Retroperitoneal Sarcoma (RPS) Target Volume and Organ at Risk (OAR) Contour Delineation Agreement Among RTOG Sarcoma Radiation Oncologists

Abstract

Purpose/Objective(s)To evaluate the variability in target volume and OAR contour delineation for RPS by Radiation Therapy Oncology Group (RTOG) sarcoma radiation oncologists (ROs).Materials/MethodsRadiation planning computed tomography (CT) scans for 2 RPS cases were distributed to 12 sarcoma ROs with instructions for contouring gross tumor volume (GTV), clinical target volume (CTV), high risk CTV (HR CTV: area judged to be at high risk of positive margins after resection), and OARs: bowel bag, small bowel, large bowel, stomach, and duodenum. Analysis of contour agreement was performed using the simultaneous truth and performance level estimation (STAPLE) algorithm and kappa statistics.ResultsEach case was contoured by 11 ROs. The first case (RPS 1) was a patient with well-differentiated (WD) liposarcoma (LPS) with a de-differentiated (DD) component, and the second case (RPS 2) was a patient with DD LPS. Contouring agreement for all volumes is shown in the Table. Agreement for GTV and CTV contours was high. However, the agreement for HR CTVs was only moderate. For OARs, agreement for stomach, bowel bag, large and small bowel was high, but agreement for duodenum was fair to moderate.ConclusionsOral Scientific Abstract 253; TableKappa Statistic Agreement for RPS Target and OAR VolumesRPS 1RPS 2Kappa Level of AgreementKappa Level of AgreementGTV0.84 Almost Perfect0.92 Almost PerfectCTV0.79 Substantial0.86 Almost PerfectHR CTV0.50 Moderate0.57 ModerateBowel Bag0.82 Almost Perfect0.79 SubstantialSmall Bowel0.73 Substantial0.78 SubstantialLarge Bowel0.73 Substantial0.82 Almost PerfectStomach0.77 Substantial0.83 Almost PerfectDuodenum0.41 Moderate0.36 Fair Open table in a new tab Purpose/Objective(s)To evaluate the variability in target volume and OAR contour delineation for RPS by Radiation Therapy Oncology Group (RTOG) sarcoma radiation oncologists (ROs). To evaluate the variability in target volume and OAR contour delineation for RPS by Radiation Therapy Oncology Group (RTOG) sarcoma radiation oncologists (ROs). Materials/MethodsRadiation planning computed tomography (CT) scans for 2 RPS cases were distributed to 12 sarcoma ROs with instructions for contouring gross tumor volume (GTV), clinical target volume (CTV), high risk CTV (HR CTV: area judged to be at high risk of positive margins after resection), and OARs: bowel bag, small bowel, large bowel, stomach, and duodenum. Analysis of contour agreement was performed using the simultaneous truth and performance level estimation (STAPLE) algorithm and kappa statistics. Radiation planning computed tomography (CT) scans for 2 RPS cases were distributed to 12 sarcoma ROs with instructions for contouring gross tumor volume (GTV), clinical target volume (CTV), high risk CTV (HR CTV: area judged to be at high risk of positive margins after resection), and OARs: bowel bag, small bowel, large bowel, stomach, and duodenum. Analysis of contour agreement was performed using the simultaneous truth and performance level estimation (STAPLE) algorithm and kappa statistics. ResultsEach case was contoured by 11 ROs. The first case (RPS 1) was a patient with well-differentiated (WD) liposarcoma (LPS) with a de-differentiated (DD) component, and the second case (RPS 2) was a patient with DD LPS. Contouring agreement for all volumes is shown in the Table. Agreement for GTV and CTV contours was high. However, the agreement for HR CTVs was only moderate. For OARs, agreement for stomach, bowel bag, large and small bowel was high, but agreement for duodenum was fair to moderate. Each case was contoured by 11 ROs. The first case (RPS 1) was a patient with well-differentiated (WD) liposarcoma (LPS) with a de-differentiated (DD) component, and the second case (RPS 2) was a patient with DD LPS. Contouring agreement for all volumes is shown in the Table. Agreement for GTV and CTV contours was high. However, the agreement for HR CTVs was only moderate. For OARs, agreement for stomach, bowel bag, large and small bowel was high, but agreement for duodenum was fair to moderate. ConclusionsOral Scientific Abstract 253; TableKappa Statistic Agreement for RPS Target and OAR VolumesRPS 1RPS 2Kappa Level of AgreementKappa Level of AgreementGTV0.84 Almost Perfect0.92 Almost PerfectCTV0.79 Substantial0.86 Almost PerfectHR CTV0.50 Moderate0.57 ModerateBowel Bag0.82 Almost Perfect0.79 SubstantialSmall Bowel0.73 Substantial0.78 SubstantialLarge Bowel0.73 Substantial0.82 Almost PerfectStomach0.77 Substantial0.83 Almost PerfectDuodenum0.41 Moderate0.36 Fair Open table in a new tab