Mínguez P, Gómez de Iturriaga A, Fernández I L, Rodeño E
Unidad de Protección Radiológica y Radiofísica, Hospital Universitario Cruces-Gurutzeta, Barakaldo, España.
Servicio de Oncología Radioterápica, Hospital Universitario Cruces-Gurutzeta, Barakaldo, España.
Rev Esp Med Nucl Imagen Mol (Engl Ed). 2018 Jan-Feb;37(1):20-27. doi: 10.1016/j.remn.2017.04.009. Epub 2017 Jun 20.
To obtain the necessary acquisition and calibration parameters in order to evaluate the possibility of detecting and quantifying Ra uptake in bone metastases of patients treated for castration resistant prostate carcinoma. Furthermore, in the cases in which the activity can be quantified, to determine the absorbed dose.
Acquisitions from a Petri dish filled with Ra were performed in the gamma camera. Monte Carlo simulations were also performed to study the partial volume effect. Formulae to obtain the detection and quantification limits of Ra uptake were applied to planar images of two patients 7 days post-administration of 55kBq/kg of Ra. In order to locate the lesions in advance, whole-body scans and SPECT/CT images were acquired after injecting Tc-HDP.
The optimal energy window was found to be at 82keV with a medium-energy collimator MEGP. Of the lesions found in the patients, only those that had been detected in both the AP and PA projections could be quantified. These lesions were those which had shown a higher Tc-HDP uptake. The estimated values of absorbed doses ranged between 0.7Gy and 7.8Gy.
Of the lesions that can be detected, it is not possible to quantify the activity uptake in some of them, which means that the absorbed dose cannot be determined either. This does not mean that the absorbed dose in these lesions can be regarded as negligible.
获取必要的采集和校准参数，以评估检测和量化接受去势抵抗性前列腺癌治疗患者骨转移灶中镭摄取情况的可能性。此外，在能够对活性进行量化的情况下，确定吸收剂量。
在γ相机中对装有镭的培养皿进行采集。还进行了蒙特卡罗模拟以研究部分容积效应。将用于获取镭摄取检测和定量限的公式应用于两名患者在给予55kBq/kg镭后7天的平面图像。为了预先定位病变，在注射锝-亚甲基二膦酸盐（Tc-HDP）后进行全身扫描和单光子发射计算机断层扫描/计算机断层扫描（SPECT/CT）图像采集。
发现使用中能准直器MEGP时，最佳能量窗口为82keV。在患者中发现的病变中，只有那些在前后位（AP）和后前位（PA）投影中均被检测到的病变才能被量化。这些病变是那些显示出较高Tc-HDP摄取的病变。估计的吸收剂量范围在0.7Gy至7.8Gy之间。
在可检测到的病变中，其中一些病变的活性摄取无法量化，这意味着吸收剂量也无法确定。但这并不意味着这些病变中的吸收剂量可被视为可忽略不计。
