Alessio Adam M, Kinahan Paul E, Manchanda Vivek, Ghioni Victor, Aldape Lisa, Parisi Marguerite T
Department of Radiology, University of Washington, Old Fisheries Center, Seattle, Washington 98195-7987, USA.
J Nucl Med. 2009 Oct;50(10):1570-7. doi: 10.2967/jnumed.109.065912.
Adult PET/CT acquisition protocols need to be modified for pediatric imaging to minimize the radiation dose while maintaining diagnostic utility. We developed pediatric PET/CT acquisition protocols customized to patient weight and estimated the dosimetry and cancer risk of these low-dose protocols to communicate basic imaging risks.
Protocols were developed for whole-body (18)F-FDG imaging of patients in PET mode with a weight-based injected activity (5.3 MBq/kg) and acquisition times (3-5 min/field of view) and for CT for attenuation correction and localization with a weight-based tube current ranging from 10 to 40 mAs. Patients were categorized on the basis of the Broselow-Luten color-coded weight scale. Dosimetry and radiation-induced cancer risk for the PET and CT acquisition in each category were derived from mean patient sizes and the interpolation of factors from accepted patient models.
Whole-body pediatric PET/CT protocols require the customization of PET-acquisition settings and task-specific selection of CT technique. The proposed weight-based protocols result in an approximate effective dose ranging from 8.0 mSv for a 9-kg patient up to 13.5 mSv for a 63-kg patient. The radiation dose from the proposed protocols is 20%-50% (depending on patient weight), the dose from PET/CT protocols that use a fixed CT technique of 120 mAs and 120 kVp. The approximate, conservative estimate of additional lifetime attributable risk (LAR) of cancer incidence for females using the proposed protocols was approximately 3 in 1,000, with a variation of 18% across patient categories. For males, the additional LAR of cancer incidence was approximately 2 in 1,000, with a variation of 16% across categories.
Low-dose PET/CT protocols for 11 patient weight categories were developed. The proposed protocols offer an initial set of acquisition parameters for pediatric PET/CT. The use of multiple categories allows for the continued refinement of dose-reduction parameters to minimize dose while maintaining image quality across the range of pediatric patient sizes.
成人PET/CT采集协议需针对儿科成像进行修改，以在保持诊断效用的同时将辐射剂量降至最低。我们制定了根据患者体重定制的儿科PET/CT采集协议，并估算了这些低剂量协议的剂量学和癌症风险，以传达基本的成像风险。
制定了PET模式下患者全身（18）F-FDG成像的协议，采用基于体重的注射活度（5.3 MBq/kg）和采集时间（3 - 5分钟/视野），以及用于衰减校正和定位的CT协议，其基于体重的管电流范围为10至40 mAs。患者根据布罗泽洛 - 卢滕颜色编码体重秤进行分类。每个类别中PET和CT采集的剂量学和辐射诱发癌症风险来自平均患者体型以及从公认患者模型中插值得到的因子。
全身儿科PET/CT协议需要定制PET采集设置并根据任务选择特定的CT技术。所提出的基于体重的协议导致有效剂量范围约为：9千克患者为8.0 mSv，63千克患者为13.5 mSv。所提出协议的辐射剂量比使用120 mAs和120 kVp固定CT技术的PET/CT协议低20% - 50%（取决于患者体重）。使用所提出协议对女性癌症发病率额外终身归因风险（LAR）的大致保守估计约为千分之三，不同患者类别间变化为18%。对于男性，癌症发病率的额外LAR约为千分之二，不同类别间变化为16%。
针对11个患者体重类别制定了低剂量PET/CT协议。所提出的协议提供了一组儿科PET/CT的初始采集参数。使用多个类别允许持续优化剂量降低参数，以在保持儿科患者体型范围内图像质量的同时将剂量降至最低。
