Transmission Dose Estimation Algorithm for in vivo Dosimertry

투과선량을 이용한 생체내 (in vivo) 선량측정을 위한 알고리즘

  • Published : 2002.09.30


Purpose : Measurement of transmission dose is useful for in vivo dosimetry of QA purpose. The objective of this study is to develope an algorithm for estimation of tumor dose using measured transmission dose for open radiation field. Materials and Methods : Transmission dose was measured with various field size (FS), phantom thickness (Tp), and phantom chamber distance (PCD) with a acrylic phantom for 6 MV and 10 MV X-ray. Source to chamber distance (SCD) was set to 150 cm. Measurement was conducted with a 0.6 co Farmer type ion chamber. Using measured data and regression analysis, an algorithm was developed lot estimation of expected reading of transmission dose. Accuracy of the algorithm was tested with flat solid phantom with various settings. Results : The algorithm consisted of quadratic function of log(A/P) (where A/P is area-perimeter ratio) and tertiary function of PCD. The algorithm could estimate dose with very high accuracy for open square field, with errors within ${\pm}0.5%$. For elongated radiation field, the errors were limited to ${\pm}1.0%$. Conclusion : The developed algorithm can accurately estimate the transmission dose in open radiation fields with various treatment settings.


  1. 우홍균, 하성환, '고에너지 방사선치료용 on-line 선량측정시스템을 위한 알고리즘의 개발,' 대한방사선방어학회지, 22(3):207-218 (1997)
  2. 우홍균, 허순녕, 이형구, 하성환, '투과선량을 이용한 on-line 선량측정에서 불균질 조직에 대한 선량 보정', 대한방사선방어학회지, 23: 139-147(1998)
  3. Urie MM, Goiten M, Loppke K, 'The role of uncertainty analysis in treatment plannning', lnt. J Radiat. Oncol. Biol. Phys., 21:91-107(1991)
  4. Millwater CJ, MacLeod AS, Thwaites DI, 'In vivo semiconductor dosimetry as part of routine quality assurance', Br. J. Radiol., 71:661-668(1998)
  5. Adeyemi A, Lord J. 'An audit of radiotherapy patient doses measured with in vivo semiconductor detectors', Br. J. Radiol., 70:399-408(1997)
  6. Calandrino R, Cattaneo GM, Fiorino C, 'Detection of systematic errors in external radiotherapy before treatment delivery', Radiother. Oncol., 45:271-274(1997)
  7. Essers M, Mijnheer BJ, 'In vivo dosimetry during external photon beam radiotherapy', Int. J. Radial. Oncol. Biol. Phys., 43(2): 245-259(1999)
  8. Noel A, Aletti P, Bey P, 'Detection of errors in individual patients in radiotherapy by systematic in vivo dosimetry', Radiother. Oncol., 34:144-151(1995)
  9. Miszczyk L, Wydmanski J. 'Evaluation of delivered dose changes during radiation therapy', Acta. Oncol., 38(2): 197-201(1999)
  10. Essers M, Lanson JH, Minjinheer BJ, 'In vivo dosimetry during conformal therapy of prostate cancer', Radiother. Oncol., 29:271-279(1993)
  11. Heukelom S, Lanson JH, Minjinheer BJ, 'In vivo dosimetry during pelvic treatment', Radiother. Oncol., 25:111-120(1992)