• Korean Journal of Radiology
• /
• 제20권1호
• /
• pp.50-57
• /
• 2019

In pediatric thoracic CT, respiratory motion is generally treated as a motion artifact degrading the image quality. Conversely, respiratory motion in the thorax can be used to answer important clinical questions, that cannot be assessed adequately via conventional static thoracic CT, by utilizing four-dimensional (4D) CT. However, clinical experiences of 4D thoracic CT are quite limited. In order to use 4D thoracic CT properly, imagers should understand imaging techniques, radiation dose optimization methods, and normal as well as typical abnormal imaging appearances. In this article, the imaging techniques of pediatric thoracic 4D CT are reviewed with an emphasis on radiation dose. In addition, several clinical applications of pediatric 4D thoracic CT are addressed in various thoracic functional abnormalities, including upper airway obstruction, tracheobronchomalacia, pulmonary air trapping, abnormal diaphragmatic motion, and tumor invasion. One may further explore the clinical usefulness of 4D thoracic CT in free-breathing children, which can enrich one's clinical practice.

• 대한소아치과학회지
• /
• 제25권3호
• /
• pp.493-498
• /
• 1998

1. CT에 의한 매복치의 위치결정은 적절한 치료계획의 수립을 가능하게 하여 시술시간의 단축과 인접치, 인접구조물의 손상을 줄여 시술후의 부작용을 줄일 수 있었다. 2. 매복된 영구치의 견인시 CR를 활용한 결과 개창부위의 정확한 위치결정과 예후에 대한 예측이 가능하였다. 3. 평면방사선사진의 판독후 악골내 병소가 의심되어 CT를 활용한 결과 병소의 확진이 가능하였다. 4. 소아의 CT촬영은 평면 방사선 촬영에 비해 증가된 방사선 피폭량, 높은 수가 때문에 적절한 증례의 선택이 중요하다.

• Journal of Radiation Protection and Research
• /
• 제46권1호
• /
• pp.1-7
• /
• 2021

Background: The use of computed tomography (CT) device has increased in the past few decades in Japan. Dose optimization is strongly required in pediatric CT examinations, since there is concern that an unreasonably excessive medical radiation exposure might increase the risk of brain cancer and leukemia. To accelerate the process of dose optimization, continual assessment of the dose levels in actual hospitals and medical facilities is necessary. This study presents organ dose estimation using pediatric cerebral CT scans in the Kyushu region, Japan in 2012 and the web-based calculator, WAZA-ARI (https://waza-ari.nirs.qst.go.jp). Materials and Methods: We collected actual patient information and CT scan parameters from hospitals and medical facilities with more than 200 beds that perform pediatric CT in the Kyushu region, Japan through a questionnaire survey. To estimate the actual organ dose (brain dose, bone marrow dose, thyroid dose, lens dose), we divided the pediatric population into five age groups (0, 1, 5, 10, 15) based on body size, and inputted CT scan parameters into WAZA-ARI. Results and Discussion: Organ doses for each age group were obtained using WAZA-ARI. The brain dose, thyroid dose, and lens dose were the highest in the Age 0 group among the age groups, and the bone marrow and thyroid doses tended to decrease with increasing age groups. All organ doses showed differences among facilities, and this tendency was remarkable in the young group, especially in the Age 0 group. This study confirmed a difference of more than 10-fold in organ doses depending on the facility and CT scan parameters, even when the same CT device was used in the same age group. Conclusion: This study indicated that organ doses varied widely by age group, and also suggested that CT scan parameters are not optimized for children in some hospitals and medical facilities.

• Korean Journal of Radiology
• /
• 제21권7호
• /
• pp.919-924
• /
• 2020

Objective: The current study reported a case series to illustrate the early computed tomography (CT) findings of coronavirus disease 2019 (COVID-19) in pediatric patients. Materials and Methods: All pediatric patients who were diagnosed with COVID-19 and who underwent CT scan in Zhongnan Hospital of Wuhan University from January 20, 2020 to February 28, 2020 were included in the current study. Data on clinical and CT features were collected and analyzed. Results: Four children were included in the current study. All of them were asymptomatic throughout the disease course (ranging from 7 days to 15 days), and none of them showed abnormalities in blood cell counts. Familial cluster was the main transmission pattern. Thin-section CT revealed abnormalities in three patients, and one patient did not present with any abnormal CT findings. Unilateral lung involvement was observed in two patients, and one patient showed bilateral lung involvement. In total, five small lesions were identified, including ground-glass opacity (n = 4) and consolidation (n = 1). All lesions had ill-defined margins with peripheral distribution and predilection of lower lobe. Conclusion: Small patches of ground-glass opacity with subpleural distribution and unilateral lung involvement were common findings on CT scans of pediatric patients in the early stage of the disease.

