An Improved Virtual Torso Phantom

• Published in: Radiation protection dosimetry 2000-01, Vol.88 (3), p.233-237
• Main Authors: Kramer, G.H., Crowley, P.
• Format: Article
• Language: English
• Subjects: Applied radiobiology (equipment, dosimetry...); Biological and medical sciences; Biological effects of radiation; Fundamental and applied biological sciences. Psychology; Tissues, organs and organisms biophysics
• ISSN: 0144-8420; 1742-3406
• DOI: 10.1093/oxfordjournals.rpd.a033040

The virtual phantom developed by the Human Monitoring Laboratory has some limitations. For example, it contained no sternum and the ribs extended all the way round the torso, whereas in reality the central part of the chest is covered with a mixture of cartilage (ribs) and bone (sternum). The ribs were located below the chest wall which added to the thickness of the chest wall. The lungs did not touch the inner surface of the chest wall along their length due to the differences in curvature between the ellipsoidal lungs and the ellipsoidal cylinder that defined the torso. As a result there was extra intervening tissue between the lungs and the chest wall. This was shown to have a noticeable effect on the simulation of low energy photons; 17 keV photons had a counting efficiency approximately a factor of 3 lower then experimentally observed. The virtual phantom has been redesigned and a comparison of measured and calculated counting efficiencies shows that it is now good representation of both LLNL or JAERI at all photon energies measured. The agreement is better than 11% over the energy range 17-240 keV.