Organ doses and risks of computed tomography examinations in Recife, Brazil

Abstract

Computed tomography (CT) examinations have increased significantly in recent years due to technological innovations. In some industrialised countries, CT contributes to the population dose as much as background radiation. In developing countries, the uses and risks of CT have not been well characterised. The purpose of this investigation was to assess potential stochastic and deterministic radiation effects from common CT exams performed in six hospitals of Recife, Pernambuco. Scanning parameters and patient gender and age were collected for a total of 285 patients undergoing CT examinations of the head (90), chest (75), abdomen (60) and abdomen-pelvis (60). The organ doses, which were calculated using the ImPACT dosimetry calculator, varied significantly among institutions. Organs such as the brain, the heart and the eye lenses, which exhibited doses as high as 85, 42 and 100 mGy, respectively, are of concern for the production of cerebrovascular and cardiovascular diseases and cataracts. Effective cancer risks were calculated using Brenner methodology and BEIR-VII risk factors. They range from 1.8 to 110.2 cases per 100000 persons for cancer induction and from 1.5 to 63.0 cases per 100000 for cancer mortality. To reduce doses, a quality assurance programme that includes procedural justification and radiation protection optimisation should be implemented.

Risk of radiation-induced malignancies from CT scanning in children who underwent shunt treatment before 6 years of age: a retrospective cohort study with a minimum 10-year follow-up

“…6,8,30 Multiple authors have then extrapolated the expected risk of future cancer from CT scanning by equating the phantom model doses to the known risk reported in the BEIR VII report. 1,3,7,9,11,12,14,18,21,22,28,34 These models predict an alarming number of future cancers. Berrington de González et al predicted 29,000 future cancers and 14,500 future deaths in the US caused by 1 year of CT scanning.…”

ICRP Publication 147: Use of Dose Quantities in Radiological Protection

“…In considering such information, clinicians will wish to take account of factors including the potential benefits of the procedure and the prognosis of the patient’s illness. (114) The use of effective dose to provide an approximate indication of possible lifetime risk of cancer incidence associated with medical procedures is not a substitute for detailed assessments of risk for individuals or specific population groups. Brenner (2008, 2012) proposed the use of an intermediate quantity, termed ‘effective risk’, in which age-specific tissue weighting factors based on lifetime cancer incidence data replace the age-averaged values used by the Commission in the calculation of effective dose; an example of the use of effective risk for the evaluation of CT examinations is provided by Andrade et al. (2012).…”

“…(114) The use of effective dose to provide an approximate indication of possible lifetime risk of cancer incidence associated with medical procedures is not a substitute for detailed assessments of risk for individuals or specific population groups. Brenner (2008Brenner ( , 2012 proposed the use of an intermediate quantity, termed 'effective risk', in which age-specific tissue weighting factors based on lifetime cancer incidence data replace the age-averaged values used by the Commission in the calculation of effective dose; an example of the use of effective risk for the evaluation of CT examinations is provided by Andrade et al (2012). While this approach takes direct account of the available data on age specificity of the different cancer types, it may give a spurious sense of accuracy unless associated uncertainties are considered.…”

Organ doses and associated cancer risks for computed tomography examinations of the thoracic region

“…In lit er a ture there are many stud ies deal ing with can cer risk as so ci ated with CT ex am i na tions. In the ma jor ity of the stud ies the ra di a tion in duced risk is calcu lated by means of an es ti mate of or gan and ef fec tive doses us ing the com puted to mog ra phy dose in dex (CTDI) val ues and/or on the ba sis of Monte Carlo calcu la tions and math e mat i cal phan toms [19][20][21][22][23]. The ad van tage of dose mea sure ments in the phan tom is the di rect mea sure ment of doses in the po si tions of sen sitive or gans or tis sues which are in dis pens able to es timate risk for par tic u lar can cers.…”