• The Journal of Korean Society for Radiation Therapy
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• v.30 no.1_2
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• pp.49-63
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• 2018

Purpose : The purpose of this study is investigating the changes of treatment plan and comparing skin dose with or without the skin flash. To investigate optimal applications of the skin flash, the changes of skin dose of each plans by various thicknesses of skin flash were measured and analyzed also. Methods and Material : Anthropomorphic phantom was scanned by CT for this study. The 2 fields hybrid IMRT and the 6 fields static IMRT were generated from the Eclipse (ver. 13.7.16, Varian, USA) RTP system. Additional plans were generated from each IMRT plans by changing skin flash thickness to 0.5 cm, 1.0 cm, 1.5 cm, 2.0 cm and 2.5 cm. MU and maximum doses were measured also. The treatment equipment was 6MV of VitalBeam (Varian Medical System, USA). Measuring device was a metal oxide semiconductor field-effect transistor(MOSFET). Measuring points of skin doses are upper (1), middle (2) and lower (3) positions from center of the left breast of the phantom. Other points of skin doses, artificially moved to medial and lateral sides by 0.5 cm, were also measured. Results : The reference value of 2F-hIMRT was 206.7 cGy at 1, 186.7 cGy at 2, and 222 cGy at 3, and reference values of 6F-sIMRT were measured at 192 cGy at 1, 213 cGy at 2, and 215 cGy at 3. In comparison with these reference values, the first measurement point in 2F-hIMRT was 261.3 cGy with a skin flash 2.0 cm and 2.5 cm, and the highest dose difference was 26.1 %diff. and 5.6 %diff, respectively. The third measurement point was 245.3 cGy and 10.5 %diff at the skin flash 2.5 cm. In the 6F-sIMRT, the highest dose difference was observed at 216.3 cGy and 12.7 %diff. when applying the skin flash 2.0 cm for the first measurement point and the dose difference was the largest at the application point of 2.0 cm, not the skin flash 2.5 cm for each measurement point. In cases of medial 0.5 cm shift points of 2F-hIMRT and 6F-sIMRT without skin flash, the measured value was -75.2 %diff. and -70.1 %diff. at 2F, At -14.8, -12.5, and -21.0 %diff. at the 1st, 2nd and 3rd measurement points, respectively. Generally, both treatment plans showed an increase in total MU, maximum dose and %diff as skin flash thickness increased, except for some results. The difference of skin dose using 0.5 cm thickness of skin flash was lowest lesser than 20 % in every conditions. Conclusion : Minimizing the thickness of skin flash by 0.5 cm is considered most ideal because it makes it possible to keep down MUs and lowering maximum doses. In addition, It was found that MUs, maximum doses and differences of skin doses did not increase infinitely as skin flash thickness increase by. If the error margin caused by PTV or other factors is lesser than 1.0 cm, It is considered that there will be many advantages in with the skin flash technique comparing without it.

• The Journal of Korean Society for Radiation Therapy
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• v.32
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• pp.7-15
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• 2020

Purpose: In modern radiotherapy technology, several methods of image guided radiation therapy (IGRT) are used to deliver accurate doses to tumor target locations and normal organs, including CBCT (Cone Beam Computed Tomography) and other devices, ExacTrac System, other than CBCT equipped with linear accelerators. In previous studies comparing the two systems, positional errors were analysed rearwards using Offline-view or evaluated only with a Yaw rotation with the X, Y, and Z axes. In this study, when using CBCT and ExacTrac to perform 6 Degree of the Freedom(DoF) Online IGRT in a treatment center with two equipment, the difference between the set-up calibration values seen in each system, the time taken for patient set-up, and the radiation usefulness of the imaging device is evaluated. Materials and Methods: In order to evaluate the difference between mobile calibrations and exposure radiation dose, the glass dosimetry and Rando Phantom were used for 11 cancer patients with head circumference from March to October 2017 in order to assess the difference between mobile calibrations and the time taken from Set-up to shortly before IGRT. CBCT and ExacTrac System were used for IGRT of all patients. An average of 10 CBCT and ExacTrac images were obtained per patient during the total treatment period, and the difference in 6D Online Automation values between the two systems was calculated within the ROI setting. In this case, the area of interest designation in the image obtained from CBCT was fixed to the same anatomical structure as the image obtained through ExacTrac. The difference in positional values for the six axes (SI, AP, LR; Rotation group: Pitch, Roll, Rtn) between the two systems, the total time taken from patient set-up to just before IGRT, and exposure dose were measured and compared respectively with the RandoPhantom. Results: the set-up error in the phantom and patient was less than 1mm in the translation group and less than 1.5° in the rotation group, and the RMS values of all axes except the Rtn value were less than 1mm and 1°. The time taken to correct the set-up error in each system was an average of 256±47.6sec for IGRT using CBCT and 84±3.5sec for ExacTrac, respectively. Radiation exposure dose by IGRT per treatment was measured at 37 times higher than ExacTrac in CBCT and ExacTrac at 2.468mGy and 0.066mGy at Oral Mucosa among the 7 measurement locations in the head and neck area. Conclusion: Through 6D online automatic positioning between the CBCT and ExacTrac systems, the set-up error was found to be less than 1mm, 1.02°, including the patient's movement (random error), as well as the systematic error of the two systems. This error range is considered to be reasonable when considering that the PTV Margin is 3mm during the head and neck IMRT treatment in the present study. However, considering the changes in target and risk organs due to changes in patient weight during the treatment period, it is considered to be appropriately used in combination with CBCT.

