The early detection of breast cancer using mammography relies on optimal positioning of the craniocaudal (CC) and the mediolateral oblique (MLO) views to include as much of the breast as possible; and subsequent assessment of image quality using valid image evaluation systems (IES). This review highlights the key positioning literature and IES; and discusses the fundamental issues impacting best practice positioning including body habitus, specifically the thorax. Due to variations in the shape of the thorax and the impact of the linear image receptor (IR) on positioning, the inclusion of all breast tissue may not be possible. Further, body habitus, including the shape of the thorax, is not reflected in any IES. Although used worldwide the lack of consideration given to individual body habitus is a key deficit of all IES. There is no mention in the literature of how to manage thoracic variability to maximise breast tissue inclusion outside of the selection of the angle of the IR in the MLO view. No known studies have investigated the degree to which the oppositional curvilinear thorax and the linear mammography IR impact the amount of breast able to be included in the image. Both issues support the need for future research.