论文标题
美元
$^{18}$F-PSMA-1007 salivary gland dosimetry: Comparison between different methods for dose calculation and assessment of inter- and intra-patient variability
论文作者
论文摘要
唾液腺（SG）的剂量法通常使用简化的计算方法和近似几何形状实现。我们的目的是比较18F-PSMA-1007注射后的不同剂量测定方法来计算SG吸收剂量（AD），并评估患者和单个SG成分的AD变化。在18F-PSMA-1007注射后，五名前列腺癌复发的患者接受了头部和颈部的PET/CT收购。将腮腺和下颌腺在CT上进行分割，以得出SGS体积和质量，而宠物则用于得出时间整合活性系数。使用以下方法计算了单个SG组件或总SG（TSG）的平均AD：i）使用Gate/Geant4进行直接的Monte Carlo（MC）模拟； ii）Olinda/EXM 2.1的球形模型（SM），采用患者特异性或标准的ICRP89器官质量（SMSTD）； iii）椭圆形模型（EM）； iv）使用来自Olinda/Exm 2.1的器官S因子和Opendose协作的MIRD方法，有或没有源自SG之外的交叉照射的贡献。计算了SG成分（Δmax）和患者（Δmax）的最大AD百分比差异。与MC相比，通过所有方法（-14.5％和-30.4％之间的平均相对差异）显着低估了单个SG组件的AD。使用MC，SM和EM，Δmax永远不会低于25％（高达113％）。使用SMSTD获得了高达702％的Δmax。关于TSG，仅当从身体的其余部分或头部其余部分交叉照射时才能获得MC的10％以内的结果。 Δmax的患者在58％至78％之间。鉴于其较大的患者内变异性，应始终考虑特定的单个SG组件质量。
Dosimetry of salivary glands (SGs) is usually implemented using simplified calculation approaches and approximated geometries. Our aims were to compare different dosimetry methods to calculate SGs absorbed doses (ADs) following 18F-PSMA-1007 injection, and to assess the AD variation across patients and single SG components. Five patients with prostate cancer recurrence underwent PET/CT acquisitions of the head and neck, 0.5, 2 and 4 hours after 18F-PSMA-1007 injection. Parotid and submandibular glands were segmented on CT to derive SGs volumes and masses, while PETs were used to derive Time-Integrated Activity Coefficients. Average ADs to single SG components or total SG (tSG) were calculated with the following methods: i) direct Monte Carlo (MC) simulation with GATE/GEANT4; ii) spherical model (SM) of OLINDA/EXM 2.1, adopting either patient-specific or standard ICRP89 organ masses (SMstd); iii) ellipsoidal model (EM); iv) MIRD approach with organ S-factors from OLINDA/EXM 2.1 and OpenDose collaboration, with or without contribution from cross irradiation originating outside the SGs. The maximum percent AD difference across SG components (δmax) and across patients (Δmax) were calculated. Compared to MC, ADs to single SG components were significantly underestimated by all methods (average relative differences between -14.5% and -30.4%). Using MC, SM and EM, δmax were never below 25% (up to 113%). δmax up to 702% were obtained with SMstd. Concerning tSG, results within 10% of the MC were obtained only if cross irradiation from the remainder of the body or from the remainder of the head was accounted for. The Δmax ranged between 58% and 78% across patients. Specific masses of single SG components should always be considered given their large intra- and inter- patient variability.
