Assessment of skin dose for breast chest wall radiotherapy as a function of bolus material.
Skin dose assessment for chest wall radiotherapy is important to ensure sufficient dose to the surface target volume without excessive skin reaction. This study quantified changes to the surface doses as a function of bolus material for conventional and intensity modulated radiation therapy (IMRT) tangential fields. Three types of bolus materials (2 mm solid, 2 mm fine mesh and 3.2 mm large mesh Aquaplast) were compared with Superflab. Surface dose measurements were performed using an Attix parallel plate chamber in a flat solid water phantom at 0 degrees , 45 degrees and 70 degrees incident angles. Over-response correction factors were applied to the Attix chamber results for different incident angles. Surface dose measurements on an anthropomorphic phantom were done using a thermoluminescent dosimeter extrapolation method. Dose characteristics of Superflab and solid Aquaplast were within 2% of solid water material. No significant differences (within 3%) in the surface dose were found between conventional and IMRT tangential techniques. The bolus effect was large for chest wall tangential radiotherapy, with up to an 82% increase using 2 mm fine mesh Aquaplast. The dosimetric effect of different Aquaplast materials has been quantified in this work. These materials can be used to create a custom bolus with potentially better reproducibility of placement.
Hsu
Shu-Hui
SH
Department of Radiation Oncology, University of Michigan, Ann Arbor, MI 48109, USA. shuihsu@umich.edu
Roberson
Peter L
PL
Chen
Yu
Y
Marsh
Robin B
RB
Pierce
Lori J
LJ
Moran
Jean M
JM
D001940:Breast / Q000528:radiation effects*; D006801:Humans; D019047:Phantoms, Imaging; D011829:Radiation Dosage; D011879:Radiotherapy Dosage; D050397:Radiotherapy, Intensity-Modulated; D012680:Sensitivity and Specificity; D012867:Skin / Q000528:radiation effects*; D013499:Surface Properties; D013819:Thermoluminescent Dosimetry; D035441:Thoracic Wall / Q000528:radiation effects*