• Journal of the Korean Society of Visualization
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• v.22 no.2
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• pp.74-81
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• 2024

Accurate tissue temperature monitoring during clinical procedures, such as laser therapy or surgery, is crucial for ensuring patient safety and treatment efficacy. Noninvasive techniques are essential to prevent tissue disturbance while providing real-time temperature data. However, current methods often struggle to accurately measure temperature at various depths within the skin, which is essential to avoid damage to surrounding healthy tissues due to excessive heat. In response to this challenge, we developed a confocal imaging system that utilizes the laser speckle imaging (LSI) technique for precise depthwise temperature monitoring. LSI uses laser light scattering to capture subtle changes in speckle patterns on the skin's surface due to temperature fluctuations within the tissue. By analyzing these changes, LSI enables accurate depth-resolved temperature measurements. This technique enhances the precision and safety of medical procedures, offering significant potential for broader clinical applications, improved patient outcomes, and better thermal management during interventions.

• Journal of the Korean Society of Radiology
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• v.11 no.7
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• pp.671-677
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• 2017

In this study, scattering factors affecting the quality of medical images were quantitatively analyzed and investigated. MCNPX simulation was conducted by using ANSI phantom, made of tissue equivalent materials, to calculate the scattering ratio occurred by the increase of the object thickness. Then, the result of the simulation was compared with the result of actual radiation measurement. In addition, we evaluated the image quality by the RMS evaluation, RSD and NPS analysis using X-ray images acquired with increasing object thickness. Furthermore, the scattering ratio was analyzed by increasing the thickness of acrylic phantom on chest phantom. The result showed that the scattering ratio was increased to 57.2%, 62.4%, and 66.8% from 48.9%, respectively, when the acrylic phantom thickness was increased by 1 inch from 6.1 inches. The results of MCNPX simulation and the actual measured scattering dose showed similar results. Also, as a result of RMS measurement from acquired x-ray images, the standard deviation decreased as the object thickness increased. However, in the RSD analysis considering the average incident dose, the results were increased from 0.028 to 0.039, 0.051, 0.062 as the acrylic phantom thickness was increased from 6.1 inches to 7.1 inch, 8.1 inch, and 9.1 inch, respectively. It can be seen that the increase of the scattering effect due to the increase of the object thickness reduces the SNR. Also, the NPS results obtained by measuring scattered radiation incident on the detector resulted in the increase of the noise as the object thickness increased.

• Proceedings of the KIEE Conference
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• 2003.11c
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• pp.600-603
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• 2003

Energy spectrum modulation of X-ray source in digital mammography has been studied. In this study, we calculated various filtered spectra using the scattering data. Primary spectra were generated by Molybdenum (Mo) and Tungsten (W) targets. The materials of added filters are Molybdenum and Rhodium (Rh) for 40 kVp Mo. primary spectrum, the amounts of photons over whole energy ranges are attenuated to 0.43 with 0.03 mm Mo filter and 0.38 with 0.06 mm Mo filter while the photons of energy ranged from 17 keV to 20 keV. The photons of low energy ranged below 17 keV are considerably attenuated. This effect brings out reducing the scattered radiation and dose to the patient, and enhancing subject contrast in the image. The results show that filtered spectra are not seriously affected by X-ray tube loadability. Because the energy range from 17 keV to 20 keV is directly transmitted although low and high energies are mainly filtered.

• Journal of Radiation Protection and Research
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• v.44 no.4
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• pp.156-160
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• 2019

Background: To compare the dose of radiation received by the fetus in a pregnant patient irradiated for head and neck cancer using helical tomotherapy and three-dimensional conformal radiation therapy (3DCRT). Materials and Methods: The patient was modeled with a humanoid phantom to mimic a gestation of 26 weeks. Radiotherapy with a total dose of 2 Gy was delivered with both tomotherapy (2.5 and 5.0 cm jaw size) and 3DCRT. The position of the fetus was predicted to be 45 cm from the field edge at the time of treatment. The delivered dose was measured according to the distance from the field edge and the fetus. Results and Discussion: The accumulated dose to the fetus was 1.6 cGy by 3DCRT and 2 and 2.3 cGy by the 2.5 and 5 cm jaw tomotherapy plans. For tomotherapy, the fetal dose with the 2.5 cm jaw was lower than that with the 5 cm jaw, although the radiation leakage was greater for 2.5 cm jaw plan due to the 1.5 fold longer beam-on time. At the uterine fundus, tomotherapy with a 5 cm jaw delivered the highest dose of 2.4 cGy. When the fetus moves up to 35 cm at the 29th week of gestation, the resultant fetal doses for 3DCRT and tomotherapy with 2.5 and 5 cm jaws were estimated as 2.1, 2.7, and 3.9 cGy, respectively. Conclusion: For tomotherapy, scattering radiation was more important due to the high monitor unit values. Therefore, selecting a smaller jaw size for tomotherapy may reduce the fetal dose. however, evaluation of risk should be individually performed for each patient.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.12
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• pp.1124-1131
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• 2011

