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Comparative Study
. 2009 Jun 1;74(2):377-82.
doi: 10.1016/j.ijrobp.2008.08.003. Epub 2008 Oct 22.

Variation in the definition of clinical target volumes for pelvic nodal conformal radiation therapy for prostate cancer

Colleen A F Lawton  1 , Jeff Michalski, Issam El-Naqa, Deborah Kuban, W Robert Lee, Seth A Rosenthal, Anthony Zietman, Howard Sandler, William Shipley, Mark Ritter, Richard Valicenti, Charles Catton, Mack Roach 3rd, Thomas M Pisansky, Michael Seider
Affiliations
Comparative Study

Variation in the definition of clinical target volumes for pelvic nodal conformal radiation therapy for prostate cancer

Colleen A F Lawton et al. Int J Radiat Oncol Biol Phys. .

Abstract

Purpose: We conducted a comparative study of clinical target volume (CTV) definition of pelvic lymph nodes by multiple genitourinary (GU) radiation oncologists looking at the levels of discrepancies amongst this group.

Methods and materials: Pelvic computed tomography (CT) scans from 2 men were distributed to 14 Radiation Therapy Oncology Group GU radiation oncologists with instructions to define CTVs for the iliac and presacral lymph nodes. The CT data with contours were then returned for analysis. In addition, a questionnaire was completed that described the physicians' method for target volume definition.

Results: Significant variation in the definition of the iliac and presacral CTVs was seen among the physicians. The minimum, maximum, mean (SD) iliac volumes (mL) were 81.8, 876.6, 337.6 +/- 203 for case 1 and 60.3, 627.7, 251.8 +/- 159.3 for case 2. The volume of 100% agreement was 30.6 and 17.4 for case 1 and 2 and the volume of the union of all contours was 1,012.0 and 807.4 for case 1 and 2, respectively. The overall agreement was judged to be moderate in both cases (kappa = 0.53 (p < 0.0001) and kappa = 0.48 (p < 0.0001). There was no volume of 100% agreement for either of the two presacral volumes. These variations were confirmed in the responses to the associated questionnaire.

Conclusions: Significant disagreement exists in the definition of the CTV for pelvic nodal radiation therapy among GU radiation oncology specialists. A consensus needs to be developed so as to accurately assess the merit and safety of such treatment.

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Conflict of interest statement

Conflict of Interest: None

Figures

Figure 1
Figure 1
Statistical analysis of prostate CTV-iliac nodes (Case 1) contoured by 11 experts. Left column are transverse view snapshots with multiple panels showing apparent estimated volume (blue), kappa chance corrected volume (pink), staple detected volume (green) original 11 experts contours (bottom right) at different confidence agreement levels (a) Agreement level of 0.2, (b) 0.5, and (c) 0.8. Right column are corresponding graphical summary of estimated volume for each method as a function of confidence agreement level.
Figure 1
Figure 1
Statistical analysis of prostate CTV-iliac nodes (Case 1) contoured by 11 experts. Left column are transverse view snapshots with multiple panels showing apparent estimated volume (blue), kappa chance corrected volume (pink), staple detected volume (green) original 11 experts contours (bottom right) at different confidence agreement levels (a) Agreement level of 0.2, (b) 0.5, and (c) 0.8. Right column are corresponding graphical summary of estimated volume for each method as a function of confidence agreement level.
Figure 2
Figure 2
Statistical analysis of prostate CTV-PS nodes (Case 1) contoured by 11 experts. Left column are transverse view snapshots with multiple panels showing apparent estimated volume (blue), kappa chance corrected volume (pink), staple detected volume (green) original 11 experts contours (bottom right) at different confidence agreement levels (a) Agreement level of 0.2, (b) 0.5, and (c) 0.8. Right column are corresponding graphical summary of estimated volume for each method as a function of confidence agreement level.
Figure 2
Figure 2
Statistical analysis of prostate CTV-PS nodes (Case 1) contoured by 11 experts. Left column are transverse view snapshots with multiple panels showing apparent estimated volume (blue), kappa chance corrected volume (pink), staple detected volume (green) original 11 experts contours (bottom right) at different confidence agreement levels (a) Agreement level of 0.2, (b) 0.5, and (c) 0.8. Right column are corresponding graphical summary of estimated volume for each method as a function of confidence agreement level.
Figure 3
Figure 3
Sagital image of the presacral (PS) lymph node contours
Figure 4
Figure 4
Coronal image of the iliac lymph node contours
See this image and copyright information in PMC

References

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