Calculation of Conversion Coefficient for Effective Dose to Patient and Physician in Interventional Cardiology Procedure Using the Monte Carlo Method

Research Article

Austin J Radiol. 2015;2(3): 1020.

Calculation of Conversion Coefficient for Effective Dose to Patient and Physician in Interventional Cardiology Procedure Using the Monte Carlo Method

William S Santos1*, Caio CS Valeriano2, Walmir Belinato2, Lucio P Neves3, Ana P Perini3, Ana F Maia2 and Linda VE Caldas1

1Instituto de PesquisasEnergéticas e Nucleares, Brazil

2Departamento de Física, Universidade Federal de Sergipe, Brazil

3Instituto de Física, Universidade Federal de Uberlândia (UFU), Av. João Naves de Ávila, 2121, Santa Mônica, 38400-902 Uberlândia, MG, Brazil

*Corresponding author: William S Santos, Institute of Nuclear and Pesquisas Energéticas, National Commission of Nuclear Energy (IPEN - CNEN / SP ), Av. LineuPrestes, 2242, Cidade Universitária, 05508-000 São Paulo, SP, Brazil

Received: March 14, 2015; Accepted: April 14, 2015; Published: April 21, 2015


Radiation doses to patients and to medical staff from coronary angiography procedures are relatively high when compared to conventional radiographic procedures. Due to the long image obtainment time, the high doses of radiation can result in deterministic and stochastic effects. In this work, the effective and equivalent tissue doses for the patient and medical staff were calculated and normalized to kerma-area product, to produce kerma-area to an equivalent dose in tissue conversion coefficients for this procedure. Simulations were carried out for four X-ray spectra (60, 70, 80 and 90 kVp) using the radiation transport MCNPX2.7.0 code. The physician in the standing position and the patient in the supine position were represented by a pair of adult mathematical anthropomorphic phantoms. The Conversion Coefficients (CCs) were obtained for irradiation geometry Antero-Posterior (AP), Postero-Anterior (PA), Left Anterior Oblique (LAO90°) and Right Anterior Oblique (RAO90°). The computational results demonstrated that the estimated organ dose values for the physician and patient vary significantly with the organ location and X-ray spectrum. The CCs of effective doses for the patient and physician determined in this study were compared to previous experimental and calculated results presented in the literature and found to be similar.

Keywords: Interventional cardiology; Anthropomorphic phantoms; Medical and occupational exposures; Monte carlo simulation


Coronary Angiography (CA) plays an important role in the diagnosis and treatment of vascular disease and other conditions that can lead to heart attack and stroke. The technique uses radiography to guide the passage of a catheter into the region of the patient’s heart. In general, the patient is examined for long periods of time during the procedure and a large number of radiographic images are obtained [1,2]. The catheter is positioned either in the heart or at the entrance of the arteries supplying the heart, and a special fluid (called a contrast medium or dye) is injected. This fluid is opaque to X-rays, and the images obtained are called angiograms. Due to the relatively long time to obtain the images, the patient and medical staff can receive high doses of radiation, which could result in stochastic effects and which have caused deterministic effects in certain cases [3,4].

Conversion Coefficients (CCs) obtained in this study are normalized to dosimetric quantities that can be obtained by direct measurement such as the Kerma-Area Product (KAP), which can be obtained from the ionization chamber installed in the X-ray equipment used in the procedure. Knowing the measured KAP, it is possible to calculate the dose that patients and physician staff are exposed to during the coronary angiography procedure. CCs for use in radiological protection have been recommended by ICRP publication 116 [5]. However, the use of these CCs is not appropriate for the calculation of effective doses in interventional radiology, because the field size and the beam quality used for these processes are not covered by the ICRP geometries. The aim of this study is to evaluate the influence of variations in tube voltage, the use of protective equipment and beam projection to the medical and occupational exposure, through the CCs for effective dose using the Monte Carlo method.

Materials and Methods

In this study we used the radiation transport MCNPX2.7.0 code [6]. This code can handle the transport and interaction of neutrons, photons and electrons in a wide range of energies and for arbitrary three-dimensional geometries. We developed a realistic irradiation scenario represented by a patient and a physician in the Interventional Cardiology (IC) procedure. Both were represented by two mathematical anthropomorphic phantoms [7]. The physician wearing a lead apron, thyroid shield and glasses with thick of 0.5mm lead was positioned on the left to the patient. The Figure 1 shows an operating table with the characteristics described.