Establishment of typical dose levels for computed tomography of the pelvis region in radiotherapy simulation procedures
Keywords:
Computed tomography, Radiotherapy simulation, Pelvis, Typical dose levelAbstract
Background: The International Commission on Radiological Protection (ICRP publication 135) introduced the use of Diagnostic Reference Levels (DRLs) for imaging procedures. DRLs are dose levels used as a reference for optimizing radiation exposure to patients.
Objective: This work aimed to survey and establish typical dose levels for computed tomography (CT) of the pelvis region in radiotherapy simulation procedures and compare the typical dose levels with another study.
Materials and methods: Volume Computed Tomography Dose Index (CTDIvol) and Dose Length Product (DLP) were collected from a patient who underwent CT of the pelvis region in radiotherapy simulation procedures at radiotherapy department of Mahavajiralongkorn Thanyaburi hospital. The total of 80 patients were included with patient's age range of 20-80 years old and patient's weight range of 45-75 kg. The parameters used for radiographic imaging of each patient were recorded. Values of typical dose levels were established using the median of CTDIvol and DLP.
Results: The parameters used for radiographic imaging were found to be the same for all patients, except for the tube current, which is automatically adjusted according to the size of the patients by the automatic tube current modulation system of CT machine. The average age and weight of the patients were 52.3 ± 11.5 years old and 58.5 ± 8.1 kg. The typical dose levels of CTDIvol and DLP were 13.0 mGy and 478.7 mGy.cm, respectively. The typical dose levels in this work were lower than another study. However, the Thai national DRLs for CT examinations of the pelvis region has not yet been established. Therefore, the results of this study may serve as a guide for further study to determine the DRLs for pelvis CT.
Conclusion: The patient dose derived from CT of the pelvis region in radiotherapy simulation procedures using parameter setting in our hospital was acceptable compared with another study.
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