Table 1 Delineation instructions for CTV Breast and the lumpectomy cavity

Window/Level (WL); Window Width (WW)

- Fixed: WL 0 Hounsfield Unit (HU) and WW of 500 HU for CT and variable WL and WW for MRI.

- Fixed: WL 0 Hounsfield Unit (HU) and WW of 500 HU for CT and variable WL and WW for MRI.

- Change of WL and WW during delineation permitted for CT and MRI.

- Change of WL and WW during delineation permitted for CT and MRI.

Appearance

- The location of the marking wire, positioned around the palpable Glandular Breast Tissue (GBT), will be used as an aid for CTV Breast delineation.

Appearance of contralateral breast (comparing with ipsilateral breast) serves as aid for LC delineation.

- The clinical target volume (CTV) breast was defined to comprise all GBT including fatty (involuted) lobes.

- Margin of the GBT is (ventrally) assumed to be situated 5 mm below the skin surface; in case of MRI the visible GBT fat is (ventrally) delineated as GBT margin.

- Delineation is performed on all CT or MRI slices that are judged to contain GBT.

- Appearance of the contralateral breast (by comparing with the ipsilateral breast) on CT or MR images.

- The preoperative mammographies and location of the palpable GBT marking wire, visible on CT or MRI, all will serve as an aid for GBT delineation.

Clips

Surgical clips (if applicable) should all be included within the delineated GBT.

All surgical clips (if applicable) should be included within delineated LC.

Seroma

Postoperative seroma/hematoma present in LC should be included within delineated GBT.

Postoperative seroma/hematoma present in LC should be included within delineated LC.