Output ratio in air for MLC shaped irregular fields

Medical Physics

Volumn 31, Issue 9, 2004, Pages 2480-2490

  Zhu, Timothy C ^a   Bjärngard, Bengt E ^a   Xiao, Ying ^b   Bieda, Mike ^a  

^a UNIVERSITY OF PENNSYLVANIA   (United States)

^b THOMAS JEFFERSON UNIVERSITY   (United States)

Author keywords

Head scatter; MLC; Monitor backscatter; Output factor; Output ratio

Indexed keywords

EMPIRICAL MODEL; EXCHANGE EFFECTS; FITTING PARAMETERS; LEAF POSITION; MONITOR UNIT CALCULATIONS; OUTPUT FACTORS; OUTPUT RATIO; SCATTER CORRECTION;

AIR; ALGORITHM; ARTICLE; CALCULATION; COLLIMATOR; INTENSITY MODULATED RADIATION THERAPY; LIGHT SCATTERING; MULTILEAF COLLIMATOR; PRIORITY JOURNAL; RADIATION FIELD;

EID: 4644253384     PISSN: 00942405     EISSN: None     Source Type: Journal    
DOI: 10.1118/1.1767052     Document Type: Article

References (32)

1. A. Dutreix, B. E. Bjärngard, A. Bridier, B. Mijnheer, J. E. Shaw, and H. Svensson, Monitor Unit Calculation For High Energy Photon Beams, 1st ed. (ESTRO and Garant Publishers, Leuven/Apeldoorn, 1997).
2. M. Tatcher and B. E. Bjarngard, "Head scatter factors and effective X ray source positions in a 25 MV linear accelerator," Med. Phys. 19, 685-686 (1992).
3. F. M. Khan, The Physics of Radiation Therapy, 2nd ed. (Williams & Wilkins, Baltimore, 1994).
4. T. C. Zhu, B. E. Bjärngard, Y. Xiao, and C. J. Yang, "Modeling the output ratio in air for megavoltage photon beams," Med. Phys. 28, 925-937 (2001).
5. P. B. Dunscombe and J. M. Nieminen, "On the field-size dependence of relative output from a linear accelerator," Med. Phys. 19, 1441-1444 (1992).
6. T. C. Zhu and B. E. Bjärngard, "The fraction of photons undergoing head scatter in x-ray beams," Phys. Med. Biol. 40, 1127 (1995).
7. S. Kim, J. R. Palta, and T. C. Zhu, "A generalized solution for the calculation of in-air output factors in irregular fields," Med. Phys. 25, 1692-1701 (1998).
8. P. H. Huang, L. M. Chin, and B. E. Bjärngard, "Scattered photons produced by beam-modifying filters," Med. Phys. 13, 57-63 (1986).
9. S. Heukelom, J. M. Hanson, and B. J. Mijnheer, "Wedge factor constituents of high energy photon beams: field size and depth dependence," Radiother. Oncol. 30, 66-73 (1994).
10. R. Bar-Deroma and B. E. Bjärngard, "The relation between wedge factors in air and water," Med. Phys. 21, 1043-1047 (1994).
11. T. C. Zhu, B. E. Bjarngard, and P. Vadash, "Scattered photons from wedges in high-energy x-ray beams," Med. Phys. 22, 1339-1342 (1995).
12. A. L. McKenzie and P. H. Stevens, "How is photon head scatter in a linear accelerator related to the concept of a virtual source?" Phys. Med. Biol. 38, 1173-1180 (1993).
13. S. Kim, C. R. Liu, C. Chen, and J. R. Palta, "Two-effective-source method for the calculation of in-air output at various source-to-detector distances in wedge fields," Med. Phys. 26, 949-955 (1999).
14. M. K. Yu, B. Murray, and R. Sloboda, "Parameterization of head-scatter factors for rectangular photon fields using an equivalent square formalism," Med. Phys. 22, 1329-1332 (1995).
15. A. Ahnesjö, "Analytic modeling of photon scatter from flattening filters in photon therapy beams," Med. Phys. 21, 1227-1235 (1994).
16. P. Vadash and B. E. Bjärngard, "An equivalent square formula for head scatter factors," Med. Phys. 20, 733-734 (1993).
17. S. Kim, T. C. Zhu, and J. R. Palta, "An equivalent square formula for determining head scatter factors of rectangular collimator settings," Med. Phys. 24, 1770-1774 (1997).
18. J. R. Palta, D. K. Yeung, and V. Frouhar, "Dosimetric considerations for a multileaf collimator system," Med. Phys. 23, 1219-24 (1996).
19. S. B. Jiang, A. L. Boyer, and C.-M. C. Ma, "Modeling the extrafocal radiation and monitor chamber backscatter for photon beam dose calculation," Med. Phys. 28, 55-66 (2000).
20. Y. Yang, L. Xing, A. L. Boyer, Y. Song, and Y. Hu, "A three-source model for the calculation of head scatter factors," Med. Phys. 29, 2024-2033 (2002).
21. M. K. Yu and R. S. Sloboda, "Effect of beam blocking on linac head scatter factors," Int. J. Radiat Oncol., Biol., Phys. 37, 465-468 (1997).
22. P. H. Huang, J. Chu, and B. E. Bjärngard, "The effect of collimator-backscatter radiation on photon output of linear accelerators," Med. Phys. 14, 268-269 (1987).
23. H. Kubo, "Telescopic measurements of backscattered radiation from secondary collimator jaws to a beam monitor chamber using a pair of slits," Med. Phys. 16, 295-298 (1989).
24. M. K. Yu, R. S. Sloboda, and F. Mansour, "Measurement of photon beam backscatter from collimators to the beam current monitor chamber using target current pulse counting and telescope techniques," Phys. Med. Biol. 41, 1107-1117 (1996).
25. C. Duzenli, B. McClean, and C. Field, "Backscatter into the beam monitor chamber: Implications for dosimetry of asymmetric collimators," Med. Phys. 20, 363-367 (1993).
26. K. L. Lam, M. S. Muthuswamy, and R. K. Ten Haken, "Measurement of backscatter to the monitor chamber of medical accelerators using target charge," Med. Phys. 25, 334-338 (1998).
27. A. Ahnesjö, T. Knöös, and A. Montelius, "Application of the convolution method for calculation of output factors for therapy photon beams," Med. Phys. 19, 295-304 (1992).
28. T. C. Zhu and B. E. Bjärngard, "The head-scatter factor for small field sizes," Med. Phys. 21, 65-68 (1994).
29. M. Abramowitz and I. A. Stegun, Handbook of Mathematical Functions, 10th ed. (Dover, New York, 1970), p. 297.
30. T. C. Zhu and B. E. Bjarngard, "Head-scatter off-axis for megavoltage x-rays," Med. Phys. 30, 533-543 (2003).
31. K. Yuen, M. S. Al-Ghazi, C. L. Swift, and C. A. White, "A practical method for the calculation of multileaf collimator shaped fields output factors," Med. Phys. 26, 2385-2389 (1999).
32. K. L. Lam, M. S. Muthuswamy, and R. K. Ten Haken, "Flattening- filter-based empirical methods to parameterize the head-scatter factor," Med. Phys. 23, 343-352 (1996).