• Progress in Medical Physics
• /
• v.20 no.4
• /
• pp.269-276
• /
• 2009

Radiation treatment techniques using photon beam such as three-dimensional conformal radiation therapy (3D-CRT) as well as intensity modulated radiotherapy treatment (IMRT) demand accurate dose calculation in order to increase target coverage and spare healthy tissue. Both jaw collimator and multi-leaf collimators (MLCs) for photon beams have been used to achieve such goals. In the Pinnacle3 treatment planning system (TPS), which we are using in our clinics, a set of model parameters like jaw collimator transmission factor (JTF) and MLC transmission factor (MLCTF) are determined from the measured data because it is using a model-based photon dose algorithm. However, model parameters obtained by this auto-modeling process can be different from those by direct measurement, which can have a dosimetric effect on the dose distribution. In this paper we estimated JTF and MLCTF obtained by the auto-modeling process in the Pinnacle3 TPS. At first, we obtained JTF and MLCTF by direct measurement, which were the ratio of the output at the reference depth under the closed jaw collimator (MLCs for MLCTF) to that at the same depth with the field size $10{\times}10\;cm^2$ in the water phantom. And then JTF and MLCTF were also obtained by auto-modeling process. And we evaluated the dose difference through phantom and patient study in the 3D-CRT plan. For direct measurement, JTF was 0.001966 for 6 MV and 0.002971 for 10 MV, and MLCTF was 0.01657 for 6 MV and 0.01925 for 10 MV. On the other hand, for auto-modeling process, JTF was 0.001983 for 6 MV and 0.010431 for 10 MV, and MLCTF was 0.00188 for 6 MV and 0.00453 for 10 MV. JTF and MLCTF by direct measurement were very different from those by auto-modeling process and even more reasonable considering each beam quality of 6 MV and 10 MV. These different parameters affect the dose in the low-dose region. Since the wrong estimation of JTF and MLCTF can lead some dosimetric error, comparison of direct measurement and auto-modeling of JTF and MLCTF would be helpful during the beam commissioning.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.19 no.4
• /
• pp.186-196
• /
• 2018

Junior colleges are higher education institutions that have played a major role in the economic development of Korea by providing the necessary human resources for its industrial development. Recently, however, they have experienced difficulties due to the reduction in the number of students. Therefore, it is time for junior colleges as a representative higher vocational education institution to change their role in this rapidly changing environment, and adopt a survival strategy through mutual cooperation and competition. The purpose of this study was to analyze the current state of the national health universities, to investigate the policy changes adopted by colleges and universities, and to utilize the results as data. This study analyzed the current status of health science colleges nationwide and investigated the policy changes as well as the directions presented to the colleges, in order to use the results as the basic data to promote the diversification of the class periods and degree programs. This study surveyed 636 professors from health sciences departments and industry workers from May 1 to May 30, 2017. 70.7% of the respondents supported the transition of the existing three-year systems of the health science departments to four-year systems. The reason for this is that it is possible to strengthen the field practice and personality education of the students by having a sufficient number of class periods, and to provide them with an equal educational background. The most anticipated effect of the transition to a four-year system is to improve the social status of medical personnel and to improve the educational environment of the colleges/universities. Moreover, the universities, associations of medical personnel and Ministry of Education are expected to play a leading role in the transition to the four-year system. Based on the results of this study, it was concluded that a more systematic and advanced vocational education system for the training of professional healthcare workers is needed in the upcoming fourth Industrial Revolution era. Also, this transition is expected to actively foster the education of advanced health care workers thanks to the diversification of the degree programs through the adjustment of the class periods which can be completed by general university (4-year) graduates.

