• Proceedings of the Korean Society of Medical Physics Conference
• /
• 2002.09a
• /
• pp.206-207
• /
• 2002

The effective dose due to the X-Ray radiography in the patient positioning for the heavy ion radiotherapy was measured on three regions, chest, upper-abdomen and pelvis. All the radiographic systems and the conditions used in the measurements were same as the clinical trial being performed in National Institute of Radiological Sciences, Japan. The organ or tissue for measurements was selected by following ICRP60$^1$ and the effective dose was calculated from measured organ doses and the surface dose.

• 연구논문집
• /
• s.31
• /
• pp.135-147
• /
• 2001

The wall-thickness of insulated pipelines can be easily evaluated by measuring the gamma-ray transmission intensity because this intensity is inversely proportional to the thickness of insulated pipeline. The main purpose of this study is to develop the nondestructive and filmless on-line inspection system of corrosion by measuring the wall thickness of insulated pipeline. The inspection system is constructed with radioisotope, 64 channel photo diode array detector, crawler system and data taking and operating software. The traditional off-line radiographic method carried out by exposing film cassettes can be replaced by this cost-effective on-line digital imaging method and the application will be greatly expected especially in the chemical and petrochemical industries.

• Progress in Medical Physics
• /
• v.21 no.1
• /
• pp.9-15
• /
• 2010

Scatter radiation considerably affects radiographic image quality by reducing image contrast and contributing to a non-uniform background. Images containing a large portion of scatter radiation may result in an incorrect diagnosis. In the past few years, many efforts have been made to reduce the effects of scatter radiation on radiographic images. The purpose of this study is to accurately measure scatter fractions and evaluate the effectiveness of beam-stop arrays. To measure scatter fraction accurately, a beam-stop array and the SFC (Scatter Fraction Calculator) program were developed. Images were obtained using the beam-stop array for both an anti-scatter technique with an anti-scatter grid and an air gap technique. The scatter fractions of the images were measured using the SFC program. Scatter fractions obtained with an anti-scatter grid were evaluated and compared to scatter fractions obtained without an anti-scatter grid. Scatter fractions were also quantitatively measured and evaluated with an air gap technique. The effectiveness of the beam-stop array was demonstrated by quantifying scatter fractions under various conditions. The results showed that a beam-stop array and the SFC program can be used to accurately measure scatter fractions in radiographic images and can be applied for both developing scatter correction methods as well as systems.

• Journal of the Korean Society of Radiology
• /
• v.5 no.6
• /
• pp.343-349
• /
• 2011

This study was aimed to evaluate the absorbed dose in brain of dental radiography. For radiographic exposure, PLD(photoluminescence dosimetry) chips placed in Rando phantom to measurement the absorbed dose to pituitary gland, orbit, maxillary sinus and submandibular glands, thyroid gland, esophagus. Equipments were used Kodak 2200, Kodak 8000C dental radiographic systems and computed tomography(Lightspeed VCT). The absorbed doses were measured at the same exposure parameters and distance by the clinical factor(kV, mA, sec). The result were as follows ; The absorbed dose for intra-oral radiography were 0.02~2.47cGy, the greatest absorbed dose was 2.47cGy for thyroid gland in maxillary right molar projection. the lowest adsorbed dose was 0.02cGy for submandibular glands in lower anterior projection. The absorbed dose for extra-oral radiography were 0.36~3.44cGy of cephalometric method, 0.14~12.82cGy of panoramic method, 8.17~253.63cGy of computed tomography, the greatest adsorbed dose was 253.63cGy for submandibular glands in maxillary CT scan. the lowest adsorbed dose was 0.14cGy for orbit in panoramic method. As a result, extra-oral radiography was measured more than intra-oral radiography. In particular, method which used computed tomography was measured more than 100 times than intra-oral radiography highly. Therefore, you must show a guideline in extra-oral radiography and an effort to reduce absorbed dose is demanded.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
• /
• v.28 no.2
• /
• pp.471-489
• /
• 1998

