Accurate, robust and harmonized implementation of morpho-functional imaging in treatment planning for personalized radiotherapy

Abstract

In this work we present a methodology able to use harmonized PET/CT imaging in dose painting by number (DPBN) approach by means of a robust and accurate treatment planning system. Image processing and treatment planning were performed by using a Matlab-based platform, called CARMEN, in which a full Monte Carlo simulation is included. Linear programming formulation was developed for a voxel-by-voxel robust optimization and a specific direct aperture optimization was designed for an efficient adaptive radiotherapy implementation. DPBN approach with our methodology was tested to reduce the uncertainties associated with both, the absolute value and the relative value of the information in the functional image. For the same H&N case, a single robust treatment was planned for dose prescription maps corresponding to standardized uptake value distributions from two different image reconstruction protocols: One to fulfill EARL accreditation for harmonization of [18F]FDG PET/CT image, and the other one to use the highest available spatial resolution. Also, a robust treatment was planned to fulfill dose prescription maps corresponding to both approaches, the dose painting by contour based on volumes and our voxel-by-voxel DPBN. Adaptive planning was also carried out to check the suitability of our proposal.Different plans showed robustness to cover a range of scenarios for implementation of harmonizing strategies by using the highest available resolution. Also, robustness associated to discretization level of dose prescription according to the use of contours or numbers was achieved. All plans showed excellent quality index histogram and quality factors below 2%. Efficient solution for adaptive radiotherapy based directly on changes in functional image was obtained. We proved that by using voxel-by-voxel DPBN approach it is possible to overcome typical drawbacks linked to PET/CT images, providing to the clinical specialist confidence enough for routinely implementation of functional imaging for personalized radiotherapy.

Implications of the Harmonization of [18F]FDG-PET/CT Imaging for Response Assessment of Treatment in Radiotherapy Planning

“…The whole planning process was carried out on the CARMEN platform [30], where image processing and segmentation were performed, and an accurate dose calculation was considered by MC simulation. For this work, a forward planning algorithm, such as BIOMAP [30] implemented on the CARMEN platform, was required, where a direct aperture of the MLC is based exclusively on segmented morphofunctional volumes in patient images [10]. Any change in volumes inherent to the followed accreditation along with the segmentation process had some distinguishable influence on the optimization process.…”

“…For this work, a configuration of an experiment with an anthropomorphic phantom (CIRS 606 model) hosting known different volumes and SUV distributions was used to find the interpolation method that best provided actual volumes [10]. Two inserts with different volumes and filled with a radioactive solution of [ 18 F]FDG were used to simulate two tumors of different sizes.…”

“…In this way, molecular images must be fused with morphological information from CT or magnetic resonance imaging data to be implemented in TPS for dose planning [9]. Positron emission tomography (PET) images can provide the visualization and quantification of the effects of treatment under monitoring to adapt the RT planning and dose prescription to the new targets if the procedure is ready to accurately consider biological changes [10].…”

Clinical Viability of Boron Neutron Capture Therapy for Personalized Radiation Treatment

“…This specific dose prescription based on the heterogeneity provided by the molecular image has been proposed even up to individual voxels corresponding to the tumor volume after the appropriate segmentation process in the image [ 140 ]. This approach has been named dose painting [ 141 ] and is being slowly implemented in treatment planning because harmonization protocols must still be established previously between a larger number of image devices worldwide, specifically PET/CT [ 142 ], enough to achieve common quantitative metrics from a larger cohort, thus being able to confirm the robust correlation between the gray level in the image and the biological information sensible to the prescription dose decision in each case.…”

Is 68Ga-DOTA-FAPI a new arrow in the quiver of dose painting in radiation dose planning in head and neck cancers?

“…Radiotherapy or combined radiochemotherapy is the main therapeutic option implemented as adjuvant or neoadjuvant approach. In recent years, sophisticated radiation dose planning using morphological and functional imaging modalities and the combination has evolved and has been proposed as a base for individualized radiotherapy planning [2]. However, until now, the clinical standard diagnostic tools to calculate the gross tumour volume (GTV) are computed tomography (CT) and magnetic resonance tomography imaging (MRI) [3].…”