Comparison of calculated dose by helical tomotherapy treatment planning machine and measured dose of radiophotoluminescence glass dosimeter in lung lesions using Rando Phantom.

AIM To examine the compatibility of the measured and calculated dose for the treatment of lung lesions by helical tomotherapy. MATERIALS AND METHODS The administered dose was measured a total of 55 times at 22 points with a radiophotoluminescence glass dosimeter (RPLGD) inserted in the position of an anthropomorphic Rando Phantom. Two Gy were prescribed and calculated with a tomotherapy planning machine for a 3-cm diameter spherical planning target volume (PTV) created in the lung area. Compatibility (measured dose/calculated dose and σ value=(D(meas)-D(calc))/D(prescribed)) × 100 (%)) was analyzed according to dosimeter location. RESULTS Deviations between measured and calculated doses for the lung lesion were within 4% for planning target volume, indicating that adequate dose delivery to the PTV was achievable. On the other hand, we found dose deviations up to 15% for the lower prescribed dose range (64% or less) for the measured dose/calculated comparison and a 6% deviation according to the σ value in or near inhomogeneous tissue. CONCLUSION Although the measured dose satisfied the clinical requirement in almost all areas including PTV, we should note that there may be discrepancies between expected calculated dose and irradiated dose in or near inhomogeneous area.