VoxelDose: A SOFTWARE FOR DOSIMETRIC EVALUATIONS IN X-RAY DIAGNOSES

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1 2007 International Nuclear Atlantic Conference - INAC 2007 Santos, SP, Brazil, September 30 to October 5, 2007 Associação Brasileira de Energia Nuclear - ABEN ISBN: VoxelDose: A SOFTWARE FOR DOSIMETRIC EVALUATIONS IN X-RAY DIAGNOSES Viriato Leal Neto 1,2, José W. Vieira 1,3, Borko Stosic 4 and Fernando R. de A. Lima 5 1 Centro Federal de Educação Tecnológica de Pernambuco Avenida Professor Luis Freire Cidade Universitária, Recife, PE viriatoleal@yahoo.com.br 2 Departamento de Energia Nuclear UFPE Avenida Professor Luis Freire Cidade Universitária, Recife, PE 3 Escola Politécnica de Pernambuco UPE Rua Benfica Madalena, Recife, PE jwvieira@br.inter.net 4 Departamento de Estatística e Informática UFRPE Dois Irmãos, s/n CEP , Recife, PE borko@ufrpe.br 5 Centro Regional de Ciências Nucleares CRCN Avenida Professor Luis Freire Cidade Universitária, Recife, PE falima@cnen.gov.br ABSTRACT In order to evaluate the dose absorbed by the patient in a series of examinations, it is necessary to accomplish simulations using an exposure computational model. Such models are fundamentally formed from a virtual representation of the human body (phantom) and a Monte Carlo code. There are several Monte Carlo codes available and also specific voxel phantoms for the two genders have been developed. However, the coupling of a voxel phantom to a Monte Carlo code is a complex process and it almost always results in the solution of a particular problem. This means that the use of these computational tools is not practicable on the routine of clinics and hospitals that carry out X-Ray examinations, because the simulations with computational models of exposition demand time, knowledge about the used code and several adjustments have to be implemented from one simulation to another. In such context, it was developed a GUI (Graphics User Interface) called VoxelDose, which contains a database with the simulation result of several X-Ray exams in C++. The database was built using the voxel phantoms MAX (Male Adult voxel) and FAX (Female Adult voxel) [1, 2], and the Monte Carlo code EGS4 (Electron Gamma Shower, version 4) [3]. The software has special menus to create databases, insert new examinations, visualize the phantom-field and the phantom-source, and obtain the summary of the doses in the organ and tissues on the screen of the monitor. If the user wants, he will be able to save or print the dosimetric results.

2 1. INTRODUCTION The present work developed a GUI (Graphics User Interface), called VoxelDose to facilitate the use of computational models of exposition based in phantoms of voxel and the Monte Code Carlo EGS4 (Electron Gamma Shower, version 4), for dosimetric evaluations with X- Ray diagnoses. VoxelDose software was developed using the Visual Microsoft C++.NET compiler and the resources of the tools package called.net Framework [4]. In the main window of the software, the user must choose the phantom, the type of examination, the type of projection, the spectre, the focus-film distance and the field to be used. This choice triggers two buttons: one to visualize the phantom-field and the phantom-source, making possible the saving or printing of images, and the other to calculate the dosimetric results, which can be saved or printed. 2. MATERIALS AND METHODS 2.1. Definition of the examinations and its parameters The Present work of thorax and abdomen examinations - AP (Anterior-Posterior), PA (Posterior-Anterior), LD/LE (Profile. LD = Lateral Direita; LE = Lateral Esquerda), was done to present the use and functionality of the VoxelDose. The parameters of the examinations were defined from visits made to Clinics and Hospitals in Recife, and Consultation to the Guidelines of direction and Recommendations for the definition of the user of the selection of parameters of the project DIMOND III image of the European Commission [5]. This brings tables with suggestions of parameters for thorax and abdomen examinations. Among these parameters the most used peak tensions in the examinations: 70 kv, 80 kv, 90 kv, 110 kv and 120 kv. To get the spectre of more probable energies for these tensions, an text file called mspectra.dat was appealed to it, that possesses 61 spectre of energies for diverse types of radioactive sources used in medicine and radioprotection. As to the fields, there is practically a standard of use and they approach to the dimensions of the film used in each case The necessary procedures to the simulation of VOXELS PHANTOM/EGS4 model To build the database it was necessary to execute the VOXEL PHANTOMS VOXELS/EGS4 computational model [6]. For this, it was necessary to develop and to connect geometry to be radiated to the EGS4, build a text file with the shock sessions for the radiation and the used ways, prepare operational data entrances, install the EGS4 and place the user s files, compile and execute the model Development and coupling of geometry

