Measuring Respiratory Tract Burdens of Magnetic Particles in Humans

ABSTRACT

Magnetometry has the potential for measuring regional deposition and clearance of magnetic tracer particles in humans. The magnetometric techniques used in the past cannot reliably measure regional deposition and they have limited ability to measure long-term clearance rates, because the signals depend on the distribution of magnetic material within the respiratory tract, which is unknown. This work presents the theory and design of two systems whose responses have been shown through computer calculations to be nearly independent of the tracer's location within the human respiratory tract This characteristic allows the total respiratory tract burden to be determined regardless of the spatial distribution of the magnetic material. One system requires measuring the average remanent magnetic field at specified locations near the head and chest. The other requires measuring the voltage induced in detector coils when the subject is oscillated between them. Some practical considerations in the construction and use of these measurement systems are discussed.