• Korea Journal of Hospital Management
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• v.7 no.2
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• pp.24-36
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• 2002

The purpose of this paper is to find the factors affecting the number of patients per physician for a day at hospital and compare them with the results of previous studies. We used data of Korean national patients survey that had been carried out by central government and local health centers from October 27th to November 11th in 1999. Descriptive analyses were performed to overview the general characteristics of our study subject. Also, we tried to find the factors affecting the number of patients per physician for a day at hospital through t test and correlation analysis. Factors affecting the number of outpatients per physician for a day at hospital are location, training type, ownership, No. of physicians, No. of beds per physician, No. of physicists per physician, No. of nursing aids per physician and No. of medical technicians per physician. While factors affecting the number of inpatients per physician for a day at hospital are location, ownership, No. of physicians, No. of beds per physician, No. of pharmacists per physician, No. of nurses per physician, No. of nursing aids per physician and No. of administrative auxiliary personnels per physician. The most correlated variable with outpatients per physician for a day at hospital is No. of medical technicians per physician while the most correlated variable with inpatients per physician for a day at hospital is No. of beds per physician. A more detailed investigation is needed for verifying factors affecting the number of patients per physician for a day at hospital and other medical institutions.

• Journal of Radiation Protection and Research
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• v.46 no.2
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• pp.39-47
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• 2021

Background: The National Institutes for Quantum and Radiological Science and Technology-National Institute of Radiological Sciences (QST-NIRS) has continuously investigated the undesired radiation exposure in ion beam radiotherapy mainly in carbon-ion radiotherapy (CIRT). This review introduces our investigations on the secondary neutron dose in CIRT with the broad and scanning beam methods. Materials and Methods: The neutron ambient dose equivalents in CIRT are evaluated based on rem meter (WENDI-II) measurements. The out-of-field organ doses assuming prostate cancer and pediatric brain tumor treatments are also evaluated through the Monte Carlo simulation. This evaluation of the out-of-field dose includes contributions from secondary neutrons and secondary charged particles. Results and Discussion: The measurements of the neutron ambient dose equivalents at a 90#x00B0; angle to the beam axis in CIRT with the broad beam method show that the neutron dose per treatment dose in CIRT is lower than that in proton radiotherapy (PRT). For the scanning beam with the energy scanning technique, the neutron dose per treatment dose in CIRT is lower than that in PRT. Moreover, the out-of-field organ doses in CIRT decreased with distance to the target and are less than the lower bound in intensity-modulated radiotherapy (IMRT) shown in AAPM TG-158 (American Association of Physicists in Medicine Task Group). Conclusion: The evaluation of the out-of-field doses is important from the viewpoint of secondary cancer risk after radiotherapy. Secondary neutrons are the major source in CIRT, especially in the distant area from the target volume. However, the dose level in CIRT is similar or lower than that in PRT and IMRT, even if the contributions from all radiation species are included in the evaluation.

• Progress in Medical Physics
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• v.23 no.4
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• pp.209-218
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• 2012

Recently, an adequate number of qualified medical physicist is needed for achieving effective treatment and securing safety to the patient, staff and the public on the course of radiation therapy, since the equipment and the technique of radiation therapy are being developed fast and becoming complex. The studies on medical physics staffing level in United State and European countries were investigated. These results were applied to the domestic situation in order to anticipate indirectly the adequate number of medical physicist in Korea. The current number of medical physicists of 6 (middle to large sized) hospitals in Korea was less than 50% of number recommended in the study. Further detailed research specified on the domestic situation is needed in order to expect adequate number of medical physicist more accurately, and particle beam therapy has to be also considered in the research since the facility site is increasing gradually.

• Progress in Medical Physics
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• v.31 no.3
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• pp.111-123
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• 2020

Deep learning (DL) is a subset of machine learning and artificial intelligence that has a deep neural network with a structure similar to the human neural system and has been trained using big data. DL narrows the gap between data acquisition and meaningful interpretation without explicit programming. It has so far outperformed most classification and regression methods and can automatically learn data representations for specific tasks. The application areas of DL in radiation oncology include classification, semantic segmentation, object detection, image translation and generation, and image captioning. This article tries to understand what is the potential role of DL and what can be more achieved by utilizing it in radiation oncology. With the advances in DL, various studies contributing to the development of radiation oncology were investigated comprehensively. In this article, the radiation treatment process was divided into six consecutive stages as follows: patient assessment, simulation, target and organs-at-risk segmentation, treatment planning, quality assurance, and beam delivery in terms of workflow. Studies using DL were classified and organized according to each radiation treatment process. State-of-the-art studies were identified, and the clinical utilities of those researches were examined. The DL model could provide faster and more accurate solutions to problems faced by oncologists. While the effect of a data-driven approach on improving the quality of care for cancer patients is evidently clear, implementing these methods will require cultural changes at both the professional and institutional levels. We believe this paper will serve as a guide for both clinicians and medical physicists on issues that need to be addressed in time.