• Journal of the Korean Chemical Society
• /
• v.59 no.5
• /
• pp.397-406
• /
• 2015

ZnO, II-VI group inorganic compound semi-conductor, has been receiving much attention due to its wide applications in various fields. Since the ZnO has 3.37 eV of a wide band gap and 60 meV of big excitation binding energy, it is well-known material for various uses such the optical property, a semi-conductor, magnetism, antibiosis, photocatalyst, etc. When applied in the field of photocatalyst, many research studies have been actively conducted regarding magnetic materials and the core-shell structure to take on the need of recycling used materials. In this paper, magnetic core-shell ZnFe₂O₄@SiO₂ nanoparticles (NPs) have been successfully synthesized through three steps. In order to analyze the structural characteristics of the synthesized substances, X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FT-IR) were used. The spinel structure of ZnFe₂O₄ and the wurtzite structure of ZnO were confirmed by XRD, and ZnO production rate was confirmed through the analysis of different concentrations of the precursors. The surface change of the synthesized materials was confirmed by SEM. The formation of SiO₂ layer and the synthesis of ZnFe₂O₄@ZnO@SiO₂ NPs were finally verified through the bond of Fe-O, Zn-O and Si-O-Si by FT-IR. The magnetic property of the synthesized materials was analyzed through the vibrating sample magnetometer (VSM). The increase and decrease in the magnetism were respectively confirmed by the results of the formed ZnO and SiO₂ layer. The photocatalysis effect of the synthesized ZnFe₂O₄ @ZnO@SiO₂ NPs was experimented in a black box (dark room) using methylene blue (MB) under UV irradiation.

• The Journal of Korean Academy of Sensory Integration
• /
• v.6 no.1
• /
• pp.13-23
• /
• 2008

Objective : The purpose of this study is to investigate awareness of rehabilitation practitioners working at community wellness centers regarding the sensory integration (SI) therapy. Methods : 121 rehabilitation practitioners working at community wellness centers, located in Seoul Gyeonggi, Daegu Gyeongbuk and Busan Ulsan, participated in a questionnaire survey to examine their awareness of SI therapy. The questionnaire constructed based on four elements of the information about SI therapy; SI therapy's purpose, target population and technical process, and the qualification of SI therapist. Correlations between general characteristics and the four awareness elements of SI information were explored. The level of recognition on SI therapy were examined in various perspective such as 'have heard', 'means of the recognition', 'easiness of getting information', 'recognition of necessity of SI therapy', 'willing to participate in professional education course' and 'opinions for improving recognition'. Result : There is significant difference in awareness of the all four elements of SI informations depends on several general characteristics; practitioner's clinical field, location of the center, whether SI service has been provided or not at the center, whether the practitioner carry out SI therapy, and the practitioner's clinical experience in SI therapy. Specially, the recognition of occupational therapists is relatively high compared other rehabilitation practitioners. In terms of level of recognition, most rehabilitation practitioners(96.7%) are well-aware of necessity of sensory integration therapy. 79.4% of the practitioners manifest somewhat of difficulty in getting information related SI therapy. 93.4% of the practitioners are willing to participate in professional education course for SI therapy. Opinion for improving recognition with the most number of people(21) chosen is 'educational revitalization'. Conclusion : Many rehabilitation practitioners working at community wellness centers recognize the necessity of understand SI therapy, but there is uneasiness to get relative and valid information. There are difference awareness of the SI therapy Revitalization of education for SI therapy may provide an opportunity to improve level recognition of rehabilitation practitioners. It is suggested that organ related rehabilitation, there is a need for public relations.

• Journal of Radiation Protection and Research
• /
• v.27 no.1
• /
• pp.37-49
• /
• 2002

The accuracy of radiation dose delivery to target volume is one of the most important factors for good local control and less treatment complication. In vivo dosimetry is an essential QA procedure to confirm the radiation dose delivered to the patients. Transmission dose measurement is a useful method of in vivo dosimetry and it's advantages are non-invasiveness, simplicity and no additional efforts needed for dosimetry. In our department, in vivo dosimetry system using measurement of transmission dose was manufactured and algorithms for estimation of transmission dose were developed and tested with phantom in various conditions successfully. This system was applied in clinic to test stability, reproducibility and applicability to daily treatment and the accuracy of the algorithm. Transmission dose measurement was performed over three weeks. To test the reproducibility of this system, X-tay output was measured before daily treatment and then every hour during treatment time in reference condition(field size; $10 cm{\times} 10 cm$, 100 MU). Data of 11 patients whose pelvis were treated more than three times were analyzed. The reproducibility of the dosimetry system was acceptable with variations of measurement during each day and over 3 week period within ${\pm}2.0%$. On anterior- posterior and posterior fields, mean errors were between -5.20% and +2.20% without bone correction and between -0.62% and +3.32% with bone correction. On right and left lateral fields, mean errors were between -10.80% and +3.46% without bone correction and between -0.55% and +3.50% with bone correction. As the results, we could confirm the reproducibility and stability of our dosimetry system and its applicability in daily radiation treatment. We could also find that inhomogeneity correction for bone is essential and the estimated transmission doses are relatively accurate.

