無均整器型加速器治療室中子劑量分布
發(fā)布時間:2018-06-07 17:53
本文選題:移除均整器技術(shù) + MV��; 參考:《中華腫瘤防治雜志》2017年17期
【摘要】:目的調(diào)強放療技術(shù)極大改善了放療計劃質(zhì)量,但相對適形放療也隨之增加了治療出束劑量及照射時間,移除均整器(flattening filter free,FFF)技術(shù)能在保持計劃質(zhì)量的前提下減少照射時間。本研究測量和分析瓦里安TrueBeam型加速器常規(guī)劑量率有均整器(flattening filter,FF)模式和超高劑量率FFF模式下中子累積劑量和持續(xù)時間,及其在機房的分布規(guī)律,為臨床使用提供參考。方法機房內(nèi)選取加速器治療高度等中心技師擺位處、治療床遠(yuǎn)端、迷路近端和防護門內(nèi)側(cè)4個位置,設(shè)置5cm×5cm、10cm×10cm和30cm×30cm 3種射野面積,出束劑量分別為500、1 000和2 000 MU,等中心位置放置30cm厚度固體水模體模擬患者身體,在10 MV X射線600 MU/min常規(guī)劑量率FF模式和2 400 MU/min超高劑量率FFF模式下,測量中子的累積劑量及消退時間,同時在機房外選取防護門外、操作室和主防護墻中心3個位置進(jìn)行測量。結(jié)果中子累積劑量與射野面積大小呈反比;距離靶中心越近,中子累積劑量越大,機房內(nèi)中子累積最大位置為治療床遠(yuǎn)端;中子累積劑量FF模式高于FFF模式,差異有統(tǒng)計學(xué)意義,P0.05。中子消退時間與出束劑量成正比;相同條件FFF模式下的中子消退時間小于FF模式,距離中心靶位點越遠(yuǎn)中子消退時間越快。結(jié)論加速器移除均整器后中子累積劑量及持續(xù)時間明顯下降,有益于患者及工作人員的輻射防護;現(xiàn)有加速器機房防中子設(shè)計同樣適用于FFF模式加速器。
[Abstract]:Objective intensity modulated radiotherapy (IMRT) has greatly improved the quality of radiotherapy plan, but the relative conformal radiotherapy has also increased the dose and time of irradiation. Removing the whole attening filter free FFFs can reduce the irradiation time while maintaining the planned quality. In this study, we measured and analyzed the neutron cumulative dose and duration of conventional dose rate in Varian TrueBeam accelerator in FFFF mode and FFF mode, and their distribution in computer room, which provided reference for clinical use. Methods in the computer room, four positions were selected as the center technician of accelerator treatment height, the distal end of the bed, the proximal end of labyrinth and the medial side of the protective door. The three kinds of field areas, 5cm 脳 5 cm ~ (-1) 10 cm 脳 10cm and 30cm 脳 30cm, were set up. The outbeam doses were 500 and 2 000 MUs, respectively. The 30cm thickness solid water motifs were placed in the isocentric position to simulate the patient's body. In the 10MV X ray 600MU / min conventional dose rate FF mode and the 2 400 MUP / min ultrahigh dose rate FFF mode, there was no significant difference between the two models. The cumulative dose and extinction time of neutrons were measured. At the same time, three positions were selected outside the machine room, such as the protective door, the operation room and the center of the main protective wall. Results the neutron accumulative dose was inversely proportional to the size of the field area, the closer to the target center, the greater the neutron cumulative dose, the greater the maximum position of neutron accumulation in the machine room was the distal end of the therapeutic bed, and the FF mode of neutron cumulative dose was higher than the FFF mode. The difference was statistically significant (P 0.05). The neutron extinction time is proportional to the beam dose, and the time of neutron extinction is smaller than that of FF model under the same condition, and the farther away from the central target, the faster the neutron extinction time. Conclusion the neutron accumulative dose and duration after the removal of the accelerator are obviously decreased, which is beneficial to the radiation protection of patients and staff, and the existing neutron protection design of the accelerator room is also suitable for the FFF mode accelerator.
【作者單位】: 鄭州大學(xué)附屬腫瘤醫(yī)院放療科;中山大學(xué)腫瘤防治中心放療科·華南腫瘤學(xué)國家重點實驗室·腫瘤醫(yī)學(xué)協(xié)同創(chuàng)新中心;河南省職業(yè)病防治研究院放射衛(wèi)生科;
【分類號】:R730.55
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