• Journal of agricultural medicine and community health
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• v.27 no.2
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• pp.159-175
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• 2002

This present study was conducted to reduce problems by analyzing training and work of sex education counselors and to come up with ways of improving sex education counseling. A survey was performed in 57 subjects at health centers who finished training on sex education counseling in Taegu Metropolitan City and cities, kuns, and gus of Kyongsangbuk Province from December, 1999 to February, 2000 on general characteristics, items relating to the work of sex education, and ways of improving work. The results are as follows. Out of the sex education counselors, there were 55 females, taking 99% out of the total counselors, and the average age of these counselors was 42 years. There were 26 nurses, and their government grade was level 7 in 36 and level 6 in 14. The members who had finished sex education counseling at each public health center was 2.1 counselors at an average. Among those had finished sex education training, 30 was not in sex counseling. When analyzed the answers given by 27 sex counselors who were counseling at the time and the results are as follows. As for the amount of work, 15 answered to have too much work and 1 little; as for having pride on being a sex education counselor, 18 answered to felt pride and 7 so-so; as for materials for sex education and counseling, 25 answered to use videos, 23 books, 10 pictures, 8 beam projectors, and 7 slides. All of the subjects answered to have other responsibilities besides sex education and counseling, and the satisfaction felt on having other responsibilities was 6 satisfied, 12 average, and 2 dissatisfied. The proportion of work load in sex education counselors was other work besides sex education 76.2%, sex education at schools 7.6%. collecting sex education materials 5.7%, counseling of adolescents 4.9%. development of sex education materials 3.5%, and administrative work related to sex education 3.1%. The biggest problem of their work was over-load in 9 respondents, lack of sex education materials in 8, lack of training in 6, and shortage of professionals in 2. As for the answer on the ways of improving matters related to work of sex education counselors, the most frequent answer was that the organizations responsible for sex education needs to be more professional and systematic, followed by dividing the work load so that they could concentrate on developing education materials and sex education and counseling. Thus, the results of the present study indicated that in order to utilize human resources efficiently, the speciality of counselors needs to be considered when making personnel transfers among health centers, and continued activity as a sex education counselor needs to promoted by reducing other overloading tasks. And systematic re-training of the counselors needs to be done, and education manuals that are diverse and realistic to applicable to the children, who are to be the subjects of sex education, need to be developed and distributed.

• Progress in Medical Physics
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• v.25 no.3
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• pp.128-138
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• 2014

