Table 1.

Questionnaire - Factors contributed to contouring variation in RTOG 1106 dry run cases

For tumor (including both primary and nodal tumors) contouring:

CT image quality (e.g. resolution, contrast, partial volume effect)

PET image quality (e.g. resolution, contrast, partial volume effect)

Uncertainties associated with the contouring tools/devices (drawing precision)

Imperfect window setting (i.e. window width and level) when contouring

Variation in SUV threshold for tumor delineation in PET image

Time spent on contouring (diligence in contour drawing)

Difficulty in defining tumor vs. some other pathologic structures (e.g. atelectasis, infection, condensation, effusion)

Difficulty in defining tumor vs. some normal structures (e.g. mediastinal vessels)

Involvement of lymph nodes

Unclear or not-so-detailed instructions and definitions in the protocol

Physician’s knowledge and judgment

Other factors (specify)

For normal tissue/OAR contouring:

CT image quality (e.g. resolution, contrast, partial volume effect)

Uncertainties associated with the contouring tools/devices (drawing precision)

Imperfect window setting (i.e. window width and level) when contouring

Time spent on contouring (diligence in contour drawing)

Unclear or not-so-detailed instructions and definitions in the protocol

Physician’s knowledge and judgment

Other factors (specify)