Two-orthogonal-view method for quantification of rad dose to neck lesions in thyroid cancer therapy patients.
Two-orthogonal-view method for quantification of rad dose to neck lesions in thyroid cancer therapy patients.
复制标题
用于量化甲状腺癌治疗患者颈部病变的 rad 剂量的两个正交视图方法。
DOI：
10.1118/1.595096
复制
发表时间：
1982
期刊：
影响因子：
3.8
通讯作者：
Beierwaltes,WH
中科院分区：
文献类型：
--
作者：
Koral,KF;Adler,RS;Carey,JE;Kline,RC;Beierwaltes,WH
本文介绍了甲状腺癌131I治疗后颈部转移灶放射剂量测定的新技术。该技术利用安装在ANG相机上的高能针孔准直器，该相机可以旋转，以记录相对于患者的已知位置的侧视和前视。提出了一种利用两个视角的背投射射线之间的最近距离来确定三维病变位置的新算法。此外，还给出了由两个针孔投影估算椭球体体积的新公式。该方法利用计算机边缘检测程序来描绘投影的病变边界。输出要么是一个视图的平均估计，要么是从两个视图得出的更明确的上限。计数的摄取是从每天的正前方图像中确定的，这些图像经过了针孔效率的校正，随着距离的增加而衰减。这种摄取通过使用空气中的校准曲线被转换成微居里。使用计算的病变深度和假设的衰减系数来应用衰减校正。剂量率是使用标准假设计算的，并在最初几天率达到峰值时以图形形式积分，并利用单一衰减指数拟合到其余几天的数据。说明性的患者数据，其中计算了三个颈部病变的剂量后，给药175mCI的131I。这些剂量包括2400拉德的下限和5300拉德和9500拉德的估计。
A new technique is described for the determination of the dose in rad to metastatic lesions in the neck following administration of131I for the treatment of thyroid carcinoma. The technique utilizes a high‐energy pinhole collimator mounted on an Anger camera which can be rotated to record lateral and anterior views from known positions relative to the patient. A new algorithm is derived for the determination of lesion location in three dimensions, utilizing the distance of closest approach between back‐projected rays from the two views. In addition, a new derivation is presented for the estimation of ellipsoid volume from two pinhole projections. The method makes use of a computer edge detection program to delineate the projected lesion boundaries. The output is either a mean estimate from one view or a more definitive upper bound derived from both views. The uptake in counts is determined from daily anterior images which are corrected for pinhole efficiency falloff with distance. This uptake is converted into microcuries by use of an in‐air calibration curve. An attenuation correction is applied using the calculated lesion depth and an assumed attenuation coefficient. The dose rate is calculated using standard assumptions and is integrated graphically over the first few days when the rate peaks and by utilizing a single‐decaying‐exponential fit to the data over the remaining days. Illustrative patient data are presented in which doses are calculated for three neck lesions after an administration of 175 mCi of131I. These doses include a lower bound of 2400 rad and estimates of 5300 and 9500 rad.