Download PI-410 What is Magnetic Fluid Hyperthermia

magneThermTM
What is ~ Magnetic Fluid Hyperthermia
Hyperthermia (thermal therapy or thermotherapy) is a type of cancer treatment in which body tissue is exposed to high
temperatures (up to 45 °C).
Research has shown that high temperatures can damage and kill cancer cells, usually with minimal injury to normal
tissues. By killing cancer cells and damaging proteins and structures within cells, hyperthermia may shrink tumors.
National Cancer Institute, USA
Hyperthermia in cancer therapy is:
1) Heating tumor above 42 oC
2) A physical treatment that could result in fewer side effects than chemotherapy
An overview of the process:

Malignant cells are more sensitive to the rise in temperature than healthy ones

MFH is based on a defined transfer of power onto magnetic nanoparticles in an alternate magnetic field
that is determined by the type of particles, frequency and magnetic field strength and which results in local generation of heat. Depending on the equilibrium temperature set in the tumour tissue, this heat may
either destroy the tumour cells directly (thermoablation) or result in a synergic reinforcement of
radiation/chemo efficacy (hyperthermia).

The challenge lies in being able to deliver an adequate quantity of the magnetic particles to generate
enough heat in the target using AC magnetic field conditions that are clinically acceptable. Most of the
laboratory and animal model based studies reported so far are characterized by the use of magnetic field
conditions that could not be safely used with a human patient. In most instances, reducing the field
strength or frequency to safer levels would almost certainly lead to such a reduction in the heat output
from the magnetic material as to render it useless in this application.

It is important therefore to understand the underlying physical mechanisms by which heat is generated in
small magnetic particles by alternating magnetic fields. Enough heat must be generated by the particles
to sustain tissue temperatures of at least 42˚C for 30 min or so.

Calculating the heat deposition rate required to achieve this is complicated by the presence of blood flow
and tissue perfusion, both of which are dominant sources of tissue cooling and both of which vary actively as tissue is heated.

The frequency and strength of the externally applied AC magnetic field used to generate the heating is
limited by deleterious physiological responses to high frequency magnetic. These include stimulation of
peripheral and skeletal muscles, possible cardiac stimulation and arrhythmia, and non-specific inductive
heating of tissue. Generally, the useable range of frequencies and amplitudes is considered to be f =
0.05–1.2MHz and H = 0–15 kAm−1.
nanoTherics Ltd
E-mail: [email protected]
Tel. + 44 1782 622112
www.nanotherics.com
PI-410

Experimental data on exposure to much higher frequency fields comes from groups such as Oleson et al who
developed a hyperthermia system based on inductive heating of tissue, and Atkinson et al who developed a
treatment system based on eddy current heating of implantable metal thermoseeds. Atkinson et al concluded
that exposure to fields where the product H x f does not exceed 4.85 × 108Am−1 s−1 is safe and tolerable for
Magnetic Fluid Hyperthermia.
The magneTherm™system from nanoTherics has the following capabilities for studies in the field of
Magnetic Fluid Hyperthermia;
f ( KHz)
f (Hz)
110
168
176
262
335
474
523
633
739
987
Ho (kA/m)
Ho (A/m)
Ho x f
19.9
13.5
18.3
18.3
13.5
8.7
15.9
7.2
12.7
9.5
19,900
13,500
18,300
18,300
13,500
8,700
15,900
7,200
12,700
9,500
2.19 x 109
2.27 x 109
3.22 x 109
4.79 x 109
4.52 x 109
4.12 x 109
8.32 x 109
4.56 x 109
9.39 x 109
9.38 x 109
110,000
168,000
176,000
262,000
262,000
335,000
474,000
523,000
739,000
987,000
The magneTherm™ has the capacity to exceed the safe and tolerable dose quoted above but also has the flexibility to
be able to vary the frequency and field strength to deliver medically relevant exposure to nanoparticles, cells
(adherent or suspension) and 3D cell structures.
Magnetic Field Amplitude vs Votage rms
Vp-p Vrms
(showing consistent Vrms/mT)
1400.00
1200.00
1000.00
800.00
600.00
400.00
200.00
0.00
mT
2.09
2.09
4.18
4.18
6.26
6.26
8.35
8.35
Vp-p
100
200
300
400
10.44 12.53 14.62 16.70 18.79 20.88 22.97
10.44 12.53 14.62 16.70 18.79 20.88 22.97
500
600
700
800
900
1000
1100
V/ mT 47.89 47.89 47.89 47.89 47.89 47.89 47.89 47.89 47.89 47.89 47.89
25.06
25.06
1200
47.89
Please note: Voltage and therefore Field Strength can be adjusted to required value.
nanoTherics Ltd
E-mail: [email protected]
Tel. + 44 1782 622112
www.nanotherics.com
PI-410