• Journal of Broadcast Engineering
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• v.9 no.4 s.25
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• pp.391-401
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• 2004

In this paper, we introduce a novel coding method to efficiently enable spatial random access for high resolution video. In terms of resolution and display size, standard display devices (such as cathode-ray tubes. monitors. PDAs, and LCDs) do not sufficiently support high resolution video such as digital cinema and panoramic video. Currently, users have no choice but to view video at lower resolution as a result of down-sampling, or only a partial region of the video due to display size limitations. Our proposed method. which we call the B-map, represents the set of starting locations of the coded segments in a picture frame. This information, or B-map, is first sent to the decoder prior to the coded data stream of the frame and is then used for fast local decoding. To test our method, we compare our B-map with JPEG tiling and the JPEG Resynchronization marker. Experimental results show that the proposed coding method requires less overhead than existing methods during the same decoding time. The results show promise for future panoramic or digital cinema applications.

• Journal of the Korean Society of Radiology
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• v.17 no.1
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• pp.11-16
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• 2023

In preclinical positron emisson tomography(PET), spatial resolution degradation occurs outside the field of view(FOV). To solve this problem, a depth of interaction(DOI) detector was developed that measures the position where gamma rays and the scintillator interact. There are a method in which a scintillation pixel array is composed of multiple layers, a method in which photosensors are arranged at both ends of a single layer, a method in which a scintillation pixel array is constituted in several layers and a photosensor is arranged in each layer. In this study, a new type of DOI detector was designed by analyzing the characteristics of the previously developed detectors. In the two-layer detector, different sizes of scintillation pixels were used for each layer, and the array size was configured differently. When configured in this form, the positions of the scintillation pixels for each layer are arranged to be shifted from each other, so that they are imaged at different positions in a flood image. DETECT2000 simulation was performed to confirm the possibility of measuring the depth of interaction of the designed detector. A flood image was reconstructed from a light signal acquired by a gamma-ray event generated at the center of each scintillation pixel. As a result, it was confirmed that all scintillation pixels for each layer were separated from the reconstructed flood image and imaged to measure the interaction depth. When this detector is applied to preclinical PET, it is considered that excellent images can be obtained by improving spatial resolution.

• Journal of the Korean Society of Radiology
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• v.18 no.2
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• pp.65-71
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• 2024

To achieve high resolution and sensitivity of positron emission tomography (PET) for small animals, the detector is constructed using very thin and long scintillation pixels. Due to the structure of these scintillation pixels, spatial resolution deterioration occurs outside the system's field of view. To solve this problem, we designed a detector that could improve spatial resolution by measuring the interaction depth and improve sensitivity by using a quasi-block scintillator. A quasi-block scintillator size of 12.6 mm x 12.6 mm x 3 mm was arranged in four layers, and optical sensors were placed on all sides to collect light generated by the interaction between gamma rays and the scintillator. DETECT2000 simulation was performed to evaluate the performance of the designed detector. Flood images were acquired by generating gamma-ray events at 1 mm intervals from 1.3 mm to 11.3 mm within the scintillator of each layer. The spatial resolution and peak-to-peak distance for each location were measured in an 11 x 11 array of flood images. The average measured spatial resolution was 0.25 mm, and the average distance between peaks was 1.0 mm. Through this, it was confirmed that all locations were separated from each other. In addition, because the light signals of all layers were measured separately from each other, the layer of the scintillator that interacted with the gamma rays could be completely separated. When the designed detector is used as a detector in a PET system for small animals, it is considered that excellent spatial resolution and sensitivity can be achieved and image quality can be improved.