In gated radiation therapy (gRT), due to residual motion, beam delivery is intended to irradiate not only the true extent of disease, but also neighboring normal tissues. It is desired that the delivery covers the true extent (i.e. clinical target volume or CTV) as a minimum, although target moves under dose delivery. The objectives of our study are to validate if the intended dose is surely delivered to the true target in gRT and to quantitatively understand the trend of dose delivery on it and neighboring normal tissues when gating window (GW), motion amplitude (MA), and CTV size changes. To fulfill the objectives, experimental and computational studies have been designed and performed. A custom-made phantom with rectangle- and pyramid-shaped targets (CTVs) on a moving platform was scanned for four-dimensional imaging. Various GWs were selected and image integration was performed to generate targets (internal target volume or ITV) for planning that included the CTVs and internal margins (IM). The planning was done conventionally for the rectangle target and IMRT optimization was done for the pyramid target. Dose evaluation was then performed on a diode array aligned perpendicularly to the gated beams through measurements and computational modeling of dose delivery under motion. This study has quantitatively demonstrated and analytically interpreted the impact of residual motion including penumbral broadening for both targets, perturbed but secured dose coverage on the CTV, and significant doses delivered in the neighboring normal tissues. Dose volume histogram analyses also demonstrated and interpreted the trend of dose coverage: for ITV, it increased as GW or MA decreased or CTV size increased; for IM, it increased as GW or MA decreased; for the neighboring normal tissue, opposite trend to that of IM was observed. This study has provided a clear understanding on the impact of the residual motion and proved that if breathing is reproducible gRT is secure despite discontinuous delivery and target motion. The procedures and computational model can be used for commissioning, routine quality assurance, and patient-specific validation of gRT. More work needs to be done for patient-specific dose reconstruction on CT images.

• Progress in Medical Physics
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• v.25 no.3
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• pp.167-175
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• 2014

The purpose of this study is to evaluate the variation of the dose which is delivered to the patients with glottis cancer under IMRT (intensity modulated radiation therapy) by using the 3D registration with CBCT (cone beam CT) images and the DIR (deformable image registration) techniques. The CBCT images which were obtained at a one-week interval were reconstructed by using B-spline algorithm in DIR system, and doses were recalculated based on the newly obtained CBCT images. The dose distributions to the tumor and the critical organs were compared with reference. For the change of volume depending on weight at 3 to 5 weeks, there was increased of 1.38~2.04 kg on average. For the body surface depending on weight, there was decreased of 2.1 mm. The dose with transmitted to the carotid since three weeks was increased compared be more than 8.76% planned, and the thyroid gland was decreased to 26.4%. For the physical evaluation factors of the tumor, PITV, TCI, rDHI, mDHI, and CN were decreased to 4.32%, 5.78%, 44.54%, 12.32%, and 7.11%, respectively. Moreover, $D_{max}$, $D_{mean}$, $V_{67.50}$, and $D_{95}$ for PTV were increased or decreased to 2.99%, 1.52%, 5.78%, and 11.94%, respectively. Although there was no change of volume depending on weight, the change of body types occurred, and IMRT with the narrow composure margin sensitively responded to such a changing. For the glottis IMRT, the patient's weight changes should be observed and recorded to evaluate the actual dose distribution by using the DIR techniques, and more the adaptive treatment planning during the treatment course is needed to deliver the accurate dose to the patients.

• Progress in Medical Physics
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• v.17 no.3
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• pp.131-135
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• 2006

A commercial ion chamber matrix was examined the characteristics and its performance for radiotherapy qualify assurance. The device was the I'mRT 2D-MatriXX (Scanditronix-Wellhofer, Schwarzenbruck, Germany). The 2D-MatriXX device consists of a 1020 vented ion chamber array, arranged in $24{\times}24cm^2$ matrix. Each ion chamber has a volume of $0.08cm^3$, spacing of 0.762 cm and minimum sampling time of 20 ms. For the investigation of the characteristics, dose linearity, output factor, short-term reproducibility and dose rate dependency were tested. In the testing of dose linearity. It has shown a good signal linearity within 1% in the range of $1{\sim}800$cGy. Dose rate dependency was found to be lower than 0.4% (Range: 100-600 Mu/min) relative to a dose rate of 300 Mu/min as a reference. Output factors matched very well within 0.5% compared with commissioned beam data using a ionization chamber (CC01, Scanditronix-Wellhofer, Schwarzenbruck, Germany) in the range of field sizes $3{\times}3{\sim}24{\times}24cm^2$. Short-term reproducibility (6 times with a interval of 15 minute) was also shown a good agreement within 0.5%, when the temperature and the pressure were corrected by each time of measurement. in addition, we compared enhanced dynamic wedge (EDW, Varian, Palo Alto, USA) profiles from calculated values in the radiation planning system with those from measurements of the MatriXX. Furthermore, anon-uniform IMRT dose fluence was tested. All the comparison studies have shown good agreements. In this study, the MatriXX was evaluated as a reliable dosimeter, and it could be used as a simplistic and convenient tool for radiotherapy qualify assurance.

