• Journal of Digital Convergence
• /
• v.16 no.12
• /
• pp.441-447
• /
• 2018

This study aims to develop digital techniques that enable repeated practice of dental radiography using augmented reality technology. A three-dimensional object was fabricated by superimposing a photograph of an adult model and a computed tomography image of a manikin phantom. The system was structured using 106 radiographs such that one of these saved radiographs is opened when the user attempts to take a radiograph on a mobile device. This system enabled users to repeatedly practice at the pre-clinical stage without exposure to radiation. We attempt to contribute to enhancing dental hygienists' competency in dental radiography using these techniques. However, a system that enables the user to actually take a radiograph based on face recognition would be more useful in terms of practice, so additional studies are needed on the topic.

• Journal of radiological science and technology
• /
• v.43 no.6
• /
• pp.431-441
• /
• 2020

The purpose of this study was to construct a model of MVCT(Megavoltage Computed Tomography) dose calculation by using Dosimetry Check™, a program that radiation treatment dose verification, and establish a protocol that can be accumulated to the radiation treatment dose distribution. We acquired sinogram of MVCT after air scan in Fine, Normal, Coarse mode. Dosimetry Check™(DC) program can analyze only DICOM(Digital Imaging Communications in Medicine) format, however acquired sinogram is dat format. Thus, we made MVCT RC-DICOM format by using acquired sinogram. In addition, we made MVCT RP-DICOM by using principle of generating MLC(Multi-leaf Collimator) control points at half location of pitch in treatment RP-DICOM. The MVCT imaging dose in fine mode was measured by using ionization chamber, and normalized to the MVCT dose calculation model, the MVCT imaging dose of Normal, Coarse mode was calculated by using DC program. As a results, 2.08 cGy was measured by using ionization chamber in Fine mode and normalized based on the measured dose in DC program. After normalization, the result of MVCT dose calculation in Normal, Coarse mode, each mode was calculated 0.957, 0.621 cGy. Finally, the dose resulting from the process for acquisition of MVCT can be accumulated to the treatment dose distribution for dose evaluation. It is believed that this could be contribute clinically to a more realistic dose evaluation. From now on, it is considered that it will be able to provide more accurate and realistic dose information in radiation therapy planning evaluation by using Tomotherapy.

• Progress in Medical Physics
• /
• v.25 no.4
• /
• pp.218-224
• /
• 2014

The small field dosimetry is very important in modern radiotherapy because it has been frequently used to treat the tumor with high dose hypo-fractionated radiotherapy or high dose single fraction stereotactic radiosurgery (SRS) with small size target. But, the dosimetry of a small field (< $3{\times}3cm^2$) has been great challenges in radiotherapy. Small field dosimetry is difficult because of (a) a lack of lateral electronic equilibrium, (b) steep dose gradients, and (c) partial blocking of the source. The objectives of this study were to measure and verify with the various detectors the output factors in a small field (<3 cm) for the 6 MV photon beams. Output factors were measured using the CC13, CC01, EDGE detector, thermoluminescence dosimeters (TLDs), and Gafchromic EBT2 films at the sizes of field such as $0.5{\times}0.5$, $1{\times}1$, $2{\times}2$, $3{\times}3$, $5{\times}5$, and $10{\times}10cm^2$. The differences in the output factors with the various detectors increased with decreasing field size. Our study demonstrates that the dosimetry for a small photon beam (< $3{\times}3cm^2$) should use CC01 or EDGE detectors with a small active volume. And also, Output factors with the EDGE detectors in a small field (< $3{\times}3cm^2$) coincided well with the Gafchromic EBT2 films.

• Progress in Medical Physics
• /
• v.17 no.3
• /
• pp.131-135
• /
• 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 Radiation Protection and Research
• /
• v.25 no.4
• /
• pp.197-205
• /
• 2000

A prototype electronic dosimeter(PED) adopting a silicon PIN diode detector as a radiation detector has been developed, manufactured and test-evaluated. A radiation signal processing circuit has been electronically tested and then the radiation detection characteristics of this PED has been performance-tested by using a reference photon radiation field. As a result in a electronic performance test, radiation signals from a detector were well observed in the signal processing circuit. The radiation detection sensitivity of this PED after several test-irradiations to $^{137}Cs$ gamma radiation source appeared to be 1.85 cps/$Gy{\cdot}h^{-1}$ with 19.3% of the coefficient of variation, which satisfied the performance criteria for the active personnel radiation monitor. Further improvement of the electronic circuit and operating program will enable the PED to be used in personal monitoring purpose.

• Journal of Radiation Protection and Research
• /
• v.21 no.2
• /
• pp.139-143
• /
• 1996

A multi-wire proportional counter with large sensitive area was designed and constructed considering diameter of anode wire. its material and space. A preamplifier connecting detector to main amplifier or counter was also designed and constructed for measurement output pulse from multi-wire proportional counter. The preamplifier was composed of charge-sensitive differential circuit. clipping circuit and amplification circuit. To test the performance of this equipment, terminal output pulse from the preamplifier was measured and compared with noise For these tests $^{239}Pu(360 Bq)\;and\; ^{90}Sr/^{90}Y(250 Bq)$ were used as radiation sources. The noise ingredient contributing to the maximum amplitude(180mV from $^{239}Pu$ and 200 mV from $^{90}Sr/^{90}Y$) was found to be very small(8 mV) Piled up pulse occurring at the output pulse of charge-sensitive differential circuit was measured as an independent pulse since this affected the amplification in the clipping circuit and amplification circuit. This information can be used to improve the loss of measurement due to piled up pulse.

