ABSTRACT
Objective To compare the dosage characteristics between three-dimensional conformal radiotherapy (3DCRT)plan and simplified inverse dynamic intensity modulated radiotherapy (IMRT)in patients with early-stage breast cancer after breast-conserving surgery.Methods 3DCRT and IMRT treament plans were designed for 14 female patients with early-stage breast cancer after breast-conserving surgery,4 of whom were left breast cancer cases.A dose of 50 Gy in 25 fractions to the whole ipsilateral breast was delivered using 6 MV photons for 3DCRT or IMRT.For 3DCRT plans,tangential field irradiation was adopted.While for IMRT,reverse dynamic intensity modulated technology was done through two pairs of tangential-likely fields, and 10 Gy was boosted to the tumor bed concomitantly in 25 fractions.The conformity index (CI),heterogenei-ty index (HI),dose and volume of organs at risk were evaluated by dose volume histograms (DVH).Results Compared with 3DCRT plans for ipsilateral lung,the high dose volumes were reduced and the low dose volumes were increased in IMRT plans.The same phenomenon was also observed for the heart of the patient with left breast cancer.The crosspoint doses of 3DCRT DVH and IMRT DVH for lung or heart were (25.16 ±9.11) Gy,(28.63 ±10.41 )Gy respectively.There was no difference between the two plans in the V10 of contra-lateral breast [IMRT(4.13 ±5.17)%∶3DCRT(1.99 ±2.43)%,t=2.11,P>0.05],but the D30 and mean of IMRT plan were higher than that of 3DCRT [(2.23 ±1.77)Gy ∶(1.20 ±0.46)Gy,t=2.58,P0.05].While the CI of IMRT plans were improved compared with 3DCRT [(0.75 ±0.07)∶(0.62 ±0.09),t =5.68,P<0.000 1]. Conclusion Compared with 3DCRT plan in patients with early-stage breast cancer after breast-conserving surgery,the main advantages of four fields simplified inverse dynamic IMRT are concomitant tumor boosting, decreasing the high dose volumes of ipsilateral lung,and improving the CI of planning target volume at the same time,but the HI is not improved.The IMRT plan is a simple,rational and feasible design scheme.
ABSTRACT
Obiective To study the regularity of three-dimensional displacement in respiration of lung cancer. Methods Af-ter CT scanning, the CT images were transferred into target planning system (TPS) to obtain three-dimensional reconstruc-tion images. Then target drawing and noting of target position, tumor volume, lung function, patient gender, age and weight were performed. The images during the course of inspiration and expiration in simulator were scanned and transferred into TPS by DICOM RT port. At last, the three-dimensional displacement curve of the interested points(X,Y and Z axis) could be obtained. Results The three-dimensional real time displacement curve of lung cancer interested points could be estab-fished by the way of collecting simulator images and drawing interested points. The maximum displacement range of the interested points were 4.2mm in Z-axis(head-foot direction), 3.8ram in X-axis(left-right direction), 2.9ram in Y-axis(ante-rior-posterior direction). Conclusion The three--dimensional real time displacement curve of lung cancer at any point of the target can be established by collecting the dynamic images in simulator and reconstructing of the corresponding images in target planning system through the DICOM RT.
ABSTRACT
BACKGROUND: Stroke-prone spontaneously hypertensive rat(SHRsp) is an animal model of hypertensive stroke commonly used. The species is hard to be maintained due to hypertension and easily affected by environmental factors, therefore the characteristics of stroke are always aberrated.OBJECTIVE: To observe the abilities of reproduction and maintaining the characteristics of hypertensive stroke in SHPsp.DESIGN: Observational controlled study based on rats.SETTING: Cardiovascular Disease Institute and Fuwai Hospital of Chinese Academy of Medical Sciences.MATERIALS: The experiment was conducted Cardiovascular Disease Institute and Fuwai Hospital of Chinese Academy of Medical Sciences during September 1999 to December 2001. Totally 93 pairs(186) strain SHRsp, 48stroke-prone spontaneously hypertensive rats of 8 weeks age as well as 98pairs(196) rats of normal blood pressure [Wistar Kyoto rat (WKY) ] were selected.METHODS: Brother sister mating method was used. And the conception rate, number of litter size(only calculating the litter size of mother rat not eating neonatal rats), rate of eating neonatal rats by mother rats were recorded and compared with those of WKY. The systolic pressure and heart rate of strain rat were measured when they were 12, 16 and 20 weeks old. In addition, 488-week SHRsp were loaded 10 g/L salty water to accelerate the occurrence of stroke and hypertension and executed when they naturally dead or 12 weeks after salty water load. The brain tissue was processed by H-E staining and observed under microscope to detect the incidence of stroke.MAIN OUTCOME MEASURES: Conception rate of female rats within 2years; litter rate of pregnant rats; eating, rate of eating neonatal rats by mother rats; systolic pressure of strain rat; heart rate; detection rate of stroke.RESULTS: Totally 93 pairs(186) strain rats of SHRsp, 98 pairs(196) WKY and 48 SHRsp of 8 weeks old entered the final analysis. In the first year there were 2 generations delivered, the average conception rate( 100% ) and average litter number (10.3 rats) of SHRsp were higher than those of WKY of the same term(90%, P ＜ 0. 001; 6. 5 rats, P ＜ 0. 001) . In the second year, there were 2 generations of which the conception rate and average litter number(89%, 8.2 rats) of SHRsp were higher than those of WKY(59%, P ＜ 0. 001; 4. 3 rats, P ＜ 0. 001). There were 87 SHRsp female rats and 67normal blood pressure rats pregnant within 2 years, the rate of eating neonatal rats within 4 weeks postnatal was 6% (5/87) which was lower than that of WKY(18%, 12/67), P ＞ 0.05. The systolic pressure of 12weeks old male rats and female rats was 191.6-223.8 mm Hg and 174. 2-196. 3 mm Hg respectively, while that of 16-week old and 20-week male rats were 219.0 -224. 9 mm Hg and 232.0 -242.6 mm Hg respectively. The blood pressure of SHRsp increased with the advancing of age. The heart rate of 12-week old male and female rats was 388-428 times per minute and 373-417times/minute respectively while that of 16-week and 20-week male rats were 392 -410 times per minute and 404-425 times per minute respectively. The pathological detection rate of 48 SHRsp was 81% (39/48).CONCLUSION: The reproduction ability of SHRsp is similar to normal rats. The blood pressure, heart rate and pathological examination of brain tissue of them all maintain the characteristics of hypertension and stroke so that they can be used as qualified experimental model.
ABSTRACT
Precise verification is required in the execution of intensity-modulated radiotherapy (IMRT) for its complexity. Thereinto, the verification of dose distributions is the emphases and nodus. Some problems in the verification by using radiotherapy planning dose verification system (DVS) are explored such as how to verify the precision and credibility, how to reduce errors in every verification step, how to provide quantified analysis. A suit of practical methods and techniques are summarized from equipment selection to quantified analysis.