用双探头符合探测计算FDG图像像素的放射性浓度

Determination of pixel radioactive concentration in dual head coincidence ^(18) F FDG PET imaging

目的 探讨由双探头SPECT符合探测 (DHC)图像像素计数值确定体内放射性浓度的方法。方法 利用模型确定定标系数 ,将图像像素计数转换成放射性浓度。在模型中注入脱氧葡萄糖 (FDG)水溶液 ,对 18种活度 (15 .15～ 2 0 4 .33MBq)的模型分别进行扫描。结果 ①由探测单计数率确定定标系数 ,其关系满足 1个四阶多项式。②由图像像素的累积计数、采集时间及定标系数确定像素的放射性浓度 ,其关系可以一经验公式表示。结论 建立了计算病灶放射性浓度的方法 。

Objective To determine the pixel radioactive concentration using the pixel counts on dual head coincidence detection (DHC) FDG images. Methods To convert the count rate per pixel into radioactivity concentration, the calibration factor (CF) was determined by phantom studies. The DHC equipment was produced by GE Hawkeye. The phantom was Toshiba AZ 618 SPECT phantom. Emission scanning was performed for 18 times with the radioactivity escalating stepwise at a range of 15.15～204.33 MBq. Results ①The CF depended on the detected single count rate, and the relationship was expressed with a biquadratic polynomial. ②The radioactive concentration of lesion pixel depended on the pixel counts, the acquisition time and CF, and the relationship was expressed with an empirical formula. Conclusion A method for calculating the pixel radioactive concentration is developed and it would lay the foundation for quantitative analysis of DHC images.