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Purpose Cone‐beam CT (CBCT)–based synthetic CT (sCT) dose calculation has the potential to make the adaptive radiotherapy (ART) pathway more efficient while removing subjectivity. This study assessed four sCT generation methods using 15 head‐and‐neck rescanned ART patients. Each patient's planning CT (pCT), rescan CT (rCT), and CBCT post‐rCT was acquired with the CBCT deformably registered to the rCT (dCBCT). Methods The four methods investigated were as follows: method 1—deformably registering the pCT to the dCBCT. Method 2—assigning six mass density values to the dCBCT. Method 3—iteratively removing artifacts and correcting the dCBCT Hounsfield units (HU). Method 4—using a cycle general adversarial network machine learning model (trained with 45 paired pCT and CBCT). Treatment plans were created on the rCT and recalculated on each sCT. Planning target volume (PTV) and organ‐at‐risk (OAR) structures were contoured by clinicians on the rCT (high‐dose PTV, low‐dose PTV, spinal canal, larynx, brainstem, and parotids) to allow the assessment of dose–volume histogram statistics at clinically relevant points. Results The HU mean absolute error (MAE) and minimum dose gamma index pass rate (2%/2 mm) were calculated, and the generation time was measured for 15 patients using the rCT as the comparator. For methods 1–4 the MAE, gamma index analysis, and generation time were as follows: 59.7 HU, 100.0%, and 143 s; 164.2 HU, 95.2%, and 232 s; 75.7 HU, 99.9%, and 153 s; and 79.4 HU, 99.8%, and 112 s, respectively. Dose differences for PTVs and OARs were all <0.3 Gy except for method 2 (<0.5 Gy). Conclusion All methods were considered clinically viable. The machine learning method was found to be most suitable for clinical implementation due to its high dosimetric accuracy and short generation time. Further investigation is required for larger anatomical changes between the CBCT and pCT and for other anatomical sites.

Purpose The quality of on‐board imaging systems, including cone‐beam computed tomography (CBCT), plays a vital role in image‐guided radiation therapy (IGRT) and adaptive radiotherapy. Recently, there has been an upgrade of the CBCT systems fused in the O‐ring linear accelerators called HyperSight, featuring a high imaging performance. As the characterization of a new imaging system is essential, we evaluated the image quality of the HyperSight system by comparing it with Halcyon 3.0 CBCT and providing benchmark data for routine imaging quality assurance. Methods The HyperSight features ultra‐fast scan time, a larger kilovoltage (kV) detector, a more substantial kV tube, and an advanced reconstruction algorithm. Imaging protocols in the two modes of operation, treatment mode with IGRT and the CBCT for planning (CBCTp) mode were evaluated and compared with Halcyon 3.0 CBCT. Image quality metrics, including spatial resolution, contrast resolution, uniformity, noise, computed tomography (CT) number linearity, and calibration error, were assessed using a Catphan and an electron density phantom and analyzed with TotalQA software. Results HyperSight demonstrated substantial improvements in contrast‐to‐noise ratio and noise in both IGRT and CBCTp modes compared to Halcyon 3.0 CBCT. CT number calibration error of HyperSight CBCTp mode (1.06%) closely matches that of a full CT scanner (0.72%), making it suitable for adaptive planning. In addition, the advanced hardware of HyperSight, such as ultra‐fast scan time (5.9 s) or 2.5 times larger heat unit capacity, enhanced the clinical efficiency in our experience. Conclusions HyperSight represented a significant advancement in CBCT imaging. With its image quality, CT number accuracy, and ultra‐fast scans, HyperSight has a potential to transform patient care and treatment outcomes. The enhanced scan speed and image quality of HyperSight are expected to significantly improve the quality and efficiency of treatment, particularly benefiting patients.

Background Cone-beam computed tomography (CBCT) provides high-quality, three-dimensional imaging of the maxillofacial region. However, its use in pediatric patients remains controversial due to radiation dose concerns and the sensitivity of immature anatomical structures to radiation damage. This study aims to determine the prevalence and indications of dental CBCT usage in children. Methods All CBCT images of pediatric patients under 15 years old, obtained from 2018 to 2025 at a university hospital, were retrospectively reviewed. Demographic data, indications for CBCT, imaging field of view (FOV), and average kVp and mA values were evaluated. Descriptive statistics and Chi-square tests were used for data analysis. Results A total of 266 CBCT images from children aged 5–14 years (mean age 11.06; 128 females, 138 males) were included. The prevalence of CBCT among all pediatric patients in this age group was found to be 2.1%. Of the CBCT scans, 175 were for the pathologies from maxilla, 88 from the mandible, and 3 involving both jaws. Imaging was most commonly performed in the anterior (incisor) region for both sexes, with a statistically significant higher rate in males (p<0.001). Surgical indications accounted for 81.6% of cases, while orthodontic indications comprised 18.4%. The most common reasons for CBCT imaging were impacted teeth (29.3%), pathological lesions (21.4%), supernumerary teeth (17.3%), and mesiodens (15.8%). The most frequently used FOV was 15x12 cm. Conclusions The prevalence of CBCT use in pediatric patients is low and is primarily preferred before surgical interventions for impacted teeth and cyst/tumor-like lesions.