• Journal of the Korean Society of Radiology
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• v.9 no.2
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• pp.101-107
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• 2015

In anteroposterior radiation test for cervical vertebra, it is general that the incidence angle of X-ray is $15^{\circ}$ to $20^{\circ}$ degrees to head regardless of position. So this study suggests appropriate incidence angle of cervical vertebra depended on the position. From 1 January 2013 to 31 December 2013, cervical spine radiographys and magnetic resonance imaging was performed in 107 people who visited P Hospital located in Pusan. Among them, 39 people(men 24, women 15) were below 80 above 20 years old(average age 54 years) with normal cervical lordosis(normal $40^{\circ}{\pm}5^{\circ}$). In erect position, the incidence angle of cervical vertebra is measured from lateral radiographic images. And in supine position, it measured from MRI sagittal images. Results based on gender, the incidence angle of cervical vertebra in erect position was $25.9^{\circ}$ for men, women was $23.1^{\circ}$, showed statistically significant (p<0.05). And the angle in supine was $11.6^{\circ}$ for men, women was $12.6^{\circ}$, showed not statistically significant (p>0.05) An analysis of age group shows, the incidence angle of cervical vertebra in erect position was $24.6^{\circ}$ under 50, and $25.0^{\circ}$ over 50. The angle in supine was $12.0^{\circ}$ under 50, and $11.9^{\circ}$ over 50. And all of them showed not statistically significant (p>0.05). At all ages, the average of incidence angles in erect position were $24.8^{\circ}$, and the angle in supine was $12.0^{\circ}$, showed statistically significant (p<0.05). The cervical vertebra incidence angle for X-ray was $15^{\circ}$ to $20^{\circ}$ degrees to head in general. But, through the results, it is recommended that the angle is $24.8^{\circ}$ in erect and $12.0^{\circ}$ in supine position. It could be shown true anteroposterior(AP) view of cervical vertebra and accurate intervertebral fusion fixing devices.

• Radiation Oncology Journal
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• v.16 no.4
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• pp.497-504
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• 1998

Purpose : To evaluate the usefulness of electronic portal imaging device through objective compare of the images acquired using an EPID and a conventional port film Materials and Methods : From Apr. to Oct. 1997, a total of 150 sets of images from 20 patients who received radiation therapy in the pelvis area were evaluated in the Inha University Hospital and Severance Hospital. A dual image recording technique was devised to obtain both electronic portal images and port film images simultaneously with one treatment course. We did not perform double exposure five to ten images were acquired from each patient. All images were acquired from posteroanterior (PA) view except images from two patients. A dose rate of 100-300 Mu/min and a 10-MV X-ray beam were used and 2-10 MUs were required to produce a verification image during treatment. Kodak diagnostic film with metal/film imaging cassette which was located on the top of the EPID detector was used for the port film. The source to detector distance was 140 cm. Eight anatomical landmarks (pelvic brim, sacrum, acetabulum. iliopectineal line, symphysis, ischium, obturator foramen, sacroiliac joint) were assessed. Four radiation oncologist joined to evaluate each image. The individual landmarks in the port film or in the EPID were rated - very clear (1), clear (2), visible (3), not clear (4), not visible (5). Results : Using an video camera based EPID system. there was no difference of image quality between no enhanced EPID images and port film images. However, when we provided some change with window level for the portal image, the visibility of the sacrum and obturator foramen was improved in the portal images than in the port film images. All anatomical landmarks were more visible in the portal images than in the port film when we applied the CLAHE mode enhancement. The images acquired using an matrix ion chamber type EPID were also improved image qualify after window level adjustment. Conclusion : The quality of image acquired using an electronic portal imaging device was comparable to that of the port film. When we used the enhance mode or window level adjustment. the image quality of the EPID was superior to that of the port film. EPID may replace the port film.

• Journal of Korean Orthopaedic Sports Medicine
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• v.8 no.1
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• pp.33-38
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• 2009

