The aim of the present study is:

1. to verify whether the delineation of the tumour bed, based on the combination of the visible postoperative changes and the position of the surgical clips on a CT scan in treatment position acquired 1 week before the start of the radiotherapy (RT), provides an accurate localisation of the boost volume compared to the localisation of the tumour on a pre-operative CT-scan.
2. to document the changes that occur in the tumour bed as seen on a CT scan as a function of the delay between surgery and radiotherapy.
3. to determine the ideal number and the positioning of the clips needed to reproduce the best treatment volume for the boost.
4. to propose new guidelines for tumour bed definition and delineation based on the study findings.

Start of the study: february 2012

Inclusion Criteria:

• Breast Cancer patients, without metastases, who will undergo breast conserving surgery and probably will receive adjuvant chemotherapy and thereafter radiotherapy.

Exclusion Criteria:

• Metastases at time of diagnosis