• Journal of radiological science and technology
• /
• v.44 no.4
• /
• pp.367-373
• /
• 2021

A quality assurance of computed tomography(CT) have done seven items that were water attenuation coefficient, noise, homogeneity, spatial resolution, contrast resolution, slice thickness, artifact using by standard phantom. But there is no quality assurance items and methods for CT simulator at domestic institutions yet. Therefore the study aimed to access the CT dose index(CTDI), table tilting, image distortion, laser accuracy, table movement accuracy and CT seven items for CT simulator quality assurance. The CTDI at the center of the head phantom was 0.81 for 80 kVp, 1.55 for 100 kVp, 2.50 for 120 mm, 0.22 for 80 kVp at the center of the body phantom, 0.469 for 100 kVp, and 0.81 for 120 kVp. The table tilting was within the tolerance range of ±1.0° or less. Image distortion had 1 mm distortion in the left and right images based on the center, and the laser accuracy was measured within ±2 mm tolerance. The purpose of this study is to improve the quality assurance items suitable for the current situation in Korea in order to protect the normal tissues during the radiation treatment process and manage the CT simulator that is implemented to find the location of the tumor more clearly. In order to improve the accuracy of the CT simulator when looking at the results, the error range of each item should be small. It is hoped that the quality assurance items of the CT simulator will be improved by suggesting the quality assurance direction of the CT simulator in this study, and the results of radiation therapy will also improve.

• Journal of Biomedical Engineering Research
• /
• v.10 no.3
• /
• pp.243-252
• /
• 1989

In this study, medical images, which are X-ray image and CT image, are compressed by the adam live coding technique. The medical images may be treated as special ones, because they are different from general images in many respects. The statistical characteristics that medical images only have in transform domain are analyzed, and then the improved quantization method is proposed for medical images. For chest X-ray image and CT head image, the better results are obtained by the improved adaptive coding technique.

• Journal of Trauma and Injury
• /
• v.29 no.4
• /
• pp.99-104
• /
• 2016

Purpose: There are many patients visited to ED in an alcohol intoxicated state. For these patients, it is difficult to predict by only clinical examination whether he/she would have brain lesion. The purpose of this study is to research whether it is possible to predict brain lesion by only clinical examination findings, with comparing patients with/without actual brain lesions. Methods: A retrospective study was performed at a university hospital for the period 11 months with the medical records. As for the inclusion group, head trauma patients with objectively proved drunk, judging by their blood ethanol concentration, and performed the brain CT were selected. In terms of medical record, Glasgow coma scale (GCS), the presence of neurologic abnormalities, the presence of lesion on brain CT of the patients, were examined. From laboratory results, blood ethanol concentration, platelet count, prothrombin time (PT), activated partial thromboplastin time (aPTT) and glucose concentration were identified. Results: For this study, there were total 80 patients of inclusion group. There was no statistically significant difference in terms of GCS score and neurological examination abnormalities, between the group with brain lesion and the group without brain lesion on brain CT. Conclusion: Alcohol intoxicated patient with head trauma visits the ED, it is not possible to distinguish or determine whether brain lesion exists or not by only clinical findings. In order to check the lesion existence, the image examination, therefore, should be considered and performed.

• Journal of Trauma and Injury
• /
• v.20 no.2
• /
• pp.83-89
• /
• 2007

Purpose: This research was performed to determine which clinical signs and symptoms of brain injury are sensitive indicators of skull fracture (SF) and intracranial injury (ICI) in head injured children. Methods: We conducted a prospective study of minor head trauma in children younger than 2 years of age for a 1-year period. Skull radiographs, brain computed tomography (CT), and data forms, including mechanism of injury, symptoms, physical findings, and hospital course, were completed for each child. Results: Of 137 study subjects, 17 (12.4%) had SF/ICI. Falls were the most common mechanism of injury, and heights of fall above 1 meter were associated with incidence of SF/ICI (p<0.05). Scalp abnormalities were not associated with incidence of SF/ICI. As for clinical symptoms, lethargy and a grouping of features (irritability & vomiting) were associated with incidence of SF/ICI (p<0.05). The incidence of seizure, loss of consciousness, vomiting, irritability, and scalp abnormality did not differ significantly between those with normal radiologic findings and those with SF/ICI. Among asymptomatic patients, 11 (14.5%) patients had SF/ICI, and among patients with normal scalp findings, 9 (12.7%) patients had SF/ICI. Conclusion: Clinical signs and symptoms, except for lethargy and a grouping of features (irritability & vomiting), were not sensitive predictors of SF/ICI. Nevertheless, SF/ICI occurred among normal children. In such a case, a liberal policy of CT scanning is warranted.

• Imaging Science in Dentistry
• /
• v.39 no.3
• /
• pp.115-120
• /
• 2009

Purpose : The purpose of this study was to determine a conversion coefficient for Hounsfield Units(HU) to material density ($g\;cm^{-3}$) obtained from cone-beam computed tomography ($CBMercuRay^{TM}$) data and to measure the hard tissue density based on the Hounsfield scale on dental head phantom. Materials and Methods : CT Scanner Phantom (AAPM) equipped with CT Number Insert consists of five cylindrical pins of materials with different densities and teflon ring was scanned by using the $CBMercuRay^{TM}$ (Hitachi, Tokyo, Japan) volume scanner. The raw data were converted into DICOM format and the HU of different areas of CT number insert measured by using $CBWorks^{TM}$. Linear regression analysis and Student t-test were performed statistically. Results : There was no significant difference (P > 0.54) between real densities and measured densities. A linear regression was performed using the density, $\rho$($g\;cm^{-3}$), as the dependent variable in terms of the HU (H). The regression equation obtained was $\rho=0.00072H-0.01588$ with an $R^2$ value of 0.9968. Density values based on the Hounsfield scale was $1697.1{\pm}24.9\;HU$ in cortical bone, $526.5{\pm}44.4\;HU$ in trabecular bone, $2639.1{\pm}48.7\;HU$ in enamel, $1246.1{\pm}39.4\;HU$ in dentin of dental head phantom. Conclusion : CBCT provides an effective option for determination of material density expressed as Hounsfield Units.

