Purpose: Latest generation linear accelerators (linacs), i.e., TrueBeam (Varian Medical Systems, Palo Alto, CA) and its stereotactic counterpart, STx, have several unique features, including high‐dose‐rate flattening‐filter‐free (FFF) photon modes, reengineered electron modes with new scattering foil geometries, updated imaging hardware/software, a novel control system. An evaluation of five linacs at three different institutions has been performed this work reports on the commissioning...

Local control and overall survival in patients with advanced head neck squamous cell cancer (HNSCC) remains dismal. Signaling through the Hedgehog (Hh) pathway is associated epithelial-to-mesenchymal transition, activation of Hh effector transcription factor Gli1 a poor prognostic this disease setting. Here, we report that increased GLI1 expression leading edge HNSCC tumors further by irradiation, where it contributes to therapeutic inhibition. blockade cyclopamine suppressed enhanced tumor...

Background and purposeRobust scatter mitigation by 2D anti-scatter grids (2D-ASG) in proton therapy cone beam computed tomography (CBCT) may improve target visualization (CT) number fidelity, allowing online dose verifications plan adaptations. However, grid artifact-free implementation of 2D-ASG depends on the CBCT system characteristics. Thus, we investigated feasibility a gantry-mounted evaluated its impact image quality.Materials methodsA prototype support platform were developed for...

High fraction of scattered radiation in cone-beam CT (CBCT) imaging degrades number accuracy and visualization low contrast objects. To suppress scatter CBCT projections, we developed a focused, two-dimensional antiscatter grid (2DASG) prototype. In this work, report on the primary transmission characteristics 2DASG prototype aimed for linac mounted, offset detector geometry systems therapy, compared its performance to conventional one-dimensional ASG (1DASG).The is an array through-holes...

In using flat panel detectors (FPD) for cone beam computed tomography (CBCT), pixel gain variations may lead to structured nonuniformities in projections and ring artifacts CBCT images. Such can be caused by change detector entrance exposure levels or hardening, they are not accounted conventional field correction methods. this work, the authors presented a method identify isolated clusters that exhibit proposed (PGC) suppress both hardening level dependent variations.To modulate spectrum...

Purpose Scattered radiation is a major cause of image quality degradation in flat panel detector‐based cone beam CT (CBCT). While recently introduced 2D antiscatter grids reject the majority scatter fluence, small percentage fluence still transmitted to detector remains challenge for implementation quantitative imaging techniques such as dual energy CBCT. Additionally, this residual also source grid‐induced artifacts, which impedes We therefore present new method achieve both robust...

Quantitative accuracy is critical for expanding the role of cone beam CT (CBCT) imaging from target localization to quantitative treatment monitoring and plan adaptations in radiation therapy. Despite advances CBCT image quality improvement methods, gap between multi-detector (MDCT) remains.

Scattered radiation remains to be a major cause of image quality degradation in Flat Panel Detector (FPD)-based Cone-beam computed tomography (CBCT). We have been investigating novel two-dimensional antiscatter grid (2D-ASG) concept reduce scatter intensity, and hence improve CBCT quality. present the first imaging experiments performed with 2D-ASG prototype, demonstrate its efficacy improving quality.A prototype septa focused x-ray source was additively manufactured from tungsten mounted on...

Purpose Three‐dimensional in‐vivo dose verification is one of the standing challenges in radiation therapy. X‐ray‐induced acoustic tomography has recently been proposed as an imaging method for use dosimetry. The aim this study was to investigate accuracy reconstructing three‐dimensional (3D) absolute using x‐ray‐induced tomography. We performed investigation two different tomographic reconstruction techniques. Methods Two examples 3D techniques x‐ray are investigated. Dose distributions...

We have been investigating two-dimensional (2D) antiscatter grids (2D ASGs) to reduce scatter fluence and improve image quality in cone beam computed tomography (CBCT). In this work, two different aspects of 2D ASGs, their rejection correction capability, were investigated CBCT experiments. To correct residual transmitted through the ASG, it was used as a measurement device with novel method: grid-based sampling.Three focused ASG prototypes grid ratios 8, 12, 16 developed for linac-mounted...

The concept of using kilovoltage (kV) and megavoltage (MV) beams concurrently has potential applications in cone beam computed tomography (CBCT) guided radiation therapy, such as single breath hold scans, metal artifact reduction, simultaneous imaging during MV treatment delivery. However, cross-scatter generated delivery degrades CBCT image quality. To address this, a 2D antiscatter grid cross scatter correction method were investigated. 3D printed, tungsten prototype was utilized to reduce...

