A head and neck hyperthermia applicator: Theoretical antenna array design
article
Purpose: Investigation into the feasibility of a circular array of dipole antennas to deposit RF-energy centrally in the neck as a function of: 1) patient positioning, 2)
antenna ring radius, 3) number of antenna rings, 4) number of antennas per ring and 5) distance between antenna rings.
Materials and Methods: Power absorption (PA) distributions in realistic, head and neck, anatomy models are calculated at 433MHz. Relative PA distributions corresponding to different set-ups were analysed using the ratio of the average PA (aPA) in the target and neck region.
Results: Enlarging the antenna ring radius from 12.5cm to 25cm resulted in a - 21% decrease in aPA. By changing the orientation of the patients with respect to the array an increase by - 11% was obtained. Increase of the amount of antenna rings led to a better focussing of the power (1 -- 2 / 3 : - 17%). Increase of the distance between the antenna rings resulted in a smaller (more target region conformal) focus but also a decreased power penetration.
Conclusions: A single optimum array setup suitable for all patients is difficult to define. Based on the results and practical limitations a setup consisting of two rings of
six antennas with a radius of 20cm and 6cm array spacing is considered a good choice providing the ability to heat the majority of patients.
antenna ring radius, 3) number of antenna rings, 4) number of antennas per ring and 5) distance between antenna rings.
Materials and Methods: Power absorption (PA) distributions in realistic, head and neck, anatomy models are calculated at 433MHz. Relative PA distributions corresponding to different set-ups were analysed using the ratio of the average PA (aPA) in the target and neck region.
Results: Enlarging the antenna ring radius from 12.5cm to 25cm resulted in a - 21% decrease in aPA. By changing the orientation of the patients with respect to the array an increase by - 11% was obtained. Increase of the amount of antenna rings led to a better focussing of the power (1 -- 2 / 3 : - 17%). Increase of the distance between the antenna rings resulted in a smaller (more target region conformal) focus but also a decreased power penetration.
Conclusions: A single optimum array setup suitable for all patients is difficult to define. Based on the results and practical limitations a setup consisting of two rings of
six antennas with a radius of 20cm and 6cm array spacing is considered a good choice providing the ability to heat the majority of patients.
TNO Identifier
223737
Source
International Journal of Hyperthermia, 23(1), pp. 59-67.
Pages
59-67
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