• Progress in Medical Physics
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• v.14 no.3
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• pp.175-183
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• 2003

Absorbed dose dosimetry protocols of high energy photon and electron beams, which are widely used and based on an air kerma (or exposure) calibration factors, have somewhat complex formalism and limitations for improving dosimetric accuracy due to the uncertainty of the physical parameters used. Recently, the IAEA and the AAPM published the absorbed dose to water-based dosimetry protocols(IAEA TRS-398 and AAPM TG-51). The dose calibration programs for these two protocols were developed. This program for high energy photon and electron beams was also developed for users to use in a window environment using the Visual C++ language. The formalism and physical parameters of these two protocols were strictly applied to the program. The tables and graphs of the physical data, and the information of ion chambers were numericalized for their incorporation into a database. This program can be useful in developing new dosimetry protocols in Korea.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.260-262
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• 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 Radiation Protection and Research
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• v.47 no.1
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• pp.39-49
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• 2022

Background: For proper monitoring of the eye lens dose, an appropriate calibration factor of a dosimeter and information about the mean energies of X-rays are indispensable. The scattered X-ray energy spectra should be well characterized in medical practices where eye lenses of medical staffs might be high. Materials and Methods: Scattered X-ray energy spectra were experimentally derived for three different types of X-ray diagnostic and therapeutic equipment, i.e., the computed tomography (CT) scan, the angiography and the fluoroscopy. A commercially available CdZnTe (CZT) spectrometer with a lead collimator was employed for the measurement of scattered X-rays, which was performed in the usual manner. Results and Discussion: From the obtained energy spectra, the mean energies of the scattered X-rays lied between 40 and 60 keV. This also agreed with that obtained by the conventional half value layer method. Conclusion: The scattered X-rays to which medical workers may be exposed in the region around the eyes were characterized by means of spectrometry. The obtained mean energies of the scattered X-rays were found to match the flat region of the dosimeter response.

• Proceedings of the Korean Society of Medical Physics Conference
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• 1999.11a
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• pp.196-197
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• 1999

• Proceedings of the Korean Society of Medical Physics Conference
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• 2006.08a
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• pp.92-92
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• 2006

• Proceedings of the Korean Society of Medical Physics Conference
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• 2006.08a
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• pp.107-107
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• 2006

• Progress in Medical Physics
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• v.4 no.2
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• pp.3-7
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• 1993

In the 7th Steering Committee Meeting held in November 1986 in Suba, Fiji, the steering committee made a decision that the Korea Research Institute of Standards and Science (KRISS) coordinates the program of the regional intercomparison of ionizing radiation measurement. Through mutual communications with the Radiation Laboratory at KRISS, five countries (Australia, China, India, Japan and Malaysia) agreed to participate in the X-ray dosimetry standards intercomparison under the auspices of KRISS.

• Progress in Medical Physics
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• v.3 no.1
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• pp.19-24
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• 1992

We have desingned multi channel dosimetry system with Intel single-chip microprocessor. We considered that this system is very useful for patient dose measurement, measurement of sealed source dose distribution and calibration of small field for stereotatic radiosurgery system We have designed that this system use commercially available semicondutor detector and personal computer can control this system and process data through RS-232C serial port.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.302-304
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• 2002

In linac-based stereotactic radiosurgery, assuring the quality of the planning and delivery of external photon beam requires accurate evaluation of beam parameters, usually including output factors, tissue-phantom ratio and off-axis ratios, and measurement of actual dose distributions from simulated treatment. We're going to test the use of calibrated radio chromic film (Gafchromic film; type MD-55, Nuclear associate) using a Lumiscan 75 digitizer to measure absolute dose and relative dose distributions for linac-based radiosurgery unit Relative dose distribution of a human-style spherical acryl phantom were measured using radiochromic film and calculated by treatment planning system. The absolute dose at the sphere center was measured by radiochromic film and micro chamber (Exradin A-14, 0.009cc). What we want to demonstrate in this work, the 'well selected' radiochromic films when external photon beam are used in linac-based stereotactic radiosurgery are very accurate detector for dosimetry.

• Progress in Medical Physics
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• v.35 no.1
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• pp.16-19
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• 2024

A new E_n score of the proficiency test (PT) is formulated; it is applicable when a correlation exists between the reference and participant's values. Based on the uncertainty propagation rule given in ISO/IEC Guide 98-3 (GUM:1995), the E_n score covering the correlation case is newly developed for the PT. The new E_n score will be applied in a future PT organized by the Korea Research Institute of Standards and Science (KRISS) dosimetry team. The new E_n score will enhance measurement traceability and contribute to improving the quality management system of participants in the KRISS PT by avoiding performance underestimation.