consequently,safety assessment and verification should be delivered prior to clinical application.

Dosimetric analysis of three kinds of irradiation technique in radiotherapy of medulloblastoma / 实用肿瘤学杂志

Objective We aimed to explore the difference of dosimetry among intensity modulated radia-tion therapy(IMRT),volumetric modulated arc therapy(VMAT)and helical tomotherapy(TOMO)in the radio-therapy of medulloblastoma.Methods Ten children's patients with the medulloblastoma were selected and de-signed in this study.A clinically feasible radiotherapy plan was designed for IMRT(5 fields),VMAT and TOMO. Conformality index(CI),homogeneity index(HI),V107,maximum dose(Dmax),organ at risk(OAR)dose-volume level,monitor units and treatment time were used to analyze in these groups.Results CI,HI,V107,Dmaxand OAR of target areas were significantly superior to VMAT and IMRT in the TOMO group of target PTV for whole brain full radiotherapy.The organ at risk dose-volume level in the TOMO group was lower than that in VMAT and IM-RT(5 fields)groups(P<0.05).The TOMO group also had the most monitor units and the longest treatment time (P<0.05).Hence,the patients in the TOMO group could irradiate completely the whole brain and full spinal cord without moving treatment couch to avoid the error from the man-made movement in VMAT and IMRT(5 fields)treatments.Conclusion In the radiotherapy of medulloblastoma,the dose distribution of patients in the TOMO group are superior to the VMAT and IMRT groups(5 fields).However,the number of monitor units and treatment time is significantly increased during treatment,and its clinical effect needed to be further studies.

Dosimetric analysis of three kinds of irradiation technique in radiotherapy of medulloblastoma / 实用肿瘤学杂志

Objective We aimed to explore the difference of dosimetry among intensity modulated radia-tion therapy(IMRT),volumetric modulated arc therapy(VMAT)and helical tomotherapy(TOMO)in the radio-therapy of medulloblastoma.Methods Ten children's patients with the medulloblastoma were selected and de-signed in this study.A clinically feasible radiotherapy plan was designed for IMRT(5 fields),VMAT and TOMO. Conformality index(CI),homogeneity index(HI),V107,maximum dose(Dmax),organ at risk(OAR)dose-volume level,monitor units and treatment time were used to analyze in these groups.Results CI,HI,V107,Dmaxand OAR of target areas were significantly superior to VMAT and IMRT in the TOMO group of target PTV for whole brain full radiotherapy.The organ at risk dose-volume level in the TOMO group was lower than that in VMAT and IM-RT(5 fields)groups(P<0.05).The TOMO group also had the most monitor units and the longest treatment time (P<0.05).Hence,the patients in the TOMO group could irradiate completely the whole brain and full spinal cord without moving treatment couch to avoid the error from the man-made movement in VMAT and IMRT(5 fields)treatments.Conclusion In the radiotherapy of medulloblastoma,the dose distribution of patients in the TOMO group are superior to the VMAT and IMRT groups(5 fields).However,the number of monitor units and treatment time is significantly increased during treatment,and its clinical effect needed to be further studies.

Dosimetric comparisons of volumetric modulated arc radiotherapy with fixed field dynamic intensity modulated radiotherapy for postoperative cervical carcinoma / 实用肿瘤学杂志

Objective The objective of this study was to compare the differences between Volumetric Modulated Arc Radiotherapy(VMAT)and Fixed Field dynamic Intensity Modulated Radiotherapy(dIMRT)in dose distribution of target and organ at risk and treatment time,and to provide basis for clinical treatment.Methods Ten patients with postoperative of cervical carcinoma were selected,VMAT and seven fields dIMRT plans were designed for each patient in Monaco 5.11 planning system.We compared the differences of dose distribution of target and organ at risk,monitor units and treatment time between VMAT and 7dIMRT.Results The average dose of target for VMAT plan(46.86 Gy)was higher than that of 7dIMRT plan(46.68 Gy)(P<0.05).The percentage of the V10 and V20 of rectum and the V30 of small intestine in VMAT plan was 0.63%,3.34% and 4.14% higher than that in 7dIMRT plan,respectively(P<0.05).The conformal index(CI),homogeneity index(HI)of PTV and the other exposure dose of organ at risk for both plans were no significant differences.The average monitor units and treatment time of VMAT plan were 13.4% and 50.6% than that of 7dIMRT plan,respectively(P<0.05).Conclusion The dose distribution of VMAT plan is better or equal to that of 7dIMRT plan,but the monitor units and treatment time of VMAT plan is decreased significantly,we suggest that VMAT plan should be used for postoperative of cervical carcinoma in clinical.

