Verification of organ doses calculated by a dose monitoring software tool based on Monte Carlo Simulation in thoracic CT protocols

Abstract

Background

The importance of monitoring of the radiation dose received by the human body during computed tomography (CT) examinations is not negligible. Several dose-monitoring software tools emerged in order to monitor and control dose distribution during CT examinations. Some software tools incorporate Monte Carlo Simulation (MCS) and allow calculation of effective dose and organ dose apart from standard dose descriptors.

Purpose

To verify the results of a dose-monitoring software tool based on MCS in assessment of effective and organ doses in thoracic CT protocols.

Material and Methods

Phantom measurements were performed with thermoluminescent dosimeters (TLD LiF:Mg,Ti) using two different thoracic CT protocols of the clinical routine: (I) standard CT thorax (CTT); and (II) CTT with high-pitch mode, P = 3.2. Radiation doses estimated with MCS and measured with TLDs were compared.

Results

Inter-modality comparison showed an excellent correlation between MCS-simulated and TLD-measured doses ((I) after localizer correction r = 0.81; (II) r = 0.87). The following effective and organ doses were determined: (I) (a) effective dose = MCS 1.2 mSv, TLD 1.3 mSv; (b) thyroid gland = MCS 2.8 mGy, TLD 2.5 mGy; (c) thymus = MCS 3.1 mGy, TLD 2.5 mGy; (d) bone marrow = MCS 0.8 mGy, TLD 0.9 mGy; (e) breast = MCS 2.5 mGy, TLD 2.2 mGy; (f) lung = MCS 2.8 mGy, TLD 2.7 mGy; (II) (a) effective dose = MCS 0.6 mSv, TLD 0.7 mSv; (b) thyroid gland = MCS 1.4 mGy, TLD 1.8 mGy; (c) thymus = MCS 1.4 mGy, TLD 1.8 mGy; (d) bone marrow = MCS 0.4 mGy, TLD 0.5 mGy; (e) breast = MCS 1.1 mGy, TLD 1.1 mGy; (f) lung = MCS 1.2 mGy, TLD 1.3 mGy.

Conclusion

Overall, in thoracic CT protocols, organ doses simulated by the dose-monitoring software tool were coherent to those measured by TLDs. Despite some challenges, the dose-monitoring software was capable of an accurate dose calculation.

Keywords

Radiation exposure organ dose radiation monitoring computed tomography Monte Carlo Simulation

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References

Pearce

Salotti

Little

et al.

A Radiation exposure from CT scans in childhood and subsequent risk of leukaemia and brain tumours: a retrospective cohort study. Lancet 2012; 380: 499–505.

BEIR VII: Committee to Assess Health Risks from Exposure to Low Levels of Ionizing Radiation, National Research Council. Health risks from exposure to low levels of ionizing radiation: BEIR VII Phase 2. Washington, DC: The National Academies Press, 2006:5.

Brenner

Hall

. Computed tomography—an increasing source of radiation exposure. N Engl J Med 2007; 357: 2277–2284.

Kanal

Butler

Sengupta

et al.

U.S. diagnostic reference levels and achievable doses for 10 adult CT examinations. Radiology 2017. doi: 10.1148/radiol.2017161911.

Guberina

Dietrich

Forsting

et al.

Comparison of eye-lens doses imparted during interventional and non-interventional neuroimaging techniques for assessment of intracranial aneurysms. J Neurointerv Surg 2017. doi: 10.1136/neurintsurg-2016-012970.

Kalender

Saltybaeva

Kolditz

et al.

Generating and using patient-specific whole-body models for organ dose estimates in CT with increased accuracy: feasibility and validation. Phys Med 2014; 30: 925–933.

Stamm

Nagel

. CT-expo- a novel program for dose evaluation in CT. Rofo 2002; 174: 1570–1576.

Guberina

Forsting

Suntharalingam

et al.

Radiation dose monitoring in the clinical routine. Rofo 2017; 189: 356–360.

Ding

Gao

Liu

et al.

VirtualDose: a software for reporting organ doses from CT for adult and pediatric patients. Phys Med Biol 2015; 60: 5601–5625.

10.

Kalender

Schmidt

Zankl

et al.

A PC program for estimating organ dose and effective dose values in computed tomography. Eur Radiol 1999; 9: 555–562.

11.

ImPACT. Imaging Performance Assessment of CT-Scanners Group ImPACT CT Patient Dosimetry Calculator v. 0.99 j. Available at: http://www.impactscan.org (accessed 15 March 2017).

12.

LeHeron

. CTDOSE - a computer program to enable the calculation of organ doses and dose indices for CT examinations , Christchurch, New Zealand: Ministry of Health, National Radiation Laboratory, 1993.

13.

Deak

van Straten

Shrimpton

et al.

Validation of a Monte Carlo tool for patient-specific dose simulations in multi-slice computed tomography. Eur Radiol 2008; 18: 759–772.

14.

Guberina

Suntharalingam

Naßenstein

et al.

Clinical evaluation of a dose monitoring software tool based on Monte Carlo Simulation in assessment of eye lens doses for cranial CT scans. Neuroradiology 2016; 58: 955–959.

15.

Zoetelief J, Julius HW and Christensen P. Recommendations for patient dosimetry in diagnostic radiology using TLD. Topical report, EUR-19604, 2000.

16.

Lechel

Becker

Langenfeld-Jäger

et al.

Dose reduction by automatic exposure control in multi-slice computed tomography: comparison between measurement and calculation. Eur Radiol 2009; 19: 1027–1034.

17.

International Commission on Radiological Protection. The 2007 Recommendations of the International Commission on Radiological Protection. ICRP publication 103. Ann ICRP 2007;37:1–332.

18.

Agostinelli

Allisonas

Amako

et al.

GEANT4 - a simulation toolkit. Nucl Instrum Methods Phys Res A 2003; 506: 250–303.

19.

Mayo

Aldrich

Muller

. Fleischner Society. Radiation exposure at chest CT: a statement of the Fleischner Society. Radiology 2003; 228: 15–21.

20.

Guberina

Lechel

Forsting

et al.

Efficacy of high-pitch CT protocols for radiation dose reduction. J Radiol Prot 2016; 36: N57–N66.

21.

Fiebich

Bohrer

Errafai

et al.

Dosis des Topogramms in der Computertomographie. Rofo 2012. doi: 10.1055/s-0032-1311122.

22.

Bayer HealthCare Medical Care. Radiation dose calculations in Radimetrics Enterprise Platform by Bayer: RAD-INF-13-05968, 2014.