Relative profile and dose verification of intensity-modulated radiation therapy Journal Article
| Authors: | Chang, J.; Mageras, G. S.; Chui, C. S.; Ling, C. C.; Lutz, W. |
| Article Title: | Relative profile and dose verification of intensity-modulated radiation therapy |
| Abstract: | Purpose: To develop a quality assurance (QA) procedure to assess the intensity profile and dosimetry for intensity-modulated (IM) treatment fields using electronic portal imaging devices (EPIDs).Methods and Materials: A series of rapidly acquired (~1/sec) portal images are summed and converted to dose. For relative intensity QA, the intended profile is subtracted point-by-point from the measured profile forming a series of error values. The standard deviation, σ, of the errors, a measure of the goodness of the match, is minimized by applying a normalization and uniform scatter subtraction from the measured profile. For dose verification (dose to isocenter), an empirically determined phantom-correction factor is added to incorporate the effect of patient presence on EPID readings. Seventy prostate treatment fields were used in a phantom study to verify these approaches. Sensitivity was studied by creating artificial mismatches.Results: The average σ for relative profile verification is 3.3% (percentage of average intended intensity) whereas artificial mismatches resulted in σ values from 5% to 27%. The average isocentric dose calculated from EPID readings is 1.001 relative to the planned dose with a standard deviation of 0.018.Conclusions: An EPID can be used for profile verification and absolute isocentric dose measurement for IM fields. Copyright (C) 2000 Elsevier Science Inc. |
| Keywords: | radiation dose; sensitivity and specificity; quality control; linear models; reproducibility of results; radiotherapy dosage; radiotherapy; algorithms; prostatic neoplasms; imrt; device; ionization chamber; phantoms, imaging; physics; dose verification; epid; radiotherapy, computer-assisted; humans; male; priority journal; article; treatment field verification; treatment qa; electronics, medical |
| Journal Title: | International Journal of Radiation Oncology, Biology, Physics |
| Volume: | 47 |
| Issue: | 1 |
| ISSN: | 0360-3016 |
| Publisher: | Elsevier Inc. |
| Date Published: | 2000-04-01 |
| Start Page: | 231 |
| End Page: | 240 |
| Language: | English |
| DOI: | 10.1016/s0360-3016(99)00555-6 |
| PUBMED: | 10758329 |
| PROVIDER: | scopus |
| DOI/URL: | |
| Notes: | Export Date: 18 November 2015 -- Source: Scopus |
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