Chang-Bok Kim

Studies on the Ability to Detect Lesions According to the Changes in the MR Diffusion Weighted Images

This study evaluated the ability of Diffusion-Weight Image (DWI), which is one of pulse sequences used in MRI based on the T2 weighted images, to detect samples placed within phantoms according to their size. Two identically sized phantoms, which could be inserted into the breast coil bilaterally, were prepared. Five samples with different sizes were placed in the phantoms, and the T2 weighted images and DWI were obtained. The Breast 2 channel coil of SIEMENS MAGNETOM Avanto 1.5 Tesla equipment was used for the experiments. 2D T2 weighted images were obtained using the following parameters: TR/TE = 6700/74 msec, Thickness/gap = 5/1 mm, Inversion Time (TI) = 130 ms, and matrix = 224 × 448. The parameters of DWI were that TR/TE = 8100/ 90 msec, Thickness/gap = 5/1 mm, matrix = 128 × 128, Inversion Time = 185 ms, and b-value = 0, 100, 300, 600, 1000 s/mm. The ratio of the sample volume on DWI compared to the T2 weighted images, which show excellent ability to detect lesions on MR images, was presented as the mean b-value. The measured b-value of the samples was obtained: 0.5 × 0.5 cm = 0.33/0.34 square × cm (103%), 1 × 1 cm = 1.28/1.25 square × cm (102.4%), 1.5 × 1.5 cm = 2.28/2.67 square x cm (85.39%), 2 × 2 cm = 3.56/4.08 square x cm (87.25%), and 2.5 × 2.5 cm = 7.53/8.77 square × cm (85.86%). In conclusion, the detection ability by the size of a sample was measured to be over 85% compared to T2 weighted image, but the detection ability of DWI was relatively lower than that of T2 weighted image.

Implementation of PACS using PDA System on Medical Images

PACS(Picture archiving communication system) is a system that enables medical images such as X -ray, CT, MRI, PET to be stored electronically viewed on computer screens so that doctors and other authorized people can access search the information as needed. But if they are not in hospital area for example on holiday or at night, that are not able to access the PACS system instantly. We have to solve this problem for more efficient patient care. So we try to suggest a method that use the PDA system that wireless LAN and CDMA cellular phone are equipped. This system may help to access easier to PACS system regardless of the location and can also attribute the development of telemedicne.

Reduction of the Useless Radiation Exposure to Patients and Improvement of the Skill to Manage the Test according to Minimizing Changes of Posture in Bone Mineral Density

As we recognize the health care, test of BMD is increased. There are various methods in BMD, Dual Energy X-ray absorptiometry (DEXA) which has high precision and accuracy, and low medical exposure dose has been widely used. To measure the changes of BMD, the test must be done as same posture at first and follow up study performed a year. we analyze the difference in the hour taken before and after the examination by radiologic technologist, frequency of scout scan, and the amount of the radiation exposure. The hour of the examination and frequency of the scout scan were shorten and the dose of the radiation exposure is reduced. As the numerical value of total subjects is converted into that of one person, the duration for the test was 52 seconds, the frequency for the scout scan 0.79 time, and the dose for the radiation exposure . When the health care provider perform the precise and easy methods to minimize changes of posture and the skillful ability to manage the test, useless radiation is decreased.

Survey for Patient Satisfaction Rate & Patient Leading System Development through RFID and OCS Worklist Program Connection

With the introduction of the computer, convenience at work may have increased but flexibility decreased along with a tendency for humans to become secondary to computers with regards to work schedules. As it exists, from entering the department of radiology to completion of imaging requires a great deal of time and difficulties in understanding the imaging process adds to patient dissatisfaction. Since clinics use RFID bars to track patient locations at comprehensive medical testing centers, departments of radiology may apply RFID and Worklist at the core of the OCS system in order to increase work efficiency and improve work flow. As a result of developing an RFID and Worklist centered OCS program, there was a vast improvement in patient satisfaction and work flow. Theses results are the basis of an RFID system that in the future may be connected to PACS and other systems with an intergrated Worklist. There is a need to realize a plan the can offer ubiquity to hospital work.

