Image-guided radiotherapy for breast cancer patients: surgical clips as surrogate for breast excision cavity

Rajko Topolnjak, Peter de Ruiter, Peter Remeijer, Corine van Vliet-Vroegindeweij, Coen Rasch, Jan-Jakob Sonke
International Journal of Radiation Oncology, Biology, Physics 2011 November 1, 81 (3): e187-95

PURPOSE: To determine the use of surgical clips as a surrogate for localization of the excision cavity and to quantify the stability of the clips' positions during the course of external beam radiotherapy for breast cancer patients, using cone beam computed tomography (CBCT) scans.

METHODS AND MATERIALS: Twenty-one breast cancer patients with surgical clips placed in the breast excision cavity were treated in a supine position with 28 daily fractions. CBCT scans were regularly acquired for a setup correction protocol. Retrospectively, the CBCT scans were registered to the planning CT scans, using gray-value registration of the excision cavity region and chamfer matching of the clips. Subsequently, residual setup errors (systematic [Σ] and random [σ]) of the excision cavity were estimated relative to the clips' registration. Finally, the stability of the clips' positions were quantified as the movement of each separate clip according to the center of gravity of the excision cavity.

RESULTS: When clips were used for online setup corrections, the residual errors of the excision cavity were Σ(left-right) = 1.2, σ(left-right) = 1.0; Σ(cranial-caudal)  = 1.3, σ(cranial-caudal) = 1.2; and Σ(anterior-posterior)  = 0.7, σ(anterior-posterior) = 0.9 mm. Furthermore, the average distance (over all patients) between the clips and centers of gravity of the excision cavities was 18.8 mm (on the planning CT) and was reduced to 17.4 mm (measured on the last CBCT scan).

CONCLUSION: Clips move in the direction of the center of gravity of the excision cavity, on average, 1.4 mm. The clips are good surrogates for locating the excision cavity and providing small residual errors.

Full Text Links

Find Full Text Links for this Article


You are not logged in. Sign Up or Log In to join the discussion.

Related Papers

Remove bar
Read by QxMD icon Read

Save your favorite articles in one place with a free QxMD account.


Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"