• Progress in Medical Physics
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• v.26 no.4
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• pp.241-249
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• 2015

As radiation therapy is one of three major cancer treatment methods, many cancer patients get radiation therapy. To exposure as much radiation to cancer while normal tissues near tumor get little radiation, medical physicists make a radiotherapy plan treatment and perform quality assurance before patient treatment. Despite these efforts, unintended medical accidents can occur by some errors. In order to solve the problem, patient internal dose reconstruction methods by measuring transit dose are suggested. As feasibility study for development of patient dose verification system, inverse square law, percentage depth dose and scatter factor are used to calculate dose in the water-equivalent homogeneous phantom. As a calibration results of ionization chamber and glass dosimeter to transit radiation, signals of glass dosimeter are 0.824 times at 6 MV and 0.736 times at 10 MV compared to dose measured by ionization chamber. Average scatter factor is 1.4 and Mayneord F factor was used to apply percentage depth dose data. When we verified the algorithm using the water-equivalent homogeneous phantom, maximum error was 1.65%.

• Radiation Oncology Journal
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• v.17 no.2
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• pp.172-178
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• 1999

Purpose : To measure the basic structural characteristics of radiation oncology facilities in Korea during 1997 and to compare personnel, equipments and patient loads between Korea and developed countries. Methods and Materials : Mail serveys we conducted in 1998 and data on treatment machines, personnel and peformed new patients were collected. Responses were obtained from the 100 percent of facilities. The consensus data of the whole country were summarized using Microsoft Excel program. Results: In Korea during 1997, 42 facilities delivered megavoltage radiation theraphy with 71 treatment machines, 100 radiation oncologists, 26 medical physicist, 205 technologists and 19,773 new patients. Eighty nine percent of facilities in Korea had linear accelators at least 6 MeV maximum photon energy. Ninety five percent of facilities had simulators while five percent of facilities had no simulator, Ninety one percent of facilities had computer planning systems and eighty three percent of facilities reported that they had a written quality assurance program. Thirty six percent of facilities had only one radiation oncologist and thirty eight percent of facilities had no medical physicists. The median of the distribution of annual patients load of a facility, patients load per a machine, patients load per a radiation oncologist, patients load per a therapist and therapists per a machine in Korea were 348 patients per a year, 263 patients per a machine, 171 patients per a radiation oncologist, 81 patients per a therapist, and 3 therapists per a machine respectively. Conclusions : The whole scale of the radiation oncology departments in Korea was smaller than Japan and USA in population ratio regard. In case of hardware level like linear accelerators, simulators and computer planning systems, there was no big differences between Korea and USA. The patients loads of radiation oncologists and therapists had no significant differences as compared with USA. However, it was desirable to consider the part time system in USA because there were a lot of hospitals which did not employ medical physicists.

• Progress in Medical Physics
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• v.26 no.2
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• pp.112-117
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• 2015

In order to establish the quality control on patient safety following the guideline presented by American Association of Physicists in Medicine (AAPM) TG-100 committee, we aim to analyze the modes based on errors occurred during treatment of patients at the radiation oncology department at Yeungnam University Hospital and establish a quality control guideline for patient safety when patient-centered radiation treatment is conducted. We aim to analyze the errors that can occur during radiation treatment at the radiation department, and assess the frequency of error, the severity of error affecting patients, and probability of proceeding without noticing error, with scores. The places where errors can take place were divided into CT simulation treatment room, treatment planning room, and treatment room for the analysis. In CT simulation treatment room, an error from using the immobilization device showed the highest Risk Priority Number (RPN) value of 60, and an error from simulation treatment information input showed the lowest of 6. In treatment planning room, an error from selecting the radiation dose calculation model showed the highest RPN value of 168, and an error of patient treatment start date showed the lowest of 36. In treatment room, a Table Bar error showed the highest RPN value of 252, a weight change error showed 190, and a Pillow error showed the lowest of 24.

