Implementation and workflow for PET monitoring of therapeutic ion irradiation: a comparison of in-beam, in-room, and off-line techniques

Abstract

An independent assessment of the dose delivery in ion therapy can be performed using positron emission tomography (PET). For that a distribution of positron emitters which appear as the result of interaction between ions of the therapeutic beam and the irradiated tissue is measured during or after the irradiation. Three concepts for PET monitoring implemented in various therapy facilities are considered in this paper. The in-beam PET concept relies on the PET measurement performed simultaneously to the irradiation by means of a PET scanner which is completely integrated into the irradiation site. The in-room PET concept allows measurement immediately after irradiation by a standalone PET scanner which is installed very close to the irradiation site. In the off-line PET scenario the measurement is performed by means of a standalone PET/CT scanner 10-30 min after the irradiation. These three concepts were evaluated according to image quality criteria, integration costs, and their influence onto the workflow of radiotherapy. In-beam PET showed the best performance. However, the integration costs were estimated as very high for this modality. Moreover, the performance of in-beam PET depends heavily on type and duty cycle of the accelerator. The in-room PET is proposed for planned therapy facilities as a good compromise between the quality of measured data and integration efforts. For facilities which are close to the nuclear medicine departments off-line PET can be suggested under several circumstances.

Clinical implementation and range evaluation of in vivo PET dosimetry for particle irradiation in patients with primary glioma

“…Off-line PET delivers very promising results using only one radiation field and a minimum delay, it is the method of choice when the PET/CTscanner is already installed and a practical solution is sought, although the optimum compromise in terms of imaging performances and cost-effectiveness seems to be the in-room scanner nowadays [14].…”

Evaluation of resistive-plate-chamber-based TOF-PET applied to in-beam particle therapy monitoring

“…When using in-beam PET, the reconstructed images are closer to the original β + distribution than the images obtained from in-room and off-line acquisitions since physical decay and wash-out are minimized. In Shakirin et al (2011) it is demonstrated that in-beam PET is the best method in terms of count rate.…”

First full-beam PET acquisitions in proton therapy with a modular dual-head dedicated system

“…A systematic comparison of these modalities shows that off-beam monitoring is not recommended, except for some specific tumours or unless the PET system is placed in the same treatment room (i.e., in-room) (Shakirin et al 2011).…”

“…Therefore, the effect is either a broadening of the β + activity spatial distribution or a paralysis of the acquisition system due to excessive random coincidence data that do not carry any information regarding the β + distribution (Enghardt et al 1999, Parodi et al 2002. Thus, state of the art in-beam PET solutions are only applicable to synchrotron-based facilities and their effectiveness is limited by the accelerator duty cycle (Nishikido et al 2010, Tashima et al 2012, Nishio et al 2010, Shakirin et al 2011.…”