Spatial Distribution of Dose in Computed Tomography with Special Reference to Thin-Slice Techniques

1987 ◽  
Vol 28 (6) ◽  
pp. 771-777 ◽  
Author(s):  
U. Moström ◽  
C. Ytterbergh
Keyword(s):  
Computed Tomography ◽  
Spatial Distribution ◽  
Dose Distribution ◽  
Absorbed Dose ◽  
Average Dose ◽  
Ct Dose ◽  
Multiple Scan ◽  
Ct Dose Index ◽  
The Difference ◽  
Dose Index

The spatial dose distribution in a cylindrical polystyrene phantom with a diameter of 200 mm was measured for seven computed tomography (CT) scanners. The measurements were performed in the head mode and mainly for narrow slices in the range 1.5 to 4 mm. Both radial and axial dose profiles were measured and the dose distribution for multiple-scan procedures was calculated. The ratio between the surface and centre doses for a single scan varied between the extremes of 1.8 and 4.3 and was generally higher for narrow than for wide slices. With multiple nominally contiguous scans the difference in absorbed dose between surface and centre locations in the object decreased, on account of scattered radiation. The CT dose index for centre locations varied considerably between the tested scanners, with a range from 5.6 to 27.2 mGy per nominal 100 mAs. For a simulated multiple-scan procedure, comparable to a CT examination of the orbits, the multiple-scan average dose varied between 4.3 and 16.4 mGy per nominal 100 mAs.

Organ doses can be estimated from the computed tomography (CT) dose index for cone-beam CT on radiotherapy equipment

2016 ◽  
Vol 36 (2) ◽  
pp. 215-229 ◽  
Author(s):  
Colin J Martin ◽  
Abdullah Abuhaimed ◽  
Marimuthu Sankaralingam ◽  
Mohamed Metwaly ◽  
David J Gentle
Keyword(s):  
Computed Tomography ◽  
Cone Beam Ct ◽  
Cone Beam ◽  
Organ Doses ◽  
Ct Dose ◽  
Ct Dose Index ◽  
Dose Index

scholarly journals Absorbed Dose in CT : Comparison by CT Dose Index

2002 ◽  
Vol 58 (4) ◽  
pp. 495-501 ◽  
Author(s):  
KENJI YAMAMOTO ◽  
TAKASHI ANDOU ◽  
HIROSHI AKAZAWA
Keyword(s):  
Absorbed Dose ◽  
Ct Dose ◽  
Ct Dose Index ◽  
Dose Index

VOLUME CT DOSE INDEX AND DOSE-LENGTH PRODUCT VALUES ACCORDING TO FACILITY SIZE IN JAPAN

2020 ◽  
Vol 188 (2) ◽  
pp. 261-269
Author(s):  
Yuta Matsunaga ◽  
Yuya Kondo ◽  
Kenichi Kobayashi ◽  
Masanao Kobayashi ◽  
Kazuyuki Minami ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Contrast Agent ◽  
Ct Scanner ◽  
Dose Length Product ◽  
Ct Dose ◽  
Volume Computed Tomography ◽  
Ct Dose Index ◽  
Computed Tomography Dose Index ◽  
Facility Size ◽  
Dose Index

Abstract The aim of this study was to investigate differences in volume computed tomography dose index (CTDIvol) and dose-length product (DLP) values according to facility size in Japan. A questionnaire survey was sent to 3000 facilities throughout Japan. Data from each facility were collected including bed number, computed tomography (CT) scan parameters employed and the CTDIvol and/or DLP values displayed on the CT scanner during each examination. The CTDIvol and DLP for 11 adult and 6 paediatric CT examinations were surveyed. Comparison of CTDIvol and DLP values of each examination according to facility size revealed key differences in CT dose between small and large facilities. This study highlights the importance of lowering the dose of coronary artery examination with contrast agent in smaller facilities and of lowering the dose of adult and paediatric head CT without contrast agent in larger facilities. The results of this study are valid in Japan.

scholarly journals Can Patient’s Body Weight Represent Body Diameter for Pediatric Size-Specific Dose Estimate in Thoracic and Abdominal Computed Tomography?

2019 ◽  
Vol 9 ◽  
pp. 24 ◽  
Author(s):  
Supika Kritsaneepaiboon ◽  
Suwadee Eng-chuan ◽  
Saowapark Yoykaew
Keyword(s):  
Computed Tomography ◽  
Body Weight ◽  
Statistical Significance ◽  
Correlation Coefficients ◽  
Effective Diameter ◽  
Dose Estimate ◽  
Ct Dose ◽  
Body Diameter ◽  
Ct Dose Index ◽  
Dose Index

Objective: The objective of the study was to determine whether body weight (BW) can be substituted for body diameters to calculate size-specific dose estimate (SSDE) in the children. Materials and Methods: A total of 196 torso computed tomography (CT) studies were retrospectively reviewed. Anteroposterior diameter (DAP) and lateral diameter (Dlat) were measured, and DAP+Dlat, effective diameter, SSDE diameter and SSDEBW were calculated. Correlation coefficients among body diameters, all SSDE types and percentage changes between CT dose index volumes and SSDEs were analyzed by BW and age subgroups. Results: Overall BW was more strongly correlated with body diameter (r = 0.919–0.960, P < 0.001) than was overall age (r = 0.852–0.898, P < 0.001). The relationship between CT dose index volume and each of the SSDE types (r = 0.934–0.953, P < 0.001), between SSDEBW and all SSDE diameters (r = 0.934–0.953, P < 0.001), and among SSDE diameters (r = 0.950–0.989, P < 0.001) overall had strong correlations with statistical significance. The lowest magnitude difference was SSDEBW−SSDEeff. Conclusion: BW can be used instead of body diameter to calculate all SSDE types, with our suggested best accuracy for SSDEeff and the least variation in age < four years and BW < 20 kg. Key Messages: Size-specific dose estimate (SSDE) is a new and accurate dose-estimating parameter for the individual patient which is based on the actual size or body diameter of the patient. BW can be an important alternative for all body diameters to estimate size-specific dose or calculate SSDE in children.

scholarly journals Calculation of the shielding safety of Computed Tomography scanner room by using MCNP5 code

2017 ◽  
Vol 1 (T4) ◽  
pp. 63-70
Author(s):  
Khanh Ai Tran ◽  
Thong Minh Cao ◽  
Phuong Nguyen Dang ◽  
Loan Thi Hong Truong ◽  
Nhon Van Mai
Keyword(s):  
Computed Tomography ◽  
Absorbed Dose ◽  
Ct Scanner ◽  
Ct Dose ◽  
Room Size ◽  
Medical Physicists ◽  
Simulation And Experiment ◽  
Ct Dose Index ◽  
Computed Tomography Scanner ◽  
Scanner Room

Shielding design of Computed Tomography scanner room is a vital work to ensure radiation safety for medical physicists and public. In this paper, we measured CTDI (CT Dose Index) and determined the normalization factor between Monte Carlo simulation and experiment values of absorbed dose. Then, the absorbed dose distribution inside and outside the CT scanner room were surveyed for the variation of the room size. In addition, the influence of photons scattered from the shielding material to patients while shrinking the sizes of the room is also studied in this work.

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