• Title/Summary/Keyword: 두부CT

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Assessment of the Eye Lens Dose Reduction by Bismuth Shields in Rando Phantom Undergoing CT of the Head (Head CT 검사 시 안구 차폐용 Bismuth사용에 의한 수정체 선량 감소에 대한 평가)

  • Cho, Pyong-Kon;Kim, You-Hyun;Choi, In-Ja;Chang, Sang-Gyu;Chung, Jung-Pyo;Lee, Hyun;Kim, Jang-Seob;Shin, Dong-Cheol;Choi, Jong-Hak;Lee, Ki-Sung;Lee, Won-Ho
    • Journal of radiological science and technology
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    • v.31 no.2
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    • pp.171-175
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    • 2008
  • The aim of this study is to assess the dose reduction of eye lens and availability of bismuth garments resulting from the use of radioprotective bismuth garments to shield the eyes of patients undergoing head CT. Rando phantom and TLDs were used to determine the amount of dose reduction by bismuth shielding of the eye in the following simulated CT scans : (a) scanning of the head including orbits, (b) scanning of the whole head, and (c) $20^{\circ}$ angled scanning of the head excluding orbits. The average dose reduction of eye lens was 43.2%, 36.0% and 1.4% for the three CT scans listed above. Significant reduction in the eye lens dose was achieved by using superficial orbital bismuth shielding during head CT scans. However, bismuth shields should not be used for the patients when their eyes are excluded from the primarily exposed region.

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Application of Total Variation Optimization for Reduction of Head CT Dose (두부 CT 선량감소를 위한 총변량 최적화의 적용)

  • Choi, Seokyoon
    • Journal of the Korean Society of Radiology
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    • v.12 no.6
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    • pp.707-712
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    • 2018
  • The number of CT examinations is increasing, and radiation exposure is also increasing. repeated tests can affect the lens and thyroid. In hospitals, there is a tendency to lack interest in major long-term radiation exposure compared to the interest in increasing image information and image quality with head CT. In this study, we analyzed the improvement of image quality by proposed method to the noisy CT images. The proposed denoising method total variance optimization only for the impulsive noise candidate pixels. Experimental results show that edge information is well preserved and impulse noise can be effectively removed. and worked very well for the images according to tube voltage and rotation time. applied to the clinical setting, it can be used as the lowest exposure condition without worrying about the image quality and it will be helpful for the CT application.

Comparison of midsagittal reference plane in PA cephalogram and 3D CT (3차원 전산화 단층촬영의 Nasion, Sella, Basion으로 구성된 정중 시상 평면과 정면 두부방사선 규격사진의 정중 시상 평면 비교)

  • Cho, Jin-Hyoung;Moon, Ji-Yeon
    • The korean journal of orthodontics
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    • v.40 no.1
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    • pp.6-15
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    • 2010
  • Objective: The aim of this study is to find the most helpful midsagittal reference plane for diagnosis in PA cephalometry compared with 3D CT. Methods: The subjects consisted of 25 adults who showed no facial asymmetry by gross inspection. 3D CT and posteroanterior cephalogram of the subjects were taken. To find the most helpful midsagittal reference plane in PA cephalometry, we considered five kinds of midsagittal planes from which the distances to five landmarks were measured and compared the result with that of 3D CT. The midsagittal plane for 3D CT was determined by the landmarks Nasion, Sella and Basion. Results: PA measurements using the midsagittal reference plane on a perpendicular plane lying through the midpoint of the right and left latero-orbitales was closest to those of 3D CT. Conclusions: It was considered that latero-orbitale perpendicular could be used as the helpful midsagittal reference plane to assess facial asymmetry in PA cephalometry.

The Evaluation of Eye Dose and Image Quality According to The New Tube Current Modulation and Shielding Techniques in Brain CT (두부 CT에서 차폐기법과 새로운 관전류변조기법에 따른 눈의 선량과 화질평가)

  • Kwon, Soonmu;Kim, Jungsu
    • Journal of the Korean Society of Radiology
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    • v.9 no.5
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    • pp.279-285
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    • 2015
  • The eye of human is a radiation sensitive organ and this organ should be shielded from radiation exposure during brain CT procedures. In the brain CT procedures, bismuth protector using to reduce the radiation exposure dose for eye. But protecting the bismuth always accompanies problem of the image quality reduction including artifact. This study aim is the eye radiation exposure dose and image quality evaluation of the new tube current modulation such as new organ based-tube current modulation, longitudinal-TCM, angular-TCM between shielding scan technique using bismuth and lead glasses. As a result, radiation dose of eye is reduced 25.88% in new OB TCM technique then reference scan technique and SNR new OB TCM is 6.05 higher than bismuth shielding scan technique and lower than reference scan technique. In clinical brain CT, new OB TCM technique will contribute to reduction of radiation dose for eye without decrease of image quality.

