A pilot study of patient-specific cardiovascular MDCT dose maps and their utility in estimating patient-specific organ and effective doses in obese patients

Carla M Thompson; Jeffrey H Yanof; Jens Wiegert; Jennifer Bullen; Nancy Obuchowski; Kavitha Yaddanapudi; Sandra S Halliburton

doi:10.1016/j.jcct.2016.01.011

A pilot study of patient-specific cardiovascular MDCT dose maps and their utility in estimating patient-specific organ and effective doses in obese patients

J Cardiovasc Comput Tomogr. 2016 May-Jun;10(3):265-8. doi: 10.1016/j.jcct.2016.01.011. Epub 2016 Jan 22.

Authors

Carla M Thompson¹, Jeffrey H Yanof², Jens Wiegert³, Jennifer Bullen⁴, Nancy Obuchowski⁴, Kavitha Yaddanapudi⁵, Sandra S Halliburton⁶

Affiliations

¹ Cardiovascular Imaging, Imaging Institute, Cleveland Clinic, Cleveland, OH, USA; Department of Chemical and Biomedical Engineering, Cleveland State University, Cleveland, OH, USA; Department of Biomedical Engineering, Lerner Research Institute Cleveland Clinic, Cleveland, OH, USA. Electronic address: [email protected].
² Philips Healthcare, Cleveland, OH, USA.
³ Philips Research, Munich, Germany.
⁴ Quantitative Health Sciences, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA.
⁵ Cardiovascular Imaging, Imaging Institute, Cleveland Clinic, Cleveland, OH, USA.
⁶ Cardiovascular Imaging, Imaging Institute, Cleveland Clinic, Cleveland, OH, USA; Department of Chemical and Biomedical Engineering, Cleveland State University, Cleveland, OH, USA; Department of Biomedical Engineering, Lerner Research Institute Cleveland Clinic, Cleveland, OH, USA; Department of Cardiovascular Medicine, Heart and Vascular Institute, Cleveland Clinic, Cleveland, OH, USA.

PMID: 26853972
DOI: 10.1016/j.jcct.2016.01.011

Abstract

Background: Estimates of effective dose (E) for cardiovascular CT are obtained from a scanner-provided dose metric, the dose-length product (DLP), and a conversion factor. These estimates may not adequately represent the risk of a specific scan to obese adults.

Objective: Our objective was to create dose maps sensitive to patient size and anatomy in the irradiated region from a patient's own CT images and compare measured E (EDoseMap) to doses determined from standard DLP conversion (EDLP) in obese adults.

Methods: 21 obese patients (mean body mass index, 39 kg/m(2)) underwent CT of the pulmonary veins, thoracic aorta, or coronary arteries. DLP values were converted to E. A Monte Carlo tool was used to simulate X-ray photon interaction with virtual phantoms created from each patient's image set. Organ doses were determined from dose maps. EDoseMap was computed as a weighted sum of organ doses multiplied by tissue-weighting factors.

Results: EDLP (mean ± SD, 5.7 ± 3.3 mSv) was larger than EDoseMap (3.4 ± 2.4 mSv) (difference = 2.3; P < .001).

Conclusion: Dose maps derived from patient CT images yielded lower effective doses than DLP conversion methods. Considering over all patient size, organ size, and tissue composition could lead to better dose metrics for obese patients.

Keywords: Dose-length product; Effective dose; Monte Carlo; Organ dose.

MeSH terms

Aorta, Thoracic / diagnostic imaging
Aortography / methods*
Body Mass Index
Cardiovascular Diseases / complications
Cardiovascular Diseases / diagnostic imaging*
Computed Tomography Angiography* / instrumentation
Coronary Angiography / instrumentation
Coronary Angiography / methods*
Coronary Vessels / diagnostic imaging
Humans
Monte Carlo Method
Multidetector Computed Tomography* / instrumentation
Obesity / complications*
Obesity / diagnosis
Patient-Specific Modeling*
Phantoms, Imaging
Phlebography / instrumentation
Phlebography / methods*
Pilot Projects
Predictive Value of Tests
Pulmonary Veins / diagnostic imaging
Radiation Dosage*
Retrospective Studies