In this paper, image reconstruction algorithm for breast cancer detection using MT(Microwave Tomography) was investigated. The breast cancer detection system under development uses 16 transmit/receive antennas. The signal waveform was a sinusoidal wave at 900 MHz. To solve the 2D inverse scattering problem, we used the 2D FDTD (Finite Difference Time Domain) method for forward calculation and LMA(Levenberg-Marquardt Algorithm) for optimization. The result of the image reconstruction using the numerical phantom by MRI(Magnetic Resonance Imaging) obtained from real patient of breast cancer showed that we can detect the position of the tumor accurately.

• The Korean Journal of Nuclear Medicine Technology
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• v.13 no.1
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• pp.3-8
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• 2009

Purpose: Onco flash shortens a scan time with half and there is a possibility of getting the data which corresponds in existing. The experiment which makes the image whose Onco Flash is excellent OSEM tried, as changes parameter of time, iteration. After reconstituting an image, produces FWHM and executes an evaluation. Materials and Methods: Siemens e.cam gamma camera, standard Jaszczak phantom and spatial resolution phantom was used. In order for the bubble not to enter, implants 2 mCi and volume 0.25 cc $^{99m}Tc$ respectively in line 3 to spatial resolution phantom. Put on that phantom on the table correctly, and acquires an image. 15 mCi putting in distilled water to mix $^{99m}Tc$ well in Jaszczak phantom and acquires image just like spatial resolution phantom. Reconstructs and converts the image to digital image as Sante program. Produce FWHM and evaluate by Amide. Results: The non-scattered image shows better FWHM value than scattered image. As time increases from 10 sec to 30 sec for 5sec interval, FWHM appeared to 30.1, 28.5, 24.5, 23.6, 23.4 mm. At the standard iteration value 4, OSEM FWHM shows 8.0 mm, and Onco Flash is 8.1 mm. As fade in iteration, FWHM value more and more decreased. Conclusion: When using Onco Flash, shortens a scan time, and enhances image quality. Also, user can adjust the parameters to improve resolution. Therefore, patient and user are satisfied with these merits.

• Journal of the Korean Society of Radiology
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• v.9 no.7
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• pp.445-448
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• 2015

Recently there has been increasing interest in the filter to reduce the proportion of low-energy photons in the polychromatic X-ray, affect the quality of the image quality by X-ray hardening effect is a situation that has been overlooked. In this study, by evaluating the change in FSR based on the filter and it was quantitatively discuss scatter dose affecting the medical image quality. The results of the experiment, as the thickness of the filter is increased, up to 13.9%p, that tends to FSR increases appearance were evaluated. Based on these results, in compliance with the thickness of the filter that has been recommended in KS standard, even while reducing the radiation dose of the patient, in addition to the noise to about 1%p within the FSR only medical image the contribution to it is conceivable. Therefore, even while reducing radiation dose of the patient, in order to improve the quality of the medical image, the use of appropriate filter is considered important.

• Journal of the Korean Society of Radiology
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• v.14 no.7
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• pp.907-913
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• 2020

There have been continuous controversies on medical X-ray protection and numerous researchers have been trying to prevent unnecessary exposure to radiation. As X-ray passes through the patient and obtains an image, it creates scattered ray due to interactions such as photoelectric effect and Compton scattering with the subject. As a result, both medical radiation staff and patient are exposed to unnecessary radiation on areas other than the target area. In response, this study will be assuming a body of a female, radiating X-ray on the phantom under the conditions of lumbar spine AP test, and measuring scattered ray around breasts and thyroid glands. Then, The experiment results were as follows. After application of non-shielding material, the average of scattered ray was 0.88 mR in thyroid measurement, 3.34 mR, Lt Axillary 3.54 mR, and Rt Axillary 3.03 mR in mamonary measurement but, After application of shielding material, the average of scattered ray was 0.16 mR in thyroid measurement, 0.60 mR, Lt Axillary 0.64 mR, and Rt Axillary 0.54 mR in mamonary measurement showing average scattered ray protection effect of about 82%. This study suggested the manufacturing method of a Jelly-type shielding material, identified the possibilities of researches on mixing various substances with radiology field, and verified the usability of the Jelly-type shielding material as a substitute for existing protection tools.