Xinjiang Uygur Medicine Image Feature Extraction and Discriminant Analysis Based on Color and Textural Features / 中国中医药信息杂志

Objective To extract Xinjiang Uyghur medicine image features and analyze the features; To investigate the image classification effect of the researched features; To find the suitable features for Xinjiang Uyghur medicine image classification; To lay the foundation for content-based medical image retrieval system of Xinjiang Uyghur medicine images.Methods The flowers and leaves of Xinjiang Uyghur medicine were treated as the research objects. First, images were under preprocessing. Then color and textural features were extracted as original features and statistics method was used to analyze the features. Maximum classification distance was used to analyze the main features obtained from image classification. At last, the classification ability of features was evaluated by Bayes discriminant analysis.Results Color and textural features were selected and classified. The correct classification rate of flower images was 85% and the correct classification rate of leaf images was 62%. The classification effect of flower images used by selected features was better than classification effect of original feature.Conclusion Compared with the classification of original features, the classification accuracy of flower medicine is higher through selected features. This research can lay a certain foundation for the further researches on Xinjiang Uyghur medicine images and the improvement of feature extraction methods.

Image Feature Extraction and Discriminant Analysis of Xinjiang Uygur Medicine Based on Color Histogram / 生物医学工程学杂志

Image feature extraction is an important part of image processing and it is an important field of research and application of image processing technology. Uygur medicine is one of Chinese traditional medicine and researchers pay more attention to it. But large amounts of Uygur medicine data have not been fully utilized. In this study, we extracted the image color histogram feature of herbal and zooid medicine of Xinjiang Uygur. First, we did preprocessing, including image color enhancement, size normalizition and color space transformation. Then we extracted color histogram feature and analyzed them with statistical method. And finally, we evaluated the classification ability of features by Bayes discriminant analysis. Experimental results showed that high accuracy for Uygur medicine image classification was obtained by using color histogram feature. This study would have a certain help for the content-based medical image retrieval for Xinjiang Uygur medicine.

Dosimetric comparison with conventional radiation therapy and intensity modulated radiation therapy for locally advanced laryngeal carcinoma / 实用肿瘤学杂志

Obejctive To compare the differences between conventional radiation therapy (3DCRT) and intensity modulated radiation therapy( IMRT) for locally advanced laryngeal carcinoma patients by ECLIPSE treat -ment planning system.Methods Six locally advanced laryngeal carcinoma patients ′treatment plans were de-signed as IMRT and 3DCRT according to ECLIPSE treatment planning system ,respectively.The following values were measured,such as V95%、D5%、D95%、Dmin and D mean of the target volume,and the D50,D33,D5, Dmax and Dmean of normal tissues.Results The dose coverage rate of GTV and GTVnd in the IMRT plan was compared to ECLIPSE treatment planning system with no statistical differences.However, there were obvious difference in CTV and some normal tissues.Conclusion Both IMRT and 3DCRT have good coverage to primary tumor and metastatic lymph nodes.IMRT can spare the parotid from high dose irradiation.

The effect of energy selection to the dose distribution of inverse planning intensity-modulated radiation therapy / 中华放射肿瘤学杂志

ObjectiveTo study the dose distribution of the intensity modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) inverse plans with different energy X-ray, to provide a reference of energy options for radiation therapy. MethodsEight cases with different disease were chosen, the plan for each case were finished with 1Arc (360°) VMAT, 9 fields IMRT and 5 fields IMRT.For each plan project, the energy selections were 4 MV, 6 MV, 8 MV and 15 MV. In the evaluation,homogeneity index ( HI), conformity index ( CI ) and external volume index ( EVI ) of target, the average dose ( Dmean) and 2％ volume in dose volume histogram ( D2 ) of serial organs at risk ( OARs), the average dose ( Dmean ) and a dose level volume ( Vx ) of parallel OARs were chosen and compared . Results Statistical analysis showed that: For the target, the result of HI were F=0. 13,0. 51,0. 09, P=0. 939,0.679,0.965,CI were F=0. 13,0.51,0.09,P=0.939,0.679,0.965, EVI were F=0. 15,0.31,0. 15,P =0. 930,0. 818,0. 931, respectively ; For the OARs of each patient, F ＜ 0. 20, P ＞ 0. 05. All results indicated there was little difference in option of energy for the same field p8roject. ConclusionsThe results indicate that the middle and low energy X-ray (6 MV or 8 MV) can satisfy the needs of IMRT and VMAT radiotherapy. Compared with middle and low energy, the high energy X-ray (15 MV ) showed little advantage in dose distribution.