1. Department of Radiation Oncology; Tufts University School of Medicine; Boston MA 02111 USA
2. Unidad Mixta de Investigación en Radiofísica e Instrumentación Nuclear en Medicina (IRIMED); Instituto de Investigación Sanitaria La Fe (IIS-La Fe)-Universitat de Valéncia; Bujassot 46100 Spain
3. Schiffler Cancer Center; Wheeling Hospital; Wheeling WV 26003 USA
4. Accredited Dosimetry and Calibration Laboratory; University of Wisconsin; Madison WI 53706 USA
5. Department of Radiation Physics; M.D. Anderson Cancer Center; Houston TX 77030 USA
6. Comprehensive Cancer Centers of Nevada; Las Vegas NV 89169 USA
7. Radiation Physics Division; National Institute of Standards and Technology; Gaithersburg MD 20899 USA
8. Department of Therapeutic Radiology; Yale University School of Medicine; New Haven CT 06510 USA
9. Medical Physics Laboratory; Medical School; University of Athens; Athens Greece