【摘要】：重離子治癌以其具有能量損失集中于射程末端的物理學(xué)特性以及高的相對生物學(xué)效應(yīng)的優(yōu)點(diǎn),被視為最理想的放射治癌方法。中國科學(xué)院近代物理研究所基于蘭州重離子研究裝置(HIRFL)自主設(shè)計(jì)重離子治癌裝置,已完成淺層和深層治癌臨床試驗(yàn),成為世界上第四個(gè)進(jìn)行了重離子臨床試驗(yàn)的國家。重離子臨床照射治療時(shí),為使腫瘤受到均勻且足夠劑量的照射,而周圍組織盡可能少受損傷,保障醫(yī)療的安全性與可靠性,需要對輻照劑量進(jìn)行實(shí)時(shí)測量與監(jiān)控。深層治癌中束流強(qiáng)度監(jiān)測系統(tǒng)的劑量監(jiān)測探測器采用積分電離室,輸出的電流信號(hào)正比于束流強(qiáng)度。深層治癌中照射束流的強(qiáng)度為0~109pps,電離室輸出電流信號(hào)峰值小于1μA,屬于小信號(hào)。為了測量該電流信號(hào),本論文設(shè)計(jì)了一種新的電流頻率轉(zhuǎn)換電路。在電路設(shè)計(jì)過程中,分析討論了各種弱電流測量方案的優(yōu)點(diǎn)與不足之處,最終選擇了可變閾值電流積分泄放式電流頻率轉(zhuǎn)換的方案。本論文對所設(shè)計(jì)電路的硬件及邏輯部分進(jìn)行詳細(xì)介紹,并給出論文完成過程中設(shè)計(jì)的兩版電路調(diào)試及測試結(jié)果。本論文設(shè)計(jì)了兩種精度的電流頻率轉(zhuǎn)換電路:10pC/pulse和0.5pC/pulse。10pC/pulse電路能夠完成雙極性電流的測量,在輸入電流極性改變時(shí)切換簡單。負(fù)電流測量范圍為0.1nA~70μA,整個(gè)范圍內(nèi)線性度好于0.46434%;正電流測量范圍為1nA~60μA,整個(gè)范圍內(nèi)線性度好于0.34288%。0.5pC/pulse電路測量范圍為0.01nA~500nA,整個(gè)范圍內(nèi)線性度好于0.04168%,完全滿足在實(shí)際應(yīng)用中的要求。論文最終對電流頻率轉(zhuǎn)換電路的結(jié)構(gòu)功能進(jìn)行總結(jié),并對下一步工作的方向和電路改進(jìn)進(jìn)行展望。
[Abstract]:Heavy ion therapy is regarded as the most ideal method for cancer treatment because of its physical characteristics of energy loss at the end of range and its high relative biological effect. The Institute of Modern Physics of the Chinese Academy of Sciences has independently designed a heavy ion cancer treatment device based on Lanzhou heavy Ion Research Facility (HIRFL). It has completed the shallow and deep cancer treatment clinical trials and has become the fourth country in the world to conduct heavy ion clinical trials. In order to make the tumor receive a uniform and sufficient dose of irradiation, and the surrounding tissue be damaged as little as possible, to ensure the safety and reliability of medical treatment, it is necessary to measure and monitor the radiation dose in real time. In the deep cancer treatment, the dose detector of the beam intensity monitoring system adopts an integrated ionization chamber, and the output current signal is proportional to the beam intensity. In deep cancer treatment, the intensity of irradiating beam is 0 ~ 109pps, and the peak output current signal of ionization chamber is less than 1 渭 A, which is a small signal. In order to measure the current signal, a new current frequency conversion circuit is designed in this paper. In the process of circuit design, the advantages and disadvantages of various weak current measurement schemes are analyzed and discussed. Finally, the variable threshold current integral discharge current frequency conversion scheme is selected. In this paper, the hardware and logic of the designed circuit are introduced in detail, and the debugging and testing results of the two sets of circuits designed during the completion of the thesis are given. In this paper, two kinds of precision current-frequency conversion circuits: 10 PC / pulse and 0.5pC/pulse.10pC/pulse circuits are designed to measure the bipolar current, which is simple to switch when the polarity of input current changes. The measurement range of negative current is 0.1nA~70 渭 A, the linearity of the whole range is better than that of 0.46434, the range of positive current measurement is 1nA~60 渭 A, the linearity of the whole range is better than that of 0.34288%.0.5pC/pulse circuit, and the linearity of the whole range is better than 0.04168, which fully meets the requirements of practical application. Finally, the structure and function of current-frequency conversion circuit are summarized, and the future work and circuit improvement are prospected.
【學(xué)位授予單位】：中國科學(xué)院大學(xué)(中國科學(xué)院近代物理研究所)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TM46;O571.6

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