Radiotherapy
Study on the conversion between CT hounsfield units and relative stopping power in proton therapy and the improvement in adipose tissue
Cui Xiangli, Jee Kyungwook, Wang Hongzhi, Hu Man, Lu Hsiaoming
Published 2019-10-25
Cite as Chin J Radiol Med Prot, 2019, 39(10): 772-777. DOI: 10.3760/cma.j.issn.0254-5098.2019.10.011
Abstract
ObjectiveTo introduce a method for calibrating the conversion from CT Hounsfield units (HU) to relative stopping power (RSP) for proton therapy, and improve the precision of the conversion in the region for adipose tissues.
MethodsThe HU and RSP values of human tissues were calculated by a stoichiometric calibration method. Animal tissue was used to simulate subcutaneous adipose tissue of patients, and the HU and RSP of the animal tissue were measured. The effect of subcutaneous adipose tissue on conversion between HU and RSP were analyzed by piecewise fitting.
ResultsThe precision of conversion curve was improved significantly with the measured HU and RSP of adipose tissue in the fitting. The effect caused by different choice in different ionization energy was less than 0.6%, and the effect of proton energy differential was less than 0.8%.
ConclusionsThe precision of conversion curve for the transformation of HU into RSP in adipose tissues could be improved by taking subcutaneous adipose tissue into account, which would reduce the range error of proton beams when such tissues are present in the target volumes or in the beam path.
Key words:
Proton therapy; Relative stopping power; Stoichiometric calibration method
Contributor Information
Cui Xiangli
Anhui Province Key Laboratory of Medical Physics and Technology, Center of Medical Physics and Technology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, China (Cui Xiangli is working at Department of Radiation Oncology, Cancer Hospital, Chinese Academy of Sciences, Hefei 230031, China)
Jee Kyungwook
Department of Radiation Oncology, Massachusetts General Hospital, Harvard Medical School, Boston 02114, USA
Wang Hongzhi
Anhui Province Key Laboratory of Medical Physics and Technology, Center of Medical Physics and Technology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, China
Hu Man
Department of Radiation, Shandong Cancer Hospital, Jinan 25011, China
Lu Hsiaoming
Department of Radiation Oncology, Massachusetts General Hospital, Harvard Medical School, Boston 02114, USA
