Dataset Information

Dosimetric impact of placement errors in optically stimulated luminescent in vivo dosimetry in radiotherapy.

ABSTRACT:

Introduction

Studies have suggested that optically stimulated luminescent dosimeters (OSLDs) can be used for in vivo dosimetry of intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT). Clinical uncertainties such as placement error have not been thoroughly investigated. The purpose of this work was to measure OSLD placement error in a clinical sample and analyze its dosimetric impact.

Methods and materials

The analysis consisted of three parts: first, quantification of placement error in a clinical sample of 128 patients yielding 293 cone-beam CT (CBCT) with visible OSLDs registered to the treatment plan; Second, correlation of placement error and clinical OSLD measurements; third, simulation of dosimeter placement in the treatment plan and correlation of recalculated dose with placement error.

Results

In the first analysis, average placement error was 9.7?±?9.5?mm. In the second analysis, placement error and measured-to-planned dose agreement yielded no correlation (R²?=?0.02) for a subsample of 77 CBCTs of 55 head-and-neck patients. Average placement error was 7.0?±?6.0?mm. Several factors, including image-guided shifts, introduced uncharacterized uncertainty to the measured-to-planned dose agreement. The third analysis isolated placement error from these other effects. Average dosimetric error was -2.4?±?19.3%. Simulated dosimetric impact was weakly correlated with placement error (R²?=?0.39). Removing outliers reduced the average dosimetric error to -2.1?±?10.9%, marginally improving the correlation (R²?=?0.44).

Conclusion

Placement error can substantially impact measured-to-planned dose agreement of OSLDs in high gradient regions, demonstrating the criticality of accurate dosimeter placement for IMRT and VMAT treatments.

SUBMITTER: Tariq M

PROVIDER: S-EPMC7807655 | biostudies-literature | 2019 Jul

REPOSITORIES: biostudies-literature

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Dosimetric impact of placement errors in optically stimulated luminescent <i>in vivo</i> dosimetry in radiotherapy.

Tariq Mahin M Gomez Cindy C Riegel Adam C AC

Physics and imaging in radiation oncology 20190701

<h4>Introduction</h4>Studies have suggested that optically stimulated luminescent dosimeters (OSLDs) can be used for <i>in vivo</i> dosimetry of intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT). Clinical uncertainties such as placement error have not been thoroughly investigated. The purpose of this work was to measure OSLD placement error in a clinical sample and analyze its dosimetric impact.<h4>Methods and materials</h4>The analysis consisted of three p ...[more]

PMID: 33458280

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