Background and purpose: To study the impact of coronal and sagittal views (CSV) on the gross tumor volume (GTV) delineation on CT and matched PET/CT scans in non-small cell lung cancer.Material and... Show moreBackground and purpose: To study the impact of coronal and sagittal views (CSV) on the gross tumor volume (GTV) delineation on CT and matched PET/CT scans in non-small cell lung cancer.Material and methods: GTV delineations were performed by 11 experienced radiation oncologists on CT and PET/CT in 22 patients. Two tumor groups were defined: Group I: Primary tumors surrounded by lung or visceral pleura, without venous invasion, and without large extensions to the chest wall or the mediastinum. Group II: Tumors invading the hilar region, heart, large vessels, pericardium, and the mediastinum and/or associated with atelectasis. Tumor volumes and inter-observers variations (SD) were calculated and compared according to the use of axial view only (AW), axial/coronal/sagittal views (ACSW) and ACSW/PET (ACSWP).Results: CSV were not frequently used (57.4% out of 242 delineations on CT). For group I, ACSW didn't improve significantly mean GTVs. SDs were small on CT and on PET (SD = 0.3 cm). For group II, ACSW had 27-46% smaller observer variation (mean SD = 0.7 cm) than AW (mean SD = 1.1 cm). The smaller observer variation of ACSW users was associated with, on average, a 40% smaller delineated volume (p = 0.038). Mean GTV of ACSWP was 21% larger than mean GTV of ACSW on CT.Conclusions: For smaller lung tumors surrounded by healthy lung tissue the effect of multiple axis delineation is limited. However, application of coronal and sagittal windows is highly beneficial for delineation of more complex tumors, with atelectasis and/or pathological lymph nodes even if PET is used. (C) 2016 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved. Show less
Purpose: The aim of this study is to ascertain the subsequent radiobiological impact of using a consensus guideline target volume delineation atlas.Materials and methods: Using a representative... Show morePurpose: The aim of this study is to ascertain the subsequent radiobiological impact of using a consensus guideline target volume delineation atlas.Materials and methods: Using a representative case and target volume delineation instructions derived from a proposed IMRT rectal cancer clinical trial, gross tumor volume (GTV) and clinical/planning target volumes (CTV/PTV) were contoured by 13 physician observers (Phase 1). The observers were then randomly assigned to follow (atlas) or not-follow (control) a consensus guideline/atlas for anorectal cancers, and instructed to re-contour the same case (Phase 2).Results: The atlas group was found to have increased tumor control probability (TCP) after the atlas intervention for both the CTV (p < 0.0001) and PTV1 (p = 0.0011) with decreasing normal tissue complication probability (NTCP) for small intestine, while the control group did not. Additionally, the atlas group had reduced variance in TCP for all target volumes and reduced variance in NTCP for the bowel. In Phase 2, the atlas group had increased TCP relative to the control for CTV (p = 0.03).Conclusions: Visual atlas and consensus treatment guideline usage in the development of rectal cancer IMRT treatment plans reduced the inter-observer radiobiological variation, with clinically relevant TCP alteration for CTV and PTV volumes. (C) 2014 Elsevier Ireland Ltd. All rights reserved. Show less
Boersma, L.J.; Janssen, T.; Elkhuizen, P.H.M.; Poortmans, P.; Sangen, M. van der; Scholten, A.N.; ... ; Vliet, C. van 2012
The purpose of this study was the prospective comparison of objective and subjective effects of target volume region of interest (ROI) delineation using mouse-keyboard and pen-tablet user input... Show moreThe purpose of this study was the prospective comparison of objective and subjective effects of target volume region of interest (ROI) delineation using mouse-keyboard and pen-tablet user input devices (UIDs). The study was designed as a prospective test/retest sequence, with Wilcoxon signed rank test for matched-pair comparison. Twenty-one physician-observers contoured target volume ROIs on four standardized cases (representative of brain, prostate, lung, and head and neck malignancies) twice: once using QWERTY keyboard/scroll-wheel mouse UID and once with pen-tablet UID (DTX2100, Wacom Technology Corporation, Vancouver, WA, USA). Active task time, ROI manipulation task data, and subjective survey data were collected. One hundred twenty-nine target volume ROI sets were collected, with 62 paired pen-tablet/mouse-keyboard sessions. Active contouring time was reduced using the pen-tablet UID, with mean +/- SD active contouring time of 26 +/- 23 min, compared with 32 +/- 25 with the mouse (p a parts per thousand currency signaEuro parts per thousand 0.01). Subjective estimation of time spent was also reduced from 31 +/- 26 with mouse to 27 +/- 22 min with the pen (p = 0.02). Task analysis showed ROI correction task reduction (p = 0.045) and decreased panning and scrolling tasks (p < 0.01) with the pen-tablet; drawing, window/level changes, and zoom commands were unchanged (p = n.s.) Volumetric analysis demonstrated no detectable differences in ROI volume nor intra- or inter-observer volumetric coverage. Fifty-two of 62 (84%) users preferred the tablet for each contouring task; 5 of 62 (8%) denoted no preference, and 5 of 62 (8%) chose the mouse interface. The pen-tablet UID reduced active contouring time and reduced correction of ROIs, without substantially altering ROI volume/coverage. Show less
Fitton, I.; Cornelissen, S.A.P.; Duppen, J.C.; Steenbakkers, R.J.H.M.; Peeters, S.T.H.; Hoebers, F.J.P.; ... ; Herk, M. van 2011