For the successful endodontic treatment, root canal should be cleaned thoroughly by accurate mechanical and chemical canal preparation and sealed completely with canal filling material without damaging the periapical tissues. The accuracy of the root canal length measurement is a prerequisite for the success of the endodontic treatment, and the root canal length is often determined by the standard periapical radiographs and digital tactile sense. In this study, the accuracy and the clinical usefulness of Digora/sup (R)/, an intraoral digital imaging processor and the conventional standard radiographs were compared by measuring the length from the top of the file to the root apex. 30 single rooted premolars were invested in a uniformly sized blocks and No.25 K-file was inserted into and fixed in each canal. Each block was placed in equal distance and position to satisfy the principle of the bisecting angle and paralleling techniques and Digora/sup (R)/ system's image and standard periapical radiographs were taken. Each radiograph was examined by 3 different observers by measuring the length from top of the file to the root apex and each data was compared and analyzed. The results were as follows; 1. In the bisecting angle technique, the average difference between the Digora/sup (R)/ system and standard periapical radiograph was 0.002 mm and the standard deviation was 0.341 mm which showed no statistically significant difference between the two systems(p>0.05). Also, in the paralleling technique, the average difference between these two system was 0.007 mm and the standard deviation was 0.323 mm which showed no statistically significant difference between the two systems(p>0.05). 2. In Digora/sup (R)/ system, the average difference between the bisecting angle and paralleling technique was -0.336 mm and the standard deviation was 0.472 mm which showed a statistically significant difference between the two techniques(p<0.05). Also, in the standard periapical radiographs, the average difference between the bisecting angle and paralleling technique was 0.328 mm and the standard deviation was 0.517 mm which showed a statistically significant difference between these two techniques(p<0.05). 3. In Digora/sup (R)/ system and the standard periapical radiographs. there was a statistically significant difference between the measurement using the bisecting angle technique and the actual length(p<0.05), But there was no statistically significant difference between the measurement using the paralleling technique and the actuallength(p>0.05). In conclusion. the determination of the root canal length by using the Digora/sup (R)/ system can give us as good an image as the standard periapical radiograph and using the paralleling technique instead of the bisecting angle technique can give a measurement closer to the actual canal length. thereby contributing to a successful result. Also. considering the advantages of the digital imaging processor such as decreasing the amount of exposure to the patient. immediate use of the image. magnification of image size. control of the contrast and brightness and the ability of storing the image can give us good reason to replace the standard periapical radiographs.

• The Journal of Korean Physical Therapy
• /
• v.25 no.5
• /
• pp.246-251
• /
• 2013

Purpose: The purpose of this study was to provide quantitative data regarding development of the chest wall in children with cerebral palsy (CP) according to Gross Motor Function Classification System (GMFCS) levels and age using the radiological image diameter measurement method. Methods: Subjects included 112 children with CP and 110 healthy children, All of the children underwent simple chest x-ray. The diameters of the upper chest ($D_{apex}$) and lower chest ($D_{base}$) were measured on the anteroposterior (AP) view of a chest x-ray, and the $D_{apex}$ to $D_{base}$ ratio was calculated. Chest wall ratios were compared among children with CP at GMFCS levels I ~ III, GMFCS levels IV and V, and healthy children. Results: The results showed significant differences between the upper and lower chest wall diameters of children with CP at GMFCS levels IV and V, and healthy children (F=4.54, p=0.01; F=3.20, p=0.04). Results of comparison between the chest wall ratios of children with CP and healthy children, showed that the upper chest walls of healthy children were significantly larger in children younger than 48 months (p<0.05), and both the upper and lower chest walls of healthy children were significantly larger compared to children with CP in children older than 48 months (p<0.05). Conclusion: Radiographic measurement for examination of chest wall development is relatively simple, and the results yield quantitative data on development of the chest wall for children with CP. In addition, therapeutic interventions may be considered based on the results.

• Proceedings of the Korean Society of Medical Physics Conference
• /
• 2002.09a
• /
• pp.260-262
• /
• 2002

An accurate measurement of dose distribution is indispensable to perform radiation therapy planning. A measurement technique using a radiographic film, which is called a film dosimetry, is widely used because it is easy to obtain a dose distribution with a good special resolution. In this study, we tried to develop an analyzing system for the film dosimetry using usual office automation equipments such as a personal computer and an image scanner. A film was sandwiched between two solid water phantom blocks (30 ${\times}$ 30 ${\times}$ 15cm). The film was exposed with Cobalt-60 ${\gamma}$-ray whose beam axis was parallel to the film surface. The density distribution on the exposed film was stored in a personal computer through an image scanner (8bits) and the film density was shown as the digital value with NIH-image software. Isodose curves were obtained from the relationship between the digital value and the absorbed dose calculated from percentage depth dose and absorbed dose at the reference point. The isodose curves were also obtained using an Isodose plotter, for reference. The measurements were carried out for 31cGy (exposure time: 120seconds) and 80cGy (exposure time: 300seconds) at the reference point. While the isodose curves obtained with our system were drawn up to 60% dose range for the case of 80cGy, the isodose curves could be drawn up to 80% dose range for the case of 31cGy. Furthermore, the isodose curves almost agreed with that obtained with the isodose plotter in low dose range. However, further improvement of our system is necessary in high dose range.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
• /
• v.12 no.1
• /
• pp.49-56
• /
• 1982

