Characteristics of Dose Distribution at Junctional Area Using the Divergency Cutout Block in the Abutted Field of Photon and Electron Beams

광자선과 전자선의 인접조사에서 선속 퍼짐현상이 고려된 전자선 차폐물을 이용한 접합 조사면의 선량분포 특성

  • Im, In-Chul (Department of Radiological Science, Dongeui University) ;
  • Lee, Jae-Seung (Department of Radiation Oncology, Good Samaritan Hospital)
  • 임인철 (동의대학교 방사선학과) ;
  • 이재승 (선린의료원 방사선종양학과)
  • Received : 2011.08.05
  • Accepted : 2011.08.23
  • Published : 2011.09.30

Abstract

This study investigated characteristics of dose distribution at junction field of X-ray and electron beams according to the method for fabricating the insert block on the electron cone. Insert block were fabricated to the divergency cutout block and the straight cutout block. For the 6 MV X-ray and 10 MeV nominal energy of electron beam, we was adjacent to the light field of X-ray and electron beam at a surface of matrix chamber and measured to beam profile of abutted field in the 0, 1, 2, 3 cm measurement depth. As a result, characteristics of dose distribution at junction field, straight block was existent that over dose area exceed the give dose more than 5% and under dose area with a rapid change in dose distribution. However, divergency block had remarkably decreased the over dose area caused by the lateral scattering effects of decrease, and being existed uniformity dose distribution in the junction field. Therefore, divergency block were the benefits of radiation dose delivery, in order to applied the clinical, measurement of electron beams according to the fabrication method of the block should be considered carefully.

Acknowledgement

Supported by : 동의대학교

References

  1. Popovtzer A, Eisbruch A. Advances in radiation therapy of head and neck cancer. Expert Rev Anticancer Ther. 2008;8(4):633-644. https://doi.org/10.1586/14737140.8.4.633
  2. Bilge H, Kucucuk H, Okutan M, Cakir A, Kucucuk S. Matchline dosimetry of half beam technique at fixed SSD using co-60 and 4 MV photons in the treatment of head and neck tumors. Physica medica. 2003;9(1): 37-42.
  3. Mahadevan A, Lee A, Holupka E, Sampson C, Liu X. An optimized multileaf feathering technique for matching single isocenter half beam 3 field head and neck radiation. Int. J. of Radiat. Oncol. Biol. Phys. 2005;63(1):S499.
  4. Armstrong DI, Tait JJ. The matching of adjacent fields in radiotherapy. Radiology. 1973;108(2):419-422. https://doi.org/10.1148/108.2.419
  5. Williamson TJ. A technique for matching orthogonal megavoltage fields. Int. J. Radiat. Oncol. Biol. Phys. 1979;5(1):111-116. https://doi.org/10.1016/0360-3016(79)90048-8
  6. Kahn FM. The physics of radiation therapy. 4th edition. 1996.
  7. Bentel GC. Radiation Therapy Planning. 2nd edition. 1996.
  8. Jonhnson JM, Khan FM. Dosimetric effects of abutting extended SSD electron fields with photons in the treatment of head and neck cancers. Int. J. Radiat. Oncol. Biol. Phys. 1994;28(3):741-747. https://doi.org/10.1016/0360-3016(94)90202-X
  9. Hopfan S, Reid A, Simpson L, Ager PJ. Clinical application arising from overlapping of adjacent radiation fields. Int. J. Radiat. Oncol. Biol. Phys. 1977;2(7):801-808. https://doi.org/10.1016/0360-3016(77)90067-0
  10. Jette D, Walker S. Electron dose calculation using multiple scattering theory; Evaluation of a new model for inhomogeneities. Med. Phys. 1992;19(5): 1241-1254. https://doi.org/10.1118/1.596756
  11. Verhaegen F, Tayler RS, Liu HH, Nahum AE. Backscatter towards the monitor ion chamber in high-energy photon and electron beams; charge integration versus Monte Carlo simulation. Phys. Med. Biol. 2000;45(11):3159-3170. https://doi.org/10.1088/0031-9155/45/11/304
  12. Jette D. Electron beam dose calculation in radiation therapy physics. 2nd edition. 1995.
  13. Bruinvis IAD, Amste AV, Elevelt AJ, Larse RV. Calculation of electron beam dose distributions of arbitrarily shaped field. Phys. Med. Biol. 1983;28(6): 667-683. https://doi.org/10.1088/0031-9155/28/6/007
  14. Kelin EE, Low DA, Purdy JA. Changes in electron beam dosimetry with a new scattering foil-applicator system on a CL2100C. Int. J. Radiat. Oncol. Biol. Phys. 1995;32(2):483-490. https://doi.org/10.1016/0360-3016(94)00452-Q
  15. Choi DR, Wolters J, Mason D, Bailie A. Modified sector-integration method for predicting the outputfactors of electron beams inculuding extended source to surface distance. Phys. Med. Biol. 2000;45(11):3367-3372. https://doi.org/10.1088/0031-9155/45/11/318
  16. Choi DR, Mobit PN, Breitman KE. The clinical implementation of a method for calculating the output factor and percent depth dose for an electron beam. Phys. Med. Biol. 2003;48(7):899-908. https://doi.org/10.1088/0031-9155/48/7/307
  17. Faddegon BA, Villarreal-Barajas JE. Final aperture superposition technique applied to fast calculation of electron output factors and depth dose curves. Med. Phys. 2005;32(11):3286-3294. https://doi.org/10.1118/1.2068947
  18. Goo EH, Lee JS, Kim MJ, Dong KR, Kweon DC, Chung WK. Physical characteristics of the electron beam distribution according to the fabrication method of the block; Based on a linear accelerator. J. Kor. Phys. Soc. 2010;57(3):506-513. https://doi.org/10.3938/jkps.57.506
  19. Poppe B, Blechschmidt A, Djouguela A, Kollhoff R, Rubach A, Willborn KC, Harder D. Two-dimensional ionization chamber arrays for IMRT plan verification. Med. Phys. 2006;33(4):1005-1015. https://doi.org/10.1118/1.2179167
  20. Spezi E, Angelini AL, Romani F, Ferri A. Characterization of a 2D ion chamber array for the verification of radiotherapy treatments. Med. Phys. 2005;50(14):3361-3373. https://doi.org/10.1088/0031-9155/50/14/012
  21. Ostinelli A, Gelosa S, Frigerio M, Monti AF. Air bubble effect during alloy cooling in shielding blocks radiotherapy. Radiol. Med. 1998;96(4):390-393.
  22. AAPM. Comprehensive QA for radiation oncology: Report of AAPM Radiation Therapy Committee Task Group No. 40. Med. Phys. 1994;21:581-618.
  23. ICRU. Radiation dosimetry, Electrons with intial energy between 1 and 50 MeV. Report No. 21. Washington D,C: International Commission on Radiation Units and Measurements, 1972.
  24. Kim JK, Kim KH, Oh YK, Kim JK, Jeong DH, Shi KC, Yan KM, Cho MJ, Park IK, Kwon HC, Moon SR, Yun HG. Dose distribution at junctional area for head and neck radiotherapy. Korean J. Med. Phys. 1972;12(2): 161-169.