• Journal of the Korean Society of Radiology
• /
• v.14 no.6
• /
• pp.841-848
• /
• 2020

In the field of radiation therapy using photon beams and electron beams, since each patient has a different sensitivity to radiation, skin side effects may occur even at the same dose. Therefore, if there is a risk of excessive dose to the skin, a dosimeter is attached to verify whether the correct dose is being investigated. However, since the skin dosimeter checks the attachment site visually by measuring a point dose, it is difficult to confirm an accurate dose distribution. As a result, the measurement and simulation errors of the material HgI₂ in the 6 MV photon beam were 3.73% and 5.24%, respectively, at the minimum thickness of 25 ㎛, and the material PbI₂ was 4.73% and 5.65%, respectively. On the other hand, as a result of the 6 MeV electron beam, the measurement and simulation errors of the material HgI₂ were 1.35% and 1.12%, respectively, at a minimum thickness of 25 ㎛, and the material PbI₂ showed relatively low attenuation error, 1.67% and 1.20%, respectively. Therefore, it was evaluated that the thickness of the photon beam within 25 ㎛ and the electron beam within 100 ㎛ is suitable to have a reduction rate error within 5%. This study presents a new research direction for a flexible dosimeter attached to the human body that is required in clinical practice and the construction conditions of a future skin dosimeter.

• Journal of Biomedical Engineering Research
• /
• v.25 no.5
• /
• pp.403-414
• /
• 2004

In the accompanying paper, we proposed a real. time volumetric imaging method using a cross array based on receive dynamic focusing and synthetic aperture focusing along lateral and elevational directions, respetively. But synthetic aperture methods using spherical waves are subject to beam spreading with increasing depth due to the wave diffraction phenomenon. Moreover, since the proposed method uses only one element for each transmission, it has a limited transmit power. To overcome these limitations, we propose a new real. time volumetric imaging method using cross arrays based on synthetic aperture technique with linear wave fronts. In the proposed method, linear wave fronts having different angles on the horizontal plane is transmitted successively from all transmit array elements. On receive, by employing the conventional dynamic focusing and synthetic aperture methods along lateral and elevational directions, respectively, ultrasound waves can be focused effectively at all imaging points. Mathematical analysis and computer simulation results show that the proposed method can provide uniform elevational resolution over a large depth of field. Especially, since the new method can construct a volume image with a limited number of transmit receive events using a full transmit aperture, it is suitable for real-time 3D imaging with high transmit power and volume rate.

• Progress in Medical Physics
• /
• v.17 no.1
• /
• pp.24-31
• /
• 2006

Automated analysis software was developed to measure the magnitude of the intrafractional and interfractional errors during breast radiation treatments. Error analysis results are important for determining suitable planning target volumes (PTV) prior to Implementing breast-conserving 3-D conformal radiation treatment (CRT). The electrical portal imaging device (EPID) used for this study was a Portal Vision LC250 liquid-filled ionization detector (fast frame-averaging mode, 1.4 frames per second, 256X256 pixels). Twelve patients were imaged for a minimum of 7 treatment days. During each treatment day, an average of 8 to 9 images per field were acquired (dose rate of 400 MU/minute). We developed automated image analysis software to quantitatively analyze 2,931 images (encompassing 720 measurements). Standard deviations ($\sigma$) of intrafractional (breathing motion) and intefractional (setup uncertainty) errors were calculated. The PTV margin to include the clinical target volume (CTV) with 95% confidence level was calculated as $2\;(1.96\;{\sigma})$. To compensate for intra-fractional error (mainly due to breathing motion) the required PTV margin ranged from 2 mm to 4 mm. However, PTV margins compensating for intefractional error ranged from 7 mm to 31 mm. The total average error observed for 12 patients was 17 mm. The intefractional setup error ranged from 2 to 15 times larger than intrafractional errors associated with breathing motion. Prior to 3-D conformal radiation treatment or IMRT breast treatment, the magnitude of setup errors must be measured and properly incorporated into the PTV. To reduce large PTVs for breast IMRT or 3-D CRT, an image-guided system would be extremely valuable, if not required. EPID systems should incorporate automated analysis software as described in this report to process and take advantage of the large numbers of EPID images available for error analysis which will help Individual clinics arrive at an appropriate PTV for their practice. Such systems can also provide valuable patient monitoring information with minimal effort.

