Analysis of CT doses to paediatric patients in four children′s hospitals in Shanghai / 中华放射医学与防护杂志

Objective:To study the distribution of CT doses to paediatric patients in Shanghai by investigating the CT dose parameters availiable in Shanghai′s children′s hospticals, and to provide the basis for establishing the diagnostic reference level for the paediatic patients subjected to CT scanning in Shanghai.Methods:In 2021, a general survey was carried out of the CT doses to the head, chest and abdomen of the scanned paediatric patients in four children′s hospitals in the municipality. The scanned paediatic patients were divided into four age groups of 0-, 1-, 5- and 10-15 years old, each with 30 subjects. The basic information were collected on the subjects, CT scanning parameters, volume CT dose index (CTDI vol) and dose length product (DLP). SPSS 16.0 was used to carry out statistical analysis of the differences in CTDI vol and DLP between different age groups at the same site and between different hospitals for the same age group at the same site. Results:The 75 th percentile values of CTDI vol and DLP for 0-, 1-, 5- and 10-15 age groups were 25, 25, 28, 43 mGy and 402, 477, 504, 752 mGy·cm, respectively, for head scanning; 2.7, 2.2, 2.8, 5.4 mGy and 40, 48, 75 and 176 mGy·cm for chest; and 4.9, 4.4, 8.2, 12 mGy and 106, 131, 273, 471 mGy·cm for abdomen. There were significant differences in CTDI vol and DLP between different age groups at the same site and between different hospitals for the same age group at the same site (head, chest and abdomen CTDI vol:χ2=221.68, 167.27, 127.07, DLP: χ2=220.63, 261.46, 216.61; for four age groups, CTDI vol: head χ2=30.46, 38.39, 25.21, 73.04, chest χ2=30.46, 35.69, 58.92, and 48.03, abdomen χ2=66.58, 41.62, 48.93, and 67.38; DLP: head χ2=28.82, 72.49, 47.72, 52.34, chest χ2=28.82, 35.95, 50.66, 41.64, abdomen χ2=45.53, 26.02 39.34, 44.24, P <0.05 ). Conclusions:The 75 th percentile values of CTDI vol and DLP for head, chest and abdomen in 4 children′s hospitals in Shanghai are lower or close to the values given in the relevant national standards and the diagnostic reference levels in some European countries, with higher DLP values on some scanning sites. The CT scanning procedures for paediatric patients needs to be further optimized.

Assessment of Adult's Abdominopelvic Computed Tomography Radiation Doses in Amhara Region, Ethiopia

BACKGROUND: Computed Tomography plays a priceless role for diagnostic and therapeutic purpose; however,applying an optimized Computed Tomography Technique to produce qualified image while delivering minimum radiation dose to patients is the common challenge. The main objective of this study was to establish local diagnostic reference levels for adult patients who visited abdominopelvic Computed Tomography examination. METHODS: A total of 158 patients who had taken abdominopelvic Computed Tomography examination from three selectedAmhara region hospitals were investigated. Both prospective and retrospective techniques of data collection were used while collecting the data in the entire sample. Two GE - Optima Computed Tomography 540 (16 slices) and one Phillips ­ Brilliance (64slices), were employed during data collections. Data for patient demographics scan protocols, Computed Tomography dose descriptors and machine specifications were collected and analyzed by using SPSS software version 26. RESULTS: The third quartile estimated computed tomography dose index volume and dose length product, which is the local Diagnostic Reference Levels, were 12 mGy and 1904 cm.mGy respectively. The investigated local Diagnostic Reference Levels of Computed Tomography Dose index volume (mGy) was comparable to other international Diagnostic Reference Levels. However, the third quartile value of dose length product (cm.mGy) was higher than other reported international Diagnostic Reference Levels. CONCLUSION: The values of local Diagnostic Reference Levels presented in this work can be used as a baseline upon which future dose measurements can be compared in Amhara region

Corrección de índice de dosis en tomografía computarizada por parámetro de diámetro efectivo según reporte 204 de la Asociación Americana de Físicos Médicos / Computed tomography dose index correction by effective diameter according to report 204 by the American Association of Physicists in Medicine

Abstract. In order to have a more accurate estimation of the dose delivered for computed tomography (CT) studies, and given that the current dose estimates do not include the size of the patient, a retrospective study was conducted on a sample of 388 patients from the radiology department of a general hospital, to make a better assessment of the dose delivered for CT scans of the chest, abdomen and pelvis in adult and paediatric patients. A comparison was made between the volume computed tomography dose index (CTDIvol) delivered by the scanner and CTDIvol value corrected by the incorporation of the effective patient diameter according to the report 204 of the American Association of Physicists in Medicine (AAPM). It was found that the values of CTDIvol vary in all cases when the patient size parameter is included, with this variation being greater as sizes go to extremes.