• Journal of Radiation Protection and Research
• /
• 제46권3호
• /
• pp.98-105
• /
• 2021

Background: In recent events of the coronavirus disease 2019 (COVID-19) pandemic, computed tomography (CT) scans are being globally used as a complement to the reverse-transcription polymerase chain reaction (RT-PCR) tests. It will be important to be aware of major organ dose levels, which are more relevant quantity to derive potential long-term adverse effect, for Korean pediatric and adult patients undergoing CT for COVID-19. Materials and Methods: We calculated organ dose conversion coefficients for Korean pediatric and adult CT patients directly from Korean pediatric and adult computational phantoms combined with Monte Carlo radiation transport techniques. We then estimated major organ doses delivered to the Korean child and adult patients undergoing CT for COVID-19 combining the dose conversion coefficients and the international survey data. We also compared our Korean dose conversion coefficients with those from Caucasian reference pediatric and adult phantoms. Results and Discussion: Based on the dose conversion coefficients we established in this study and the international survey data of COVID-19-related CT scans, we found that Korean 7-year-old child and adult males may receive about 4-32 mGy and 3-21 mGy of lung dose, respectively. We learned that the lung dose conversion coefficient for the Korean child phantom was up to 1.5-fold greater than that for the Korean adult phantom. We also found no substantial difference in dose conversion coefficients between Korean and Caucasian phantoms. Conclusion: We estimated radiation dose delivered to the Korean child and adult phantoms undergoing COVID-19-related CT examinations. The dose conversion coefficients derived for different CT scan types can be also used universally for other dosimetry studies concerning Korean CT scans. We also confirmed that the Caucasian-based CT organ dose calculation tools may be used for the Korean population with reasonable accuracy.

• Pediatric Gastroenterology, Hepatology & Nutrition
• /
• 제27권3호
• /
• pp.176-185
• /
• 2024

Purpose: Acute pancreatitis (AP) is common among children in Bangladesh. Its management depends mainly on risk stratification. This study aimed to assess the severity of pediatric AP using computed tomography (CT). Methods: This cross-sectional, descriptive study was conducted in pediatric patients with AP at the Department of Pediatric Gastroenterology and Nutrition, BSMMU, Dhaka, Bangladesh. Results: Altogether, 25 patients with AP were included, of whom 18 (mean age, 10.27±4.0 years) were diagnosed with mild AP, and 7 (mean age, 10.54±4.0 years) with severe AP. Abdominal pain was present in all the patients, and vomiting was present in 88% of the patients. Etiology was not determined. No significant differences in serum lipase, serum amylase, BUN, and CRP levels were observed between the mild and severe AP groups. Total and platelet counts as well as hemoglobin, hematocrit, serum creatinine, random blood sugar, and serum alanine aminotransferase levels (p>0.05) were significantly higher in the mild AP group than in the severe AP group (p=0.001). The sensitivity, specificity, positive predictive value, and negative predictive value of CT severity index (CTSI) were 71.4%, 72.2%, 50%, and 86.7%, respectively. In addition, significant differences in pancreatic appearance and necrosis were observed between the two groups on CT. Conclusion: CT can be used to assess the severity of AP. In the present study, the CTSI effectively assessed the severity of AP in pediatric patients.

• 식품보건융합연구
• /
• 제4권1호
• /
• pp.23-31
• /
• 2018

The main issue of CT is radiation dose reduction to patient. The purpose of this study was to estimate the image quality and dose by iterative reconstruction (IR) for adults and pediatrics. Adult and pediatric images of phantom were obtained with 120 and 140 kV, respectively, in accordance with radiation dose in terms of volume CT dose index ($CTDI_{vol}$): 10, 15, 20, 25, 30, 35 mGy. Then, the adult and the pediatric images are reconstructed by filtered-backprojection (FBP) and iterative reconstruction (IR). The images were analyzed by signal-to-noise ratio (SNR). SNR is improved when IR and 140 kV are applied to acquire adult and pediatric images. In the adult abdomen, according to diagnostic reference level, the SNR values of bone were increased about 27.84 % and 27.77 % at 120 kV and 140 kV, and the tissue's SNR values of the IR were increased about 29.84 % and 33.46 % 120 and 140 kV, respectively. Dose is reduced to 40% in adults abdomen images when using IR reconstruction. In pediatric images, the bone's SNR were also increased about 17.70% and 18.17 % at 120 kV and 140 kV. The tissue's SNR were increased about 26.73 % and 26.15 % at 120 kV and 140 kV. Radiation dose is reduced from 30% to 50% for bone and tissue images. In the case of examinations for adult and pediatric CT, IR technique reduces radiation dose to patient, and it could be applied to adult and pediatric imaging.

