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Water and tissue equivalence of a new PRESAGE® formulation for 3D proton beam dosimetry: A Monte Carlo study

Journal Article


Abstract


  • Purpose: To evaluate the water and tissue equivalence of a new PRESAGE ® 3D dosimeter for proton therapy. Methods: The GEANT4 software toolkit was used to calculate and compare total dose delivered by a proton beam with mean energy 62 MeV in a PRESAGE® dosimeter, water, and soft tissue. The dose delivered by primary protons and secondary particles was calculated. Depth-dose profiles and isodose contours of deposited energy were compared for the materials of interest. Results: The proton beam range was found to be ≈27 mm for PRESAGE®, 29.9 mm for soft tissue, and 30.5 mm for water. This can be attributed to the lower collisional stopping power of water compared to soft tissue and PRESAGE®. The difference between total dose delivered in PRESAGE® and total dose delivered in water or tissue is less than 2 across the entire watertissue equivalent range of the proton beam. The largest difference between total dose in PRESAGE® and total dose in water is 1.4, while for soft tissue it is 1.8. In both cases, this occurs at the distal end of the beam. Nevertheless, the authors find that PRESAGE® dosimeter is overall more tissue-equivalent than water-equivalent before the Bragg peak. After the Bragg peak, the differences in the depth doses are found to be due to differences in primary proton energy deposition; PRESAGE® and soft tissue stop protons more rapidly than water. The dose delivered by secondary electrons in the PRESAGE® differs by less than 1 from that in soft tissue and water. The contribution of secondary particles to the total dose is less than 4 for electrons and ≈1 for protons in all the materials of interest. Conclusions: These results demonstrate that the new PRESAGE® formula may be considered both a tissue- and water-equivalent 3D dosimeter for a 62 MeV proton beam. The results further suggest that tissue-equivalent thickness may provide better dosimetric and geometric accuracy than water-equivalent thickness for 3D dosimetry of this proton beam. © 2012 American Association of Physicists in Medicine.

UOW Authors


  •   Baldock, Clive (external author)

Publication Date


  • 2012

Citation


  • Gorjiara, T., Kuncic, Z., Doran, S., Adamovics, J., & Baldock, C. (2012). Water and tissue equivalence of a new PRESAGE® formulation for 3D proton beam dosimetry: A Monte Carlo study. Medical Physics, 39(11), 7071-7079. doi:10.1118/1.4757922

Scopus Eid


  • 2-s2.0-84868601637

Start Page


  • 7071

End Page


  • 7079

Volume


  • 39

Issue


  • 11

Abstract


  • Purpose: To evaluate the water and tissue equivalence of a new PRESAGE ® 3D dosimeter for proton therapy. Methods: The GEANT4 software toolkit was used to calculate and compare total dose delivered by a proton beam with mean energy 62 MeV in a PRESAGE® dosimeter, water, and soft tissue. The dose delivered by primary protons and secondary particles was calculated. Depth-dose profiles and isodose contours of deposited energy were compared for the materials of interest. Results: The proton beam range was found to be ≈27 mm for PRESAGE®, 29.9 mm for soft tissue, and 30.5 mm for water. This can be attributed to the lower collisional stopping power of water compared to soft tissue and PRESAGE®. The difference between total dose delivered in PRESAGE® and total dose delivered in water or tissue is less than 2 across the entire watertissue equivalent range of the proton beam. The largest difference between total dose in PRESAGE® and total dose in water is 1.4, while for soft tissue it is 1.8. In both cases, this occurs at the distal end of the beam. Nevertheless, the authors find that PRESAGE® dosimeter is overall more tissue-equivalent than water-equivalent before the Bragg peak. After the Bragg peak, the differences in the depth doses are found to be due to differences in primary proton energy deposition; PRESAGE® and soft tissue stop protons more rapidly than water. The dose delivered by secondary electrons in the PRESAGE® differs by less than 1 from that in soft tissue and water. The contribution of secondary particles to the total dose is less than 4 for electrons and ≈1 for protons in all the materials of interest. Conclusions: These results demonstrate that the new PRESAGE® formula may be considered both a tissue- and water-equivalent 3D dosimeter for a 62 MeV proton beam. The results further suggest that tissue-equivalent thickness may provide better dosimetric and geometric accuracy than water-equivalent thickness for 3D dosimetry of this proton beam. © 2012 American Association of Physicists in Medicine.

UOW Authors


  •   Baldock, Clive (external author)

Publication Date


  • 2012

Citation


  • Gorjiara, T., Kuncic, Z., Doran, S., Adamovics, J., & Baldock, C. (2012). Water and tissue equivalence of a new PRESAGE® formulation for 3D proton beam dosimetry: A Monte Carlo study. Medical Physics, 39(11), 7071-7079. doi:10.1118/1.4757922

Scopus Eid


  • 2-s2.0-84868601637

Start Page


  • 7071

End Page


  • 7079

Volume


  • 39

Issue


  • 11