Purpose: We wanted to report the clinical characteristics and arthroscopic findings of radial tear in medial meniscus posterior horn insertion, commonly occurs in patient over middle age with documentary review. Materials and Methods: Retrograde study using hospital records was done to 40 cases in 40 patients who visited our hospital and had been performed knee arthroscopic surgery due to medial meniscus posterior horn insertion tear between January, 2005 to April, 2007. Seven cases were male and 33 cases were female with the mean age of 61 (range, 47-80). Trauma history, stage of arthritis, period between pain and operation, MRI findings, clinical symptoms and operation methods were evaluated. Results : Six cases had trauma history while 34 cases didn't. In simple x-ray, using Kellgren-Lawrence classification, 31 cases were between stage 0 and II while 9 cases were stage III. In arthroscopic exam, there were 17 cases of Outerbridge grade IV, 4 cases of grade III, 9 cases of grade II, 9 cases of grade I. The mean duration of pain was 5.3 months. In MRI, at least one finding of cleft in axial or coronal view or ghost sign in sagittal view was found in all cases. The shape of meniscus tears were blunt in 18 cases, transverse in 12 and degenerative tear in 10. Subtotal meniscectomy was performed in 16 cases, partial meniscectomy in 10 cases and meniscal repair in 14 cases. Conclusion : Medial meniscus posterior horn insertion tear occurs in patients over middle age is rarely related to trauma history but causes painful mechanical symptom and usually accompany arthritis. Meniscectomy can be done for the treatment but repair can be considered is some cases. Further study on the treatment result will be needed.

• Journal of the Korean Arthroscopy Society
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• v.13 no.1
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• pp.8-13
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• 2009

Purpose: We used tibialis allograft for the reconstruction of ACL and used Hybrid femoral fixation utilizing $Endobutton^{(R)}$ and $Rigidfix^{(R)}$ for femoral fixation, and used $Retroscrew^{(R)}$ and additional fixation for tibial fixation to evaluate the clinical results. Materials and Methods: The ACL reconstruction were performed from February 2004 to February 2007 utilizing Hybrid femoral fixation and $Retroscrew^{(R)}$ and 32 patients, 32 cases which were available for year-long observation (12 to 25 months). The clinical results (Lysholm knee score, IKDC grade) and the radiologic results(bone tunnel expansion, Telos anterior displacement test) were evaluated. Results: The Lysholm knee score was improved from the average of $67.9{\pm}5.4$ points (range: 51~77) before operation and to $94.1{\pm}6.8$ points (range: 68~98) at the last follow up (p<0.05). 22 cases (69%) were evaluated normal (A), 9 cases (28%) were evaluated nearly normal (B) and only 1 case (3%) was evaluated not normal (C) at IKDC final evaluation and no case was evaluated abnormal. From $Telos^{(R)}$ stress x-ray evaluation, difference from the opposite knee was improved average 13.2 mm{\pm}5.8 (range: 6~21 mm) to average $3.4\;mm{\pm}2.8$ (range: 0~11 mm) after operation (p<0.05). The femoral and tibial tunnel were widened by 18.7% and 9.6% in the AP view and 12.4% and 8.5% in the lateral view, respectively (p<0.05). However, any statistic significance was not observed between bone tunnel expansion and knee joint functions (p>0.05). Conclusion: An ACL reconstruction with tibialis allograft using Hybrid femoral fixation and $Retroscrew^{(R)}$ enabled anatomical fixation of the graft tendon with satisfactory clinical results.

• Journal of radiological science and technology
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• v.31 no.4
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• pp.367-377
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• 2008

We studied the change of bone mineral density (BMD) by age, body mass index (BMI), coffee, carbonated drink, alcohol, smoking, and exercise in adults who checked in health center. The number of study subjects was total 268 persons (women of 136 persons and men of 132 persons). The BMD was determined in lumbar spine and femoral neck by dual energy x-ray absorptiometry. And we got some results as below : 1. In women, mean body height was $155.8{\pm}6.0cm$, mean body weight was $56.8{\pm}7.9kg$, and mean BMI was $23.4{\pm}3.1kg/m^2$. In men, mean body height was $169.1{\pm}6.0cm$, mean body weight was $69.0{\pm}9.5kg$, and mean BMI was $24.1{\pm}2.7kg/m^2$. 2. BMD decreased as age increased, and the age was the most determinant factor for BMD (p<0.01). Women's BMD decreased rapidly in the groups aged $\geq$50s, while men's BMD decreased gradually with age. In addition, for both sex, lower BMD was measured in lumbar spine than in femoral neck. 3. BMD increased in high BMI, and BMD with BMI increased distinctly in the group aged 50s. But their relationship was not significant. 4. In view of the distribution by three BMD categories, women's BMD was mostly normal in the groups aged $\geq$40s, but the rate of osteopenia and osteoporosis was similar in the group aged 50s, and the rate of osteoporosis was the highest in the groups aged 60s and 70s. Men's BMD was mostly normal through all groups except the group aged 70s. 5. Coffee and carbonated drink were not influenced in BMD. But alcohol-drinking group showed higher BMD than non-drinking group, and alcohol was statistically significant determinant for BMD (p<0.05). Smoking and exercise were not statistically significant determinant of BMD.

