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A dose based approach for evaluation of inter-observer variations in target delineation

Kristensen, Ingrid LU ; Nilsson, Kristina ; Agrup, Måns ; Belfrage, Karin ; Embring, Anna ; Haugen Cange, Hedda ; Svärd, Anna-Maja ; Knöös, Tommy LU and Nilsson, Per LU (2017) In Technical innovations & patient support in radiation oncology 3-4. p.41-47
Abstract

Background and purpose: Substantial inter-observer variations in target delineation have been presented previously. Target delineation for paediatric cases is difficult due to the small number of children, the variation in paediatric targets, the number of study protocols, and the individual patient's specific needs and demands. Uncertainties in target delineation might lead to under-dosage or over-dosage. The aim of this work is to apply the concept of a consensus volume and good quality treatment plans to visualise and quantify inter-observer target delineation variations in dosimetric terms in addition to conventional geometrically based volume concordance indices.

Material and methods: Two paediatric cases were used to... (More)

Background and purpose: Substantial inter-observer variations in target delineation have been presented previously. Target delineation for paediatric cases is difficult due to the small number of children, the variation in paediatric targets, the number of study protocols, and the individual patient's specific needs and demands. Uncertainties in target delineation might lead to under-dosage or over-dosage. The aim of this work is to apply the concept of a consensus volume and good quality treatment plans to visualise and quantify inter-observer target delineation variations in dosimetric terms in addition to conventional geometrically based volume concordance indices.

Material and methods: Two paediatric cases were used to demonstrate the potential of adding dose metrics when evaluating target delineation diversity; Hodgkin's disease (case 1) and rhabdomyosarcoma of the parotid gland (case 2). The variability in target delineation (PTV delineations) between six centres was quantified using the generalised conformity index, CIgen, generated for volume overlap. The STAPLE algorithm, as implemented in CERR, was used for both cases to derive a consensus volumes. STAPLE is a probabilistic estimate of the true volume generated from all observers. Dose distributions created by each centre for the original target volumes were then applied to this consensus volume.

Results: A considerable variation in target segmentation was seen in both cases. For case 1 the variation was 374-960 cm3 (average 669 cm3) and for case 2; 65-126 cm3 (average 109 cm3). CIgen were 0.53 and 0.70, respectively. The DVHs in absolute volume displayed for the delineated target volume as well as for the consensus volume adds information on both "compliant" target volumes as well as outliers which are hidden with just the use of concordance indices.

Conclusions: The DVHs in absolute volume add valuable and easily understood information to various indices for evaluating uniformity in target delineation.

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author
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organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Technical innovations & patient support in radiation oncology
volume
3-4
pages
41 - 47
external identifiers
  • pmid:32095566
ISSN
2405-6324
DOI
10.1016/j.tipsro.2017.10.002
language
English
LU publication?
yes
additional info
© 2017 The Authors. Published by Elsevier Ireland Ltd on behalf of European Society for Radiotherapy & Oncology.
id
4b17a0d1-2cce-4173-9bdc-8643ca9215c4
date added to LUP
2020-09-24 09:25:20
date last changed
2020-09-25 02:31:30
@article{4b17a0d1-2cce-4173-9bdc-8643ca9215c4,
  abstract     = {<p>Background and purpose: Substantial inter-observer variations in target delineation have been presented previously. Target delineation for paediatric cases is difficult due to the small number of children, the variation in paediatric targets, the number of study protocols, and the individual patient's specific needs and demands. Uncertainties in target delineation might lead to under-dosage or over-dosage. The aim of this work is to apply the concept of a consensus volume and good quality treatment plans to visualise and quantify inter-observer target delineation variations in dosimetric terms in addition to conventional geometrically based volume concordance indices.</p><p>Material and methods: Two paediatric cases were used to demonstrate the potential of adding dose metrics when evaluating target delineation diversity; Hodgkin's disease (case 1) and rhabdomyosarcoma of the parotid gland (case 2). The variability in target delineation (PTV delineations) between six centres was quantified using the generalised conformity index, CIgen, generated for volume overlap. The STAPLE algorithm, as implemented in CERR, was used for both cases to derive a consensus volumes. STAPLE is a probabilistic estimate of the true volume generated from all observers. Dose distributions created by each centre for the original target volumes were then applied to this consensus volume.</p><p>Results: A considerable variation in target segmentation was seen in both cases. For case 1 the variation was 374-960 cm3 (average 669 cm3) and for case 2; 65-126 cm3 (average 109 cm3). CIgen were 0.53 and 0.70, respectively. The DVHs in absolute volume displayed for the delineated target volume as well as for the consensus volume adds information on both "compliant" target volumes as well as outliers which are hidden with just the use of concordance indices.</p><p>Conclusions: The DVHs in absolute volume add valuable and easily understood information to various indices for evaluating uniformity in target delineation.</p>},
  author       = {Kristensen, Ingrid and Nilsson, Kristina and Agrup, Måns and Belfrage, Karin and Embring, Anna and Haugen Cange, Hedda and Svärd, Anna-Maja and Knöös, Tommy and Nilsson, Per},
  issn         = {2405-6324},
  language     = {eng},
  month        = {11},
  pages        = {41--47},
  series       = {Technical innovations & patient support in radiation oncology},
  title        = {A dose based approach for evaluation of inter-observer variations in target delineation},
  url          = {http://dx.doi.org/10.1016/j.tipsro.2017.10.002},
  doi          = {10.1016/j.tipsro.2017.10.002},
  volume       = {3-4},
  year         = {2017},
}