Dedicated mobile volumetric cone-beam computed tomography for human brain imaging: A phantom study.

Recent studies have demonstrated that shape-sensing robotic bronchoscopy with mobile cone-beam computed tomography (CBCT) guidance results in superb diagnostic outcomes for the diagnosis of peripheral lung lesions. Given the more favorable safety profile and the ability to also stage the mediastinum with endobronchial ultrasound when indicated, the combination of these technologies is likely to replace percutaneous computed tomography (CT)-guided biopsies of peripheral lung nodules in the years to come. Hands-on training in simulators, mannequins or cadaveric models is paramount before adopting this technique, but certain procedural and pre-procedural steps can only be practiced during true cases. Just like with any other new technology, there is an expected learning curve that physicians will go through before obtaining the desired procedural outcomes. Through the current manuscript we share some guidance based on years of research and clinical experience, which we hope will shorten the learning curve for newly adopters of these technologies. We have incorporated into our practice a systematic approach that maximizes the efficiency of patient positioning, integration of mobile CBCT and shape-sensing robotic bronchoscopy, as well as prevention of atelectasis and target motion. We believe this approach is key to maximizing efficiency and procedural outcomes, and we are honored to share it with the readers.

PurposePedicle screw fixation provides 3-column stabilization, multidimensional control, and a higher rate of interbody fusion. Although computed tomography (CT) is recommended for the postoperative assessment of pedicle screw fixation, its use is limited due to the radiation exposure dose. The purpose of this preliminary retrospective study was to assess the clinical usefulness of low-dose mobile cone-beam CT (CBCT) for the postoperative evaluation of pedicle screw fixation.MethodsThe author retrospectively reviewed postoperative mobile CBCT images of 15 patients who underwent posterior pedicle screw fixation for spinal disease from November 2019 to April 2020. Pedicle screw placement was assessed for breaches of the bony structures. The breaches were graded based on the Heary classification.ResultsThe patients included 11 men and four women, and their mean age was 66±12 years. Of the 122 pedicle screws, 34 (27.9%) were inserted in the thoracic segment (from T7 to T12), 82 (67.2%) in the lumbar segment (from L1 to L5), and six (4.9%) in the first sacral segment. Although there were metal-related artifacts, the image of the screw position (according to Heary classification) after surgery could be assessed using mobile CBCT at all levels (T7–S1).ConclusionsMobile CBCT was accurate in determining the location and integrity of the pedicle screw and identifying the surrounding bony structures. In the postoperative setting, mobile CBCT can be used as a primary modality for assessing the accuracy of pedicle screw fixation and detecting postoperative complications.

Letters to the Editor.

Objective To investgate the application value of low-dose CT scanning in right adrenal vein imaging. Methods A total of 124 patients were enrolled in the study who were suspected as primary aldosteronism and requiring a contrast enhanced CT examination on adrenal glands. Four patients were excluded according to the exclusion criteria, so that the rest 120 patients were divided equally into three groups. Group A was a control group with conventional radiation dose using tube voltage of 120 kV and automatic mA. It was divided into A1, A2 and A3 groups according to arterial phase, portal venous phase and parenchymal phase. Group B was a experimental group with conventional tube voltage of 120 kV and automatic mA, which was divided into B1, B2 and B3 groups according to arterial phase, late arterial phase and portal venous phase. Group C was a low-dose experimental group with a tube voltage of 100 kV and a tube current of 150 mA only in the second phase, the remaining scanning parameters and method were the same as that of group B. The subjective scores of the images of groups A, B and C were statistically analyzed, and the CT values of the right adrenal vein(RAV), the right adrenal gland(RAG), and the fat of anterior abdominal wall at different scan phases were measured. The dose length products (DLP) were recorded and the signal-to-noise ratios (SNR), contrast-to-noise ratios (CNR), effective doses (E) of the three groups were calculated and compared. Results The subjective scores of the two observers were consistent (Kappa value=0.63); the subjective scores of the B2 images were statistically significant (H=7.18, P<0.05). Difference of subjective scores between B2 and A2 was statistically significant ( t=-18.03, P<0.05). The CT values of RAV, SNR, and CNR of the B2 group were higher than those of the A2 group (t=36.99, 6.92, 9.02, P<0.05). The radiation dose comparison showed that the effective dose (E) was 45.52% lower in the low-dose group than the conventional dose group with the statistically significant difference(t=12.19, P<0.05). Conclusions Using MDCT scanning technique with lower tube voltage and lower tube current of 100 kV-150 mA, the detection rate of right adrenal vein can reach 95% in the late arterial phase, and the effective dose can be reduced about 45.52% on the basis of ensuring image quality. Key words: Computed tomography; Low radiation dose; Adrenal vein; Primary aldosteronism; Effective radiation dose