3 The geometry to be radiated must be build in text files according to the decoding programmed in the EGS4. In this work, the task of creation of the files was carried through by software FANTOMAS [7]. Phantoms without the arms (maxsb and faxsb) had been developed from the original versions of MAX and FAX [1, 2] models and used in the simulations of the examinations of thorax and abdomen profile in this work. Once the geometries defined the user s files of the phantom.code.mor EGS4 were adapted to the thorax simulations and abdomen Building of file with the shock sessions The shock sessions for photons and electrons were obtained in the own EGS4, where data were supplied such as the energy interval and the elementary compositions of constituent means of phantoms The operational Entrance Data The FANTOMAS software [7] was also used to create the texts files with operational entrance data (one for each model), called Expo.input, for the Monte Carlo simulation to be carried through: The examination identification number (ID), Resolution of phantom voxels, the ID of the used spectre, the focus-film distance, the field dimensions (height and width), the point source ID - AP, PA, LD and LE -, the number of histories (10 8 ), the cut-off energies for electrons (200 kev) and photons (2 kev), and name of the exit file Compilation and execution of the model With the installed EGS4 and the user s files duly placed, the compiler FORTRAN PowerStation 4.0 of the package Microsoft Developer Studio was used, to tie to the mass of general data and specific data produced by the user in MORTRAN3 [8]. Thus, getting phantoms.exe. The simulation of each planned examination took 2.5 on average h, in a Pentium 4 of 3.0 MHz with 512 MB of memory. The exit of each simulation presents a form with diverse information on the dosimetric Monte Carlo simulation and results for all the radiosensitive organs and tissues. The gotten forms turn to be text files that the user can make use through the Interface. 3. RESULTS AND CONCLUSIONS The simulations results were organized in two text files named MaxBD.txt and FaxBD.txt. These files will used be to demonstrate the GUI of VoxelDose performance To create a data base and to insert an examination The Figure 1 presents the main window of VoxelDose software. To create a database, click in the menu File menu item Criar Novo Banco de Dados it is written the name of the new database to be saved, for example, MaxBD.txt Salvar.

4 Figure 1: Main window of VoxelDose software presenting the Sub-menus of the menu File. In case of insertion of a certain examination, it is clicked the menu Arquivo menu item Inserir Novo Exame to type a number in the text box Posição do Exame no BD... and the button Abrir arquivos do BD e do Exame Abra o arquivo txt do BD... Abrir Arquivo do BD e do Exame TXT... Abra o arquivo txt do Exame... Abrir um Exame... Salva o Novo BD como To visualize and to get the results of the examination In the main window of VoxelDose, it is clicked, in the sequence, the radio buttons Max Tórax AP Selecionar o Espectro, a Distância Foco-Filme e o Campo and it is chosen one of the available examinations, for example, Max_Torax_AP_Exame_7: Espectro: 100 KVP DIAGNOSTIC,2 MM AL,HWS: 3 MM AL, DFF = 100 cm, Largura: 35, Altura: 43 cm, Figure 2. Figure 2: Main window of the VoxelDose presenting the steps during the selection of an examination.

5 With the definition of the intended examination, the Visualizar a Região do Exame and Calcular buttons are qualified. By setting the button Visualizar a Região do Exame two secondary windows appear: Field and Field-Source, showing, respectively, the field object of the examination and the position of the source related to phantom, Figure 3. Figure 3: Images visualized after the trigging of the button To visualize the Region of the Examination. Finally, when clicking the button Calcular, a secondary window appears, Formulário, with the summary of the doses in the radiosensitive organs and tissues related to the selected examination, Figure 4. Figure 4: Window Form with the summary of the doses.

6 The current version of the GUI VoxelDose allows the obtainment of dosimetric results for a predefined examination in a few seconds. It can be very useful in clinics and hospitals for the monitoring of the dosimetric distribution in patients who are submitted to the successive diagnoses involving the X-Rays. The current results are printed in the general format of conversion coefficients between, for example, dose/kerma in the air. In new versions of this GUI, it will also be possible to obtain dose/dose in the private dosimeter, most common coefficient of conversion in radiodiagnoses. It is also intended to extend the number of examinations and make the database available on the Internet. ACKNOWLEDGMENTS The authors are grateful to CNPQ and CEFET-PE for the financial support. REFERENCES 1. R. Kramer, J.W. Vieira, H. J. Khoury, F. R. A. Lima, D. Fuelle. All about MAX: a male adult voxel phantom for Monte Carlo calculations in radiation protection dosimetry, Phys. Med. Biol., Vol. 48, p , R. Kramer, J. W. Vieira, H. J. Khoury, F. R. A. Lima, E. C. M. Loureiro, V. J. M. Lima, G. Hoff. All about FAX: a Female Adult voxel Phantom for Monte Carlo Calculation in Radiation Protection Dosimetry, Phys. Med. Biol., 49, , EGS4 Source Code Availability and Distribution (2006). 4. J. Templeman, A. Olsen, Microsoft visual c++.net, step by step. Version 2003, Microsoft Press, USA, Projeto DIMOND III da European Commission (2004), (2007) 6. J. W. Vieira, Construção de um modelo computacional de exposição para cálculos dosimétricos utilizando o código Monte Carlo EGS4 e fantomas de voxels, Tese de Doutorado, DEN-UFPE, Recife-PE, Brasil, J. W. Vieira, B. Stosic, F. R. A. Lima, R. Kramer, A. M. Santos, V. J. M. Lima. Um software para editar fantomas de voxels e calcular coeficientes de conversão para a proteção radiológica, 1º Congresso Brasileiro de Proteção Radiológica, Rio de Janeiro, 02 a 05 de Novembro de W. R. Nelson, H. Hirayama, D. W. O Rogers. The EGS4 code system, Report SLAC- 265, Stanford Linear Accelerator Center, Stanford University, Stanford, California, CEMBER, H. Introduction to health physics, 3 rd edition, McGraw-Hill, M. H. Kalos, P. A. Whitlock. Monte Carlo methods, Vol. 1, Basics: Wiley & Sons, New York, USA, Comissão Nacional de Energia Nuclear, Diretrizes básicas de proteção radiológica NN (2006). 12. P.J. Collins, D. Gorbatkov, F. W. Shultz. A graphical user interface diagnostic radiology dosimetry using Monte Carlo (MCNP) simulation, 10 th International Congress of the International Radiation Protection Association, IRPA, Hiroshima, Japan, May 2000.