• Beam quality and dose perturbation of 6 MV flattening-filter-free linac 

      Tsiamas, P.; Sajo, E.; Cifter, F.; Theodorou, K.; Kappas, C.; Makrigiorgos, M.; Marcus, K.; Zygmanski, P. (2014)
      The aim of this study is twofold: (a) determination of the spectral differences for flattening-filter-free (FFF) versus standard (STD) linac under various clinical conditions, (b) based on an extensive list of clinically ...
    • Classification tree based protein structure distances for testing sequence-structure correlation 

      Zintzaras, E. (2008)
      A methodology for testing the correlation between the sequence and structure distances of proteins is proposed. Structure distances were derived by applying a forward growing classification tree algorithm on defined ...
    • A comparison of alternative unit root tests 

      Halkos, G. E.; Kevork, I. S. (2005)
      In this paper we evaluate the performance of three methods for testing the existence of a unit root in a time series, when the models under consideration in the null hypothesis do not display autocorrelation in the error ...
    • A comparison of Monte Carlo simulation with experimental dosimetric techniques for a 6 MV stereotactic radiotherapy unit 

      Tsougos, I. M.; Theodorou, K.; Bazioglou, M. A.; Stathakis, S.; Kappas, C. (2004)
      Purpose: To compare Monte Carlo simulation with conventional dosimetry techniques for stereotactic radiotherapy (SRT), since accurate dosimetry of narrow photon beams is very complicated and has often been questioned, ...
    • Extreme between-study homogeneity in meta-analyses could offer useful insights 

      Ioannidis, J. P. A.; Trikalinos, T. A.; Zintzaras, E. (2006)
      Objectives: Meta-analyses are routinely evaluated for the presence of large between-study heterogeneity. We examined whether it is also important to probe whether there is extreme between-study homogeneity. Study Design: ...
    • HELOW: A program for testing extreme homogeneity in meta-analysis 

      Zintzaras, E.; Ioannidis, J. P. (2014)
      Meta-analysis aims to synthesize results from different studies. Although, in a meta-analysis the presence of large between-study heterogeneity is routinely evaluated, in some instances is also important to probe whether ...
    • Heterogeneity testing in meta-analysis of genome searches 

      Zintzaras, E.; Ioannidis, J. P. A. (2005)
      Genome searches for identifying susceptibility loci for the same complex disease often give inconclusive or inconsistent results. Genome Search Meta-analysis (GSMA) is an established non-parametric method to identify genetic ...
    • A modification of flattening filter free linac for IMRT 

      Tsiamas, P.; Seco, J.; Han, Z.; Bhagwat, M.; Maddox, J.; Kappas, C.; Theodorou, K.; Makrigiorgos, M.; Marcus, K.; Zygmanski, P. (2011)
      Purpose: This study investigates the benefits of a modified flattening filter free (FFF) linac over the standard (STD) linac equipped with the flattening filter. Energy and angular spread of the electron beam of the FFF ...
    • Patient-specific internal radionuclide dosimetry 

      Tsougos, I.; Loudos, G.; Georgoulias, P.; Theodorou, K.; Kappas, C. (2010)
      The development of patient-specific treatment planning systems is of outmost importance in the development of radionuclide dosimetry, taking into account that quantitative three-dimensional nuclear medical imaging can be ...