Clinical indication for intraoperative 3D imaging during open reduction of fractures of the mandibular angle

ObjectiveCone‐beam computed tomography (CBCT) is a promising imaging modality for sinonasal evaluation, with advantages of relatively low radiation dose, low cost, and quick outpatient imaging. Our study aimed to compare the diagnostic performance and image quality of CBCT with those of multi‐detector computed tomography (MDCT) with different slice thickness.MethodsWe retrospectively reviewed 60 consecutive patients who had undergone both CBCT and MDCT. MDCT images was reconstructed with 1 and 3 mm slice thickness. The quantitative image quality parameters (image noise, signal‐to‐noise ratio [SNR], and contrast‐to noise ratio [CNR] were calculated and compared between the two imaging modalities. Two observers (ENT surgeon and neuroradiologist) evaluated the presence of seven sinonasal anatomic variations in each patient and interobserver agreements were analyzed. The diagnostic performance of CBCT (0.3 mm) and MDCT (3 mm) was assessed and compared with that of high resolution MDCT (1 mm), which is considered as the gold standard.ResultsThe image noise was significantly higher and SNR and CNR values were lower in the CBCT (0.3 mm) group than in the MDCT groups (1 and 3 mm). The diagnostic performance of CBCT (0.3 mm) was similar to that of MDCT (1 mm) and superior to that of MDCT (3 mm). The highest interobserver agreement was for high resolution MDCT (1 mm), followed by CBCT (0.3 mm), and MDCT (3 mm).ConclusionConsidering its low radiation dose, low cost, and ease of clinical access, CBCT may be a useful imaging modality for as first line sinonasal evaluation and repeated follow up.Study design: Retrospective study in a tertiary referral university center.Level of evidence: NA.

We compared the effective dose from panoramic radiography with that from cone beam CT (CBCT) using dose area product under adult and child exposure conditions. The effective doses of the cephalo, panorama, implant and dental modes of Alphard 3030 (Asahi Roentgen Ind., Co. Ltd, Kyoto, Japan) CBCT and the Jaw, Wide, Facial and temporomandibular joint modes of Rayscan Symphony (RAY Co., Ltd, Hwaseong, Republic of Korea) CBCT were compared with those of CRANEX(®) 3+CEPH (Soredex Orion Corporation, Helsinki, Finland) panoramic radiography equipment under adult and child exposure conditions. Each effective dose was calculated using a conversion formula from dose area product meter measured values (VacuTec Messtechnik GmbH, Dresden, Germany). The conversion formulae used were suggested by Helmrot and Alm Carlsson and Batista et al, and they were applied with the tube voltage taken into consideration. The maximum effective doses from the Alphard 3030 and Rayscan Symphony were 67 and 21 times greater than that from panoramic radiography, respectively. The ratios of the effective dose under the child setting to that under the adult condition were 0.60-0.62 and 0.84-0.95, and the maximum differences in effective doses between the adult and child exposure settings were equivalent to 27 and 4 times greater than a panoramic examination in the Alphard 3030 and Rayscan Symphony, respectively. The effective CBCT doses were higher than those of panoramic radiography. The differences in effective doses between the adult and child CBCT settings were dependent on equipment type and exposure parameters. Therefore, adequate mode selection and control of exposure as well as further research are necessary to minimize the effective dose to patients, especially for radiosensitive children.

