• Journal of radiological science and technology
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• v.32 no.3
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• pp.307-312
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• 2009

The purpose of our study was to determine the eyeradiation dose when performing routine multi-detector computed tomography (MDCT). We also evaluated dose reduction and the effect on image quality of using a bismuth eye shield when performing head MDCT. Examinations were performed with a 64MDCT scanner. To compare the shielded/unshielded lens dose, the examination was performed with and without bismuth shielding in anthropomorphic phantom. To determine the average lens radiation dose, we imaged an anthropomorphic phantom into which calibrated photoluminescence glass dosimeter (PLD) were placed to measure the dose to lens. The phantom was imaged using the same protocol. Radiation doses to the lens with and without the lensshielding were measured and compared using the Student t test. In the qualitative evaluation of the MDCT scans, all were considered to be of diagnostic quality. We did not see any differences in quality between the shielded and unshielded brain. The mean radiation doses to the eyewith the shield and to those without the shield were 21.54 versus 10.46 mGy, respectively. The lens shield enabled a 51.3% decrease in radiation dose to the lens. Bismuth in-plane shielding for routine eye and head MDCT decreased radiation dose to the lenswithout qualitative changes in image quality. The other radiosensitive superficial organs specifically must be protected with shielding.

• Radiation Oncology Journal
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• v.16 no.4
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• pp.517-529
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• 1998

Purpose : Although many studies have investigated the dosimetric aspects of stereotactic radiosurgery in terms of target volume, the absorbed doses at extracranial sites: especially the lens or thyroid - which are sensitive to radiation for deterministic or stochastic effect -have infrequently been reported. The aim of this study is to evaluate what effects the parameters of radiosurgery have on the absorbed doses of the lens and thyroid in patients treated by stereotactic radiosurgery, using a systematic plan in a humanoid phantom. Materials and Methods : Six isocenters were selected and radiosurgery was planned using the stereotactic radiosurgery system which the Department of Therapeutic Radiology at Seoul National University College of Medicine developed. The experimental radiosurgery plan consisted of 6 arc planes per one isocenter, 100 degrees for each arc range and an accessory collimator diameter size of 2 cm. After 250 cGy of irradiation from each arc, the doses absorbed at the lens and thyroid were measured by thermoluminescence dosimetry. Results : The lens dose was 0.23$\pm$0.08$\%$ of the maximum dose for each isocenter when the exit beam did not pass through the lens and was 0.76$\pm$0.12$\%$ of the maximum dose for each isocenter when the exit beam passed through the lens. The thyroid dose was 0.18$\pm$0.05$\%$ of the maximum dose for each isocenter when the exit beam did not pass through the thyroid and was 0.41$\pm$0.04$\%$ of the maximum dose for each isocenter when the exit beam Passed through the thyroid. The passing of the exit beam is the most significant factor of organ dose and the absorbed dose by an arc crossing organ decides 80$\%$ of the total dose. The absorbed doses of the lens and thyroid were larger as the isocenter sites and arc planes were closer to each organ. There were no differences in the doses at the surface and 5 mm depth from the surface in the eyelid and thyroid areas. Conclusion : As the isocenter and arc plane were placed closer to the lens and thyroid, the doses increased. Whether the exit beams passed through the lens or thyroid greatly influenced the lens and thyroid dose. The surface dose of the lens and thyroid consistently represent the tissue dose. Even when the exit beam passes through the lens and thyroid, the doses are less than 1$\%$ of the maximum dose and therefore, are too low to evoke late complications, but nevertheless, we should try to minimize the thyroid dose in children, whenever possible.

• Proceedings of the KAIS Fall Conference
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• 2010.11b
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• pp.907-910
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• 2010

치과 진료시 파로라마 장치를 이용한 검사에서 유리선량계를 사용하여 피검자의 피폭선량을 측정하였다. 수정체의 피폭선량 영향을 평가하기 위하여 안경의 재질에 따라 수정체의 피폭선량을 측정하였다. 치아위치별 피폭선량 측정결과 82.4-2,340${\mu}Sv$ 선량분포로 나타나 최대 300% 이상의 피폭선량 차이를 보였다. 따라서 효과적이고 정확한 진단과 피폭선량 관리를 위해서는 장치제조시 예열시간 단축 과차폐등의 조치가 필요할 것으로 생각된다. 안경을 착용하였을 때 착용하지 않았을 때 비하여 수정체의 피폭선량이 안경의 재질에 따라서 1회 검사 시 20-75${\mu}Sv$ 증가되는 것으로 측정되었다. 그러므로 피폭 선량을 최소화하고 효율적인 검사를 위해 치과 파노라마 검사시 안경을 벗고 검사할 것을 권고 한다.

