Nuclear Instruments and Methods in Physics Research A 497 (2003) 129–134 A dedicated system for breast cancer study with combined SPECT–CT modalities A. Del Guerra a, *, G. Di Domenico b , A. Fantini b , M. Gambaccini b , L. Milano b , N. Sabba b , A. Taibi b , A. Tartari b , A. Tuffanelli b , G. Zavattini b , R. Pani c , R. Pellegrini c , A. Soluri c , M.N. Cinti c , A. Bevilacqua d , D. Bollini d , M. Gombia d , N. Lanconelli d , F. Arfelli e , R. Longo e , A. Olivo e , S. Pani e , P. Poropat e , L. Rigon e a Department of Physics, University of Pisa and INFN Sezione di Pisa, Via F. Buonarotti 2, 56127 Pisa, Italy b Department of Physics, University of Ferrara and INFN Sezione di Ferrara, via Paradiso 12, 44100 Ferrara, Italy c Department of Experimental Medicine, University of Rome La Sapienza, viale Regina Elena 324, 00161 Rome, Italy d Department of Physics, University of Bologna and INFN Sezione di Bologna, via C. Berti Pichat 6/2, 40127 Bologna, Italy e Department of Physics, University of Trieste and INFN Sezione di Trieste, via Valerio 2, 34127 Trieste, Italy Abstract A prototype of a combined CT–SPECT tomograph for breast cancer study has been developed and evaluated. It allows to perform scintimammography and X-ray CT in the same geometrical conditions. The CT system is based on a quasi-monochromatic beam tuned at 28 keV and an array of ultra fast ceramic scintillators coupled to photodiodes whilst the SPECT system is based on two scintillator matrices coupled to position sensitive photomultipliers. CT and SPECT sinograms of a test phantom were recorded and reconstruted with both modalities. Image fusion of CT and SPECT images was then performed. The developed CT–SPECT prototype is able to detect a region of interest of 1 cm 3 , with a 10:1 tumour/background concentration ratio, within an object having a diameter of 8 cm. r 2002 Elsevier Science B.V. All rights reserved. PACS: 87.59.e; 87.59.Fm; 87.59.Ta; 87.62.+n Keywords: Breast cancer; Computed tomography; Scintimammography; Image fusion 1. Introduction Although conventional mammography is the most widespread technique in clinical practice, its limitations in terms of specificity and sensitivity are well known [1,2]. To improve the diagnostic information scintigraphic techniques have been used, and in particular scintimammography with an Anger camera [3,4]. The recent introduction of dedicated imagers with small field of view (FOV) coupled to a moderate breast compression has allowed to increase the sensitivity up to 80% for tumour size between 0.5 and 1 cm [5]. An alter- native technique has also been proposed with the breast in a pendular prone position and a dedicated ring for its SPECT imaging. It has been *Corresponding author. Tel.: +39-050-2214942; fax: +39- 050-2214333. E-mail address: delguerra@pi.infn.it (A. Del Guerra). 0168-9002/03/$ - see front matter r 2002 Elsevier Science B.V. All rights reserved. PII:S0168-9002(02)01902-2