Estudo de indicadores de dose para níveis de referência em exames de tomografia computadorizada pediátrica

Abstract

Computed Tomography (CT) significantly contributes to diagnostic medicine in a non-invasive manner; however, it is responsible for the highest doses in the population in imaging diagnosis. Thus, it becomes necessary to evaluate the indicators associated with the radiation dose received by patients in CT exams, especially pediatric patients due to their radiosensitivity. Such indicators allow for the optimization of doses and the implementation of tools for radiological protection. In this study, a survey was conducted to determine the typical values of pediatric CT scans of the head, chest, and abdomen in general and pediatric hospitals using the dose descriptors Size-Specific Dose Estimates (SSDE), Dose Length Product (DLP), and Computed Tomography Dose Index (CTDI) and compared the different metrics. A total of 2525 exams were collected at the pediatric hospital and 823 exams at the general hospital. When comparing the typical values for CT scans of the head, chest, and abdomen across all age groups (0 to 18 years), it was observed that the pediatric hospital presents relatively lower dose indicators than the general hospital, due to age-specific protocols and, in some cases, weight. When analyzing the factors dependent on the patient’s size, these showed variations according to the CT when considering the effective diameter (Deff). When analyzing the SSDE values for skull and thorax exams, using the water equivalent diameter (Dw) instead of Deff resulted in more representative values. For abdominal exams, using Deff was more representative for SSDE. When comparing the dose indicators CTDI, DLP, and SSDE, it is concluded that due to the pediatric hospital having specific protocols by age group and sometimes by weight, it results in values with better optimization. The results indicate that chest exams require additional optimization. Finally, local reference values (NRDL) were established for Curitiba (Brazil), using a large sample and incorporating various dose indices (SSDE, CTDI, and DLP) for pediatric patients in CT scans of the head, chest, and abdomen, concluding that SSDE is the most representative indicator for optimization and radiological protection.