Imaging the attenuation coefficients of magnetically constrained positron beams in matter

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• 作者：Charles C. Watson ^{charles.c.watson@siemens.com" class="auth_mail" title="E-mail the corresponding author}
• 关键词：PET ; positron emission tomography ; PAT ; positron attenuation tomography ; MRI ; magnetic resonance imaging ; CT ; computed tomography ; LAC ; linear attenuation coefficient ; FOV ; field of view ; PS ; polystyrene ; PE ; polyethylene ; FWHM ; full width at half maximum ; BSC ; beam softening correction ; 3D ; three-dimensional
• 刊名：Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms
• 出版年：2016
• 出版时间：15 September 2016
• 年：2016
• 卷：383
• 期：Complete
• 页码：234-244
• 全文大小：2930 K

文摘

This paper describes a method for tomographically imaging the linear attenuation coefficients (LACs) of positron beams in heterogeneous materials. A β⁺${\beta }^{+}$ ray emitter such as ⁶⁸Ga, placed in a uniform 3T static magnetic field, generates a well-defined positron beam that maintains its spatial coherence over an attenuation of more than 10^-3${10}^{-3}$ while signaling its intensity via the annihilation radiation it generates. A positron emission tomography (PET) system embedded in the magnetic field measures the positron–electron annihilation distribution within objects illuminated by the beam. It’s shown that this image can be decomposed into maps of the positron beam’s flux and its material-dependent LACs without need for auxiliary measurements or transmission of the beam completely through the object. The initial implementation employs a hybrid PET/magnetic resonance imaging (MRI) scanner developed for medical applications. Mass thicknesses up to 0.55 g/cm² at a spatial resolution of a few millimeters have been imaged.