Analysis and Evaluation of Computed Tomography Dose Index (CTDI) of Pediatric Brain by Hospital Size (병원규모별 소아 두부 CT 검사 선량지표 분석 평가)

  • Kim, Hyeonjin;Lee, Hyoyeong;Im, Inchul
    • Journal of the Korean Society of Radiology
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    • v.10 no.7
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    • pp.503-510
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    • 2016
  • Even though children are exposed to the same amount of radiation, their effective dose amount is higher than those of adults. Therefore, it is very important to reduce the amount of unnecessary radiation exposure because children have a higher radiosensitivity and a smaller body size than adults. In this study, the proposal to seek ways to reduce the amount of radiation is drawn by comparing and analyzing CT Dose Index(CTDI) on the pediatric head CT which was performed at the Busan regional hospitals, to the national diagnostic reference levels. For this, the pediatric head CT scan was conducted among the CT equipments that were installed in downtown Busan. From 2,043 children 10 years old or less who were referred to the pediatric head CT scan, targeting the 28 CT equipments in the 24 hospitals that transmit dose reports to PACS, were examined retrospectively. As a result, the average value of CTDIvol, computed tomography dose index (CTDI) of infant brain, across the hospital, was 31.18 mGy, with DLP of $444.73mGy{\cdot}cm$, which exceeded the diagnostic reference level. The lower the age, the more management is needed for radiation. However, the reality is that the CT examinations are being conducted with a dose that exceeds the reference level as the age of the aged is exceeded. For this purpose, the study seeks to determine the degree of doses of doses outside the diagnostic reference level and analyze the cause of the excess dose and devise measures to reduce the dose reduction.

Radiation Exposure Evaluation of Visual Organs using Bismuth Shielding Material on Head CT Scan (두부 CT촬영 시 비스무스 차폐체를 활용한 시각 기관의 방사선피폭평가)

  • Kang, Se-Sik;Kim, Changsoo;Kim, Jung-Hoon
    • 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%.

Estimate of Radiation Doses in MDCT Using Patient Weight (MDCT 검사에서 환자 체중을 이용한 선량 평가)

  • Kwon, Seong-Ohk;Dong, Kyung-Rae;Kweon, Dae-Cheol;Goo, Eun-Hoe;Choi, Ji-Won;Chung, Woon-Kwan
    • Progress in Medical Physics
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    • v.21 no.3
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    • pp.246-252
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    • 2010
  • The purpose of this study provides measurements of radiation dose from MDCT of head, chest, abdomen and pelvic examinations. A series of dose quantities that are measured of patient weight to compare the dose received during MDCT examinations. Data collected included: weight together with CT dose descriptors, volume CT dose index (CTDIvol) and dose length product (DLP). The effective dose was also estimated and served as collective dose estimation data. Data from 1,774 adult patients attending for a CT examination of the head (n=520) or chest (n=531) or abdomen (n=724) was obtained from spiral CT units using a same CT protocol. Mean values of CTDIvol was a range of 48.6 mGy for head and 6.9, 10.5 mGy for chest, abdomen examinations, respectively. And mean values of DLP was range of 1,604 $mGy{\cdot}cm$ for head, 250 $mGy{\cdot}cm$ for chest, 575 $mGy{\cdot}cm$ for abdomen examinations, respectively. Mean effective dose values for head, chest, abdominal CT were 3.6, 4.2, and 8.6 mSv, respectively. The degree of CTDIvol and DLP was a positive correlation with weight. And there was a positive correlation for weight versus CTDIvol ($r^2$=0.62), DLP ($r^2$=0.694) in chest. And head was also positive correlation with weight versus CTDIvol ($r^2$=0.691), DLP ($r^2$=0.741). We conclude that CTDIvol and DLP is an important determinant of weight within the CT examinations. The results for this study suggest that CT protocol should be tailored according to patient weight.

Comparison of SARs of Human Heads Exposed to Mobile Phone (이동통신단말기에 노출된 인체 두부에 따른 전자파 비흡수율 비교)

  • Lee, Ae-Gyeong;Choe, Hyeong-Do;Choe, Jae-Ik
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.37 no.11
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    • pp.32-41
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    • 2000
  • A new anatomical head model was implemented based on the MR and CT images of the head of a volunteer whose head shape is close to the domestic standard. In order to compare SARs (specific absorption rates) of heads with different shapes, we calculated SARs in the two anatomical head models. The one is the new model and the other is that of the black race and was made at National Library Medicine in USA. The head model and a phone model were arranged in the computational space to be the touch or cheek position of CENELEC (European Committee for Electrotechnical Standardisation) and FCC guidelines. From the obtained results, we can see that the smaller head produces the higher whole head-averaged SAR. However, it seems that the localized SAR averaged over 1 g or 10 g is more dependent on the shape of the auricle rather than that of the head size.

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Analyzed the Computed Tomography Dose Index (CTDI) to the Pediatric Brain CT by Reason of the Observation for the Exposure Dose: Base on a Hospital (소아 두부 전산화단층촬영 선량지표 분석을 통한 피폭선량 모니터링: 일개병원 사례 중심으로)

  • Lee, Jae-Seung;Kim, Hyun-Jin;Im, In-Chul
    • The Journal of the Korea Contents Association
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    • v.15 no.6
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    • pp.290-296
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    • 2015
  • The purpose of this study was to derive the proposals and to suggest the exposure dose reduction scheme on pediatric head CT scan by analyzing and comparing CT dose index (CTDI) and the national diagnostic reference levels. From January 2014 to December, 231 children under 10years who were requested a pediatric head CT scan with head injury were examined. Research methods were to research and analyze the general characteristics kVp, mA test coverage $CTDI_{vol}$ and DLP referring to dose reports and electronic medical record (EMR). As a result, 7.4%(17 patients) of the total subjects in $CTDI_{vol}$ showed a national diagnostic reference levels exceeding. For DLP 41.6%(96 patients) in excess was relatively higher than $CTDI_{vol}$. DLP was exceeded more than about 60% that is higher than the CT dose index presented by Korea Food & Drug Administration. it is cause of high DLP that scan range increased more than about 30% wider than the standard test coverage presented in Health Insurance Review & Assessment Service. In conclusion, it is able to significantly lower the dose if it is complied with checking the baseline scan range of pediatric head CT scan and appropriately adjusting the protocol.