Purpose: To develop a delineation tool that refines physician-drawn contours of the gross tumor volume (GTV) in nasopharynx cancer, using combined pixel value information from x-ray computed... Show morePurpose: To develop a delineation tool that refines physician-drawn contours of the gross tumor volume (GTV) in nasopharynx cancer, using combined pixel value information from x-ray computed tomography (CT) and magnetic resonance imaging (MRI) during delineation.Methods: Operator-guided delineation assisted by a so-called "snake" algorithm was applied on weighted CT-MRI registered images. The physician delineates a rough tumor contour that is continuously adjusted by the snake algorithm using the underlying image characteristics. The algorithm was evaluated on five nasopharyngeal cancer patients. Different linear weightings CT and MRI were tested as input for the snake algorithm and compared according to contrast and tumor to noise ratio (TNR). The semi-automatic delineation was compared with manual contouring by seven experienced radiation oncologists.Results: A good compromise for TNR and contrast was obtained by weighing CT twice as strong as MRI. The new algorithm did not notably reduce interobserver variability, it did however, reduce the average delineation time by 6 min per case.Conclusions: The authors developed a user-driven tool for delineation and correction based a snake algorithm and registered weighted CT image and MRI. The algorithm adds morphological information from CT during the delineation on MRI and accelerates the delineation task. (C) 2011 American Association of Physicists in Medicine. [DOI: 10.1118/1.3611045] Show less
Purpose: Variations in target volume delineation represent a significant hurdle in clinical trials involving conformal radiotherapy. We sought to determine the effect of a consensus guideline-based... Show morePurpose: Variations in target volume delineation represent a significant hurdle in clinical trials involving conformal radiotherapy. We sought to determine the effect of a consensus guideline-based visual atlas on contouring the target volumes.Methods and Materials: A representative case was contoured (Scan 1) by 14 physician observers and a reference expert with and without target volume delineation instructions derived from a proposed rectal cancer clinical trial involving conformal radiotherapy. The gross tumor volume (GTV), and two clinical target volumes (CTVA, including the internal iliac, presacral, and perirectal nodes, and CTVB, which included the external iliac nodes) were contoured. The observers were randomly assigned to receipt (Group A) or nonreceipt (Group B) of a consensus guideline and atlas for anorectal cancers and then instructed to recontour the same case/images (Scan 2). Observer variation was analyzed volumetrically using the conformation number (CN, where CN = 1 equals total agreement).Results: Of 14 evaluable contour sets (1 expert and 7 Group A and 6 Group B observers), greater agreement was found for the GTV (mean CN, 0.75) than for the CTVs (mean CN, 0.46-0.65). Atlas exposure for Group A led to significantly increased interobserver agreement for CTVA (mean initial CN, 0.68, after atlas use, 0.76; p = .03) and increased agreement with the expert reference (initial mean CN, 0.58; after atlas use, 0.69; p = .02). For the GTV and CTVB, neither the interobserver nor the expert agreement was altered after atlas exposure.Conclusion: Consensus guideline atlas implementation resulted in a detectable difference in interobserver agreement and a greater approximation of expert volumes for the CTVA but not for the GTV or CTVB in the specified case. Visual atlas inclusion should be considered as a feature in future clinical trials incorporating conformal RT. (C) 2011 Elsevier Inc. Show less
Rasch, C.R.N.; Steenbakkers, R.J.H.M.; Fitton, I.; Duppen, J.C.; Nowak, P.J.C.M.; Pameijer, F.A.; ... ; Herk, M. van 2010
Purpose: To determine the variation in target delineation of nasopharyngeal carcinoma and the impact of measures to minimize this variation.Materials and methods: For ten nasopharyngeal cancer... Show morePurpose: To determine the variation in target delineation of nasopharyngeal carcinoma and the impact of measures to minimize this variation.Materials and methods: For ten nasopharyngeal cancer patients, ten observers each delineated the Clinical Target Volume (CTV) and the CTV elective. After 3D analysis of the delineated volumes, a second delineation was performed. This implied improved delineation instructions, a combined delineation on CT and co-registered MRI, forced use of sagittal reconstructions, and an on-line anatomical atlas.Results: Both for the CTV and the CTV elective delineations, the 3D SD decreased from Phase 1 to Phase 2, from 4.4 to 3.3 mm for the CTV and from 5.9 to 4.9 mm for the elective. There was an increase agreement, where the observers intended to delineate the same structure, from 36 to 64 surface % (p = 0.003) for the CTV and from 17 to 59% (p = 0.004) for the elective. The largest variations were at the caudal border of the delineations but these were smaller when an observer utilized the sagittal window. Hence, the use of sagittal side windows was enforced in the second phase and resulted in a decreased standard deviation for this area from 7.7 to 3.3 mm (p = 0.001) for the CTV and 7.9 to 5.6 mm ( p = 0.03) for the CTV elective.Discussion: Attempts to decrease the variation need to be tailored to the specific causes of the variation. Use of delineation instructions multimodality imaging, the use of sagittal windows and an on-line atlas result in a higher agreement on the intended target. Show less