• The Journal of Korean Society for Radiation Therapy
• /
• v.29 no.2
• /
• pp.65-73
• /
• 2017

Purpose: Machine Performance Check (MPC) is a self-checking software based on the Electronic Portal Imaging Device (EPID) to measure daily beam outputs without external installation. The purpose of this study is to verify the usefulness of MPC by comparing and correlating daily beam output of QA Beamchecker PLUS. Materials and Methods: Linear accelerator (Truebeam 2.5) was used to measure 10 energies which are composed of photon beams(6, 10, 15 MV and 6, 10 MV-FFF) and electron beams(6, 9, 12, 16 and 20 MeV). A total of 80 cycles of data was obtained by measuring beam output measurement before treatment over five months period. The Pearson correlation coefficient was used to evaluate the consistency of the beam output between the MPC and the QA Beamchecker PLUS. In this study, if the Pearson correlation coefficient is; (1) 0.8 or higher, the correlation is very strong (2) between 0.6 and 0.79, the correlation is strong (3) between 0.4 and 0.59, the correlation is moderate (4) between 0.2 and 0.39, the correlation is weak (5) lower than 0.2, the correlation is very weak. Results: Output variations observed between MPC and QA Beamchecker PLUS were within 2 % for photons and electrons. The beam outputs variations of MPC were $0.29{\pm}0.26%$ and $0.30{\pm}0.26%$ for photon and electron beams, respectively. QA Beamchecker PLUS beam outputs were $0.31{\pm}0.24%$ and $0.33{\pm}0.24%$ for photon and electron beams, respectively. The Pearson correlation coefficient between MPC and QA Beamchecker PLUS indicated that photon beams were very strong at 15 MV, and strong at 6 MV, 10 MV, 6 MV-FFF and 10 MV-FFF. For electron beams, the Pearson correlation coefficient were strong at 16 MeV and 20 MeV, moderate at 9 MeV and 12 MeV, and very weak at 6 MeV. Conclusion: MPC showed significantly strong correlation with QA Beamchecker PLUS when testing with photon beams and high-energy electron beams in the evaluation of daily beam output, but the correlation when testing with low-energy electron beams (6 MeV) appeared to be low. However, MPC and QA Beamchecker PLUS are considered to be suitable for checking daily beam output, as they performed within 2 % of beam output consistency during the observation. MPC which can perform faster than the conventional daily beam output measurement tool, is considered to be an effective method for users.

• Progress in Medical Physics
• /
• v.16 no.3
• /
• pp.130-137
• /
• 2005

In total body irradiation (T81) for leukemia, we have a two methode. One is a AP (anterior-posterior) method and the other is a Lateral methode. Our hospital used lateral methode. T81 must consider about body contour, because of homogeneous dose distribution. For compensation about irregular body contour, we use compensator. For T81 treatment, we must be considered, accurate manufacture of compensator and accurate calculation of dose. We developed the automatic program for T81. This program accomplished for compensator design and dose calculation for irregular body. This program was developed for uses to use in a windows environment using the IDL language. In this program, it use energy data for each energy: TMR, output factor, inverse square law, spoiler, field size factor. This program reduces the error to happen due to the manual. As a development of program, we could decrease the time of treatment plan and care the patient accurately.

• Radiation Oncology Journal
• /
• v.10 no.1
• /
• pp.85-93
• /
• 1992

We have studied the dosimetric properties of electron beam using Lyon intraoperative device for intraoperative radiation therapy. The dosimetry data had compiled in such a way that a quick and correct decision regarding the cone shape, energy, and accurate calculations could be made. Using 3 dimensional water phantom, we have got the following data: cone output ratios, surface dose, $d_{max}$, $d_{90}$, flatness, symmetry, beam profiles, isodose curve, and SSD correction factors. The cone output ratios were measured with straight and bevelled cone, respectively. As the cone size and the energy were reduced, the cone output ratios decreased rapidly. With the flattening filter, the surface dose increased by electron beam to $85.3\%$, $89.2\%$, and $93.4\%$, for 6 MeV, 9 MeV, and 12 MeV, respectively. It is important to increase the surface dose to $90\%$ or more. Inspite of diminishing dose rate and beam penetration, this flattening filter increases the treatment volume significantly. With the combination of the three levels collimation and the flattening filter, we achieved good homogeneity of the beam and better flatness and the diameter of the 90$\%$ isodose curve was increased. It is important to increase the area that is included in the $90\%$ isodose level. The value of measured and calculated SSD correction factors did not agree over the clinically important range from 100 cm to 110 cm.

• Journal of radiological science and technology
• /
• v.31 no.2
• /
• pp.123-127
• /
• 2008

Purpose: As the demand of a simple and precise method increases to evaluate the performance of the inverter type x-ray unit, we evaluated the usefulness of the recently-introduced X-ray Multi-Function Test Device (moldel : Xi (unfors)-prestige). Method: We compared the performance of X-ray Multi-Function Test Device (XMFTD) which is non-inveasive type device with the performance of Dynalyzer III that has been most widely used inveasive type measure device. Result: X-ray output dose was increased a little in the XMFTD, but both devices were below the performance evaluation standard, 0.002 in the output reproducibility. Linearity of XMFTD were below 0.1 which means that Dynalyzer III showed more excellency in linearity. As the the accuracy of exposure factor, 1.8 and 2 tube voltage, 2.01 and 2.3 tube current were measured. The exposure time was also measured by 0.01 sec ${\pm}10%$. Both devices were within the acceptance of performance evaluatioin standard. Conclusion: We proved the usefulness of X-ray Multi-Function Test Device (model: Xi (unfors)-prestige) to evaluated the performance on reproductibility and linearity of X-ray output and accuracy of exposure factor of inverter type unit.