• Progress in Medical Physics
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• v.24 no.4
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• pp.315-322
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• 2013

The aim of this work is to verify the self-quality assurances in medical institutions in Korea through the external audits by the group of experts and have a mutual discussion of the systematic problems. In order to validate the external audits 30 of 80 medical institutions across the nation were picked out considering the regional distribution and the final 25 institutions applied voluntarily to take part in this work. The basic rules were setup that any information of the participants be kept secrete and the measurements be performed with the dosimetry system already verified through intercomparision. The outputs for 2 or more photon beams, the accuracy of gantry rotation and collimator rotation and the poistional accuracy of MLC movement were measured. The findings for the output measurement showed the differences of -0.8%~4.5%, -0.79%~3.01%, and -0.7%~0.07% with respect to that of the verified dosimetry system for the 6MV, 10MV, and 15MV, respectively. For the reference absorbed dose 8 (16%) of 50 photon beams in 25 medical institutions differed 2.0% or greater from the reference value. The coincidences of Field size with x-ray beam and radiation isocenters of Gantry roration and collimator rotation gave the results of within ${\pm}2$ mm for every institute except 2 institutions. The positional accuracy of MLC movement agreed to within ${\pm}1$ mm for every institute. For the beam qualities of 6 MV photon beams kQ values showed the distribution within 0.4% between maximum and minimum. For the protocols 21 institutions (84%) used absorbed dose to water based protocol while 4 insitutions (16%) used air kerma based one. 22 institutions employed the SSD technique while 3 institutions did the SAD one. External audit plays an important role in discovering the systematic problems of self-performing Quality Assurances and having in depth discussion for mutual complementation. Training experts of international level as well as national support system are required so that both the group of experts of medical physicists and government laboratory could perform together periodical and constant external audits.

• Korean Journal of Digital Imaging in Medicine
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• v.12 no.2
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• pp.127-132
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• 2010

In this study, the correlation among the changes of Modulation Transfer Function(MTF) in the noise and high-contrast resolution and the change of Contrast to noise ratio(CNR) in the low-contrast resolution will be examined to investigate the estimation of image quality according to the type of algorithms. The image data obtained by scanning American Association of Physicists in Medicine(AAPM) phantom was applied to each algorithm and the exposure condition of 120 kVp, 250 mAs, and then the CT number and noise were measured. The MTF curved line of the high-contrast resolution was calculated with Point Spread Function(PSF) by using the analysis program by Philips, resulting in 0.5 MTF, 0.1 MTF and 0.02 MTF respectively. The low-contrast resolution was calculated with CNR and the uniformity was measured to each algorithm. Since the measurement value for the uniformity of the equipment was below ${\pm}$ 5 HU, which is the criterion figure, it was found to belong to the normal range. As the algorithm got closer from soft to edge, the standard deviation of CT number increased, which indicates that the noise increased as well. As for MTF, 0.5 MTF, 0.1 MTF and 0.02 MTF were all sharp algorithms, and as the algorithm got closer from soft to edge, it was possible to distinguish more clearly with the naked eye. On the other hand, CNR gradually decreased, because the difference between the contrast hole CT number and the acrylic CT number was the same while the noise of hole increased.

• Progress in Medical Physics
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• v.26 no.3
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• pp.185-191
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• 2015

As radiation therapy is one of three major cancer treatment methods, many cancer patients get radiation therapy. Because of the invisible and scattering characteristics of radiation, it is impossible to identify the quality and the amount of radiation and secondary cancer could be induced by scattered radiation. Because of advanced technique of radiation therapy and the reasons mentioned above, quality assurance of radiotherapy machine should be performed completely. International organizations such as International Atomic Energy Agency (IAEA), American Association of Physicists in Medicine (AAPM) suggest report of quality assurance to recommend united method of radiotherapy machine quality assurance. Domestic society of medical physics, however, is too small to make such a report, domestic hospitals selectively choose some of contents in global suggestions. As there are no suggestions for domestic hospitals and global suggestions are being updated, we did a survey about quality assurance for radiotherapy machine. The questionnaire is composed of possession of radiotherapy machine, items performed for quality assurance and manpower, etc. 37 of 72 hospitals answered to survey. These results could be used for making domestic standard quality assurance procedure.