• Radiation Oncology Journal
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• v.10 no.2
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• pp.155-161
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• 1992

The eye lens is known to be radiosensitive organ and catarat can be induced by relatively low dose of radiation. In the treatment of head and neck tumors, shielding blocks are frequently used to minimize dose on sensitive organs. The shielding block, which is made of high atomic number materials (cerrobend), produce significant dose perturbations in megavoltage photon beams. The effects of these perturbations of eye shielding blocks are measured with film and ion chambers for the treatment of head and neck malignancies. Optimum parameters for the treatment are suggested.

• Proceedings of the KAIS Fall Conference
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• 2011.05b
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• pp.586-589
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• 2011

치과 진료시 파노라마 장치를 이용한 검사에서 유리선량계를 사용하여 피검자의 피폭선량을 측정하였다. 특히 방사선에 민감한 수정체의 피폭선량을 줄이기 위하여 자체 제작한 Pb 밴딩의 크기에 따라 수정체 피폭선량을 측정한 결과 Pb밴딩의 크기에 따라서 수정체의 피폭선량이 다르다는 것을 확인할 수 있었다. Pb밴딩의 크기가 3*20*0.2cm에서는 정상치보다 피폭선량이 증가하는 경향을 보였으며 5*20*0.2cm 이상의 크기에서는 피폭선량이 감소하는 결과를 보였다. 또한 획득되어진 영상 7*20*0.2cm 크기에서 진단에 부적합한 영상으로 판정 되었다. 그러므로 피폭선량을 최소화하고 효과적인 파노라마 검사를 수행하기 위해서는 Pb 밴딩 5*20*0.2cm이상 6*20*0.2cm이하 크기를 사용하여 검사에 활용하면 피폭선량이 감소될 것으로 기대한다.

• Journal of the Korean Society of Radiology
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• v.18 no.3
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• pp.283-292
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• 2024

Radiation side effects and complications on the ocular adnexa during electron beam therapy for orbital lymphoma can increase the incidence of posterior subcapsular cataracts. This study simulated a medical linear accelerator and a mathematical model of the eye using monte carlo simulations to evaluate the dose to the ocular adnexa and compare the shielding effectiveness on different parts of the ocular adnexa based on lens shield thickness. The dose assessment results of the ocular adnexa showed that the lens's sensitive area had the highest absorbed dose distribution when no shield was used, followed by the lens's non-sensitive area, the anterior chamber, vitreous humor, cornea, and eyelid in descending order. With the use of a shield, a 2 mm thick shield demonstrated a dose reduction effect of over 90% in the lens's sensitive area, over 83% in the non-sensitive area and anterior chamber, and a dose reduction effect of 30 to 62% in the vitreous body, cornea, and eyelid. For dose reduction in the lens's sensitive area during electron beam therapy for orbital lymphoma, it is necessary to use a shield of at least 2 mm thickness. Additionally, shielding strategies considering the thickness and area of the shield for other ocular adnexa besides the lens are required.

• Journal of Radiation Protection and Research
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• v.37 no.2
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• pp.96-102
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• 2012

International Commission on Radiological Protection (ICRP) has revised its recommendations concerning the tissue reaction to ionizing radiation in accordance with consideration of the detriment arising from non-cancer effects of radiation on health based on recent epidemiological basis. Particularly, for the lens of the eye, the threshold in absorbed dose revised to be 0.5 Gy, for occupational exposure in planned exposure situation the commission recommended "An equivalent dose limit for the lens of the eye of 20 mSv in a year, averaged over defined periods of 5 years, with no single year exceeding 50 mSv." To monitor the radiation exposure of radiation worker, TLD is typically provided and the lens of eye dose can be assessed by run of dose calculation algorithm with TL element response data. This study is to assess equivalent dose of the lens of eye using the Harshaw TLD system and its two different dose calculation algorithms. The result provides the Harshaw TLD system showed the assessment of the lens of eye dose with 48.84% error range.

