Dimofte Andreea, Finlay Jarod, Ong Yi Hong, Zhu Timothy C
Departments of Radiation Oncology, University of Pennsylvania, Philadelphia, PA.
Proc SPIE Int Soc Opt Eng. 2018 Mar;10476. doi: 10.1117/12.2288561.
Successful outcome of Photodynamic therapy (PDT) depends on accurate delivery of prescribed light dose. A quality assurance program is necessary to ensure that light dosimetry is correctly measured. We have instituted a QA program that include examination of long term calibration uncertainty of isotropic detectors for light fluence rate, power meter head intercomparison for laser power, stability of the light-emitting diode (LED) light source integrating sphere as a light fluence standard, laser output and calibration of in-vivo reflective fluorescence and absorption spectrometers. We examined the long term calibration uncertainty of isotropic detector sensitivity, defined as fluence rate per voltage. We calibrate the detector using the known calibrated light fluence rate of the LED light source built into an internally baffled 4″ integrating sphere. LED light sources were examined using a 1mm diameter isotropic detector calibrated in a collimated beam. Wavelengths varying from 632nm to 690nm were used. The internal LED method gives an overall calibration accuracy of ±4%. Intercomparison among power meters was performed to determine the consistency of laser power and light fluence rate measured among different power meters. Power and fluence readings were measured and compared among detectors. A comparison of power and fluence reading among several power heads shows long term consistency for power and light fluence rate calibration to within 3% regardless of wavelength. The standard LED light source is used to calibrate the transmission difference between different channels for the diffuse reflective absorption and fluorescence contact probe as well as isotropic detectors used in PDT dose dosimeter.
光动力疗法（PDT）的成功结果取决于规定光剂量的准确输送。质量保证计划对于确保光剂量测定的正确测量是必要的。我们制定了一个质量保证计划，包括检查用于光通量率的各向同性探测器的长期校准不确定度、激光功率的功率计探头相互比较、作为光通量标准的发光二极管（LED）光源积分球的稳定性、激光输出以及体内反射荧光和吸收光谱仪的校准。我们检查了各向同性探测器灵敏度的长期校准不确定度，其定义为每电压的通量率。我们使用内置在内部有挡板的4英寸积分球中的LED光源的已知校准光通量率来校准探测器。使用在准直光束中校准的1毫米直径各向同性探测器检查LED光源。使用了从632纳米到690纳米变化的波长。内部LED方法给出的总体校准精度为±4%。进行功率计之间的相互比较，以确定不同功率计测量的激光功率和光通量率的一致性。在探测器之间测量并比较功率和通量读数。几个功率探头之间的功率和通量读数比较表明，无论波长如何，功率和光通量率校准的长期一致性在3%以内。标准LED光源用于校准用于漫反射吸收和荧光接触探头以及PDT剂量计中使用的各向同性探测器的不同通道之间的传输差异。