• Journal of the Korean Society of Radiology
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• v.7 no.3
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• pp.213-219
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• 2013

Currently, about 35 cyclotrons have been operating in South Korea. Most of them are mainly used for the synthesis of radiopharmaceuticals such as $^{18}FDG$, which is a cancer tracer for nuclear medicine. Highly enriched $H_2{^{18}}O$ containing up to 98% of $^{18}O/O$ isotope ratio is used as the target for $^{18}F$ production. The price of the highly enriched $H_2{^{18}}O$ ranges 60~70 USD/g, and all of them have been imported from foreign country in spite of the very expensive price. The target (enriched $H_2{^{18}}O$) is non-radioactive before the proton beam irradiation. But, the post-irradiation target (used $H_2{^{18}}O$) must be managed following the National Radiation Safety Regulations, because it turns into radioactive by the radioactivation of the impurities within the target. Recently, nevertheless of the fast increasing amount of used $H_2{^{18}}O$ in accordance with the increasing number of nuclear medicine cases, any activation analysis on the used $H_2{^{18}}O$ have been conducted yet in Korea. In this research, activation analysis have been conducted to confirm the specific radioactivity(Bq/g) of each radioisotopes within the used $H_2{^{18}}O$. The analysis have been done on the 3 of 20g samples collected from the used $H_2{^{18}}O$ storages at different cyclotron centers. Based on the results, it was confirmed that the "used $H_2{^{18}}O$" contains gamma emitters such as $^{56}Co$, $^{57}Co$, $^{58}Co$, and $^{54}Mn$ as well as the considerable amount of beta emitter $^3H$. It was also confirmed that the only one sample contained over exemption level of gamma emitters while the specific activity of tritium was lower than the exemption level in all samples. The specific activity of radioisotopes were measured different levels in the samples depending on the elapsed time after irradiation. Further study on the activation of the "used $H_2{^{18}}O$" is definitely necessary, nevertheless the as-is results of this research must be useful in establishing a rational "used $H_2{^{18}}O$" management protocol.

• Radiation Oncology Journal
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• v.24 no.4
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• pp.300-308
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• 2006

$\underline{Purpose}$: To develop a wireless CCTV system in semi-beam's eye view (BEV) to monitor daily patient setup in radiation therapy. $\underline{Materials\;and\;Methods}$: In order to get patient images in semi-BEV, CCTV cameras are installed in a custom-made acrylic applicator below the treatment head of a linear accelerator. The images from the cameras are transmitted via radio frequency signal (${\sim}2.4\;GHz$ and 10 mW RF output). An expected problem with this system is radio frequency interference, which is solved utilizing RF shielding with Cu foils and median filtering software. The images are analyzed by our custom-made software. In the software, three anatomical landmarks in the patient surface are indicated by a user, then automatically the 3 dimensional structures are obtained and registered by utilizing a localization procedure consisting mainly of stereo matching algorithm and Gauss-Newton optimization. This algorithm is applied to phantom images to investigate the setup accuracy. Respiratory gating system is also researched with real-time image processing. A line-laser marker projected on a patient's surface is extracted by binary image processing and the breath pattern is calculated and displayed in real-time. $\underline{Results}$: More than 80% of the camera noises from the linear accelerator are eliminated by wrapping the camera with copper foils. The accuracy of the localization procedure is found to be on the order of $1.5{\pm}0.7\;mm$ with a point phantom and sub-millimeters and degrees with a custom-made head/neck phantom. With line-laser marker, real-time respiratory monitoring is possible in the delay time of ${\sim}0.17\;sec$. $\underline{Conclusion}$: The wireless CCTV camera system is the novel tool which can monitor daily patient setups. The feasibility of respiratory gating system with the wireless CCTV is hopeful.

