| Popis: |
Accelerated partial breast irradiation (APBI) is a popular method of adjuvant radiation therapy after tumor resection for early-stage breast cancer due mainly to the reduced total treatment time. Despite the successes of APBI, many patients do not qualify, and local control rates for APBI may be half that of WBI. Improvements to the APBI technique should be sought to allow more patients to qualify and to improve clinical outcomes. We propose the addition of partial-breast hyperthermia therapy to accelerated partial-breast irradiation (PBHI) to provide additional benefits. A prototype PBHI system was developed at the University of Toledo. The PBHI device uses a removable heating element to heat the balloon fill solution and surrounding tissue. System feasibility was verified through modeling using the finite-element partial differential equation solver package COMSOL Multiphysics (COMSOL Inc., Burlington, MA). We modeled our balloon as a 6 cm diameter inner sphere within a 20 cm diameter sphere of breast tissue. The temperature at the balloon surface was kept at 46 0C for one hour. A temperature of 41 0C is reached at the 1 cm margin of the balloon in approximately 30 minutes. The attenuation of the PBHI balloon applicator was measured using gafchromic film and compared to a standard Mammosite applicator. The PBHI applicator shows increased attenuation, estimated at 3.5 % radially, with a maximum increase in attenuation of 10% in a small region off the tip of the applicator. The homogeneity of the balloon surface temperature was investigated during heating at 4 locations on the balloon surface. A temperature gradient of 2 0C was observed from the top of the balloon (46 0C) to the bottom (44 0C) due to convection. Tissue heating in a porcine tissue model was performed. A balloon temperature of 46 0C was used to reach a temperature of 41 0C at 1 cm depth in approximately 30 minutes. PBHI may expand the patient population qualifying for PBI, or improve local control, thus providing an enhanced treatment option with minimized side effects. The prototype device shows good performance and the potential for a clinically useable PBHI system. |
