Teaching and learning threshold concepts in radiation physics for professional practice

Abstract

Radiation therapy has undergone significant changes with regard to new medical imaging technologies, including computerised tomography (CT) and magnetic resonance imaging (MRI). Practitioners now have access to technologies that provide anatomical information in an infinite selection of views. Earlier advances in three-dimensional conformal radiation therapy (3D-CRT) allowed for the site of treatment to be accurately located. Intensity modulated radiotherapy (IMRT) enabled practitioners to accurately focus the ionising radiation beam, while modulating the intensity of the dose being administered. Currently, using image-guided radiotherapy (IGRT) methods, radiation therapists can track the effectiveness of treatment in real-time to provide better protection for the organs and tissue that are not targeted for treatment. The changes described above have fundamentally changed radiation therapy practice, and thus have implications for the training of radiation therapists. This thesis argues that without a deep understanding of the science underpinning the advancements in radiation therapy techniques, practitioners will be unlikely to achieve the necessary level of accuracy and consistency in treatment. Radiation physics concepts, such as sources and types of ionising radiation, ionisation, the isocentre and the Inverse Square Law underpin competent and safe practice. Threshold concepts, such as those listed above, have been identified as concepts that pose difficulty to students due to its complexity and the increased levels of cognitive challenge required to master a threshold concept. In applied disciplines, such as radiation physics, threshold concepts are strongly associated with competent practice. This study focused on the first year radiation physics curriculum and addressed the overarching research question: What is the relationship between threshold concepts in the radiation physics curriculum and radiation therapy practice? The study was guided by a translation device that combined two conceptual frameworks namely the Threshold Concept Framework and Legitimation Code Theory’s (LCT) Semantics dimension. LCT is a knowledge base theory that explains the complexity of knowledge structures. The Semantics dimension provided an explanation of the difficulty of concepts and proposed five pedagogies for the cumulative learning of complex concepts. A case study research design and methodology guided the research process. Data for the study comprised curriculum documents, and semi structured focus group and individual interviews with students, academic staff and clinical educators. The data were analysed using a translation device to show the semantic profile of curriculum documents, pedagogies and participants’ different understandings of the threshold concepts in radiation physics. The study found that threshold concepts in radiation physics underpin competent and safe practice. An external language of description was developed to identify the characteristics of threshold concepts. A virtual clinical environment was proposed as one of the pedagogies to aid mastering of threshold concepts through visualisation of the unseen by facilitating students’ understanding of threshold concepts for competent and safe radiation therapy practice. The study showed that students’ mastery of threshold concepts in radiation physics is critical for practice.