深圳大学学报理工版

通过理论仿真和实验检测结果,分析由医用直线加速器产生的X射线照射铅块所产生的光声信号特性.使用光电二极管搭建一个光电检测电路,检测到医用直线加速器所产生的脉冲X射线的光脉冲宽度约为4 μs.采用K-wave工具包仿真分析脉冲宽度为几个微秒的光脉冲所产生的光声信号.搭建了一个光声信号检测系统,对比分析分别使用Olypus V301商用探头与自制的PZT- 4陶瓷换能器时的检测性能.结果表明,两款探头都检测到了光声信号,V301商用探头检测结果与理论仿真波形一致性较好,但信噪比低,而本研究设计的PZT- 4检测灵敏度高,但检测到的信号波形与理论仿真结果偏差较大.两款探头在检测脉冲宽度为4 μs 的X射线脉冲所产生的声信号时都存在不足,为更好的检测该光声信号,需设计一款中心频率在70 kHz附近、带宽较宽、检测灵敏度较高的探头.

The aim of this paper is to analyze the characteristics of the photo-acoustic(PA)signal, which is induced by irradiating the lead with X-ray from a medical linear accelerator. Related theoretical simulations and experiments are done. A photodiode detection circuit is put up to detect the width of X-ray pulses, which is about 4 μs. The K-wave software is used to simulate and analyze the PA signal generated by X-ray whose pulse width was several microseconds. We also put up a single element photo-acoustic signal acquisition system and carry out the comparative experiments with Olympus V301 commercial probe and the probe designed by the piezoelectric ceramics PZT- 4. Results show that both probes can detect the PA signal. The signal detected by V301 is in good accordance with the simulation signal waveform, but has low signal noise ratio. The probe designed by PZT- 4 has high sensitivity, but the detected signal deviates from the simulation waveform. Both probes have shortcomings in detecting the PA signals generated by X-ray pulse with a pulse width of 4 μs. Both simulation and experiment results indicate that a probe with high sensitivity, wide bandwidth and 70 kHz center frequency should be designed to detect the PA signal without distortion and with higher signal noise ratio.

引言
1 光电检测电路及X光脉冲检测结果
2 理论仿真
3 实验及结果
4 结语

图1 光电检测电路及光电二极管实物图<br/>Fig.1 Photoelectric detection circuit and photo of photodiode

图1 光电检测电路及光电二极管实物图
Fig.1 Photoelectric detection circuit and photo of photodiode

图2 光电二极管检测结果<br/>Fig.2 Detection result of photodiode

图2 光电二极管检测结果
Fig.2 Detection result of photodiode

图3 K-wave初始压力分布<br/>Fig.3 Initial pressure distribution

图3 K-wave初始压力分布
Fig.3 Initial pressure distribution

图4 不同脉宽光源对应产生不同的光声信号<br/>Fig.4 Photo-acoustic(PA)singals generated using lights with different pulse width

图4 不同脉宽光源对应产生不同的光声信号
Fig.4 Photo-acoustic(PA)singals generated using lights with different pulse width

图5 光声信号采集实验系统原理示意框图<br/>Fig.5 The system structure of photoacoustic signal acquisition

图5 光声信号采集实验系统原理示意框图
Fig.5 The system structure of photoacoustic signal acquisition

图6 奥林巴斯V301及其阻抗特性<br/>Fig.6 Olympus transducer V301 and its impedance characteristic

图6 奥林巴斯V301及其阻抗特性
Fig.6 Olympus transducer V301 and its impedance characteristic

图7 PZT- 4陶瓷换能器及其阻抗特性<br/>Fig.7 Ceramic transducer PZT- 4 and its impedance characteristic

图7 PZT- 4陶瓷换能器及其阻抗特性
Fig.7 Ceramic transducer PZT- 4 and its impedance characteristic

图8 Olympus V301换能器接收到的信号及光声信号频谱<br/>Fig.8 The PA signals detected by V301-SU and its frequency spectrum

图8 Olympus V301换能器接收到的信号及光声信号频谱
Fig.8 The PA signals detected by V301-SU and its frequency spectrum

图9 PZT- 4陶瓷封装换能器接收到的信号及光声信号频谱<br/>Fig.9 The PA signals detected by PZT- 4 transducer and the frequency spectrum

图9 PZT- 4陶瓷封装换能器接收到的信号及光声信号频谱
Fig.9 The PA signals detected by PZT- 4 transducer and the frequency spectrum

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备注

引言

1 光电检测电路及X光脉冲检测结果

2 理论仿真

3 实验及结果

4 结语

期刊信息

备注

引言

1 光电检测电路及X光脉冲检测结果

2 理论仿真

3 实验及结果

4 结 语

期刊信息

4 结语