A review of dose calculation approaches with cone beam CT in photon and proton therapy

Abstract

Background and purpose: The use of cone beam computed tomography (CBCT) for performing dose calculations in radiation therapy has been widely investigated as it could provide a quantitative analysis of the dosimetric impact of changes in patients during the treatment. The aim of this review was to classify different techniques adopted to perform CBCT dose calculation and to report their dosimetric accuracy with respect to the metrics used. Methods and materials: A literature search was carried out in PubMed and ScienceDirect databases, based upon the following keywords: "cone beam computed tomography", "CBCT", "cone beam CT", "dose calculation", "accuracy". Sixty-nine peer-reviewed relevant articles were included in this review: thirty-one patient studies, fifteen phantom studies and twenty-three patient & phantom studies. Most studies were found to have focused on head and neck, lung and prostate cancers. Results: The techniques adopted to perform CBCT dose calculation have been grouped in six categories labelled as (1) pCT calibration, (2) CBCT calibration, (3) HU override, (4) Deformable image registration, (5) Dose deformation, and (6) Combined techniques. Differences between CBCT dose and reference dose were reported both for target volumes and OARs. Conclusions: A comparison among the available techniques for CBCT dose calculations is challenging as many variables are involved. Therefore, a set of reporting standards is recommended to enable meaningful comparisons among different studies. The accuracy of the results was strongly dependent on the image quality, regardless of the methods used, highlighting the need for dose validation and quality assurance standards. the results are highly variable due to different devices, protocols, datasets, metrics of comparison, treatment sites and treatment planning systems (TPS) being reported in the different studies. This wide variety in the dose reconstruction methodologies and reporting methods used in this expanding field has identified a need to review the current status of the field. This work considers the current

Evaluation of a cycle-generative adversarial network-based cone-beam CT to synthetic CT conversion algorithm for adaptive radiation therapy

“…A CBCT possesses image artifacts due to detector scatter, patient specific scatter, image lag and beam hardening, making dose calculations prone to errors. Many calibration approaches for accurate dose calculations on CBCT currently exist [10]: Patient-or population-specific CT number to electron density calibration (CT-ED-calibration) [11], bulk density override [12], image processing algorithms that further improve the image quality [13][14][15] or deformable image registration (DIR) [7,8] between the CBCT and the treatment planning CT (pCT) to create a deformed CT or a deformed dose in order to assess anatomical and dosimetric changes [16,17]. Recently, deep learning (DL) approaches gained popularity since they can be custom tailored to individual treatment components like image processing and can substantially accelerate time-consuming workflow steps in ART [18,19].…”

Dosimetric Impact of Inter-Fraction Anatomical Changes in Carbon Ion Boost Treatment for High-Risk Prostate Cancer (AIRC IG 14300)

“…In recent years, the introduction of new advanced techniques of IGRT using online cone beam computed tomography (CBCT) allows the tracking of daily positioning and anatomical changes of patients in treatment position. It also has the potential to be used to evaluate the dose-of-the-day distributions in comparison to the dose distribution calculated on the planning computed tomography (pCT) ( 3 ).…”

Dose Estimation by Geant4-Based Simulations for Cone-Beam CT Applications: A Systematic Review

“…X-ray medical imaging has undergone tremendous technological advances for the diagnosis and treatment of a breadth of examinations and procedures [1]. In particular, due to its rich and robust image information and shorter examination time [2][3][4][5], conebeam computed tomography (CBCT) has become standard in recent clinical applications as adaptive radiotherapy treatment [6], image-guided radiation therapy (IGRT) [6][7][8][9][10][11][12], maxillofacial applications [13][14][15], cone-beam breast tomography (CBBCT) [16][17][18][19][20][21][22][23], or proton computed tomography for particle therapy [24][25][26][27][28]. CBCT is a new technology using a cone-shaped beam and a detector that rotate 360 • around the patient, able to acquire projected data in a single rotation [29].…”