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Integral dose conservation in radiotherapy.

Publication ,  Journal Article
Reese, AS; Das, SK; Curie, C; Marks, LB
Published in: Med Phys
March 2009

Treatment planners frequently modify beam arrangements and use IMRT to improve target dose coverage while satisfying dose constraints on normal tissues. The authors herein analyze the limitations of these strategies and quantitatively assess the extent to which dose can be redistributed within the patient volume. Specifically, the authors hypothesize that (1) the normalized integral dose is constant across concentric shells of normal tissue surrounding the target (normalized to the average integral shell dose), (2) the normalized integral shell dose is constant across plans with different numbers and orientations of beams, and (3) the normalized integral shell dose is constant across plans when reducing the dose to a critical structure. Using the images of seven patients previously irradiated for cancer of brain or prostate cancer and one idealized scenario, competing three-dimensional conformal and IMRT plans were generated using different beam configurations. Within a given plan and for competing plans with a constant mean target dose, the normalized integral doses within concentric "shells" of surrounding normal tissue were quantitatively compared. Within each patient, the normalized integral dose to shells of normal tissue surrounding the target was relatively constant (1). Similarly, for each clinical scenario, the normalized integral dose for a given shell was also relatively constant regardless of the number and orientation of beams (2) or degree of sparing of a critical structure (3). 3D and IMRT planning tools can redistribute, rather than eliminate dose to the surrounding normal tissues (intuitively known by planners). More specifically, dose cannot be moved between shells surrounding the target but only within a shell. This implies that there are limitations in the extent to which a critical structure can be spared based on the location and geometry of the critical structure relative to the target.

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Published In

Med Phys

DOI

ISSN

0094-2405

Publication Date

March 2009

Volume

36

Issue

3

Start / End Page

734 / 740

Location

United States

Related Subject Headings

  • Tomography, X-Ray Computed
  • Radiotherapy, Intensity-Modulated
  • Radiotherapy, Conformal
  • Radiotherapy Planning, Computer-Assisted
  • Radiotherapy Dosage
  • Prostatic Neoplasms
  • Nuclear Medicine & Medical Imaging
  • Male
  • Imaging, Three-Dimensional
  • Humans
 

Citation

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Reese, A. S., Das, S. K., Curie, C., & Marks, L. B. (2009). Integral dose conservation in radiotherapy. Med Phys, 36(3), 734–740. https://doi.org/10.1118/1.3070585
Reese, Adam S., Shiva K. Das, Charles Curie, and Lawrence B. Marks. “Integral dose conservation in radiotherapy.Med Phys 36, no. 3 (March 2009): 734–40. https://doi.org/10.1118/1.3070585.
Reese AS, Das SK, Curie C, Marks LB. Integral dose conservation in radiotherapy. Med Phys. 2009 Mar;36(3):734–40.
Reese, Adam S., et al. “Integral dose conservation in radiotherapy.Med Phys, vol. 36, no. 3, Mar. 2009, pp. 734–40. Pubmed, doi:10.1118/1.3070585.
Reese AS, Das SK, Curie C, Marks LB. Integral dose conservation in radiotherapy. Med Phys. 2009 Mar;36(3):734–740.

Published In

Med Phys

DOI

ISSN

0094-2405

Publication Date

March 2009

Volume

36

Issue

3

Start / End Page

734 / 740

Location

United States

Related Subject Headings

  • Tomography, X-Ray Computed
  • Radiotherapy, Intensity-Modulated
  • Radiotherapy, Conformal
  • Radiotherapy Planning, Computer-Assisted
  • Radiotherapy Dosage
  • Prostatic Neoplasms
  • Nuclear Medicine & Medical Imaging
  • Male
  • Imaging, Three-Dimensional
  • Humans