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Abstract
Annotatsiya: Tor ⁶⁰Co gamma-nurlari nurlanishlarida yutilgan dozani hisoblash uchun, birlamchi dozani P0(dm, r), kollimator sochilishini Sc (r) va fantom (toʻqima) sochilishini TAR(d,r) tavsiflovchi analitik funksiyalar asosida quyidagi formula taklif etilgan va bu funksiyalar miqdoriy jihatdan aniqlandi:
D(d,r) = P₀ (dm, r) * Sc (r) * TAR(d,r)
Radiusi atigi 0,2 sm ga teng boʻlgan juda tor nurlar uchun ham yutilgan doza qiymati hisoblab chiqildi. Taklif etilgan analitik modelning ishonchliligi Gamma Pichoq (Gamma Knife) tizimi uchun amalda o‘lchangan doza ma’lumotlari bilan taqqoslandi. Olingan natijalar eksperimental ma’lumotlar bilan yuqori darajada mos kelishi aniqlandi.
References
1. P. S. Nizin and R. B. Mooij, ‘‘Tissue–air ratios for narrow 60Co gammaray beams,’’ Med. Phys. 25, 1458–1463 ~1998.
2. A. L. McKenzie, ‘‘Cobalt-60 gamma-ray beams,’’ Br. J. Radiol. Suppl. 25, 46–61 ~1996.
3. A. Wu, G. Lindner, A. H. Maitz, A. M. Kalend, L. D. Lunsford, J. C. Flickinger, and W. D. Bloomer, ‘‘Physics of Gamma Knife approach on convergent beams in stereotactic radiosurgery,’’ Int. J. Radiat. Oncol., Biol., Phys. 18, 941–949 ~1990.
4. R. B. Mooij ~Columbia University, personal communication, 1998.
5. J. Arndt ~ELEKTA Instrument, personal communication, 1998.
6. J. E. Burns, ‘‘Definition of tissue–air ratio,’’ Br. J. Radiol. Suppl. 25, 177–182 ~1996.
7. ICRU Report 23, Measurement of Absorbed Dose in a Phantom Irradiated by a Single Beam of X or Gamma Rays ~ICRU, Washington, DC,
1973.
8. P. S. Nizin and X. S. Chang, ‘‘Primary dose in photon beams with lateral electron disequilibrium,’’ Med. Phys. 18, 744–748 ~1991.
9. P. S. Nizin, ‘‘Electronic equilibrium and primary dose in collimated photon beams,’’ Med. Phys. 20, 1721–1729 ~1993.
10. J. J. M. van Gasteren, S. Heukelom, H. J. van Kleffens, R. van der Laarse, J. L. M. Vanselaar, and C. F. Westermann, ‘‘The determination of phantom and collimator scatter components of the output of megavoltage photon beams: Measurements of the collimator scatter part with a beamcoaxial narrow cylindrical phantom,’’ Radiother. Oncol. 20, 250–257 ~1991.
11. K. Lam and R. K. Ten Haken, ‘‘In phantom determination of the head scatter factor Sc,’’ Med. Phys. 22, 963 ~1995.
12. H. E. Johns and J. R. Cunningham, The Physics of Radiology, 3rd ed. ~Charles C. Thomas, Springfield, IL, 1974.
13. P. S. Nizin, ‘‘Geometrical aspects of scatter-to-primary ratio and primary dose,’’ Med. Phys. 18, 153–160 ~1991.
14. P. S. Nizin, G.-X. Qian, and H. Rashid, ‘‘Zero-field dose data for 60Co and other high-energy photon beams in water,’’ Med. Phys. 20, 1353– 1360 ~1993.
15. B. E. Bja¨rngard and P. L. Petti, ‘‘Description of the scatter component in photon-beam data,’’ Phys. Med. Biol. 33, 21–32 ~1988.
16. K. R. Kase and G. K. Svensson, ‘‘Head scatter data for several linear accelerators ~4–18 MV,’’ Med. Phys. 13, 530–532 ~1986.
17. F. M. Khan, The Physics of Radiation Therapy, 2nd ed. ~Williams and Wilkins, Baltimore, MD, 1992.
18. P. S. Nizin, D. M. Bellezza, and R. B. Mooij, ‘‘The elements of tissue–air ratio and systematic error,’’ Med. Phys. 23, 1191–1197 ~1996.
19. B. E. Bja¨rngard and R. L. Siddon, ‘‘A note on equivalent circles, squares, and rectangles,’’ Med. Phys. 9, 258–260 ~1982.