• Imaging Science in Dentistry
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• v.45 no.4
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• pp.263-265
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• 2015

Cone-beam computed tomography (CBCT) is routinely recommended for dental diagnosis and treatment planning. CBCT exposes patients to less radiation than does conventional CT. Still, lack of proper education among dentists and specialists is resulting in improper referral for CBCT. In addition, aiming to generate high-quality images, operators may increase the radiation dose, which can expose the patient to unnecessary risk. This letter advocates appropriate radiation dosing during CBCT to the benefit of both patients and dentists, and supports moving from the concept of "as low as reasonably achievable" (ALARA) to "as low as diagnostically acceptable" (ALADA).

• Journal of The Korean Radiological Technologist Association
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• v.28 no.1
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• pp.112-119
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• 2002

Purpose : The purpose of this study is to evaluate the usefulness, after we compare and analyze the difference about the location of a lesion and the result of diagnosis on chest radiographs(CR) and low dose computed tomography(LDCT) in subjects for healt

• Tuberculosis and Respiratory Diseases
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• v.57 no.2
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• pp.118-124
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• 2004

Lung cancer is the leading cause of cancer death for men and women in the industrialized world. It is desirable to detect disease at a stage when it is not causing symptoms and when control or cure is possible. If the screening test detects patients with the disease at an early stage, they can be examined to confirm the diagnosis and intervention can alter the natural history of the disease. The results of screening programs designed to detect early lung cancer using either conventional chest radiograph or sputum cytology are disappointing for a diagnostic screening test. Because of advances in helical CT imaging techniques, screening for lung cancer has been suggested as a possible method of improving outcome. Findings in recent publications suggest that substantial dose reduction is possible in chest CT. The advantages of low-dose CT are more sensitive than chest radiograph for detecting small pulmonary nodules that may be lung cancers, shorter scanning time than conventional chest CT scan without intravenous contrast injection, cheaper cost than standard CT, low radiation dose. However, the true clinical significance of the small tumors found by screening is still unknown, and their effect on mortality awaits future investigation. Furthermore, in addition to detecting an increased number of lung cancers, low-dose CT found at least one indeterminate nodule in many of all screened patients. The majority should be benign but evaluation of all these indeterminate nodules is not a trivial problem in routine practice. In conclusion, lung cancer screening with low-dose CT is a complex subject. The true effectiveness of lung cancer screening (a reduction in mortality from lung cancer) with low-dose CT can be determined through well-designed randomized control trials with enrolment of appropriate subjects.

• Asian Spine Journal
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• v.12 no.6
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• pp.1010-1016
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• 2018

Study Design: Retrospective cohort study. Purpose: To report on spinal fusion assessment using computed tomography (CT) after adult spinal deformity (ASD) surgery using ultra-low dose recombinant human bone morphogenetic protein 2 (RhBMP-2). Overview of Literature: The reported dose of RhBMP-2 needed for successful spinal posterolateral fusion in ASD ranges from 10 to 20 mg per spinal level. This study reports the use of ultra-low dose of RhBMP-2 (0.07 mg per facet) to achieve spinal fusion in multilevel ASD surgery. Methods: Consecutive patients who underwent ASD surgery using ultra-low dose RhBMP-2 were recruited. Routine postoperative CT analysis for spinal fusion was performed by two spine surgeons. Inter-observer agreement was calculated for facet fusion (FF) and interbody fusion (IBF) at 6 and 12 months after the procedure. Results: Six consecutive ASD patients with a mean age of 62 years (28-72 years) were examined. Each patient received a total dose of 12 mg with an average dose of $0.69{\pm}0.2mg$ (0.42-1 mg) per single FF and $1.38{\pm}0.44mg$ (0.85-2 mg) for IBF. Total 131 FF and 15 IBF were examined in the study, with 88 FFs and nine IBFs being analyzed specifically at 6 months after the surgery. FF and IBF reported by surgeons A and B at 6 months were 97.7% vs. 91.9% FF, respectively (${\kappa}=0.95$) and 100% vs. 100% IBF, respectively (${\kappa}=1$). Two patients underwent longitudinal follow-up CT at 12 months, and the FF rates reported by surgeons A and B were 100% vs. 95.8%, respectively (${\kappa}=0.96$). Five out of nine facet (56%) non-unions were identified at the cross-links. The remaining four facet pseudarthrosis were noted at 1-2 spinal levels caudal to the cross-links. At the final clinical follow-up, there was no rod breakage, deformity progression, neurological deficit, or symptom recurrence. The Oswestry Disability Index improved by an average of $32.8{\pm}6.3$, while the mental component summary of the 36-item Short-Form Health Survey improved by an average of $4.7{\pm}2.1$, and physical component summary improved by an average of $10.5{\pm}2.1$. Conclusions: To our knowledge, this is the first study to report a CT that defined 92%-98% FF and 100% IBF using the lowest reported dose of RhBMP-2 in multilevel ASD surgery. The use of ultra-low dose RhBMP-2 reduces the RhBMP-2 related complications and healthcare costs.

• Imaging Science in Dentistry
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• v.50 no.4
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• pp.365-371
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• 2020

While silent sinus syndrome (SSS) is familiar to otolaryngologists and ophthalmologists, it is a rare clinical entity in dentistry and is likely to be underdiagnosed due to dentists' lack of awareness of this condition. SSS presents a diagnostic challenge to dentists, as patients typically have no history of trauma or sinusitis. The characteristic feature of SSS is a gradual retreat of the maxillary sinus walls, resulting in enophthalmos and hypoglobus. Multidetector (multislice) computed tomography is the imaging modality of choice for SSS and other paranasal sinus diseases. Cone-beam computed tomography promises to be an alternative low-dose imaging modality. This report describes 3 cases of SSS in adults, who had no identified clinical symptoms except diminutive and opacified maxillary sinuses, as well as the inward bowing of the sinus walls as noted on cone-beam computed tomographic imaging.

