Double-Field Hadrontherapy Treatment Monitoring With the INSIDE In-Beam PET Scanner: Proof of Concept

Abstract

Positron Emission Tomography (PET) is a well established imaging technique for range monitoring in hadrontherapy. Multiple fields delivery is a standard protocol in treatments, but because of washout and residual activity background from previous irradiation plans, to this date a quantitative verification of the particle range for each beam field is still an open issue. In this paper, the proof of concept of a new method to evaluate with a PET detector the activity range of the second field of a treatment is discussed. A proton and a carbon ion treatment plan with two parallelopposed beam fields were delivered on PMMA phantoms. In both cases, the second beam field was extracted from the first irradiation residual activity and compared to a reference image, obtained from the experimental acquisition of the second field alone. Results demonstrate good agreement between the extracted second field and the reference image, with average difference in the activity range along the preferential direction of the beam less than 0.5 mm for protons, and 1.5 mm for carbon ions. Without taking into account any preferential direction, differences within 0.5 mm were found for both cases. The method will soon be tested with non-homogeneous phantoms and, successively, also with in-vivo clinical data.

Detection of Interfractional Morphological Changes in Proton Therapy: A Simulation and In Vivo Study With the INSIDE In-Beam PET

“…The MC simulation was developed in FLUKA, including all the characteristics and calibration of the INSIDE in-beam PET detector and all the features of the CNAO beam line and pencil beam scanning temporal structure [31,32]. The MC simulation was previously validated on phantoms with both monoenergetic beams [33] and treatment plans, for either protons [34,35] or carbon ions [36]. Furthermore, it was validated with the clinical measurement of the first patient ever monitored with the INSIDE in-beam PET scanner, where its agreement with the experimental measurements was found to have an uncertainty compatible with the agreement found when comparing two consecutive days measurements [37].…”

Challenges in Monte Carlo Simulations as Clinical and Research Tool in Particle Therapy: A Review

“…Recently, new cross section data for 10 C, 11 C, and O 15 , very useful for future benchmark studies, were published by different groups [133,136], where the work of Horst et al [136] concerns also data relative to C-C and C-O collisions. Since recently, the use of PET monitoring technique is under consideration also in the case of ion therapy [137]. The prediction capability for shortlived β + emitters remains subject to uncertainties.…”

Capability of MLEM and OE to Detect Range Shifts With a Compton Camera in Particle Therapy

“…Compared to the former method, this technique is more appropriate for complex treatment plans and can accommodate data obtained from various fields. For this article, the method proposed in [36] was slightly modified to account for truncation artifacts in z-direction. First, the image was filtered with a 3 × 3 × 3 mm 3 Gaussian filter.…”

“…Next, the images were summed up in z-direction. Further filtering and contour extraction was performed as described in [36]. The contours from two images were then compared voxel-wise within the Bragg-peak region.…”