Vision 20/20: Positron emission tomography in radiation therapy planning, delivery, and monitoring

Abstract

Positron emission tomography (PET) is increasingly considered as an effective imaging method to support several stages of radiation therapy. The combined usage of functional and morphological imaging in state-of-the-art PET/CT scanners is rapidly emerging to support the treatment planning process in terms of improved tumor delineation, and to assess the tumor response in follow-up investigations after or even during the course of fractionated therapy. Moreover, active research is being pursued on new tracers capable of providing different insights into tumor function, in order to identify areas of the planning volume which may require additional dosage for improved probability of tumor control. In this respect, major progresses in the next years will likely concern the development and clinical investigation of novel tracers and image processing techniques for reliable thresholding and segmentation, of treatment planning and beam delivery approaches integrating the PET imaging information, as well as improved multimodal clinical instrumentation such as PET/MR. But especially in the rapidly emerging case of ion beam therapy, the usage of PET is not only limited to the imaging of external tracers injected to the patient. In fact, a minor amount of positron emitters is formed in nuclear fragmentation reactions between the impinging ions and the tissue, bearing useful information for confirmation of the delivered treatment during or after therapeutic irradiation. Different implementations of unconventional PET imaging for therapy monitoring are currently being investigated clinically, and major ongoing research aims at new dedicated detector technologies and at challenging applications such as real-time imaging and time-resolved in vivo verification of motion compensated beam delivery. This paper provides an overview of the different areas of application of PET in radiation oncology and discusses the most promising perspectives in the years to come for radiation therapy planning, delivery, and monitoring.

Design of a new tracking device for on-line beam range monitor in carbon therapy

“…New dose monitoring devices need to be introduced into clinical use, to fully exploit the capability of particle therapy to deliver the dose as planned over the cancer position [2,3]. Currently beam monitors are used to control the dose application during the patient treatment while some attempts of using PET scans just after the treatment are reported in literature (for a review see [4]).…”

Ionizing radiation‐induced acoustics for radiotherapy and diagnostic radiology applications

“…To this end, detection of secondary emissions for in vivo verification of the beam range is a very active area of research worldwide, aiming to reduce the above mentioned range uncertainties for safer delivery of more conformal treatments in the clinical practice. So far most of the studies already reaching clinical testing have been focused on bulky instrumentation aiming to detect primarily photon radiation resulting from nuclear‐based interactions, so called positron emission tomography and prompt gamma imaging …”

“…So far most of the studies already reaching clinical testing have been focused on bulky instrumentation aiming to detect primarily photon radiation resulting from nuclear-based interactions, so called positron emission tomography and prompt gamma imaging. 54,55 On the other hand, interest was recently renewed in the exploitation of acoustic emissions, which are intrinsically related to the energy deposition process. In contrast to the already mentioned earlier attempts in the 1990s, 29 the trend of modern technologies with superposition of narrow pencil beams (so called pencil beam scanning, 56 ), even intrinsically pulsed in the case of latest-generation compact proton therapy accelerators, 57 inherently favors generation of acoustic emissions according to Eqs.…”

Radiation hardness of dsipm sensors in a proton therapy radiation environment

“…The first approach to have been developed is positron emission tomography (PET) of the positron emitting nuclides produced by the proton beam in the patient; the second, more recently investigated, class of techniques makes use of prompt gamma rays, which are emitted on a subnanosecond timescale in the decay of excited atomic nuclei. For an overview of this subject, especially related to proton therapy, we refer to some recent reviews [2]- [8].…”