• Journal of Chest Surgery
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• v.32 no.5
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• pp.442-447
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• 1999

Introduction: Understanding the normal distribution of the tracheal diameter and crross- sectional area is one of the key elements in the management of various tracheal pathologies or tracheal reconstruction for the patients in growing age. However, data for Korean standard has been lacking. This study was designed to analyze retrospectively the distribution of tracheal diameter and cross-sectional area in young Koreans, which can afford fundamental data for the management of tracheal diseases. Material and Method: Of the patients who underwent computerized tomogram of the chest between May 1996 and August 1998, one hundred six young patients(age range: 0-20 years) were included. Patients with any conditions which might affect the tracheal cross-sectional area or diameter, such as tracheal disease, previous operation, mediastinal tumor, or obstructive lung disease were excluded from the study. Gender distribution was 69 males and 37 females. Tracheal diameters, anterior-posterior and transverse, were measured at the level of the thoracic inlet(level I) and the aortic arch(level II). Types of the trachea were divided into round, oval, or horseshoe shaped on cross-sectional view, and the dimension was calculated by using the equation of A=1/4$\pi$ab(A; area, $\pi$; 3.14, a; anterior-posterior diameter, b; transverse diameter). We analyzed the distribution of the diameter at each level and compared the cross-sectional area with respect to age and gender. A p-value lower than 0.05 wa considered significant. Result: The trachea of patients less than 5 years old were round in shape at both of level I and II, and no differences in cross-sectional area was observed between the levels(p=NS). As the age increased, the trachea become oval in shape at level I while it remained round in shape at level II(p=0.020). The tracheal diameter and cross-sectional area increased as the age increased with a linear correlation(r>0.9). In patients less than 5 years of age, female patients showed larger cross-sectional area than male patients (p=0.020), and it was reversed in patients older than 15 years of age(p=0.002). Conclusion: From the above results, we suggest chest computerized tomogram as a safe and reliable tool in measuring the tracheal diameter and cross-sectional area. We also provide the data as a standard for distribution of the tracheal diameter and cross-sectional area in young Korean population.

• Journal of Korean Orthopaedic Sports Medicine
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• v.9 no.1
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• pp.41-47
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• 2010

Purpose: To compare the obliquity of femoral tunnels prepared with transtibial (TT) versus anteromedial portal technique (AM) using x-ray in single-bundle anterior cruciate ligament (ACL) reconstruction. Materials and Methods: Among one-hundred thirty two patients who were undergoing ACL reconstruction from January 2007 to December 2009, thirty patients using TT and twenty patients using AM, those who had single-bundle ACL reconstruction, were evaluated with plain radiographs including anteroposterior, intercondylar notch and lateral view to compare the obliquity of bone tunnels. Results: The mean coronal obliquity of femoral tunnel for TT was $71^{\circ}$ (range; $65^{\circ}{\sim}77^{\circ}$), while for AM was $51^{\circ}$ (range; $39^{\circ}{\sim}60^{\circ}$) and the mean sagittal obliquity of femoral tunnel for TT was $22.7^{\circ}{\pm}7.8$, while for AM was $30.2^{\circ}{\pm}6.9$, their differences between them were statistically significant (P<0.05). However, there were no differences between two techniques on the tibial tunnel obliquity in coronal and sagittal plane. Conclusion: Anterior cruciate ligament reconstruction using AM portal technique allows more horizontally oriented and divergent femoral tunnel compared to that of transtibial technique. This seems to enable the graft placement into the femoral footprint and preserve the posterior cortical wall.