### Theoretical comparison of two interstitial ultrasound applicators designed to induce cylindrical zones of tissue ablationTheoretical comparison of two interstitial ultrasound applicators designed to induce cylindrical zones of tissue ablation

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 Author Lafon, C. ♦ Chavrier, F. ♦ Prat, F. ♦ Chapelon, J. Y. ♦ Cathigl, D. Source SpringerLink Content type Text Publisher Springer-Verlag File Format PDF Copyright Year ©1999 Language English
 Subject Domain (in DDC) Technology ♦ Engineering & allied operations Subject Keyword Ultrasound ♦ Interstitial ♦ Plane or tubular transducers ♦ Theoretical model ♦ Biomedical Engineering ♦ Human Physiology ♦ Imaging ♦ Radiology ♦ Computer Applications Abstract Although interstitial techniques are invasive, they are still the first-line therapeutic modalities for certain types of tumour. They are mainly relevant to tumours that are either inoperable or located so deep that access is complicated. Of the various types of radiation that can be delivered by the interstitial route, ultrasound is the most suitable for deep heating. The study compares the efficacy of two types of applicator with respect to their ability to induce cylindrical zones of coagulation necrosis. The transducer of the first applicator is tubular, whereas the second is plane and can rotate around its axis. Both have an external diameter of 4mm, are fitted with surface cooling systems and operate at 10.7 MHz and 14W.cm$^{−2}$. Comparison involves mathematical modelling of ablated tissue in the targeted area by resolving the bioheat transfer equation (BHTE) using an algorithm based on finite differences. The BHTE gives a temperature value from which the thermal dose can be determined. It is shown that tissue ablation by tubular transducers is slow, and, in consequence, perfusion disturbs the heating pattern: in vivo, irradiation with a tubular transducer lasting 1081 s would be required to ablate a tissue mass with a radius of 8mm. The corresponding period using a rotating plane transducer with 20 firing angles is only 618s. The mean exposure time of each shot lasts 31±7s. Therefore perfusion would have much less impact in the case of therapy administered using a plane transducer than that using a tubular one. ISSN 01400118 Age Range 18 to 22 years ♦ above 22 year Educational Use Research Education Level UG and PG Learning Resource Type Article Publisher Date 1999-01-01 Publisher Place Berlin, Heidelberg e-ISSN 17410444 Journal Medical and Biological Engineering and Computing Volume Number 37 Issue Number 3 Page Count 6 Starting Page 298 Ending Page 303