FLASH radiotherapy is a hotspot in the domain of tumor radiotherapy in recent years, which delivers at ultra-high dose rate (usually > 100 Gy/s) in an ultra-short time (1−50 ms) to the target volume. The FLASH effect will be generated after the organism is treated with FLASH radiotherapy, which makes the tumor more easy to be killed and the normal tissue is protected after radiotherapy. Because of the differences in sensitivity to FLASH radiotherapy between tumor tissues and normal tissues, FLASH radiotherapy has a subversive advantage in the treatment of tumors. In this paper, several studies since 1959 on the effects of ultra-high dose rate rays and FLASH radiation on cells and organisms are summarized. As the predecessor of FLASH radiotherapy, ultra-high dose rate radiotherapy has laid a very important foundation for the development of FLASH radiotherapy.
【摘要】目的探讨早期乳腺癌保乳术中电子线放射治疗(intraoperative radiotherapy with electron,ELIOT)的可行性,评价术后并发症和术后乳房外观。方法2007年6月2009年6月期间,共有26例早期乳腺癌(肿瘤直径不超过25 cm)患者接受乳腺癌保乳手术及ELIOT,放疗剂量为21 Gy(分割照射58～60 Gy)。术后1年内第1、2、3个月,第6、9、12个月,1年后每6个月评估一次,主要评估切口愈合状况、并发症、乳房外观及肿瘤复发情况。结果术后切口愈合时间14～22 d,平均17 d。随访2～25个月,平均12个月,有2例切口脂肪液化,11例切口水肿伴引流液较多,全组无切口感染或血肿。随访期间内,未发现局部复发、远处转移或对侧乳腺癌。手术切口愈合后、术后6个月,1、2年对乳房外观评价结果:优秀者分别依次为577%、667%、727%及100%;好者分别依次为346%、222%、182%及0;一般者分别依次为77%、111%、91%及0。结论乳腺癌保乳术后行ELIOT 疗效确切、安全,对早期乳腺癌患者是一种方法简便,疗效确切、安全的选择。
摘要:目的:探讨伽玛刀治疗颅内肿瘤并发放射性脑损伤的MRI影像表现及其组织病理学基础。方法:回顾性分析8例经手术及病理证实的放射性脑损伤的MRI表现;其中,星形胶质细胞瘤4例,转移性腺癌2例,血管母细胞瘤1例,鼻咽癌1例。结果:病变位于小脑半球、额叶、颞叶及顶叶,8例9个病灶共有2种MRI表现:5例6个病灶平扫T1WI呈低、等信号,T2WI呈稍高、高信号,增强扫描呈“结节状”、“花环状”强化;3个病灶平扫为类圆形,T1WI呈均匀低信号,T2WI呈高信号,边界清楚,增强扫描囊腔无强化,囊壁轻度均匀强化。所有病例均有占位效应。结论:伽玛刀所致放射性脑损伤具有一定的特征性,特别是囊状坏死。
Aiming at the disadvantages of traditional direct aperture optimization (DAO) method, such as slow convergence rate, prone to stagnation and weak global searching ability, a gradient-based direct aperture optimization (GDAO) is proposed. In this work, two different optimization methods are used to optimize the shapes and the weights of the apertures. Firstly, in order to improve the validity of the aperture shapes optimization of each search, the traditional simulated annealing (SA) algorithm is improved, the gradient is introduced to the algorithm. The shapes of the apertures are optimized by the gradient based SA method. At the same time, the constraints between the leaves of multileaf collimator (MLC) have been fully considered, the optimized aperture shapes are meeting the requirements of clinical radiation therapy. After that, the weights of the apertures are optimized by the limited-memory BFGS for bound-constrained (L-BFGS-B) algorithm, which is simple in calculation, fast in convergence rate, and suitable for solving large scale constrained optimization. Compared with the traditional SA algorithm, the time cost of this program decreased by 15.90%; the minimum dose for the planning target volume was improved by 0.29%, the highest dose for the planning target volume was reduced by 0.45%; the highest dose for the bladder and rectum, which are the organs at risk, decreased by 0.25% and 0.09%, respectively. The results of experiment show that the new algorithm can produce highly efficient treatment planning a short time and can be used in clinical practice.
Non-coding RNA (ncRNA) is a newly discovered functional RNA different from messenger RNA, which can participate in the regulation of tumor occurrence and development. Studies have shown that ncRNA can participate in the regulation of radiotherapy response to gastric cancer, and its mechanism may be related to its influence on DNA damage repair, gastric cancer cell stemness, apoptosis, and activation of epidermal growth factor receptor signal pathway. This article summarizes the mechanism of ncRNA regulating the response of gastric cancer to radiotherapy, and looks forward to the potential clinical application of ncRNA in the resistance of gastric cancer to radiotherapy.
In order to decrease the radiotherapy error caused by target motion, an adaptive radiation therapy system for target movement compensation has been designed and passed by simulation test. The real-time position of the target labelled by a mark was captured by the control system and compared with the reference point. Then the treatment couch was controlled to move in the opposite direction for compensation according to that position information. The three dimensional movement of the treatment bed relied on three independent stepping motors which were controlled by a control system. Experiments showed that the adaptive radiation therapy system was able to reduce the therapy error caused by target movement. It would be useful in radiotherapy clinical practice with high real-time position precision.
Intensity-modulated radiotherapy planning for nasopharyngeal carcinoma is very complex. The quality of plan is often closely linked to the experience of the treatment planner. In this study, 10 nasopharyngeal carcinoma patients at different stages were enrolled. Based on the scripting of Pinnacle3 9.2 treatment planning system, the computer program was used to set the basic parameters and objective parameters of the plans. At last, the nasopharyngeal carcinoma intensity-modulated radiotherapy plans were completed automatically. Then, the automatical and manual intensity-modulated radiotherapy plans were statistically compared and clinically evaluated. The results showed that there were no significant differences between those two kinds of plans with respect to the dosimetry parameters of most targets and organs at risk. The automatical nasopharyngeal carcinoma intensity-modulated radiotherapy plans can meet the requirements of clinical radiotherapy, significantly reduce planning time, and avoid the influence of human factors such as lack of experience to the quality of plan.