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Dosimetry of an In-Line Kilovoltage Imaging System and Implementation in Treatment Planning

Published:January 21, 2014DOI:https://doi.org/10.1016/j.ijrobp.2013.12.007

      Purpose

      To present the beam properties of the Siemens 70-kV and 121-kV linear accelerator-mounted imaging modalities and commissioning of the 121-kV beam in the Philips Pinnacle treatment planning system (TPS); measurements in an Alderson phantom were performed for verification of the model and to estimate the cone-beam CT (CBCT) imaging dose in the head and neck, thorax, and pelvis.

      Methods and Materials

      The beam profiles and depth–dose curve were measured in an acrylic phantom using thermoluminescent dosimeters and a soft x-ray ionization chamber. Measurements were imported into the TPS, modeled, and verified by phantom measurements.

      Results

      Modeling of the profiles and the depth–dose curve can be achieved with good quality. Comparison with the measurements in the Alderson phantom is generally good; only very close to bony structures is the dose underestimated by the TPS. For a 200° arc CBCT of the head and neck, a maximum dose of 7 mGy is measured; the thorax and pelvis 360° CBCTs give doses of 4-10 mGy and 7-15 mGy, respectively.

      Conclusions

      Dosimetric characteristics of the Siemens kVision imaging modalities are presented and modeled in the Pinnacle TPS. Thermoluminescent dosimeter measurements in the Alderson phantom agree well with the calculated TPS dose, validating the model and providing an estimate of the imaging dose for different protocols.
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      References

        • Islam M.K.
        • Purdie T.G.
        • Norrlinger B.D.
        • et al.
        Patient dose from kilovoltage cone beam computed tomography imaging in radiotherapy.
        Med Phys. 2006; 33: 1573-1582
        • Amer A.
        • Marchant T.
        • Sykes J.
        • et al.
        Imaging doses from the Elekta Synergy X-ray cone beam CT system.
        Br J Radiol. 2007; 80: 476-482
        • Ding G.X.
        • Coffey C.W.
        Radiation dose from kilovoltage cone beam computed tomography in an image-guided radiotherapy procedure.
        Int J Radiat Oncol Biol Phys. 2009; 73: 610-617
        • Blessing M.
        • Bhagwat M.S.
        • Lyatskaya Y.
        • et al.
        Kilovoltage beam model for flat panel imaging system with bow-tie filter for scatter prediction and correction.
        Phys Med. 2012; 28: 134-143
        • Alaei P.
        • Ding G.
        • Guan H.
        Inclusion of the dose from kilovoltage cone beam CT in the radiation therapy treatment plans.
        Med Phys. 2010; 37: 244-248
        • Alaei P.
        • Spezi E.
        Commissioning kilovoltage cone-beam CT beams in a radiation therapy treatment planning system.
        J App Clin Med Phys. 2012; 13: 19-33
        • Fast M.F.
        • Krauss A.
        • Oelfke U.
        • et al.
        Position detection accuracy of a novel linac-mounted intrafractional x-ray imaging system.
        Med Phys. 2012; 39: 109-118
        • Stützel J.
        • Oelfke U.
        • Nill S.
        A quantitative image quality comparison of four different image guided radiotherapy devices.
        Radiother Oncol. 2008; 86: 20-24
        • Fast M.F.
        • Koenig T.
        • Oelfke U.
        • et al.
        Performance characteristics of a novel megavoltage cone-beam-computed tomography device.
        Phys Med Biol. 2012; 57: N15-N24
      1. Heuss K. Markus B. DGMP-Bericht Nr. 5, Praxis der Weichstrahldosimetrie. Deutsche Gesellschaft für Medizinische Physik, Berlin, Germany1986
        • Davis S.D.
        • Ross C.K.
        • Mobit P.N.
        • et al.
        The response of LiF thermoluminescence dosemeters to photon beams in the energy range from 30 kV X rays to 60Co gamma rays.
        Radiat Prot Dosim. 2003; 106: 33-43
        • Alaei P.
        • Gerbi B.J.
        • Geise R.A.
        Generation and use of photon energy deposition kernels for diagnostic quality x rays.
        Med Phys. 1999; 26: 1687-1697
        • Poirier Y.
        • Kouznetsov A.
        • Tambasco M.
        A simplified approach to characterizing a kilovoltage source spectrum for accurate dose computation.
        Med Phys. 2012; 39: 3041-3050
        • Ding G.X.
        • Munro P.
        • Pawlowski J.
        • et al.
        Reducing radiation exposure to patients from kV-CBCT imaging.
        Radiother Oncol. 2010; 97: 585-592
        • Palm A.
        • Nilsson E.
        • Herrnsdorf L.
        Absorbed dose and dose rate using the Varian OBI 1.3 and 1.4 CBCT system.
        J Appl Clin Med Phys. 2010; 11: 229-240
        • Spezi E.
        • Downes P.
        • Jarvis R.
        • et al.
        Patient-specific three-dimensional concomitant dose from cone beam computed tomography exposure in image-guided radiotherapy.
        Int J Radiat Oncol Biol Phys. 2012; 83: 419-426
        • Ding G.X.
        • Munro P.
        Radiation exposure to patients from image guidance procedures and techniques to reduce the imaging dose.
        Radiother Oncol. 2013; 108: 91-98
        • Song W.Y.
        • Kamath S.
        • Ozawa S.
        • et al.
        A dose comparison study between XVI and OBI CBCT systems.
        Med Phys. 2008; 35: 480-486
        • Stock M.
        • Palm A.
        • Altendorfer A.
        • et al.
        IGRT induced dose burden for a variety of imaging protocols at two different anatomical sites.
        Radiother Oncol. 2012; 102: 355-363
        • Shah A.
        • Aird E.
        • Sheckdar J.
        Contribution to normal tissue dose from concomitant radiation for two common kV-CBCT systems and one MVCT system used in radiotherapy.
        Radiother Oncol. 2012; 105: 139-144
        • Hyer D.E.
        • Serago C.F.
        • Kim S.
        • et al.
        An organ and effective dose study of XVI and OBI cone-beam CT systems.
        J Appl Clin Med Phys. 2010; 11: 181-197
        • Marinello G.
        • Mege J.P.
        • Besse M.C.
        • et al.
        Radiothérapie des cancers de la prostate: Évaluation in vivo de la dose délivrée par tomographie conique de basse énergie (kV).
        Cancer Radiother. 2009; 13: 353-357

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