• Journal of Plant Biotechnology
• /
• v.48 no.3
• /
• pp.179-185
• /
• 2021

Indoor gardening includes wall greening, terrariums, and flower arrangements. Among these types of indoor gardens, the terrarium is easy to access for the general public, but in Korea, because of the focus on esthetics, the original purpose of creating terrariums, which was to grow plants sustainably in an enclosed space, has been lost. In addition, miniaturization of plants is required to grow plants in an enclosed space. Since the available plant species suitable for a terrarium are limited, only plants such as succulents, cacti, and moss have been used. In this study, Bronze (X Graptosedum) was used, and these problems were solved using the following three methods: placement and growth of virus-free plants in the terrarium; extending the diversity of plants with minimal size that can be planted in terrariums; and reducing the price of in vitro plants with minimal size by achieving large-scale production. In particular, tissue-cultured succulents were developed into a Vivorium by replacing the tissue culture container and renewing the composition of the plant. This paper suggests a new indoor horticultural field, Vivorium, that can improve the current limitations of terrariums and make them more accessible to the general public. The introduction and popularization of new indoor gardening fields with the increase in single-person households and indoor activities in the Pandemic era can also improve psychological stability among people and in the society.

• Journal of Radiation Protection and Research
• /
• v.23 no.3
• /
• pp.139-147
• /
• 1998

Purpose: Tissue inhomogeneity such as lung affects tumor dose as well as transmission dose in new concept of on-line dosimetry which estimates tumor dose from transmission dose using the new algorithm. This study was carried out to confirm accuracy of correction by tissue density in tumor dose estimation utilizing transmission dose. Methods: Cork phantom (CP, density $0.202\;gm/cm^3$) having similar density with lung parenchyme and polystyrene phantom (PP, density $1.040\;gm/cm^3$) having similar density with soft tissue were used. Dose measurement was carried out under condition simulating human chest. On simulating AP-PA irradiation, PPs with 3 cm thickness were placed above and below CP, which had thickness of 5, 10, and 20 cm. On simulating lateral irradiation, 6 cm thickness of PP was placed between two 10 cm thickness CPs additional 3 cm thick PP was placed to both lateral sides. 4, 6, and 10 MV x-ray were used. Field size was in the range of $3{\times}3$ cm through $20{\times}20$ cm, and phantom-chamber distance (PCD) was 10 to 50 cm. Above result was compared with another sets of data with equivalent thickness of PP which was corrected by density. Result: When transmission dose of PP was compared with equivalent thickness of CP which was corrected with density, the average error was 0.18 (${\pm}0.27$) % for 4 MV, 0.10 (${\pm}0.43$) % for 6 MV, and 0.33 (${\pm}0.30$) % for 10 MV with CP having thickness of 5 cm. When CP was 10 cm thick, the error was 0.23 (${\pm}0.73$) %, 0.05 (${\pm}0.57$) %, and 0.04 (${\pm}0.40$) %, while for 20 cm, error was 0.55 (${\pm}0.36$) %, 0.34 (${\pm}0.27$) %, and 0.34 (${\pm}0.18$) % for corresponding energy. With lateral irradiation model, difference was 1.15 (${\pm}1.86$) %, 0.90 (${\pm}1.43$) %, and 0.86 (${\pm}1.01$) % for corresponding energy. Relatively large difference was found in case of PCD having value of 10 cm. Omitting PCD with 10 cm, the difference was reduced to 0.47 (${\pm}$1.17) %, 0.42 (${\pm}$0.96) %, and 0.55 (${\pm}$0.77) % for corresponding energy. Conclusion When tissue inhomogeneity such as lung is in tract of x-ray beam, tumor dose could be calculated from transmission dose after correction utilizing tissue density.