Thermal therapy for breast tumors by using a cylindrical ultrasound phased array with multifocus pattern scanning: a preliminary numerical study

Abstract

The purpose of this study is to investigate the feasibility of using a 1 MHz cylindrical ultrasound phased array with multifocus pattern scanning to produce uniform heating for breast tumor thermal therapy. The breast was submerged in water and surrounded by the cylindrical ultrasound phased array. A multifocus pattern was generated and electrically scanned by the phased array to enlarge the treatment lesion in single heating. To prevent overheating normal tissues, a large planning target volume (PTV) would be divided into several planes with several subunits on each plane and sequentially treated with a cooling phase between two successive heatings of the subunit. Heating results for different target temperatures (T(tgt)), blood perfusion rates and sizes of the PTV have been studied. Furthermore, a superficial breast tumor with different water temperatures was also studied. Results indicated that a higher target temperature would produce a slightly larger thermal lesion, and a higher blood perfusion rate would not affect the heating lesion size but increase the heating time significantly. The acoustic power deposition and temperature elevations in ribs can be minimized by orienting the acoustic beam from the ultrasound phased array approximately parallel to the ribs. In addition, a large acoustic window on the convex-shaped breast surface for the proposed ultrasound phased array and the cooling effect of water would prevent the skin overheating for the production of a lesion at any desired location. This study demonstrated that the proposed cylindrical ultrasound phased array can provide effective heating for breast tumor thermal therapy without overheating the skin and ribs within a reasonable treatment time.

Design and characterization of a laterally mounted phased-array transducer breast-specific MRgHIFU device with integrated 11-channel receiver array

“…For example, simulations of a breast-specific cylindrical ultrasound phased-array were performed on a breast model and initial phantom experiments were completed using a cylindrically mounted single solid transducer that was mechanically rotated. 18,19 The first laterally shooting HIFU transducer system to be used in malignant tissue on a patient 9 was not used beyond the initial feasibility study. A recent report 20 described a laterally shooting 384-element phasedarray transducer for breast MRgHIFU treatments.…”

SonoKnife: Feasibility of a line‐focused ultrasound device for thermal ablation therapy

“…[45][46][47][48][49] However, the literature does not have many reports on the use of a linefocused acoustic device for thermal therapy except for a 1990 patent by Lele, who proposed it for hyperthermia applications (nonablative temperatures), and the more recent development of slightly focused curvilinear applicators for transurethral prostate thermal therapy. [50][51][52] Lele's patent mentioned the potential advantage of lower intensities afforded by line-focusing over point-focusing transducers.…”

Ultrasound ablation enhances drug accumulation and survival in mammary carcinoma models

“…Here, we observe that the circular ablation protocol was capable of coagulating a large region of tumor, with a rapid, 60-second treatment time and, when augmented with chemotherapy, was curative. Alternatively, the application of multiple treatment points in a grid is applied in the ExAblate clinical system (44,45) and from phased treatment arrays (46). Sequential treatment of multiple points requires rest periods for tissue cooling as well as frequent mechanical repositioning of the ultrasound transducer; therefore, we observed that a circular protocol provides substantial time savings in our model.…”