Improved dose distribution with a universal acrylic breast compensator.
Wedge filters frequently do not provide optimal distribution in the chest wall, lung, and areolar-nipple complex because they extend through the entire width of tangential radiation fields for breast cancer. In addition, medial wedge filters increase dose to the contralateral breast. In order to overcome these shortcomings, a new method of acrylic compensation was investigated. A universal acrylic breast compensator (ABC) was designed, with patient data, to extend anteriorly from the central axis. To accurately display build-up data, the ABC was entered into the treatment planning system as a wedge filter. Dose homogeneity within the compensated breast, chest wall, and lung volumes was assessed using 3-D planning and dose volume histograms. Dose to the contralateral breast was evaluated using thermoluminescent dosimetry in a polystyrene phantom. Opened, wedged, and compensated conditions were irradiated using the above described techniques. Due to lack of extension of the ABC posteriorly to the central axis (allowing lung inhomogeneity to correct for increased patient thickness), ABCs reduced the high dose regions in the chest wall and lung as compared to wedge filters. ABCs reduced hot spot in the areolar-nipple complex more efficiently as compared to wedge filters. ABCs also reduced dose to the contralateral breast by more than 20% relative to wedge filters. Wedge filters can be inefficient because of lung transmission and contour topography. Excessive dose to the chest wall, lung, and areolar-nipple complex, and contralateral breast can be alleviated with the use of a universal acrylic breast compensator. Its convenience and dosimetric advantages both in treatment planning and daily application offer a useful tool in the management of breast cancer.
Department of Therapeutic Radiology, University of Minnesota, Minneapolis 55455, USA.
J M
JM
Johnson
R A
RA
Potish
F M
FM
Khan
D000180:Acrylic Resins; D001940:Breast / Q000528:radiation effects; D001943:Breast Neoplasms / Q000532:radiotherapy*; D004867:Equipment Design; D005260:Female; D005374:Filtration / Q000295:instrumentation*; D006801:Humans; D008168:Lung / Q000528:radiation effects; D009558:Nipples / Q000528:radiation effects; D019047:Phantoms, Imaging; D011137:Polystyrenes; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D011882:Radiotherapy, High-Energy; D013819:Thermoluminescent Dosimetry; D013909:Thorax / Q000528:radiation effects
D000180:Acrylic Resins; D011137:Polystyrenes