Dose reconstruction from PET images in carbon ion therapy: a deconvolution approach

Abstract

Dose and range verification have become important tools to bring carbon ion therapy to a higher level of confidence in clinical applications. Positron emission tomography is among the most commonly used approaches for this purpose and relies on the creation of positron emitting nuclei in nuclear interactions of the primary ions with tissue. Predictions of these positron emitter distributions are usually obtained from time-consuming Monte Carlo simulations or measurements from previous treatment fractions, and their comparison to the current, measured image allows for treatment verification. Still, a direct comparison of planned and delivered dose would be highly desirable, since the dose is the quantity of interest in radiation therapy and its confirmation improves quality assurance in carbon ion therapy. In this work, we present a deconvolution approach to predict dose distributions from PET images in carbon ion therapy. Under the assumption that the one-dimensional PET distribution is described by a convolution of the depth dose distribution and a filter kernel, an evolutionary algorithm is introduced to perform the reverse step and predict the depth dose distribution from a measured PET distribution. Filter kernels are obtained from either a library or are created for any given situation on-the-fly, using predictions of the -decay and depth dose distributions, and the very same evolutionary algorithm. The applicability of this approach is demonstrated for monoenergetic and polyenergetic carbon ion irradiation of homogeneous and heterogeneous solid phantoms as well as a patient computed tomography image, using Monte Carlo simulated distributions and measured in-beam PET data. Carbon ion ranges are predicted within less than 0.5 mm and 1 mm deviation for simulated and measured distributions, respectively.

Monte Carlo investigation of the characteristics of radioactive beams for heavy ion therapy

“…Some of these fragments are positron-emitting radionuclides, which continue to travel a short distance in the target before coming to a stop, where they eventually decay. Measuring of the distribution of these secondary positron-emitting fragments offers a unique opportunity for nonÂinvasive, real-time and/or offline quality assurance (QA) in heavy ion therapy via positron emission tomography (PET) 9–16 .…”

Feasibility study of patient‐specific dose verification in proton therapy utilizing positron emission tomography (PET) and generative adversarial network (GAN)

“…For patient studies, the agreement between a Monte Carlo simulated PET profile and a measured PET profile was ~30% 26 . For monoenergetic carbon beams, one study investigated the kernel‐based approach with both simulation and measurement 47 . For the simulation, the MRE was 1.39% in a bone‐PMMA slab and 0.86% in a PMMA‐gelatin slab, respectively.…”

“…26 For monoenergetic carbon beams, one study investigated the kernel-based approach with both simulation and measurement. 47 For the simulation, the MRE was 1.39% in a bone-PMMA slab and 0.86% in a PMMA-gelatin slab, respectively. For the measurement, the MRE was 3.65% for a PMMA phantom and 9.65% for a gelatin phantom.…”

Development of a Multiuse Human-Scale Single-Ring OpenPET System

“…This work was partially supported by the Japan Society for the Promotion of Science (JSPS) KAKENHI (25242052, 19KK0280) The range verification for particle therapy is an active research area. In addition to PET-based methods using dual-head or partial ring geometries to allow the beam to pass through [12][13][14][15][16][17][18][19][20][21][22][23][24], collimators-based [25]- [28], timing-based [29], [30], and Compton camera techniques-based [31]- [35] methods targeting prompt gamma rays are being studied. Although these methods are classified as 2D or limited angle imaging, OpenPET has the potential to acquire highly accurate 3D images because of its full ring geometry.…”