Purpose To evaluate the cumulative radiobiological impact of daily megavoltage cone‐beam computed tomography (MV‐CBCT) imaging dose based on normal tissue complication probability (NTCP) and excess absolute risk (EAR) of secondary malignancies among radiotherapy patients treated for breast, pelvic, and head & neck cancers. This study investigated whether MV‐CBCT imaging dose warrants protocol personalization according to patient age, anatomical treatment site, and organ‐specific radiosensitivity. Methods This retrospective study included cohorts of breast (n = 30), pelvic (n = 17), and head & neck (n = 20) cancer patients undergoing radiotherapy with daily MV‐CBCT. Imaging dose distributions employing two common MV‐CBCT protocols (5 and 10 MU per fraction) were analyzed. NTCP values were estimated using logistic models, while EAR were calculated using Schneider's organ equivalent dose (OED)‐based model, integrating organ‐specific dose, patient age, and established tissue‐specific risk coefficients. Comparative statistical analyses were conducted using paired t‐tests, and results were further stratified by patient age (< 40, 40–60, > 60 years). Results In breast cancer patients, NTCP values increased significantly for lung tissue when comparing the 10 MU protocol to the 5 MU one (p < 0.001), while those for heart and breast tissues showed minimal and insignificant differences. EAR estimations revealed substantial risk increases among younger breast cancer patients (< 40 years), with some exceeding 15 cases per 10 000 person‐years under the 10 MU protocol. Conversely, pelvic and head & neck cohorts demonstrated consistently low NTCP and EAR values (< 1%), with no meaningful differences observed between the two imaging protocols. Across all cancer sites, younger age consistently correlated with higher secondary cancer risks. Conclusion Routine daily MV‐CBCT imaging at the 10 MU protocol possesses minimal additional risk in pelvic and head & neck radiotherapy. However, among breast cancer patients, particularly those under 40 years, the 10 MU protocol significantly elevates the theoretical secondary cancer risk estimates and lung NTCP. These findings support transitioning from conventional uniform imaging approach toward personalized MV‐CBCT protocols, tailored according to patient age, anatomical site, and organ radiosensitivity. A stratified imaging framework is proposed to optimize clinical outcomes, balancing treatment accuracy, and long‐term patient safety.

Background: This study analysed whether vertical measurements in the maxillary posterior region are more accurate using panoramic radiography (PAN) or cone-beam computed tomography (CBCT). Methods: Corresponding maxillary posterior regions on both PAN and CBCT images were selected and examined for vertical measurements. The vertical distance between the bone crest and the floor of the maxillary sinus was measured. Measurements in edentulous regions were performed using a similar procedure. Additionally, the vertical height of any defect, if present, was measured. Results were evaluated statistically. Results: When comparing corresponding regions on the CBCT and PAN images, 204 patients with a total of 341 measurements (n = 341) met the inclusion criteria. The mean values for all measurements were 7.21 ± 3.74 mm on PAN and 7.62 ± 4.06 mm on CBCT. The mean difference between all paired measurements was −0.41 ± 1.03 mm. Significant differences between PAN and CBCT were observed (p < 0.001). Defects were detected in 58 (17%) of the 341 measurements. The mean defect height was 1.85 ± 1.05 mm on PAN and 1.99 ± 1.00 mm on CBCT. No significant differences were noted between PAN and CBCT (p = 0.052). Conclusions: Although the relationship between vertical height measurements on PAN and CBCT showed a significant difference of −0.41 ± 1.03 mm for all paired measurements, the difference was very small upon closer inspection. Both PAN and CBCT are suitable methods for measuring vertical heights in the posterior maxilla.

Unlike patients receiving implants or endodontic treatment, most orthodontic patients are children who are particularly sensitive to ionizing radiation. Cone-beam computed tomography (CBCT) carries risks and benefits in orthodontics. The principal risks and limitations include ionizing radiation, the presence of artifacts, higher cost, limited accessibility, and the need for additional training. However, this imaging modality has several recognized indications in orthodontics, such as the assessment of impacted and ectopic teeth, assessment of pharyngeal airway, assessment of mini-implant sites, evaluation of craniofacial abnormalities, evaluation of sinus anatomy or pathology, evaluation of root resorption, evaluation of the cortical bone plate, and orthognathic surgery planning and evaluation. CBCT is particularly justified when it brings a benefit to the patient or changes the outcome of the treatment when compared with conventional imaging techniques. Therefore, CBCT should be considered for clinical orthodontics for selected patients. Prescription of CBCT requires judicious and sound clinical judgment. The central question of this narrative review article is: when does CBCT add value to the practice of orthodontics? To answer this question, this article presents discussion on radiation dosage of CBCT and other imaging techniques used in orthodontics, limitations of CBCT in orthodontics, justifying the use of CBCT in orthodontics, and the benefits and evidence-based indications of CBCT in orthodontics. This review summarizes the central themes and topics in the literature regarding CBCT in orthodontics and presents ten orthodontic cases in which CBCT proved to be valuable.