• The Bulletin of The Korean Astronomical Society
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• v.39 no.2
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• pp.90-90
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• 2014

The Immersion Grating Infrared Spectrometer (IGRINS) is the first astronomical spectrograph that uses a silicon immersion grating as its dispersive element. IGRINS fully covers the H and K band atmospheric transmission windows in a single exposure. It is a compact high-resolution cross-dispersion spectrometer whose resolving power R is 40,000. An individual volume phase holographic grating serves as a secondary dispersing element for each of the H and K spectrograph arms. On the 2.7m Harlan J. Smith telescope at the McDonald Observatory, the slit size is $1^{{\prime}{\prime}}{\times}15^{{\prime}{\prime}}$. IGRINS has a plate scale of 0.27" pixel-1 on a $2048{\times}2048$ pixel Teledyne Scientific & Imaging HAWAII-2RG detector with a SIDECAR ASIC cryogenic controller. The instrument includes four subsystems; a calibration unit, an input relay optics module, a slit-viewing camera, and nearly identical H and K spectrograph modules. The use of a silicon immersion grating and a compact white pupil design allows the spectrograph collimated beam size to be 25mm, which permits the entire cryogenic system to be contained in a moderately sized ($0.96m{\times}0.6m{\times}0.38m$) rectangular Dewar. The fabrication and assembly of the optical and mechanical components were completed in 2013. From January to July of this year, we completed the system optical alignment and carried out commissioning observations on three runs to improve the efficiency of the instrument software and hardware. We describe the major design characteristics of the instrument including the system requirements and the technical strategy to meet them. We also present the instrumental performance test results derived from the commissioning runs at the McDonald Observatory.

• Asia pacific journal of information systems
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• v.19 no.3
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• pp.25-49
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• 2009

Advances in technology have resulted in the emergence of new information systems. The convergence of IT and manufacturing sectors has blurred the boundaries among industries. Also, such convergence has become established as a paradigm to build a new area. Especially the convergence of broadcasting and telecommunication, notably in the case of IPTV (Internet Protocol Television), is among the most salient examples of its kind in recent years as a major case of disruptive technology innovation. Despite its much fanfare, such convergence, however, has not fulfilled the expectation; it has not produced positive economic effects while negatively affecting the growth of IPIV. Stakeholders in and around IPIV including telecommunication companies, broadcasting corporations, and government bodies wish to gain control of IPTV under their wings. IPTV has drifted in the midst of conflicts among the stakeholders in and around IPTV, particularly telecommunication and broadcasting organizations in a broad sense. Our empirical research intends to deal with how audiences accept IPTV and how firms provide IPTV services to utilize their resources. Three research questions in this paper include, first, whether Technology Acceptance Model (TAM) can sufficiently explain the acceptance of IPTV as an information system. The second question concerns with empirically testing the playful aspect of IPTV to increase its audience acceptance. Last, but not least, this paper deals with how firms can efficiently and effectively allocate their limited resources to increase IPTV viewers. To answer those three main questions of our study, we collect data from 197 current subscribers of high speed internet service and/or cable/satellite television. Empirical results show that 'perceived usefulness (PU) $\rightarrow$ Intention to use' and 'perceived ease of use (PEU) $\rightarrow$ Intention to use' are significant. Also, 'perceived ease of use' is significantly related to 'perceived usefulness.' Perceived ease of handling IPTV without much effort can positively influence the perceived value of IPTV. In this regard, engineers and designers of IPTV should pay more attention to the user-friendly interface of IPTV. In addition, 'perceived playfulness (PP)' of IPTV is positively related to 'intention to use'. Flow, fun and entertainment have recently gained greater attention in the research concerned with information systems. Such attention is due to the changing features of information systems in recent years that combine the functional and leisure attributes. These results give practical implications to the design of IPTV that reflects not just leisure but also functional elements. This paper also investigates the relationship between 'perceived ease of use (PEU)' and 'perceived playfulness (PP).' PEU is positively related to pp. Audiences without fear can be attracted more easily to the user-friendly IPTV, thereby perceiving the fun and entertainment with ease. Practical implications from this finding are that, to attract more interest and involvement from the audience, IPTV needs to be designed with similar or even more user friendly interface. Of the factors related to 'intention to use', 'perceived usefulness (PU)' and 'perceived ease of use (PEU)' have greater impacts than 'perceived playfulness (PP).' Between PU and PEU, their impacts on 'intention to use' are not significantly different statistically. Managerial implications of this finding are that firms in preparation for the launch of IPTV service should prioritize the functions and interface of IPTV. This empirical paper also provides further insight into the ways in which firms can strategically allocate their limited resources so as to appeal to viewers, both current and potential, of IPTV.