• Journal of Radiation Industry
• /
• v.12 no.4
• /
• pp.365-372
• /
• 2018

The use of CT examinations is increasing rapidly and radiation dose from CT examinations is much higher than other diagnostic radiography examinations including general radiography and mammography. DRLs used to optimize the radiation dose of patients by diagnostic radiology in each country. The objective of this study was to investigate and to analyze the status of DRLs from CT examinations in domestic and other countries. In other countries, DRLs were set for each age group and each examination considering the medical situation of each country. In Korea, DRLs were set for adults and children in 2017. For adults, DRLs were set for 13 examinations. Reported DLP values were 1119, 297, $472mGy{\cdot}cm$ for head, chest and abdomen pelvis examination, respectively. For children, DRLs were set for head examinations. Reported DLP values were 298 (0~1 years), 404 (2~5 years), 494 (6~10 years), 1,088 (11~15 years) $mGy{\cdot}cm$. DRLs of Korea were similar to other countries for head examinations. For chest examinations and abdomen pelvis examinations were relatively lower than other countries. As a major reason for relatively low radiation dose, it is considered to contribute the activity and management of medical radiation safety at national level.

• Journal of Audiology & Otology
• /
• v.23 no.4
• /
• pp.193-196
• /
• 2019

Background and Objectives: Facial nerve stimulation (FNS) is a complication of cochlear implantation (CI). This study compared the thickness and density of the bone separating the upper basal turn of the cochlea (UBTC) and the labyrinthine segment of the facial nerve (LSFN) on preoperative computed tomography (CT) in patients with and without FNS after CI. Subjects and Methods: Adult patients who underwent CI from January 2011 to February 2017 with preoperative CT at a tertiary referral hospital were considered for this retrospective case-control study. Patients were divided into two groups: with FNS (n=4) and without FNS (n=53). The density and thickness of the bone between the LSFN and UBTC were measured on preoperative CT. Charts were reviewed for other parameters. Results: A statistically significant difference was seen in the thickness (p=0.007) but not in the density (p=0.125) of the bone between the UBTC and LSFN. Four patients had FNS at the mid-range electrode arrays, and one of them additionally had FNS at the basal arrays. Conclusions: Decreased thickness of the bone between the UBTC and LSFN can explain postoperative FNS, confirming the histologic and radiologic findings in previous studies, which indicated that the thickness of the temporal bone between the LSFN and UBTC is less in patients who experience FNS. While the density in this region was also less, it was not statistically significant.

• Korean Journal of Audiology
• /
• v.23 no.4
• /
• pp.193-196
• /
• 2019

Background and Objectives: Facial nerve stimulation (FNS) is a complication of cochlear implantation (CI). This study compared the thickness and density of the bone separating the upper basal turn of the cochlea (UBTC) and the labyrinthine segment of the facial nerve (LSFN) on preoperative computed tomography (CT) in patients with and without FNS after CI. Subjects and Methods: Adult patients who underwent CI from January 2011 to February 2017 with preoperative CT at a tertiary referral hospital were considered for this retrospective case-control study. Patients were divided into two groups: with FNS (n=4) and without FNS (n=53). The density and thickness of the bone between the LSFN and UBTC were measured on preoperative CT. Charts were reviewed for other parameters. Results: A statistically significant difference was seen in the thickness (p=0.007) but not in the density (p=0.125) of the bone between the UBTC and LSFN. Four patients had FNS at the mid-range electrode arrays, and one of them additionally had FNS at the basal arrays. Conclusions: Decreased thickness of the bone between the UBTC and LSFN can explain postoperative FNS, confirming the histologic and radiologic findings in previous studies, which indicated that the thickness of the temporal bone between the LSFN and UBTC is less in patients who experience FNS. While the density in this region was also less, it was not statistically significant.

• Korean Journal of Head & Neck Oncology
• /
• v.23 no.1
• /
• pp.58-62
• /
• 2007

Schwannoma is a benign well-encapsulated tumors arising from the sheath of Schwann cell of the peripheral motors, sensory, and cranial nerves, but not from the optic and olfactory nerves. Since it is relatively common in the head and neck region, it should be included in the differential diagnosis of head and neck tumor. However, reports of laryngeal involvement have rarely appeared in the literature. We have experienced a 50-year old woman and 39-year old woman with history of progressive voice change. We recognized a benign mass at the false cord area with the telelaryngoscope and CT. The tumors were successfully removed by transoral CO2 laser resection without tracheotomy.

• Korean Journal of Head & Neck Oncology
• /
• v.25 no.2
• /
• pp.163-167
• /
• 2009

Sinonasal malignant tumors comprise less than 1% of all cancers and 3% of all malignant tumors of the head and neck, which explains a lack of large series addressing the clinical characteristics and management of these tumors. Neck node metastasis occurs in only about 7% to 15% of malignant tumors compared with other head and neck cancers. A 90-yr-old woman presented with left palpable neck mass and right nasal mass occupying nasal cavity. Fine needle aspiration biopsy of left neck mass results in metastatic squamous cell carcinoma(SCC). PET/CT shows intense FDG uptake in right nasal cavity with bone invasion. Histopathologic examination of excised lesion in the right nasal cavity revealed SCC. We report here on a primary sinonasal SCC with contralateral lymph node metastasis.