• Journal of radiological science and technology
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• v.25 no.1
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• pp.63-71
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• 2002

The aim of this study Is to develop a simple and fast method which computes in-vivo doses from transmission doses measured doting patient treatment using an ionization chamber. Energy fluence and the dose that reach the chamber positioned behind the patient is modified by three factors: patient attenuation, inverse square attenuation. and scattering. We adopted a straightforward empirical approach using a phantom transmission factor (PTF) which accounts for the contribution from all three factors. It was done as follows. First of all, the phantom transmission factor was measured as a simple ratio of the chamber reading measured with and without a homogeneous phantom in the radiation beam according to various field sizes($r_p$), phantom to chamber distance($d_g$) and phantom thickness($T_p$). Secondly, we used the concept of effective field to the cases with inhomogeneous phantom (patients) and irregular fields. The effective field size is calculated by finding the field size that produces the same value of PTF to that for the irregular field and/or inhomogeneous phantom. The hypothesis is that the presence of inhomogeneity and irregular field can be accommodated to a certain extent by altering the field size. Thirdly, the center dose at the prescription depth can be computed using the new TMR($r_{p,eff}$) and Sp($r_{p,eff}$) from the effective field size. After that, when TMR(d, $r_{p,eff}$) and SP($r_{p,eff}$) are acquired. the tumor dose is as follows. $$D_{center}=D_t/PTF(d_g,\;T_p){\times}(\frac{SCD}{SAD})^2{\times}BSF(r_o){\times}S_p(r_{p,eff}){\times}TMR(d,\;r_{p,eff})$$ To make certain the accuracy of this method, we checked the accuracy for the following four cases; in cases of regular or irregular field size, inhomogeneous material included, any errors made and clinical situation. The errors were within 2.3% for regular field size, 3.0% irregular field size, 2.4% when inhomogeneous material was included in the phantom, 3.8% for 6 MV when the error was made purposely, 4.7% for 10 MV and 1.8% for the measurement of a patient in clinic. It is considered that this methode can make the quality control for dose at the time of radiation therapy because it is non-invasive that makes possible to measure the doses whenever a patient is given a therapy as well as eliminates the problem for entrance or exit dose measurement.

• Journal of Radiation Protection and Research
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• v.31 no.4
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• pp.203-210
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• 2006

Purpose : To estimate the dose to the embryo/fetus of a pregnant patient with brain tumors, and to design an shielding device to keep the embryo/fetus dose under acceptable levels Materials and Methods : A shielding wall with the dimension of 1.55 m height, 0.9 m width, and 30 m thickness is fabricated with 4 trolleys under the wall. It is placed between a Patient and the treatment head of a linear accelerator to attenuate the leakage radiation effectively from the treatment head, and is placed 1 cm below the lower margin of the treatment field in order to minimize the dose to a patient from the treatment head. An anti-patient scattering neck supporters with 2 cm thick Cerrobend metal is designed to minimize the scattered radiation from the treatment fields, and it is divided into 2 section. They are installed around the patient neck by attach from right and left sides. A shielding bridge for anti-room scattered radiation is utilized to place 2 sheets of 3 mm lead plates above the abdomen to setup three detectors under the lead sheets. Humanoid phantom is irradiated with the same treatment parameters, and with and without shielding devices using TLD, and ionization chambers with and without a build-up cap. Results : The dose to the embryo/fetus without shielding was 3.20, 3.21, 1.44, 0.90 cGy at off-field distances of 30, 40, 50, and 60 cm. With shielding, the dose to embryo/fetus was reduced to 0.88, 0.60, 0.35, 0.25 cGy, and the ratio of the shielding effect varied from 70% to 80%. TLD results were 1.8, 1.2, 0.8, 1.2, and 0.8 cGy. The dose measured by the survey meter was 10.9 mR/h at the patient's surface of abdomen. The dose to the embryo/fetus was estimated to be about 1 cGy during the entire treatment. Conclusion : According to the AAPM Report No 50 regarding the dose limit of the embryo/fetus during the pregnancy, the dose to the embryo/fetus with little risk is less than 5 cGy. Our measurements satisfy the recommended values. Our shielding technique was proven to be acceptable.