Investigation of the potential use of LaBr 3 :Ce scintillators for scintimammography imaging Khalid S. Alzimami a,b,n , Salem A. Sassi c , Abdulrahman A. Alfuraih a , Nicholas M. Spyrou a,b a Department of Radiological Sciences, King Saud University, P.O. Box 10219, Riyadh 11432, Kingdom of Saudi Arabia b Department of Physics, University of Surrey, Guildford, Surrey GU2 7XH, UK c Joint Department of Physics, The Royal Marsden NHS Foundation Trust, Sutton, Surrey SM2 5PT, UK article info Available online 19 June 2010 Keywords: Scintimammography LaBr 3 :Ce NaI(Tl) GATE Monte Carlo simulation abstract The motivation of this study is to exploit the high light yield and excellent energy resolution of LaBr 3 :Ce scintillators compared with NaI(Tl) crystal in scintimammograpic imaging systems. A dedicated gamma camera and 3D phantom were modelled using GATE Monte Carlo code under a variety of imaging situations including lession sizes, tumour activity-to-background ratios and tumour depths. The major finding of the present study is that LaBr 3 :Ce crystal-based cameras have the potential to detect small lesions ( r10 mm) at clinical TBR. & 2010 Elsevier B.V. All rights reserved. 1. Introduction Being the most common and most feared malignancy in women, breast cancer is the second leading cause of cancer death in developed countries [1]. The gold standard of detecting breast cancer early is by screening mammography, which is currently the only screening method available that is proven to reduce breast cancer mortality [2]. However, this technique suffers from lower specificity and sensitivity and therefore patients with dense breasts have been admitted to undergo unnecessary biopsies [3]. Using standard gamma cameras in planar scintimammography has proven useful in the assessment of patients with breast lesions particularly in cases when mammography is imprecise and in women with dense breasts [4]. This technique, however, only demonstrates high sensitivity for tumours 41 cm in diameter [5] and therefore cannot be considered as a screening procedure. For this reason, great importance has been given to the development of dedicated cameras with high intrinsic spatial characteristics in order to enhance the sensitivity and specificity of small tumour detection with scintimammography. Use of a detector with a small field of view (FOV) allows greater flexibility in patient positioning, facilitating the acquisition of projections similar to those of X-ray mammography. Moreover, by placing the detector directly against the breast mild compression can also be applied to breast tissue, resulting in reduced breast thickness, increased target-to-background ratio and improved spatial resolution. In addition to reducing breast (source) detector distance, the choice of detector material plays a vital role in improving breast lesion detectability. Cerium-doped lanthanum crystals, particu- larly LaBr 3 :Ce, are of interest in SPECT imaging due to their high scintillation yield and superior energy resolution. When com- pared with NaI(Tl), LaBr 3 :Ce has 60% more light output and better energy resolution (6–7% vs. 9% FWHM) [6]. LaBr3:Ce also has the added advantage of shorter attenuation length, which would reduce the scintillator volume by 25%, therefore improving intrinsic spatial resolution [7]. The main thrust of this study was to investigate the potential use of LaBr 3 :Ce materials in the constuction of dedicated scintimammography gamma cameras in comparison with NaI(Tl), using GATE Monte Carlo simulations. Imaging performance was assessed by calculating signal-to-noise ratio (SNR) and simulated tumour full-width-half-maximum (FWHM) under a variety of imaging situations. 2. Monte Carlo simulations Monte Carlo simulations are increasingly used in nuclear medicine imaging to assist in the design of new medical imaging devices for emission tomography. GEANT4 application for tomo- graphic emission (GATE; version 3.1.2) as used in this study is a relatively new Monte Carlo simulation package based on GEANT4 dedicated to nuclear imaging applications [8]. GATE combines the advantages of the Geant4 simulation toolkit, well-validated physics models, complicated geometry description, powerful visualisation and time-dependent phenomena management. The GATE Monte Carlo simulation code has been extensively described and validated elsewhere [8–11]. Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/nima Nuclear Instruments and Methods in Physics Research A 0168-9002/$ - see front matter & 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.nima.2010.06.189 n Corresponding author. Tel.: + 966 1469 3567; fax: + 966 1469 3565. E-mail address: kalzimami@ksu.edu.sa (K.S. Alzimami). Nuclear Instruments and Methods in Physics Research A 633 (2011) S282–S285