Interobserver Delineation Variation Using CT versus Combined CT + MRI in Intensity–Modulated Radiotherapy for Prostate Cancer

Villeirs, Geert; Vaerenbergh, Koen Van; Vakaet, Luc; Bral, Samuel; Claus, Filip; Neve, Wilfried J. De; Verstraete, Koenraad; Meerleer, Gert O. De

doi:10.1007/s00066-005-1383-x

Cited by 166 publications

(121 citation statements)

References 28 publications

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“…In the last few decades, magnetic resonance imaging (MRI) has found its way into the radiotherapy workflow as it provides superior soft tissue contrast with respect to CT (Debois et al 1999, Dirix et al 2014, thus enabling more accurate delineation of target regions and critical structures (Roach et al 1996, Rasch et al 1999, Villeirs et al 2005.…”

Section: Introductionmentioning

confidence: 99%

Quantification of confounding factors in MRI-based dose calculations as applied to prostate IMRT

et al. 2017

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Magnetic resonance (MR)-only radiotherapy treatment planning requires pseudo-CT (pCT) images to enable MR-based dose calculations. To verify the accuracy of MR-based dose calculations, institutions interested in introducing MR-only planning will have to compare pCT-based and computer tomography (CT)-based dose calculations. However, interpreting such comparison studies may be challenging, since potential differences arise from a range of confounding factors which are not necessarily specific to MR-only planning. Therefore, the aim of this study is to identify and quantify the contribution of factors confounding dosimetric accuracy estimation in comparison studies between CT and pCT. The following factors were distinguished: set-up and positioning differences between imaging sessions, MR-related geometric inaccuracy, pCT generation, use of specific calibration curves to convert pCT into electron density information, and registration errors.The study comprised fourteen prostate cancer patients who underwent CT/ MRI-based treatment planning. To enable pCT generation, a commercial solution (MRCAT, Philips Healthcare, Vantaa, Finland) was adopted. IMRT plans were calculated on CT (gold standard) and pCTs. Dose difference maps in a high dose region (CTV) and in the body volume were evaluated, and the contribution to dose errors of possible confounding factors was individually quantified.We found that the largest confounding factor leading to dose difference was the use of different calibration curves to convert pCT and CT into electron density (0.7%). The second largest factor was the pCT generation Inter-scan differences due to patient repositioning, MR-related geometric inaccuracy, and registration errors did not significantly contribute to dose differences (0.01%). The proposed approach successfully identified and quantified the factors confounding accurate MRI-based dose calculation in the prostate. This study will be valuable for institutions interested in introducing MR-only dose planning in their clinical practice.

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Section: Introductionmentioning

confidence: 99%

Quantification of confounding factors in MRI-based dose calculations as applied to prostate IMRT

et al. 2017

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“…Villers et al compared delineations of CT alone and CT with MRI in combination of 3 ROs and clinical target volume (CTV) plotted on CT were larger than CTV volumes plotted on CT with MRI. [15] In our study, when we compared volumes of the RO on CT and MRI, prostate volume was clearer and volume was smaller because MRI images provided more detail of the soft tissue. We were careful to ensure that MRI and CT images were taken at the same position and within the same cross-sectional area in order to ensure that the images were recorded with the least possible amount of error.…”

Section: Discussionmentioning

confidence: 75%

Comparison of Two Different Discipline Obtained By Using Drafted Contours Planning Techniques in The Treatment of Prostate Cancer

Çetin¹,

Degerli²,

Ergelen³

et al. 2016

TJ Oncol

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OBJECTIVEThis study is a comparison of contoured diagnostic images derived from computed tomography (CT) and magnetic resonance imaging (MRI) by both a radiation oncologist (RO) and a radiologist (R) using volumetric modulated arc therapy (VMAT) and intensity modulated radiation therapy (IMRT) techniques. METHODSCT and MRI sections of 16 patients were contoured by the RO and the R. Planning target volume (PTV) criteria assessed were conformity index (CI), homogeneity index (HI), volume covered by 98% isodose line (V 98%) and maximum dose (D max ). In critical organs, 40 Gy organ area volume (V 40 ), 65 Gy organ area volume (V 65 ), and D mean criteria were evaluated. Paired samples t-test was used for statistical analysis. RESULTSPTV and critical organs were compared. MRI PTV and bladder volume drawn by R were lower. Comparison of CT images revealed IMRT plans were superior in terms of D max and CI, while V 40 and D mean values for rectum and bladder were lower in MRI-based VMAT plans. In MRI plans, IMRT was superior in terms of PTV, D max , CI, V 65 , and D mean for critical organs; however, critical organs were well preserved with both planning techniques. CONCLUSIONThere was some difference between contouring of the R and the RO, which was reflected in the treatment plans.

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“…The majority of studies deal with approaches that describe the overlapping area between contoured volumes, using metrics, such as CI and DC [22][23][24][26][27][28][29][30][31]. Moreover, when moving to 3D representation, metrics, such as variation of the COM, allow to evaluate the volume displacements in space [27,32,33].…”

Section: Discussionmentioning

confidence: 99%

Delineation of the larynx as organ at risk in radiotherapy: a contouring course within “Rete Oncologica Piemonte-Valle d’Aosta” network to reduce inter- and intraobserver variability

et al. 2016

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Mean percentage of intersection and DC strongly increased after the course, rising from 57.76 to 93.83 % and from 0.68 to 0.89, respectively. CI enhanced from 0.06 to 0.31. Conclusions This study shows an improvement in larynx definition after the contouring course with lower interobserver variability and major consistency compared to the reference volume. Other specific educational activities may further increase the quality of radiation therapy contouring in this setting.

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Interobserver Delineation Variation Using CT versus Combined CT + MRI in Intensity–Modulated Radiotherapy for Prostate Cancer

Abstract: Addition of MRI to CT in consensus reading with a radiologist results in a moderate decrease of the CTV, but an important decrease of the interobserver delineation variation, especially at the prostatic apex.

Cited by 166 publications

References 28 publications

Quantification of confounding factors in MRI-based dose calculations as applied to prostate IMRT

Quantification of confounding factors in MRI-based dose calculations as applied to prostate IMRT

Comparison of Two Different Discipline Obtained By Using Drafted Contours Planning Techniques in The Treatment of Prostate Cancer

Delineation of the larynx as organ at risk in radiotherapy: a contouring course within “Rete Oncologica Piemonte-Valle d’Aosta” network to reduce inter- and intraobserver variability

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