Daisuke Kawahara1, Shuichi Ozawa1,2, Hisashi Nakano3, Katsumaro Kubo4, Takehiro Shiinoki5, Tomoki Kimura1, Yasushi Nagata1,2. 1. Department of Radiation Oncology, Institute of Biomedical & Health Sciences, Hiroshima University, Japan. 2. Hiroshima High-Precision Radiotherapy Cancer Center, Japan. 3. Department of Radiation Oncology, Niigata University Medical and Dental Hospital, Japan. 4. Department of Radiation Oncology, Hiroshima Prefectural Hospital, Japan. 5. Department of Radiation Oncology, Graduate School of Medicine, Yamaguchi University, Japan.
Abstract
BACKGROUND: Previously, the physical dose-enhancement factor (DphysEF) enhancement was introduced. However, the dose enhancement considering the biological effectiveness was not shown. PURPOSE: The aim of the current study was to evaluate the biological dose-enhancement factor (DbioEF) by the dose rate and to compare the DphysEF and the DbioEF in Lipiodol for liver Stereotactic Body Radiation Therapy (SBRT). MATERIALS AND METHODS: Flattening-filter-free (FFF) 6-MV (6MVX) and 10MVX beams were delivered by TrueBeam. A virtual inhomogeneity phantom and a liver SBRT patient-treatment plan were used. The DphysEF and lineal energy distribution ( y ) distribution was calculated from Monte Carlo simulations. Using a microdosimetric-kinetic (MK) model that is estimated based on the linear-quadratic formula for Lipiodol using human liver hepatocellular cells (HepG2), the biological dose and biological dose enhancement factor (DbioEF) were calculated. The dose rate in the simulation was changed from 0.1 to 24 Gy/min. RESULTS: The DbioEF (DR:2Gy/min) and DphysEF with 10MVX FFF beam were 23.2% and 19.1% at maximum and 12.8% and 11.1% on average in the Lipiodol. In the comparison of the DbioEF between 0.1-24 Gy/min, the DbioEF was 21.2% and 11.1% with 0.1 Gy/min for 6MVX and 10 MVX, respectively. The DbioEF was larger than DEF for the 6MVX and 10MVX FFF beams. In clinical cases with the 10MVX FFF beam, the DbioEF and DphysEF in the Lipiodol region can increase the in-tumor dose by approximately 11% and 10%, respectively, without increasing the dose to normal tissue. CONCLUSIONS: The lower-energy and higher-dose-rate beams were contributed to the biological dose. The Lipiodol caused the enhancement of the physical dose and biological effectiveness. ADVANCES IN KNOWLEDGE: The biological dose enhancement (DbioEF) should be considered in the high-density material such as the Lipiodol.
BACKGROUND: Previously, the physical dose-enhancement factor (DphysEF) enhancement was introduced. However, the dose enhancement considering the biological effectiveness was not shown. PURPOSE: The aim of the current study was to evaluate the biological dose-enhancement factor (DbioEF) by the dose rate and to compare the DphysEF and the DbioEF in Lipiodol for liver Stereotactic Body Radiation Therapy (SBRT). MATERIALS AND METHODS: Flattening-filter-free (FFF) 6-MV (6MVX) and 10MVX beams were delivered by TrueBeam. A virtual inhomogeneity phantom and a liver SBRT patient-treatment plan were used. The DphysEF and lineal energy distribution ( y ) distribution was calculated from Monte Carlo simulations. Using a microdosimetric-kinetic (MK) model that is estimated based on the linear-quadratic formula for Lipiodol using human liver hepatocellular cells (HepG2), the biological dose and biological dose enhancement factor (DbioEF) were calculated. The dose rate in the simulation was changed from 0.1 to 24 Gy/min. RESULTS: The DbioEF (DR:2Gy/min) and DphysEF with 10MVX FFF beam were 23.2% and 19.1% at maximum and 12.8% and 11.1% on average in the Lipiodol. In the comparison of the DbioEF between 0.1-24 Gy/min, the DbioEF was 21.2% and 11.1% with 0.1 Gy/min for 6MVX and 10 MVX, respectively. The DbioEF was larger than DEF for the 6MVX and 10MVX FFF beams. In clinical cases with the 10MVX FFF beam, the DbioEF and DphysEF in the Lipiodol region can increase the in-tumor dose by approximately 11% and 10%, respectively, without increasing the dose to normal tissue. CONCLUSIONS: The lower-energy and higher-dose-rate beams were contributed to the biological dose. The Lipiodol caused the enhancement of the physical dose and biological effectiveness. ADVANCES IN KNOWLEDGE: The biological dose enhancement (DbioEF) should be considered in the high-density material such as the Lipiodol.
Authors: Michael K K Leung; James C L Chow; B Devika Chithrani; Martin J G Lee; Barbara Oms; David A Jaffray Journal: Med Phys Date: 2011-02 Impact factor: 4.071
Authors: Fada Guan; Lawrence Bronk; Uwe Titt; Steven H Lin; Dragan Mirkovic; Matthew D Kerr; X Ronald Zhu; Jeffrey Dinh; Mary Sobieski; Clifford Stephan; Christopher R Peeler; Reza Taleei; Radhe Mohan; David R Grosshans Journal: Sci Rep Date: 2015-05-18 Impact factor: 4.379