Cone Beam Computed Tomography (CBCT) has gained a broad acceptance in dentomaxillofacial imaging. Computed Tomography (CT) is another imaging modality for diagnosis and preoperative assessments of the head and neck region. Considering the increased radiation exposure and high cost of CT, this study sought to subjectively assess the image quality of CBCT and Multi Slice CT (MSCT). A dry human mandible was scanned by five CBCT systems (New Tom 3G, Scanora, CRANEX 3D, Promax and Galileos) and one MSCT system. Three independent oral and maxillofacial radiologists reviewed the CBCT and MSCT scans for the quality of 10 landmarks namely mental foramen, trabecular bone, Periodontal Ligament (PDL), dentin, incisive canal, mandibular canal, dental pulp, enamel, lamina dura and cortical bone using a five-point scale. Significant differences were found between MSCT and CBCT and among the five CBCT systems (p<0.05) in visualization of different anatomical structures. A fine structure such as the incisive canal was significantly less visible and more variable among the systems in comparison with other anatomical landmarks such as the mental foramen, mandibular canal, cortical bone, dental pulp, enamel and dentin (p<0.05). The Cranex 3D and Promax systems were superior to MSCT and all other CBCT systems in visualizing anatomical structures. The CBCT image quality was superior to that of MSCT even though some variability existed among different CBCT systems in visualizing fine structures. Considering the low radiation dose and high resolution, CBCT may be beneficial for dentomaxillofacial imaging.

Characterization of a Novel Radiopaque Perirectal Hydrogel Spacer for Prostate Cancer Radiotherapy

Purpose:Cone beam computed tomography (CBCT) imaging is on increasing demand for high‐performance image‐guided radiotherapy such as online tumor delineation and dose calculation. However, the current CBCT imaging has severe scatter artifacts and its current clinical application is therefore limited to patient setup based mainly on the bony structures. This study's purpose is to develop a CBCT artifact correction method.Methods:The proposed scatter correction method utilizes the planning CT to improve CBCT image quality. First, an image registration is used to match the planning CT with the CBCT to reduce the geometry difference between the two images. Then, the planning CT‐based prior information is entered into the Bayesian deconvolution framework to iteratively perform a scatter artifact correction for the CBCT mages. This technique was evaluated using Catphan phantoms with multiple inserts. Contrast‐to‐noise ratios (CNR) and signal‐to‐noise ratios (SNR), and the image spatial nonuniformity (ISN) in selected volume of interests (VOIs) were calculated to assess the proposed correction method.Results:Post scatter correction, the CNR increased by a factor of 1.96, 3.22, 3.20, 3.46, 3.44, 1.97 and 1.65, and the SNR increased by a factor 1.05, 2.09, 1.71, 3.95, 2.52, 1.54 and 1.84 for the Air, PMP, LDPE, Polystryrene, Acrylic, Delrin and Teflon inserts, respectively. The ISN decreased from 21.1% to 4.7% in the corrected images. All values of CNR, SNR and ISN in the corrected CBCT image were much closer to those in the planning CT images. The results demonstrated that the proposed method reduces the relevant artifacts and recovers CT numbers.Conclusion:We have developed a novel CBCT artifact correction method based on CT image, and demonstrated that the proposed CT‐guided correction method could significantly reduce scatter artifacts and improve the image quality. This method has great potential to correct CBCT images allowing its use in adaptive radiotherapy.

