# A highly accurate determination of absorbed power during nanomagnetic hyperthermia

## TL;DR

This paper introduces a highly accurate method for measuring absorbed power in magnetic hyperthermia by improving Q factor measurement accuracy through transient signal analysis, enabling detection of minute nanoparticle amounts.

## Contribution

It presents an order of magnitude improvement in Q factor measurement accuracy using transient signals and pulse phase-cycling, enhancing power absorption detection in nanomagnetic hyperthermia.

## Key findings

- Achieved significant improvement in Q factor measurement accuracy.
- Demonstrated detection of minute ferrite nanoparticle amounts.
- Successfully located embedded ferrite in a phantom study.

## Abstract

Absorbed power of nanoparticles during magnetic hyperthermia can be well determined from changes in the quality factor ($Q$ factor) of a resonator, in which the radiofrequency (RF) absorbent is placed. We present an order of magnitude improvement in the $Q$ factor measurement accuracy over conventional methods by studying the switch-on and off transient signals of the resonators. A nuclear magnetic resonance (NMR) console is ideally suited to acquire the transient signals and it also allows to employ the so-called pulse phase-cycling to remove transient artifacts. The improved determination of the absorbed power is demonstrated on various resonators in the 1-30 MHz range including standard solenoids and also a birdcage resonator. This leads to the possibility to detect minute amounts of ferrite nanoparticles which are embedded in the body and also the amount of the absorbed power. We demonstrate this capability on a phantom study, where the exact location of an embedded ferrite is clearly detected.