Correlations between contouring similarity metrics and simulated treatment outcome for prostate radiotherapy

D. Roach; M. G. Jameson; J. A. Dowling; M. A. Ebert; P. B. Greer; A. M. Kennedy; S. Watt; L. C. Holloway

doi:10.1088/1361-6560/aaa50c

Correlations between contouring similarity metrics and simulated treatment outcome for prostate radiotherapy

D. Roach, M. G. Jameson, J. A. Dowling, M. A. Ebert, P. B. Greer, A. M. Kennedy, S. Watt, L. C. Holloway

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Abstract

Many similarity metrics exist for inter-observer contouring variation studies, however no correlation between metric choice and prostate cancer radiotherapy dosimetry has been explored. These correlations were investigated in this study. Two separate trials were undertaken, the first a thirty-five patient cohort with three observers, the second a five patient dataset with ten observers. Clinical and planning target volumes (CTV and PTV), rectum, and bladder were independently contoured by all observers in each trial. Structures were contoured on T2-weighted MRI and transferred onto CT following rigid registration for treatment planning in the first trial. Structures were contoured directly on CT in the second trial. STAPLE and majority voting volumes were generated as reference gold standard volumes for each structure for the two trials respectively. VMAT treatment plans (78 Gy to PTV) were simulated for observer and gold standard volumes, and dosimetry assessed using multiple radiobiological metrics. Correlations between contouring similarity metrics and dosimetry were calculated using Spearman's rank correlation coefficient. No correlations were observed between contouring similarity metrics and dosimetry for CTV within either trial. Volume similarity correlated most strongly with radiobiological metrics for PTV in both trials, including TCP_Poisson (ρ = 0.57, 0.65), TCP_Logit (ρ = 0.39, 0.62), and EUD (ρ = 0.43, 0.61) for each respective trial. Rectum and bladder metric correlations displayed no consistency for the two trials. PTV volume similarity was found to significantly correlate with rectum normal tissue complication probability (ρ = 0.33, 0.48). Minimal to no correlations with dosimetry were observed for overlap or boundary contouring metrics. Future inter-observer contouring variation studies for prostate cancer should incorporate volume similarity to provide additional insights into dosimetry during analysis.

Original language	English
Article number	035001
Pages (from-to)	1-20
Number of pages	20
Journal	Physics in Medicine and Biology
Volume	63
Issue number	3
DOIs	https://doi.org/10.1088/1361-6560/aaa50c
Publication status	Published - Feb 2018
Externally published	Yes

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@article{a582b26ded184af1900f8544693ce032,

title = "Correlations between contouring similarity metrics and simulated treatment outcome for prostate radiotherapy",

abstract = "Many similarity metrics exist for inter-observer contouring variation studies, however no correlation between metric choice and prostate cancer radiotherapy dosimetry has been explored. These correlations were investigated in this study. Two separate trials were undertaken, the first a thirty-five patient cohort with three observers, the second a five patient dataset with ten observers. Clinical and planning target volumes (CTV and PTV), rectum, and bladder were independently contoured by all observers in each trial. Structures were contoured on T2-weighted MRI and transferred onto CT following rigid registration for treatment planning in the first trial. Structures were contoured directly on CT in the second trial. STAPLE and majority voting volumes were generated as reference gold standard volumes for each structure for the two trials respectively. VMAT treatment plans (78 Gy to PTV) were simulated for observer and gold standard volumes, and dosimetry assessed using multiple radiobiological metrics. Correlations between contouring similarity metrics and dosimetry were calculated using Spearman's rank correlation coefficient. No correlations were observed between contouring similarity metrics and dosimetry for CTV within either trial. Volume similarity correlated most strongly with radiobiological metrics for PTV in both trials, including TCPPoisson (ρ = 0.57, 0.65), TCPLogit (ρ = 0.39, 0.62), and EUD (ρ = 0.43, 0.61) for each respective trial. Rectum and bladder metric correlations displayed no consistency for the two trials. PTV volume similarity was found to significantly correlate with rectum normal tissue complication probability (ρ = 0.33, 0.48). Minimal to no correlations with dosimetry were observed for overlap or boundary contouring metrics. Future inter-observer contouring variation studies for prostate cancer should incorporate volume similarity to provide additional insights into dosimetry during analysis.",

keywords = "contouring, inter-observer variability, prostate, similarity metrics, VMAT",

author = "D. Roach and Jameson, {M. G.} and Dowling, {J. A.} and Ebert, {M. A.} and Greer, {P. B.} and Kennedy, {A. M.} and S. Watt and Holloway, {L. C.}",

note = "Funding Information: The authors would like to thank Dr Wei Xuan for statistical advice, and Kirrily Cloak and Rohan Gray for treatment planning feedback.Additional thanks is given to Michelle Krawiec,Robba Rai,Professor Jim Denham, Dr Jeremiah De Leon,Dr Karen Lim,Dr Megan Berry,Dr Rohen White,Professor Sean Bydder,Dr Hendrick Tan, Dr Jeremy Croker,Dr Alycea McGrath,Dr Robert Jan Smeenk,and Dr John Matthews.The project was funded by NHMRC project grant number 1077788. Publisher Copyright: {\textcopyright} 2018 Institute of Physics and Engineering in Medicine.",

year = "2018",

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doi = "10.1088/1361-6560/aaa50c",

language = "English",

volume = "63",

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T1 - Correlations between contouring similarity metrics and simulated treatment outcome for prostate radiotherapy

AU - Roach, D.

