Dose Assessment in Computed Tomography Examination and Establishment of Local Diagnostic Reference Levels in Mazandaran, Iran

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Abstract

Background

Medical X-rays are the largest man-made source of public exposure to ionizing radiation. While the benefits of Computed Tomography (CT) are well known in accurate diagnosis, those benefits are not risk-free. CT is a device with higher patient dose in comparison with other conventional radiation procedures.

Objective

This study is aimed at evaluating radiation dose to patients from Computed Tomography (CT) examination in Mazandaran hospitals and defining diagnostic reference level (DRL).

Methods

Patient-related data on CT protocol for four common CT examinations including brain, sinus, chest and abdomen & pelvic were collected. In each center, Computed Tomography Dose Index (CTDI) measurements were performed using pencil ionization chamber and CT dosimetry phantom according to AAPM report No. 96 for those techniques. Then, Weighted Computed Tomography Dose Index (CTDIW), Volume Computed Tomography Dose Index (CTDI vol) and Dose Length Product (DLP) were calculated.

Results

The CTDIw for brain, sinus, chest and abdomen & pelvic ranged (15.6-73), (3.8-25. 8), (4.5-16.3) and (7-16.3), respectively. Values of DLP had a range of (197.4-981), (41.8-184), (131-342.3) and (283.6-486) for brain, sinus, chest and abdomen & pelvic, respectively. The 3rd quartile of CTDIW, derived from dose distribution for each examination is the proposed quantity for DRL. The DRLs of brain, sinus, chest and abdomen & pelvic are measured 59.5, 17, 7.8 and 11 mGy, respectively.

Conclusion

Results of this study demonstrated large scales of dose for the same examination among different centers. For all examinations, our values were lower than international reference doses.

Related collections

Most cited references 14

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Cancer risks from diagnostic radiology.

E J Hall, D J Brenner (2008)

In recent years, there has been a rapid increase in the number of CT scans performed, both in the US and the UK, which has fuelled concern about the long-term consequences of these exposures, particularly in terms of cancer induction. Statistics from the US and the UK indicate a 20-fold and 12-fold increase, respectively, in CT usage over the past two decades, with per caput CT usage in the US being about five times that in the UK. In both countries, most of the collective dose from diagnostic radiology comes from high-dose (in the radiological context) procedures such as CT, interventional radiology and barium enemas; for these procedures, the relevant organ doses are in the range for which there is now direct credible epidemiological evidence of an excess risk of cancer, without the need to extrapolate risks from higher doses. Even for high-dose radiological procedures, the risk to the individual patient is small, so that the benefit/risk balance is generally in the patients' favour. Concerns arise when CT examinations are used without a proven clinical rationale, when alternative modalities could be used with equal efficacy, or when CT scans are repeated unnecessarily. It has been estimated, at least in the US, that these scenarios account for up to one-third of all CT scans. A further issue is the increasing use of CT scans as a screening procedure in asymptomatic patients; at this time, the benefit/risk balance for any of the commonly suggested CT screening techniques has yet to be established.

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National survey of doses from CT in the UK: 2003.

Sheila Hillier, P Shrimpton, Cathryn Lewis … (2006)

A review of patient doses from CT examinations in the UK for 2003 has been conducted on the basis of data received from over a quarter of all UK scanners, of which 37% had multislice capability. Questionnaires were employed to collect scan details both for the standard protocols established at each scanner for 12 common types of CT examination on adults and children, and for samples of individual patients. This information was combined with published scanner-specific CT dose index (CTDI) coefficients to estimate values of the standard dose indices CTDI(w) and CTDI(vol) for each scan sequence. Knowledge of each scan length allowed assessment of the dose-length product (DLP) for each examination, from which effective doses were then estimated. When compared with a previous UK survey for 1991, wide variations were still apparent between CT centres in the doses for standard protocols. The mean UK doses for adult patients were in general lower by up to 50% than those for 1991, although doses were slightly higher for multislice (4+) (MSCT) relative to single slice (SSCT) scanners. Values of CTDI(vol) for MSCT were broadly similar to European survey data for 2001. The third quartile values of these dose distributions have been used to derive UK national reference doses for examinations on adults (separately for SSCT and MSCT) and children as initial tools for promoting patient protection. The survey has established the PREDICT (Patient Radiation Exposure and Dose in CT) database as a sustainable national resource for monitoring dose trends in CT through the ongoing collation of further survey data.

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Patient doses in CT examinations in Switzerland: implementation of national diagnostic reference levels.

P. Trueb, Francis R Verdun, Keith Stuessi … (2010)

Diagnostic reference levels (DRLs) were established for 21 indication-based CT examinations for adults in Switzerland. One hundred and seventy-nine of 225 computed tomography (CT) scanners operated in hospitals and private radiology institutes were audited on-site and patient doses were collected. For each CT scanner, a correction factor was calculated expressing the deviation of the measured weighted computed tomography dose index (CTDI) to the nominal weighted CTDI as displayed on the workstation. Patient doses were corrected by this factor providing a realistic basis for establishing national DRLs. Results showed large variations in doses between different radiology departments in Switzerland, especially for examinations of the petrous bone, pelvis, lower limbs and heart. This indicates that the concept of DRLs has not yet been correctly applied for CT examinations in clinical routine. A close collaboration of all stakeholders is mandatory to assure an effective radiation protection of patients. On-site audits will be intensified to further establish the concept of DRLs in Switzerland.

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Author and article information

Journal

Journal ID (nlm-ta): J Biomed Phys Eng

Journal ID (iso-abbrev): J Biomed Phys Eng

Journal ID (publisher-id): JBPE

Title: Journal of Biomedical Physics & Engineering

Publisher: Shiraz University of Medical Sciences (Shiraz, Iran )

ISSN (Electronic): 2251-7200

Publication date Collection: December 2015

Publication date (Electronic): 01 December 2015

Volume: 5

Issue: 4

Pages: 177-184

Affiliations

[1 ]School of Medicine, Babol University of Medical Sciences, Babol, Iran

[2 ]Department of Medical Physics, Faculty of Medicine, Babol University of Medical Sciences, Babol, Iran

[3 ]Department of Medical Physics, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran

[4 ]Department of Radiology, Mazandaran University of Medical Sciences, Sari, Iran

[5 ]Department of Radiology, Babol University of Medical Sciences, Babol, Iran

Author notes

*Corresponding author: A. Shabestani-Monfared, Department of Medical Physics, Faculty of Medicine, Babol University of Medical Sciences, Babol, Iran E-mail: monfared1345@gmail.com

Article

Publisher ID: jbpe-5-177

PMC ID: 4681462

SO-VID: db8cf53e-0f7d-4e44-9a5d-d1579e54e7fd

License:

This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial 3.0 Unported License ( http://creativecommons.org/licenses/by/3.0/), which permits unrestricted use, distribution and reproduction in any medium, provided the original work is properly cited.

Dose Assessment in Computed Tomography Examination and Establishment of Local Diagnostic Reference Levels in Mazandaran, Iran

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Abstract

Background

Objective

Methods

Results

Conclusion

Related collections

Metrics and Research Assessment

Most cited references 14

Cancer risks from diagnostic radiology.

National survey of doses from CT in the UK: 2003.

Patient doses in CT examinations in Switzerland: implementation of national diagnostic reference levels.

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