To suppress scatter in cone beam computed tomography (CBCT), two-dimensional antiscatter grids (2D grid) have been recently proposed. In this work, we developed several grid prototypes with higher ratios and smaller pitches than previous designs, quantified their primary transmission properties the context of CBCT for radiation therapy. Three focused 2D were at 12 16, 2 3 mm. Their measured between 80-140 kVp, benchmarked against a high performance radiographic (1D using Varian TrueBeam...

Cone beam computed tomography (CBCT) has potential advantages for developing portable, cost-effective point-of-care CT systems intracranial imaging, such as early stroke diagnosis, hemorrhage detection, and intraoperative navigation. However, large volume imaging with flat panel detector based CBCT significantly increases the scattered radiation fluence which reduces its image quality utility. To address these issues, a compact concept enhanced was investigated imaging. The new system...

While two-dimensional antiscatter grids (2D grid) reduce scatter intensity substantially in Cone Beam Computed Tomography (CBCT), a small fraction of scattered radiation is transmitted through the 2D grid to detector. Residual limits accuracy CT numbers and interferes with correction grid's septal shadows, or footprint, projections. If shadows are not adequately suppressed projections, it will lead ring artifacts CBCT images. In this work, we present new method correct residual by employing...

Two-dimensional antiscatter grids (2DASG) for cone beam computed tomography (CBCT) is a new area of research to reduce scatter intensity, and consequently improve CBCT image quality. One the challenges in implementation 2DASGs their septa shadows that are impinged on projections. If these artifacts not corrected, they may lead ring images. In this work, we present novel method suppress FPD-based images.Briefly, our first detects locations 2DASG's projections then, reduces projection pixel...

The pharmacokinetic behavior of iodine contrast agents makes it difficult to achieve significant enhancement during contrast-enhanced cone-beam CT (CE-CBCT). This study modeled this dynamic optimize CE-CBCT and improve the localization liver lesions for SBRT. We developed a model that allows controlled changing concentrations using static phantoms. A projection database consisting multiple phantom images differing iodine/scan conditions was built. To reconstruct hepatic concentrations, data...

Simultaneous use of kilovoltage (kV) and megavoltage (MV) beams has numerous potential applications in cone beam computed tomography (CBCT)-guided radiotherapy, such as fast MV+kV CBCT for single breath-hold scan, tumor localization with kV imaging during MV therapy delivery, metal artifact suppression. However, the introduction results a large MV-cross scatter fluence incident on Flat Panel Detector (FPD), thus, deteriorating low contrast visualization Hounsfield Unit (HU) accuracy. In this...

Abstract Background Dual‐energy (DE) imaging techniques in cone‐beam computed tomography (CBCT) have potential clinical applications, including material quantification and improved tissue visualization. However, the performance of DE CBCT is limited by effects scattered radiation, which restricts its use to small object imaging. Purpose This study investigates feasibility decomposition reducing scatter with a 2D anti‐scatter grid measurement‐based correction method. Specifically,...

Abstract Background Online dose calculations before the delivery of radiation treatments have applications in verification, online adaptation treatment plans, and simulation‐free planning. While by directly utilizing CBCT images are desired, dosimetric accuracy can be compromised due to relatively lower HU images. Purpose In this work, we propose a novel imaging pipeline enhance CBCT‐based pelvis region. Our approach aims improve images, thereby improving overall prior delivery. Methods An...

Purpose In animal irradiation models, reported dose can vary significantly from the actual doses delivered. We describe an effective method for in vivo verification.Materials and methods Mice bearing commercially-available cell line or patient-derived tumor orthotopic flank xenografts were irradiated using a 160 kVp, 25 mA X-ray source. Entrance was evaluated optically-stimulated luminescence dosimeters (OSLD) exit assessed radiochromic film dosimetry.Results Tumor position within field...

Energy sensitive and photon counting detectors can provide improved tissue visualization material quantification capabilities in Cone Beam Computed Tomography (CBCT) systems. However, their implementation CBCT systems is more challenging, which part due to high fluence of scattered X-rays wide cone angle geometry. Specifically, scatter contamination lower energy spectrum challenges reconstruction fidelity images by using X-rays. To address this problem, we investigated a robust rejection...