Irregular surface compensation for radiotherapy of the breast: correlating depth of the compensation surface with breast size and resultant dose distribution

Abstract

ABSTRACT. Irregular surface compensation uses dynamic multileaf collimators to modify the fluence to an irregular surface along the cranio-caudal axis. The depth of the compensation surface can be varied by specifying a user-defined parameter called the transmission penetration depth (TPD). In our institution, a review has been carried out of 60 breast patients treated using irregular surface compensation of the tangent fields. The effect of changes in the TPD on the dose distribution was investigated, and the optimum TPD was correlated with the maximum field separation (S max ) along the posterior border. Reducing the TPD below 50% pushes the dose towards the front of the breast. This reduces hot spots at the medial and lateral regions next to the posterior border of the tangential fields, particularly for patients with large separation. In 23/60 patients, with a mean S max of 23.9 ¡ 1.6 cm, a TPD between 35% and 45% was used to reduce the proportion of the planning target volume receiving more than 107% of the prescribed dose by 3.4% ¡ 2.8%. Our department protocol states that, subject to an acceptable dose distribution, a TPD of 40% is used if S max is greater than 24 cm; for smaller separations, a TPD of 50% is used.

Improvement of dose distribution with irregular surface compensator in whole breast radiotherapy

“…These include the field-in-field (FIF) technique, the use of electronic compensation and inverse planning intensity modulated radiation therapy (IP-IMRT). [67891011121314]…”

Comparison of semiautomated tangential VMAT with 3DCRT for breast or chest wall and regional nodes

“…The VMAT planning method utilized the tangential VMAT method described by Virén et al 1. This beam arrangement was combined with an approximately 240° arc used to treat the AX and SC PTVs.…”

“…These arc ranges were chosen based on the recommendations of Virén et al.,1 and preliminary testing within the RayStation system. The RayStation dual arcs function was used to allow the gantry to pass each location twice in the breast/chest wall region and provide better coverage.…”

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Radiation burden from modern radiation therapy techniques including proton therapy for breast cancer treatment - clinical implications

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