Key Points
- Researchers from Spain and the UK developed a new focused ultrasound system for using hyperthermia to treat several tumor spheroids simultaneously. This will allow potential treatments of tumors to be tested more rapidly.
- The team designed, 3-D printed, and then coupled the acoustic hologram lens with a high-intensity focused ultrasound transducer.
- The system more uniformly delivered thermal dose, modifying the natural focus of the transducer, and allowed simultaneous exposure to several tumors.
A collaborative team from the Institute of Instrumentation for Molecular Imaging (I3M) at the Polytechnic University of Valencia, in Spain, and the Institute for Cancer Research (ICR), in London (a Focused Ultrasound Center of Excellence) developed a new way of treating several 3D tumor models (spheroids) simultaneously, thus improving the throughput when doing dose finding studies.
Prior research into acoustic lenses has focused on achieving uniform pressures across multiple targets, however in the case of adjacent foci, this can lead to non-uniform thermal dose (i.e., heating), which arises from heat diffusion between adjacent targets. To address this issue, the researchers used acoustic and thermal simulations to design a 3-D printed acoustic lens based on predicted thermal dose. The group tested the new lens coupled to the high-intensity focused ultrasound (HIFU) transducer for which it was designed in a tissue-mimicking phantom with multiple “tumor” wells to determine whether it could apply uniform hyperthermia across a large volume of tissue to reach multiple tumor targets. In cancer treatment, hyperthermia can be used in conjunction with immunotherapy or to sensitize a tumor to radiotherapy or chemotherapy.
The I3M and ICR teams found that the use of the holographic lens with the ultrasound-mediated hyperthermia:
- More uniformly delivered a thermal dose,
- Tuned the natural focus of a transducer, and
- Allowed simultaneous exposure to several tumor spheroids.
When using the system for comparative in-vitro experiments, the research group found the ultrasound system to be more lethal than polymerase chain reaction heating (i.e., heating in the absence of an ultrasound pressure field) for the same thermal dose.
“The seven-focus lens that we tested worked well for exposing tumor spheroids to hyperthermia, evaluating the thermal dose in real-time, and then stopping treatment after the intended dose was delivered,” said Professor Gail ter Haar, PhD, the article’s senior author. “The focused ultrasound also improved control of the tumor spheroid’s growth.”
“The design and 3D printing of ultrasound acoustic lenses is an emerging area of research that promises to extend the capabilities of existing focused ultrasound systems and to allow the use of simpler transducers for complex applications,” said Matt Eames, PhD, the Foundation’s Director of Extramural Research.
See the Full, Open Access Article in Cancers (Basel)