• Journal of the Korean Society of Radiology
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• v.16 no.5
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• pp.619-625
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• 2022

In the field of imaging medicine, computed tomography is one of the most common test methods and one of the most frequently used test methods in hospitals. However, it is accompanied by a very high radiation exposure compared to other test methods. In order to reduce exposure, CT scans should be performed only when absolutely necessary, and even if the tests are performed because they are absolutely necessary, a protocol that serves the purpose of the test and allows the test to be performed in a small dose should be used. In this study, we wanted to learn about the most up-to-date radiation dose usage information used by the region's leading general hospitals and develop a diagnostic reference level (DRL). In the experimental results, the Head CT and Abdomen CT tests showed that DLP was higher than the NRPB (U.K) and Korean DRL. The DLP values used by Chest CT were low for all 3 types of CT devices. The hospital found that efforts to reduce exposure should be made during CT examinations, and in particular, Head CT and Abdomen CT determined that efforts to reduce exposure were necessary.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.39 no.5
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• pp.251-253
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• 2013

Inferior alveolar nerve block obtained maximum anesthetic effect using a small dose of local anesthetic agent, which also has low a complication incidence. Complications of an inferior alveolar nerve block include direct nerve damage, bleeding, trismus, temporary facial nerve palsy, and etc. Among them, the major iatrogenic complication is dental needle fracture. A fragment that disappears into the soft tissue would be hard to remove, giving rise to a legal problem. A 31-year-old woman was referred for the removal of a broken needle, following an inferior alveolar nerve block. Management involved the removal of the needle under local anesthesia with pre- and peri-operative computed tomography scans.

• Progress in Medical Physics
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• v.29 no.4
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• pp.150-156
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• 2018

This study aims to develop an improved Feldkamp-Davis-Kress (FDK) reconstruction algorithm using anisotropic total variation (ATV) minimization to enhance the image quality of low-dose cone-beam computed tomography (CBCT). The algorithm first applies a filter that integrates the Shepp-Logan filter into a cosine window function on all projections for impulse noise removal. A total variation objective function with anisotropic penalty is then minimized to enhance the difference between the real structure and noise using the steepest gradient descent optimization with adaptive step sizes. The preserving parameter to adjust the separation between the noise-free and noisy areas is determined by calculating the cumulative distribution function of the gradient magnitude of the filtered image obtained by the application of the filtering operation on each projection. With these minimized ATV projections, voxel-driven backprojection is finally performed to generate the reconstructed images. The performance of the proposed algorithm was evaluated with the catphan503 phantom dataset acquired with the use of a low-dose protocol. Qualitative and quantitative analyses showed that the proposed ATV minimization provides enhanced CBCT reconstruction images compared with those generated by the conventional FDK algorithm, with a higher contrast-to-noise ratio (CNR), lower root-mean-square-error, and higher correlation. The proposed algorithm not only leads to a potential imaging dose reduction in repeated CBCT scans via lower mA levels, but also elicits high CNR values by removing noisy corrupted areas and by avoiding the heavy penalization of striking features.

• Journal of Radiation Industry
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• v.11 no.3
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• pp.131-137
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• 2017

To compare the radiation dose and image noise of low dose computed tomography (CT) and high resolution CT using the fixed tube current technique and automatic tube current modulation (CARE Dose 4D). Chest CT and human anthropomorphic phantom were used the RPL (radiophotoluminescence) dosimeters. For image evaluation, standard deviation of mean CT attenuation coefficient and CT attenuation coefficient was measured using ROI analysis function. The effective dose was calculated using CTDIvol and DLP. CARE Dose 4D was reduced by 74.7% and HRCT by 64.4% compared to the fixed tube current technique in low dose CT of chest phantom. In CTDIvol and DLP, the dose of CARE Dose 4D was reduced by fixed tube current technique. For effective dose, CARE Dose 4D was reduced by 47% and HRCT by 46.9% compared to the fixed tube current method, and the dose of CARE Dose 4D was significantly different (p<.05). Noise in the image was higher than that in the fixed tube current technique. Noise difference in the image of CARE Dose 4D in low dose CT was significant (p<.05). The low radiation dose and the noise difference of the CARE Dose 4D were compared with the fixed tube current technique in low dose CT and HRCT using chest phantom. The radiation doses using CARE Dose 4D were in accordance with the national and international dose standards. CARE Dose 4D should be applied to low dose CT and HRCT for clinical examination.

• Imaging Science in Dentistry
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• v.53 no.4
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• pp.283-289
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• 2023

The apnea-hypopnea index is widely regarded as a measure of the severity of obstructive sleep apnea (OSA), a condition characterized by recurrent episodes of apnea or hypopnea during sleep that induce airway collapse. OSA is a catastrophic problem due to the wide range of health issues it can cause, including cardiovascular disease and memory loss. This review was conducted to clarify the roles of various imaging modalities, particularly cone-beam computed tomography (CBCT), in the diagnosis of and preoperative planning for OSA. Unfortunately, 2-dimensional imaging techniques yield insufficient data for a comprehensive diagnosis, given the complex anatomy of the airway. Three-dimensional (3D) imaging is favored as it more accurately represents the patient's airway structure. Although computed tomography and magnetic resonance imaging can depict the actual 3D airway architecture, their use is limited by factors such as high radiation dose and noise associated with the scans. This review indicates that CBCT is a low-radiation imaging technique that can be used to incidentally identify patients with OSA, thereby facilitating early referral and ultimately enhancing the accuracy of surgical outcome predictions.