Generation and use of measurement-based 3-D dose distributions for 3-D dose calculation verification.

Robin L Stern, B. A. Fraass, A. Gerhardsson, D. L. McShan, K. L. Lam

Research output: Contribution to journalArticle

24 Citations (Scopus)

Abstract

A 3-D radiation therapy treatment planning system calculates dose to an entire volume of points and therefore requires a 3-D distribution of measured dose values for quality assurance and dose calculation verification. To measure such a volumetric distribution with a scanning ion chamber is prohibitively time consuming. A method is presented for the generation of a 3-D grid of dose values based on beam's-eye-view (BEV) film dosimetry. For each field configuration of interest, a set of BEV films at different depths is obtained and digitized, and the optical densities are converted to dose. To reduce inaccuracies associated with film measurement of megavoltage photon depth doses, doses on the different planes are normalized using an ion-chamber measurement of the depth dose. A 3-D grid of dose values is created by interpolation between BEV planes along divergent beam rays. This matrix of measurement-based dose values can then be compared to calculations over the entire volume of interest. This method is demonstrated for three different field configurations. Accuracy of the film-measured dose values is determined by 1-D and 2-D comparisons with ion chamber measurements. Film and ion chamber measurements agree within 2% in the central field regions and within 2.0 mm in the penumbral regions.

Original languageEnglish (US)
Pages (from-to)165-173
Number of pages9
JournalMedical Physics
Volume19
Issue number1
DOIs
StatePublished - Jan 1992
Externally publishedYes

Fingerprint

Ions
Film Dosimetry
Photons
Radiotherapy
Therapeutics

ASJC Scopus subject areas

  • Biophysics

Cite this

Generation and use of measurement-based 3-D dose distributions for 3-D dose calculation verification. / Stern, Robin L; Fraass, B. A.; Gerhardsson, A.; McShan, D. L.; Lam, K. L.

In: Medical Physics, Vol. 19, No. 1, 01.1992, p. 165-173.

Research output: Contribution to journalArticle

Stern, Robin L ; Fraass, B. A. ; Gerhardsson, A. ; McShan, D. L. ; Lam, K. L. / Generation and use of measurement-based 3-D dose distributions for 3-D dose calculation verification. In: Medical Physics. 1992 ; Vol. 19, No. 1. pp. 165-173.
@article{2f528a6030534d50b3503cdf6ef391f6,
title = "Generation and use of measurement-based 3-D dose distributions for 3-D dose calculation verification.",
abstract = "A 3-D radiation therapy treatment planning system calculates dose to an entire volume of points and therefore requires a 3-D distribution of measured dose values for quality assurance and dose calculation verification. To measure such a volumetric distribution with a scanning ion chamber is prohibitively time consuming. A method is presented for the generation of a 3-D grid of dose values based on beam's-eye-view (BEV) film dosimetry. For each field configuration of interest, a set of BEV films at different depths is obtained and digitized, and the optical densities are converted to dose. To reduce inaccuracies associated with film measurement of megavoltage photon depth doses, doses on the different planes are normalized using an ion-chamber measurement of the depth dose. A 3-D grid of dose values is created by interpolation between BEV planes along divergent beam rays. This matrix of measurement-based dose values can then be compared to calculations over the entire volume of interest. This method is demonstrated for three different field configurations. Accuracy of the film-measured dose values is determined by 1-D and 2-D comparisons with ion chamber measurements. Film and ion chamber measurements agree within 2{\%} in the central field regions and within 2.0 mm in the penumbral regions.",
author = "Stern, {Robin L} and Fraass, {B. A.} and A. Gerhardsson and McShan, {D. L.} and Lam, {K. L.}",
year = "1992",
month = "1",
doi = "10.1118/1.596873",
language = "English (US)",
volume = "19",
pages = "165--173",
journal = "Medical Physics",
issn = "0094-2405",
publisher = "AAPM - American Association of Physicists in Medicine",
number = "1",

}

TY - JOUR

T1 - Generation and use of measurement-based 3-D dose distributions for 3-D dose calculation verification.

AU - Stern, Robin L

AU - Fraass, B. A.

AU - Gerhardsson, A.

AU - McShan, D. L.

AU - Lam, K. L.

PY - 1992/1

Y1 - 1992/1

N2 - A 3-D radiation therapy treatment planning system calculates dose to an entire volume of points and therefore requires a 3-D distribution of measured dose values for quality assurance and dose calculation verification. To measure such a volumetric distribution with a scanning ion chamber is prohibitively time consuming. A method is presented for the generation of a 3-D grid of dose values based on beam's-eye-view (BEV) film dosimetry. For each field configuration of interest, a set of BEV films at different depths is obtained and digitized, and the optical densities are converted to dose. To reduce inaccuracies associated with film measurement of megavoltage photon depth doses, doses on the different planes are normalized using an ion-chamber measurement of the depth dose. A 3-D grid of dose values is created by interpolation between BEV planes along divergent beam rays. This matrix of measurement-based dose values can then be compared to calculations over the entire volume of interest. This method is demonstrated for three different field configurations. Accuracy of the film-measured dose values is determined by 1-D and 2-D comparisons with ion chamber measurements. Film and ion chamber measurements agree within 2% in the central field regions and within 2.0 mm in the penumbral regions.

AB - A 3-D radiation therapy treatment planning system calculates dose to an entire volume of points and therefore requires a 3-D distribution of measured dose values for quality assurance and dose calculation verification. To measure such a volumetric distribution with a scanning ion chamber is prohibitively time consuming. A method is presented for the generation of a 3-D grid of dose values based on beam's-eye-view (BEV) film dosimetry. For each field configuration of interest, a set of BEV films at different depths is obtained and digitized, and the optical densities are converted to dose. To reduce inaccuracies associated with film measurement of megavoltage photon depth doses, doses on the different planes are normalized using an ion-chamber measurement of the depth dose. A 3-D grid of dose values is created by interpolation between BEV planes along divergent beam rays. This matrix of measurement-based dose values can then be compared to calculations over the entire volume of interest. This method is demonstrated for three different field configurations. Accuracy of the film-measured dose values is determined by 1-D and 2-D comparisons with ion chamber measurements. Film and ion chamber measurements agree within 2% in the central field regions and within 2.0 mm in the penumbral regions.

UR - http://www.scopus.com/inward/record.url?scp=0026491753&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0026491753&partnerID=8YFLogxK

U2 - 10.1118/1.596873

DO - 10.1118/1.596873

M3 - Article

C2 - 1620042

AN - SCOPUS:0026491753

VL - 19

SP - 165

EP - 173

JO - Medical Physics

JF - Medical Physics

SN - 0094-2405

IS - 1

ER -