A study on comparative analysis of SUVs before and after correction with use of recovery coefficient (RC) in partial volume effect (PVE)

Abstract This study calculated the recovery coefficient (RC) to correct for the partial volume effect (PVE) of a positron emission tomography/computed tomography (PET/CT) scanner by conducting a phantom experiment and analysing the standardised uptake value (SUVs) before and after the correction by applying the calculated RC to the data of a real PET/CT scan. An American College of Radiology (ACR) phantom was used to dilute 20·72 MBq (0·56 mCi) fluorine-18 fluoro-deoxy-glucgose (18F-FDG) uniformly in 1000 ml distilled water, which was injected into a hot cylinder (2·5, 1·6, 1·2 and 0·8 cm in diameter). In addition, 18F-FDG in 33·30 MBq (0·90 mCi), 22·20 MBq (0·60 mCi) and 16·65 MBq (0·45 mCi) was diluted uniformly in 6440 ml distilled water, which was filled with background radioactivity. Subsequently, the experiment was conducted three times under a hot cylinder to background radioactivity ratio (H/B ratio) of 4∶1, 6∶1 and 8∶1. The equipment of Biograph Truepoint 40 was used to conduct a phantom experiment and scan patients based on the whole body protocol. This research purposed 30 patients who visited this hospital to undergo a PET/CT scan from July to August 2011 and were diagnosed with lung cancer. The RC calculated based on the study results was used to compare and analyse the SUVs before and after the PVE correction. When the H/B ratio was 4∶1, the RC was 0·75, 0·72, 0·40 and 0·27 at a hot cylinder diameter of 2·5, 1·6, 1·2 and 0·8 cm, respectively. When the H/B ratio was 6∶1, the respective RC was 0·74, 0·59, 0·55 and 0·43. The respective RC at an H/B ratio of 8∶1 was 0·77, 0·76, 0·58 and 0·42. Overall, the RC decreased with decreasing size of the hot spot region. Among the patients diagnosed with lung cancer, 30 patients were selected randomly for sampling to compare and analyse the maximum SUVs before and after the correction. The average SUVs before and after the correction were 7·83 and 10·31.

A study on quantitative analysis of field size and dose by using gating system in 4D conformal radiation treatment

This study evaluated the gating-based 4-D conformal radiation therapy (4D-CT) treatment planning by a comparison with the common 3-D conformal radiation therapy (3D-CT) treatment planning and examined the change in treatment field size and dose to the tumors and adjacent normal tissues because an unnecessary dose is also included in the 3-D treatment planning for the radiation treatment of tumors in the chest and abdomen. The 3D-CT and gating-based 4D-CT images were obtained from patients who had undergone radiation treatment for chest and abdomen tumors in the oncology department. After establishing a treatment plan, the CT treatment and planning system were used to measure the change in field size for analysis. A dose volume histogram (DVH) was used to calculate the appropriate dose to planning target volume (PTV) tumors and adjacent normal tissue. The difference in the treatment volume of the chest was 0.6 and 0.83 cm on the X- and Y-axis, respectively, for the gross tumor volume (GTV). Accordingly, the values in the 4D-CT treatment planning were smaller and the dose was more concentrated by 2.7% and 0.9% on the GTV and clinical target volume (CTV), respectively. The normal tissues in the surrounding normal tissues were reduced by 3.0%, 7.2%, 0.4%, 1.7%, 2.6% and 0.2% in the bronchus, chest wall, esophagus, heart, lung and spinal cord, respectively. The difference in the treatment volume of the abdomen was 0.72 cm on the X-axis and 0.51 cm on the Y-axis for the GTV; and 1.06 cm on the X-axis and 1.85 cm on the Y-axis for the PTV. Therefore, the values in the 4D-CT treatment planning were smaller. The dose was concentrated by 6.8% and 4.3% on the GTV and PTV, respectively, whereas the adjacent normal tissues in the cord, Lt. kidney, Rt. kidney, small bowels and whole liver were reduced by 3.2%, 4.2%, 1.5%, 6.2% and 12.7%, respectively. The treatment field size was smaller in volume in the case of the 4D-CT treatment planning. In the DVH, the 4D-CT treatment planning showed a higher dose concentration on the part to be treated than the 3D-CT treatment planning with a lower dose to the adjacent normal tissues. Overall, the gating-based 4D-CT treatment planning is believed to be more helpful than the 3D-CT treatment planning.