• Journal of the Korean Society of Radiology
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• v.13 no.6
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• pp.889-894
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• 2019

Upper gastrointestinal series is an examination that uses X-rays. It is important to defend against exposure to radiation during upper gastrointestinal examination because the organs, such as thyroid gland, lens, breasts, and gonads, with relatively high biological sensitivity to radiation are distributed on the examination area. We have made a whole body phantom that can change the depth of organs. radiation dose of eye, thyroid gland, breast and gonads were measured by the same procedure as the actual upper gastrointestinal examination. When performed only fluoroscopy the mean dose reduction of lens, thyroid gland, breast and gonads was 62.2%. The mean dose reduction of lens, thyroid gland, breast and gonads was 59.0% when both fluoroscopy and spot shoot were performed. Therefore, when performed upper gastrointestinal examination it was confirmed that shielding of the lens, thyroid gland, breast and gonads was effective in decreasing the exposure dose. The manufactured human phantom can be used in measuring radiation dose for deep organ because it can adjust the height corresponding to the organs located in the human body.

• The Journal of the Korea Contents Association
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• v.16 no.7
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• pp.451-456
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• 2016

To analyse the absorbed radiation dose of the visual organs (eyes, corneas, lenses) during a head CT scan, a with the purpose of radiation protection was designed. Afterwards, the reduction rate of radiation dose when using an eye-shielding was analyzed. The results showed that the higher the energy, the higher the absorbed dose of the eyes. Excluding the head, the organs with high dose were the eyes, corneas, and lenses, respectively. Furthermore, the dose reduction rate before and after shielding was between 38% and 55% for the eyes, and between 35% and 52% for the corneas. In the case of the lenses, when the front was shielded, the reduction rate was 51%, and when the front and the side were shielded simultaneously, the reduction rate was 67%.

• Journal of the Korean Society of Radiology
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• v.12 no.1
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• pp.47-52
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• 2018

Brain perfusion CT scanning is often employed usefully in clinical conditions as it accurately and promptly provides information about the perfusion state of patients having acute ischemic stroke with a lot of time constraints and allows them to receive proper treatment. Despite those strengths of it, it also has a serious weakness that Lens may be exposed to a lot of dose of radiation in it. In this study, as a way to reduce the dose of radiation to Lens in brain perfusion CT scanning, this researcher conducted an experiment with Bismuth shielding and change of patients' position. TLD (TLD-100) was placed on both lens using the phantom (PBU-50), and then, in total 4 positions, parallel to IOML, parallel to IOML (Bismuth shielding), parallel to SOML, and parallel to SOML (Bismuth shielding), brain perfusion scanning was done 5 times for each position, and dose to Lens were measured. Also, to examine how the picture quality changed in different positions, 4 areas of interest were designated in 4 spots, and then, CT number and noise changes were measured and compared. According to the results of conducting one-way ANOVA on the doses measured, as the significance probability was found to be 0.000, so there was difference found in the doses of radiation to crystalline lenses. According to the results of Duncan's post-hoc test, with the scanning of being parallel to IOML as the reference, the reduction of 89.16% and 89.66% was observed in the scanning of being parallel to SOML and that of being parallel to SOML (Bismuth shielding) respectively, so the doses to Lens reduced significantly. Next, in the scanning of being parallel to IOML (Bismuth shielding), the reduction of 37.12% was found. According to the results, reduction in the doses of radiation was found the most significantly both in the scanning of being parallel to SOML and that of being parallel to SOML (Bismuth shielding). With the limit of the equivalent dose to Lens as the reference, this researcher conducted comparison with the dose to occupational exposure and dose to Public exposure in the scanning of being parallel to IOML and found 39.47% and 394.73% respectively; however in the scanning of being parallel to SOML (Bismuth shielding), considerable reduction was found as 4.08% and 40.8% respectively. According to the results of evaluation on picture quality, every image was found to meet the evaluative standards of phantom scanning in terms of the measurement of CT numbers and noise. In conclusion, it would be the most useful way to reduce the dose of radiation to Lens to use shields in brain perfusion CT scanning and adjust patients' position so that their lens will not be in the field of radiation.