Cone beam computed tomography (CBCT) has potential advantages for developing portable, cost-effective point-of-care CT systems for 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 and utility. To address these issues, a compact CBCT concept with enhanced image quality was investigated for intracranial imaging. The new system features a novel antiscatter collimator and data correction method to address the challenges in imaging large volumes with CBCT. A benchtop CBCT prototype was constructed. Imaging studies with anthropomorphic phantoms showed that soft tissue visualization, Hounsfield Unit (HU) accuracy, contrast, and spatial resolution increased significantly with the proposed CBCT concept, and they were comparable to the values measured in the gold standard multidetector-row CT (MDCT) images. Contrast-to-noise ratio (CNR) in CBCT images was within 12–31% of the CNR in MDCT images. These findings indicate that a compact CBCT system integrated with effective scatter suppression techniques may have increased utility in the context of brain imaging, and the proposed approach may enable the development of point-of-care CT systems for head imaging based on flat panel detector based CBCT technology.

Microcalcifications (HAp, CaCO3, and CaC2O4) in breast tissue may indicate malignancy. Early-stage breast cancer diagnosis may benefit from the clinical application of dual-energy techniques. Dual-energy cone-beam computed tomography (CBCT) could strongly contribute to an accurate diagnosis, especially in dense breasts. This study focused on photon-counting detector alternatives to the standard cesium iodide (CsI) that CBCT currently relies on and investigated potential advantages over the employed CsI scintillators. Denser detector materials with a higher effective atomic number than CsI could improve image quality. A micro-CBCT was simulated in GATE using seven different detector configurations (CsI, bismuth germanate (BGO), lutetium oxyorthosilicate (LSO), lutetium–yttrium oxyorthosilicate (LYSO), gadolinium aluminum gallium garnet (GAGG), lanthanum bromide (LaBr3), and cadmium zinc telluride (CZT)) and four breast tissue phantoms containing microcalcifications of both type I and type II. The dual-energy methodology was applied to planar and tomographic acquisition data. Tomographic data were reconstructed using filtered backprojection (FBP) and the ordered-subsets expectation-maximization (OSEM) algorithm. Image quality was measured using contrast-to-noise ratio (CNR) values. Both monoenergetic and polyenergetic models were considered. CZT and GAGG crystals presented higher CNR values than CsI. HAp microcalcifications exhibited the highest CNR values, which, when accompanied by OSEM, could be distinguished for classification. Detector configurations based on CZT or GAGG crystals could be adequate alternatives to CsI in dual-energy CBCT.

Advances in the scientific fields of photogrammetry and computer vision have led to the development of automated multi-image methods that solve the problem of 3D reconstruction. Simultaneously, 3D scanners have become a common source of data acquisition for 3D modeling of real objects/scenes/human bodies. This article presents a comprehensive overview of different 3D modeling technologies that may be used to generate 3D reconstructions of outer or inner surfaces of different kinds of targets. In this context, it covers the topics of 3D modeling using images via different methods, it provides a detailed classification of 3D scanners by additionally presenting the basic operating principles of each type of scanner, and it discusses the problem of generating 3D models from scans. Finally, it outlines some applications of 3D modeling, beyond well-established topographic ones.

IntroductionTo increase efficiency of adaptive radiotherapy (ART), we tested a cone beam computed tomography (CBCT) correction algorithm to evaluate the feasibility of utilizing daily CBCTs for treatment planning.MethodsA lung phantom was scanned with a CT and CBCT on two different linacs. The CBCTs were processed through a correction algorithm in the treatment planning system (TPS). The algorithm reduces artifacts and adjusts image intensity to more closely match the planning CT, to generate corrected CBCTs. Voxels outside the CBCT field of view (FOV) are replaced with voxels from the planning CT. A treatment plan was first generated on the CT, then recalculated on the corrected CBCTs. The same workflow was followed for seven previously adapted head and neck and seven sarcoma patients. Each patient's adaptive plan was recalculated on the corrected CBCTs. Dose differences were analyzed for these plans using a 3%/2 mm gamma analysis.ResultsBoth Ethos and TrueBeam CBCT plans on the phantom had high matching dose per voxel according to gamma analysis. After corrections of some registration errors, all 14 plans achieved gamma passing rate above 95% (3%/2 mm).ConclusionsThe CBCT correction algorithm demonstrates potential to reduce the need for re-simulation and enable faster offline adaptive planning without sacrificing dose calculation accuracy.