• Journal of the Korean Society of Radiology
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• v.1 no.3
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• pp.5-10
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• 2007

This study was performed to measure about exposure dose during simple abdmon radiation radiography. The exposure dose was measured by PDD, surface dose, respectively. The result was as followed: 1. When tube voltage were increased with 60-85kv, surface dose were increased. When FFD(focus film distance) at the 50-150cm and mAs were increased, surface dose were decreased. 2. The percentage depth dose(PDD) were appeared 50% below depth dose at 4cm with 60-75kv, and 6cm depth with 80-85kv, 5% below depth dose at 12cm with 60kv, and depth with 65-85kv. 3. The percentage forward scatter increased from 10% to 11.78% at the 60-85kv. The back scatter dose were increase from 25% to 37% at the 60-85kv. The side scatter dose were affected to heel effect.

• 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.

• Radiation Oncology Journal
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• v.11 no.2
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• pp.449-454
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• 1993

The skin sparing effect associated with high energy x-ray or gamma ray beams may be reduce or lost under certain conditions of treatment. Current trends in using large fields. Shield carrying trays, compensating filters, and isocentric methods of treatment have posed problems of increased skin dose which sometimes become a limiting factor in giving adquate tumor doses. We used the shallow ion chamber to measure the phantom surface dose and the physical treatment variables for Co-60 gamma ray, 4MV and 10 MV x-ray beam. The dependence of percent surface dose on field sizes, atomic number of the shielding tray materials and its distance from the surface for 4, 10MV x-rays and Co-60 gamma ray is qualitatively similar. The use of 2 mm thick tin filter is recommended for situations where a low atomic number tray is introduced into the beam at distances less than 15 cm from the surface and with the large field sized for 4 MV x-ray beam. In case of Co-60 gamma ray, the lead glass tray is suitable for enhancement of skin sparing. Also, the filter distance should be as large as possible to achieve substantial skin sparing.

• Journal of the Korean Society of Radiology
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• v.10 no.8
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• pp.597-602
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• 2016

Recent clinical field utilizes the aluminium filter in order to reduce the low-energy photons. However, the usage of the filter can cause adverse effect on the image quality because of the scattered dose that is generated by X-ray hardening phenomenon. Further, usage of filter with improper thickness can be a reason of dose creep phenomenon where unnecessary exposure is generated towards the patient. In this study, the author evaluated the RMS and the RSD analysis in order to have a quantitative evaluation for the effect of forward scattering dose by the filter on the image. as a result of the study, the FSR and the RSD was increased together with the increasing of thickness of the filter. In this study the RSD means the standard deviation of the mean value is relatively size. It can be understood that the signal-to-noise ratio decreases when the average value is taken as a signal and the standard deviation is judged as a noise. The signal-to-noise ratio can understanding as index of resolution at image. Based on these findings, it was quantitatively verified that there is a correlation of the image quality with the FSR by using an additional filter. The results, a 2.5 mmAl which is as recommended by NCRP in the tube voltage of 70 kVp or more showed the 14.6% on the RSD when the filter was not in used. these results are considered able to be utilized as basic data for the study about the filter to improve the quality of the image.

• Journal of the Korean Society of Radiology
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• v.13 no.4
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• pp.589-596
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• 2019

X-rays used for diagnosis have a continuous energy distribution. However, photons with low energy not only reduce image contrast, but also contribute to the patient's radiation exposure. Therefore, clinics currently use filters made of aluminum. Such filters are advantageous because they can reduce the exposure of the patient to radiation. However, they may have negative effects on imaging quality, as they lead to increases in the scattered dose. In this study, we investigated the effects of the scattered dose generated by an aluminum filter on medical image quality. We used the relative standard deviation and the scatter degradation factor as evaluation indices, as they can be used to quantitatively express the decrease in the degree of contrast in imaging. We verified that the scattered dose generated by the increase in the thickness of the aluminum filter causes degradation of the quality of medical images.