Portal dose images II: Patient dose estimation

Xingren Ying, Lewis Y. Geer, John W. Wong

Research output: Contribution to journalArticlepeer-review


Due to the many sources of uncertainties in radiotherapy, conventional treatment planning can only provide a nominal presentation of the dose delivered to the patient. Provided that large setup errors can be detected and corrected, we propose that measured and calculated portal dose images can be used to improve estimation of patient dose. The iterative approach described in this paper requires an accurate method of dose calculations, 3-dimensional CT data that closely represents the patient and the measured portal dose image. From the CT data, a portal dose image is calculated for comparison with the measured one. The differences are then used to modify the original CT data so that a new image can be calculated. The process is repeated until the calculated and measured images agree to satisfaction. At that point, the internal dose is calculated using the modified CT data. If the method is successful, daily portal dose images could be used to cumulatively estimate patient dose throughout the course of treatment. This manuscript describes 60Co simulation results to demonstrate the feasibility of the approach.

Original languageEnglish (US)
Pages (from-to)1465-1475
Number of pages11
JournalInternational journal of radiation oncology, biology, physics
Issue number6
StatePublished - Jun 1990
Externally publishedYes


  • On-line radiotherapy imaging
  • Patient dose estimation
  • Treatment uncertainties
  • Treatment verification

ASJC Scopus subject areas

  • Radiation
  • Oncology
  • Radiology Nuclear Medicine and imaging
  • Cancer Research


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