Brain images are the scientific icon of our age, replacing Bohr’s planetary atom as the symbol of science. Many businesses have realized that brain images make their products or services appear to be especially scientific and cutting edge, whether they are selling to high-level corporate executives or the viewers of TV infomercials. Of course, brain imaging is increasingly able to deliver practically useful information about people and their thought processes, so one cannot assume that all claims are bogus. Society is currently being challenged to sort out which of the new applications of brain imaging perform as claimed, which are immature but promising, and which are snake oil. Cognitive neuroscientists must take the lead in evaluating these new applications and informing the public about them. Our task is not simply to be the ‘‘bad science’’ police but to participate in a variety of ways as citizen-scientists with knowledge and skills that are relevant to society’s needs. This includes provoking discussion with businesses concerning the evidence for their claims, which their nonexpert customers cannot do for themselves, and educating the public about the prospects and the limitations of brain imaging. Unrealistic, financially motivated claims about functional brain imaging can have a negative impact on society at large and on our field. If too much is promised and not delivered, funders may become wary of cognitive neuroscience and skeptical about its genuine potential. Bad advice given to businesses concerning marketing and personnel selection could lead to expensive mistakes, and bad advice given to governments concerning security screening and interrogation could lead to far worse. Yet imaging is being offered for these applications now, with scant evidence of validity. One example of unfounded claims based on brain imaging comes from the firm FKF Applied Research, whose Web site boasts a client list of Fortune 500 companies. Among their projects is a study of political campaigns, and their advice to American presidential candidates appeared in the New York Times last winter (Iacoboni et al., 2007). The authors made extensive use of what Poldrack (2006) has called reverse inference. For example, anterior cingulate activation in response to pictures of one candidate was taken to indicate voters’ conflicted feelings, whereas for another candidate insular activation was taken as a sign that he evoked feelings of disgust. Such inferences ignore the fact that many mental states can be associated with activation in a given area, the ACC and the insula included (Aron et al., 2007; Farah, 2007; see also Iacoboni, 2008; Poldrack, 2008). Another profitable but unproven application of brain imaging is as an aid to diagnosis for psychiatric disorders such as depression, anxiety, attention deficit hyperactivity disorder, and autism. Definitive diagnoses are not always possible in psychiatry, especially in pediatric psychiatry, and companies such as the Amen Clinics and Brain Matters are profiting by suggesting that they have a more scientific basis for diagnosis than conventional psychiatry. Tens of thousands of individuals, many of them children, have been exposed to the radiation of two SPECT scans and paid thousands of dollars out of pocket (because insurers will not pay) against the advice of many experts including the American Psychiatric Association’s Council on Children, Adolescents and their Families (Flaherty et al., 2005). The Amen Clinics are now marketing their services outside the medical arena, advising couples with marital problems and even ‘‘prescreening’’ couples. Dr. Amen has suggested routine brain imaging of presidential candidates, given that ‘‘the brain is involved in everything humans do: how we think, how we feel, how we get along with others, how we negotiate, how we pay attention in meetings and how we turn away the advances of White House interns or decide to invade a country based on contradictory intelligence’’ (Amen, 2007). Laboratory fMRI research on deception has been prematurely commercialized by companies such as Cephos (http://www.cephoscorp.com) and No Lie MRI (http://www. noliemri.com), which are offering their services to individuals, companies, and governments. Their Web sites emphasize the attributes of science and objectivity and of course feature brain images prominently along with claims such as ‘‘the technology used by No Lie MRI represents the first and only direct measure of truth verification and lie detection in human history!’’ Although published research on the kinds of methods used by these companies documents impressively high levels of accuracy approaching 90% under laboratory conditions (Davatzikos et al., 2005), this is not sufficient accuracy for high-stakes decision-making nor will this performance necessarily generalize to real-world situations. As cognitive neuroscientists, we have many opportunities in the course of our careers to help society sort the valid from the invalid applications of brain imaging. For those of us in academics, teaching is a powerful means to

Comparison between effective radiation dose of CBCT and MSCT scanners for dentomaxillofacial applications