• 핵의학기술
• /
• 제15권2호
• /
• pp.53-59
• /
• 2011

최근 PET/CT 검사는 성인 암환자뿐만 아니라 소아 암환자에게도 많이 적용하고 있다. 그러나 소아 환자의 경우 성인에 비하여 방사성 감수성이 높아 피폭선량의 관리를 필요로 하고 있다. 그러므로 본 저자는 팬텀을 이용하여 소아 PET/CT 검사 시 감쇄보정 CT 선량과 영상을 평가하였다. 3대의 PET/CT 장비 (Discovery STe, BiographTruepoint 40, Discovery 600)로 소아 사이즈의 아크릴 팬텀과 이온 챔버 선량계 (Unfous Xi CT, Sweden)를 이용하여 CT 영상획득 조건 (10, 20, 40, 80, 100, 160 mA; 80, 100, 120, 140 kVp)을 변화시켜 심부선량과 $CTDI_{vol}$ 값을 평가하였다. 그리고 NEMA PET Phantom$^{TM}$을 이용하여 같은 CT 조건으로 PET 영상을 획득하여 감쇄보정 된 각 PET 영상을 SUV 값과 신호 대 잡음 비로 평가하였다. 심부선량은 일반적으로 소아복부 CT 조건 (100 kVp, 100 mA) 보다 최소 CT 조건 (80 kVp, 10 mA)에서의 심부선량은 약 92% 감소 되었고, $CTDI_{vol}$ 값은 약 88% 감소되었다. 각 CT 조건에 따라 감쇄 보정된 PET 영상은 SUV 값에 변화가 없었고, 신호 대 잡음 비도 영향을 받지 않았다. 팬텀을 이용한 소아 PET/CT 실험시 최저 선량 CT 조건 (80 kVp, 10 mA) 을 적용하여 감쇄보정을 진행한 PET 영상에는 영향 없었다. 소아 환자의 PET/CT 검사 시 CT 의 진단이 필요 없는 PET 영상만을 획득하고자 한다면, 소아 환자의 신체에 적절히 적용한 최저선량 CT 을 감쇄보정을 하여, 유효 선량을 성인에 비하여 약 90% 이상 감소시켜 피폭 선량 저감에 도움이 될 것이다.

• Korean Journal of Radiology
• /
• 제22권8호
• /
• pp.1397-1415
• /
• 2021

The use of pediatric cardiothoracic CT for congenital heart disease (CHD) was traditionally limited to the morphologic evaluation of the extracardiac thoracic vessels, lungs, and airways. Currently, the applications of CT have increased, owing to technological advancements in hardware and software as well as several dose-reduction measures. In the previously published part 1 of the guideline by the Asian Society of Cardiovascular Imaging Congenital Heart Disease Study Group, we reviewed the prerequisite technical knowledge for clinical applications in a user-friendly and vendor-specific manner. Herein, we present the second part of our guideline on contemporary clinical applications of pediatric cardiothoracic CT for CHD based on the consensus of experts from the Asian Society of Cardiovascular Imaging CHD Study Group. This guideline describes up-to-date clinical applications effectively in a systematic fashion.

• 대한소아치과학회지
• /
• 제34권2호
• /
• pp.222-233
• /
• 2007

치과 수복 재료 검사 시 가장 중요하고 기본적인 것은 치아와 수복물 사이의 미세누출에 대한 평가이다. 미세 누출을 평가하는 방법은 여러 가지가 있지만 이들 대부분은 많은 단점들을 가지고 있다. 최근에 개발된 미세 단층촬영법(micro-CT)을 이용하면 시편을 비파괴적으로 처리하여 특정 밀도에 해당하는 부분의 3차원적 영상을 얻을 수 있으므로, 이를 이용하면 정확하고 정량적인 미세누출 평가도 가능할 것이다. 이 연구의 목적은 micro-CT를 사용하여, 레진 수복물의 미세 누출도를 정량적이고 비파괴적으로 측정할 수 있는 새로운 방법을 찾아내고, 이 새로운 방법을 기존의 색소 침투법과 비교해보는 것이다. 이를 위해, 위의 두 가지 방법을 사용하여 두 종류의 상아질 접착 시스템의 미세누출도가 평가되었다. 사람의 건전 소구치 40개를 임의로 20개씩 두 군으로 나누고 다음과 같이 처리하였다. Group 1 : $Adper^{TM}$ Singe Bond 사용 후 제 V급 와동 레진 수복, Gourp 2 : $Adper^{TM}\;Promp^{TM}$ L-pop 사용 후 제 V급 와동 레진 수복 모든 치아의 5급 와동은 $Filtek^{TM}$ Supreme으로 수복하였다. 그 후 각 군 중 10개의 치아는 micro-CT를 사용하여 미세 누출도를 평가하고, 나머지 10개는 기존의 색소 침투법으로 평가하였다. 이 연구의 결과는 다음과 같았다. 1. Micro-CT를 사용한 경우, 1군은 2군보다 통계적으로 유의성 있게 적은 양의 미세 누출을 보였다(p<0.01). 2. 기존의 색소 침투법을 사용한 경우에서 1군은 2군보다 적은 미세누출을 보였으며 이는 통계적으로 유의성이 있었다. (p<0.01). 3. 두 군간의 미세 누출도는 micro-CT를 사용한 방법에서 더 현저한 차이를 보였다. 4. 두 가지 방법 모두에서 법랑질 변연 부분보다 상아질 변연 부분에서 더 많은 미세 누출을 보였다.