Resumen. Con el objetivo de tener una estimación de dosis más exacta entregada por los estudios de tomografía computarizada (TC) y dado que los estimadores de dosis actuales no incluyen el tamaño del paciente en la estimación, se realizó un estudio retrospectivo en una muestra de 388 pacientes de un servicio de radiología de un hospital general, para calcular las dosis entregadas en exámenes de TC de tórax, abdomen y pelvis en pacientes adultos y pediátricos. Se elaboró y realizó una comparación entre el índice de dosis de TC (CTDI VOL) entregado por el equipo y el CTDI VOL corregido mediante la incorporación del parámetro del diámetro efectivo del paciente según el reporte 204 de la Asociación Americana de Físicos Médicos (AAPM). Se pudo comprobar que los valores de CTDI VOL varían en la totalidad de los casos al ingresar el parámetro de tamaño del paciente y que esta variación es mayor a medida que los tamaños se van a los extremos.

Efectos del voltaje de tubo en la dosis de radiación y calidad de imagen en fantoma en tomografía computarizada multicorte pediátrica / Effect of tube voltage on radiation dose and image quality in paediatric MSCT

Abstract. The use of CT has continued to increase in the last few years, making it the largest contributor to the collective world dose. Children are not exempt from this, with a potentially increasing risk. The effect of tube voltage as a tool for dose reduction has been studied with the aim of investigating methods for optimisation in MSCT, including assessing its effect on image quality. It has been observed that when using the same kV values, the CTDIw is higher by a factor of 2 for the paediatric phantom compared to the adult phantom. A significant reduction in CTDIw was corroborated when lowering the kV, with fewer effects on noise in the paediatric image. On the other hand, a kV reduction allows better contrast when imaging bony structures and using contrast media.

El incremento en el uso de la TC es sostenido en los últimos años, llegando a ser la mayor contribución a la dosis colectiva mundial. Los niños no están exentos de ello, con un riesgo potencialmente creciente. Con el objetivo de estudiar métodos de optimización en TCMC se investigó el efecto del voltaje de tubo como herramienta de reducción de dosis gracias al uso de fantomas representativos, evaluando paralelamente su efecto sobre la calidad de imagen. Se observó que para el fantoma pediátrico el CTDIw es mayor en un factor de 2 con respecto a su símil adulto para iguales valores de kV. Se constató que una reducción en el kV permite una notoria disminución de CTDIw, con menores efectos sobre el ruido en la imagen pediátrica. Por otro lado, una reducción de kV permite mejorar el contraste de estructuras óseas y con medio de contraste yodado.

Estimation of the Risk of Cancer Associated with Pediatric Cranial Computed Tomography.

Background: The role of Computed Tomography (CT) in the medical diagnosis of diseases has greatly expanded, despite the potential risk of cancer following exposures to ionising radiation (X-Ray) from this modality. This risk is particularly of great concern in children, who are more radiosensitive and have many years to manifest radiation effect than adults. Aims: To estimate risk of cancer induction from Pediatric cranial CT. Materials and Methods: A total of 203 patients, who were referred from various pediatric clinics and wards for cranial CT in a teaching hospital in the South Western Nigeria between the year 2011 and 2013 were considered. All patients were grouped into four age (year) groups: less than 1, 1-5, 5-10 and 10-15. A mathematical method was used to estimate the risk of cancer from the effective dose(ED) calculated from volume computed tomography dose index (CTDIvol), dose length product (DLP) and standard conversion factor. Results: The range of CTDIvol (mGy) received by all patients was 10–250 mGy while majority of the patients received 50–100. The range of DLP (mGy.cm) received by all patients and majority of patients was 500–5000 and 2001–2500 respectively. The range of ED (mSv) received by all patients and majority of the patients was 1–25 and 5–10 respectively. The risk estimated with respect to patients’ age showed that patient in the age group 1–5 years have the highest risk of cancer induction while the risk based on gender showed no significant difference. Conclusion: Over 60% of pediatric patients received more than the recommended values of CTDIvol, DLP and ED from cranial CT. Urgent steps must be taken to ensure compliant with international recommended precautions for dose reduction in pediatric medical imaging.

A method to correct the characterizations of MDCT / 中国医学装备

Objective:To correct the characterizations of MDCT radiation dose by exploring the relationship between CTDIw,∞ and CTDIw.Methods: CTDI100 and CTDI∞ were measured under the conditions of different collimations, pitches and tube voltages of Siemens Definition Flash CT, and CTDIw and CTDIw,∞ were calculated.Results: There were significant differences between CTDIw and CTDIw,∞ which were measured at 0.05 level. And there were no significant differences between CTDIw,∞ after corrected and CTDIw,∞ which were measured at 0.05 level.Conclusion:The characterizations of MDCT which were commonly used were not accurate enough. The result after correction were very closed to the real CTDIw,∞. This showed that the method to correct CTDIw of Siemens Definition Flash CT was mostly accurate. And methods to correct CTDIw of other MDCT needed to be further studied.