The aim of this study was to compare Orthopantomograms (OPT) and Computed Tomography (CT) with Cone Beam Computed Tomography (CBCT) in patients with Medication-Related OsteoNecrosis of the Jaws (MRONJ). The study included 25 patients (6 males and 19 females) with MRONJ who had a history of long-term bisphosphonate therapy or one of the recently re-entered MRONJ drugs and underwent OPT, CT and/or CBCT for determination of the extent of disease. We excluded patients with maxillary neoplasia. Considering the presence of early and late signs, OPT was diagnostic in 6 out of 17 cases (35%), while CT and CBCT were diagnostic in 25 out of 25 cases (100%). Analysing the different radiant doses delivered by the selected radiological methods on a phantom, it was found that a more significant effective dose was spread by CT (2.6 mSv) than CBCT (0.164 mSv) or OPT (0.02 mSv). CBCT, from our experience, is a candidate to replace OPT in the first diagnostic step in patients with suspected MRONJ, generating less effective doses and artefacts from metal components than CT.

To reduce radiation exposure to paediatric neurosurgical patients from computed tomography (CT), a CT scanning protocol - lower radiation dose and selective scan segment (LDSS) protocol was used for CT brain at the authors' hospital. To evaluate the amount of reduction in radiation exposure by using this LDSS protocol compared to their usual protocol, the authors prospectively documented their findings. From May 2010 to June 2011, paediatric neurosurgical patients requiring CT brain, and when it was not a clinical emergency and there was baseline CT or MRI brain available, were evaluated for the LDSS protocol. The LDSS protocol used a lower tube current-time product and a shorter scan length to attain a lower total radiation dose. The CT scanning parameters of the patients' usual CT brain and LDSS CT were recorded and compared. Adverse events were also recorded. A total of 24 paediatric patients were included. Using the LDSS protocol, the effective doses were between 9% and 80% of the usual protocol and, in 20 patients, ≤50% of the usual protocol. The tube voltage was 120 kV. For patients below 10 years old, 100 mA s was adequate for the purposes of their CTs; in some patient categories, it was lower than 100 mA s. For patients aged 10 or above, 150 mA s was used. The scan length varied. Radiation exposure from CT brain in paediatric neurosurgical patients could be reduced by adopting a CT scanning protocol, which aimed dynamically at a lower tube current-time product and a shorter scan length than the usual settings at a hospital.

To evaluate the feasibility of a synchronized moving grid (SMOG) system to remove scatter artifacts, improve the contrast-to-noise ratio (CNR), and reduce image lag artifacts in cone-beam CT (CBCT). The SMOG system proposed here uses a rapidly oscillating, synchronized moving grid attached to the kV source. Multiple partial projections are taken at different grid positions to form a complete projection in each gantry position, before the gantry moves to the next position during a scan. The grid has a low transmission factor, and it is used for both scatter reduction and scatter measurement for postscan scatter correction. Experimental studies using a static grid and an enlarged CATphan phantom were performed to evaluate the potential CNR enhancement for different SMOG exposure numbers (1, 2, and 4). Simulation studies were performed to evaluate the image lag correction for different exposure numbers (2, 3, and 4) and grid interspace widths in SMOG using the data from an anthropomorphic pelvis phantom scan. Imaging dose of SMOG was also estimated by measuring the imaging dose in a CIRS CT dose phantom using a static grid. SMOG can enhance the CNR by 16% and 13% when increasing exposure number from 1 to 2 and from 2 to 4, respectively. This enhancement was more dramatic for larger phantoms and smaller initial exposure numbers. Simulation results indicated that SMOG could reduce the lag to less than 4.3% for 2-exposure mode and to less than 0.8% for 3-exposure mode when the grid interspace width was 1.4 cm. Increasing the number of exposures in SMOG dramatically reduced the residual lag in the image. Reducing the grid interspace width somewhat reduced the residual lag. Skin line artifacts were removed entirely in SMOG. Point dose measurement showed that imaging dose of SMOG at isocenter was similar as that of a conventional CBCT. Compared to our previously developed static-grid dual-rotation method, the proposed SMOG technique has the advantages of enhancing the CNR, correcting the image lag, and reducing the delivery time. Once implemented, SMOG has the potential to remove scatter and image lag artifacts, and significantly enhance CNR for CBCT using the same scanning time as conventional CBCT.