The purpose of this study was to observe the anatomic variation of condylar head and the positional relationship between condylar head and other anatomic structures of head by means of cephalometry using the submentovertex cephalogram from each person in centric occlusion for producing a good quality of temporomandibular joint radiograph. The 100 submentovertex cephalograms of 100 Korean adults consisted of 50 females ranged from 20 to 24 years age and 50 males ranged from 22 to 30 years age, were studied and analyzed statistically. The results were as follows; 1. The mean of the horizontal angulation of condylar head to the transmeatal line (EE-LA) was 18.5° (S.D. 7.9°), and all measurements that indicate the horizontal angulation of condylar head showed considerable differences among individuals. 2. In the comparison of male vs. female in the measurements, statistically significant differences were found in the majority of measurement items, and with exception of R-LA and LA-LA, the rest of these measurements were larger in male than in female. 3. In the comparison of left vs. right in the measurements, statistically significant differences were found in the majority of measurement items, and with exception of PC-CC, the rest of these measurements were larger in right than in left. As above, because the majority of measurements that involve the horizontal angulation of condylar head varied among individuals, between male and female, and between left and right, the condition of various temporomandibular joint radiography should be determined by means of cephalometry using the submentovertex cephalogram for producing the accurate radiographic image of temporomandibular joint.

• The Korean Journal of Pain
• /
• v.25 no.2
• /
• pp.99-104
• /
• 2012

Background: Previous studies have shown that if performed without radiographic guidance, the loss of resistance (LOR) technique can result in inaccurate needle placement in up to 30% of lumbar epidural blocks. To date, no study has shown the efficacy of measuring the depth of the posterior complex (ligamentum flavum, epidural space, and posterior dura) ultrasonographically to distinguish true and false LOR. Methods: 40 cervical epidural blocks were performed using the LOR technique and confirmed by epidurograms. Transverse ultrasound images of the C6/7 area were taken before each cervical epidural block, and the distances from the skin to the posterior complex, transverse process, and supraspinous ligament were measured on each ultrasound view. The number of LOR attempts was counted, and the depth of each LOR was measured with a standard ruler. Correlation of false and true positive LOR depth with ultrasonographically measured depth was also statistically analyzed. Results: 76.5% of all cases (26 out of 34) showed false positive LOR. Concordance correlation coefficients between the measured distances on ultrasound (skin to ligamentum flavum) and actual needle depth were 0.8285 on true LOR. Depth of the true positive LOR correlated with height and weight, with a mean of $5.64{\pm}1.06cm$, while the mean depth of the false positive LOR was $4.08{\pm}1.00cm$. Conclusions: Ultrasonographic measurement of the ligamentum flavum depth (or posterior complex) preceding cervical epidural block is beneficial in excluding false LOR and increasing success rates of cervical epidural blocks.

• Journal of Periodontal and Implant Science
• /
• v.32 no.2
• /
• pp.379-388
• /
• 2002

For the success of dental implant, accurate radiographic evaluation is prerequisite for planning the location of the osseointegrated implants and avoiding injury to vital structures. CT/MPR(computed tomography/multiplanar reformation) shows improved visualization of inferior alveolar canal. In order to obtain cross-sectional images parallel to the teeth, the occlusal plane is used to orientate for the axial plane. If the direction of axial plane is not parallel to the occlusal plane, the reformatted cross-sectional scans will be oblique to the planned fixture direction and will not show the actual dimension of the planned fixture's location. If the available bone height which measured in the cross-sectional view is much greater than the actual available bone height, penetration of canal may occur. The aim of this study is to assess the effect of the axial plane to measurement of available bone height for dental implant in computed tomography of the mandible. 40 patients who had made radiographic stents and had taken CT were selected. The sites that were included in the study were 45 molar regions. In the central panoramic scan, the length from alveolar crest to superior border of inferior alveolar canal(available bone height, ABH) was measured in direction of reformatted cross-sectional plane(uncorrected ABH). Then, length from alveolar crest to superior border of canal was measured in direction of stent(corrected ABH). The angle between uncorrected ABH and corrected ABH was measured. From each ABH, available fixture length was decided by $Br{{\aa}}nemark$ system. The results were following ; the difference between two ABHs was statistically significant in both first and second molar(p< 0.01). The percentage of difference more than 1 mm was 8.7% in first molar and 15.5% in second molar. The percentage of difference more than 2 mm was 2.0% in first molar and 6.6% in second molar. The maximum value of difference was 2.5 mm in first molar and 2.2 mm in second molar. The correlations between difference of 2 ABHs and angle was positive correlations in both first and second molar. The correlation coefficient was 0.534 in first molar and 0.728 in second molar. The second molar has a stronger positive correlation. The percentage of disagreement between 2 fixture lengths from two ABHs was 24.4% in first molar and 28.9% in second molar.