AU - Jameson, M. G.

AU - Dowling, J. A.

AU - Ebert, M. A.

AU - Greer, P. B.

AU - Kennedy, A. M.

AU - Watt, S.

AU - Holloway, L. C.

N1 - Funding Information: The authors would like to thank Dr Wei Xuan for statistical advice, and Kirrily Cloak and Rohan Gray for treatment planning feedback.Additional thanks is given to Michelle Krawiec,Robba Rai,Professor Jim Denham, Dr Jeremiah De Leon,Dr Karen Lim,Dr Megan Berry,Dr Rohen White,Professor Sean Bydder,Dr Hendrick Tan, Dr Jeremy Croker,Dr Alycea McGrath,Dr Robert Jan Smeenk,and Dr John Matthews.The project was funded by NHMRC project grant number 1077788. Publisher Copyright: © 2018 Institute of Physics and Engineering in Medicine.

PY - 2018/2

Y1 - 2018/2

N2 - Many similarity metrics exist for inter-observer contouring variation studies, however no correlation between metric choice and prostate cancer radiotherapy dosimetry has been explored. These correlations were investigated in this study. Two separate trials were undertaken, the first a thirty-five patient cohort with three observers, the second a five patient dataset with ten observers. Clinical and planning target volumes (CTV and PTV), rectum, and bladder were independently contoured by all observers in each trial. Structures were contoured on T2-weighted MRI and transferred onto CT following rigid registration for treatment planning in the first trial. Structures were contoured directly on CT in the second trial. STAPLE and majority voting volumes were generated as reference gold standard volumes for each structure for the two trials respectively. VMAT treatment plans (78 Gy to PTV) were simulated for observer and gold standard volumes, and dosimetry assessed using multiple radiobiological metrics. Correlations between contouring similarity metrics and dosimetry were calculated using Spearman's rank correlation coefficient. No correlations were observed between contouring similarity metrics and dosimetry for CTV within either trial. Volume similarity correlated most strongly with radiobiological metrics for PTV in both trials, including TCPPoisson (ρ = 0.57, 0.65), TCPLogit (ρ = 0.39, 0.62), and EUD (ρ = 0.43, 0.61) for each respective trial. Rectum and bladder metric correlations displayed no consistency for the two trials. PTV volume similarity was found to significantly correlate with rectum normal tissue complication probability (ρ = 0.33, 0.48). Minimal to no correlations with dosimetry were observed for overlap or boundary contouring metrics. Future inter-observer contouring variation studies for prostate cancer should incorporate volume similarity to provide additional insights into dosimetry during analysis.

AB - Many similarity metrics exist for inter-observer contouring variation studies, however no correlation between metric choice and prostate cancer radiotherapy dosimetry has been explored. These correlations were investigated in this study. Two separate trials were undertaken, the first a thirty-five patient cohort with three observers, the second a five patient dataset with ten observers. Clinical and planning target volumes (CTV and PTV), rectum, and bladder were independently contoured by all observers in each trial. Structures were contoured on T2-weighted MRI and transferred onto CT following rigid registration for treatment planning in the first trial. Structures were contoured directly on CT in the second trial. STAPLE and majority voting volumes were generated as reference gold standard volumes for each structure for the two trials respectively. VMAT treatment plans (78 Gy to PTV) were simulated for observer and gold standard volumes, and dosimetry assessed using multiple radiobiological metrics. Correlations between contouring similarity metrics and dosimetry were calculated using Spearman's rank correlation coefficient. No correlations were observed between contouring similarity metrics and dosimetry for CTV within either trial. Volume similarity correlated most strongly with radiobiological metrics for PTV in both trials, including TCPPoisson (ρ = 0.57, 0.65), TCPLogit (ρ = 0.39, 0.62), and EUD (ρ = 0.43, 0.61) for each respective trial. Rectum and bladder metric correlations displayed no consistency for the two trials. PTV volume similarity was found to significantly correlate with rectum normal tissue complication probability (ρ = 0.33, 0.48). Minimal to no correlations with dosimetry were observed for overlap or boundary contouring metrics. Future inter-observer contouring variation studies for prostate cancer should incorporate volume similarity to provide additional insights into dosimetry during analysis.

KW - contouring

KW - inter-observer variability

KW - prostate

KW - similarity metrics

KW - VMAT

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JO - Physics in Medicine and Biology

JF - Physics in Medicine and Biology

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M1 - 035001

ER -

Correlations between contouring similarity metrics and simulated treatment outcome for prostate radiotherapy

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