Using tumor biology to guide radiotherapy
RefleXion’s patented technology uniquely leverages Positron Emission Tomography (PET) during radiotherapy to enable non-invasive tracking and direct treatment of tumors. PET’s fundamentally slow image-acquisition time is circumvented using RefleXion’s novel treatment system, which enables simultaneous treatment of metastatic disease as well as real-time dose adaptation to specific biological and functional characteristics of the tumor.
During PET imaging, a patient is injected with a radiotracer and areas that uptake the tracer become signal emitters. These emissions are in the form of back-to-back or coincident photons separated by ~180 degrees. Coincident photon pairs are then captured by PET detectors over a period of several minutes and used to reconstruct a tomographic image of the tracer distribution in the body.
RefleXion’s integrated PET-radiotherapy system uses coincident photon pairs to guide the radiotherapy treatment beam as the signals are detected in real-time, thereby circumventing PET’s slow image acquisition time. An animation of the proposed system geometry is found below:
Results - Digital Patient Study
The results below depict Monte Carlo simulations of a 3 cm (diameter) tumor moving 2 cm peak-to-peak in a human phantom. With RefleXion's PET-emission guidance, a 30% increase in the minimum dose to the tumor volume is achieved while maintaining the same dose to healthy tissue as compared to uniform coverage of the planning target volume
Using data acquired from a PET scan of a breast cancer patient with a lung metastasis, Monte Carlo dose simulations were carried out on the 3.3 cc lung met with superior-inferior motion of 8.5 mm peak-to-peak. With RefleXion's PET-emission guidance, a 15% increase in the minimum dose to the tumor volume is achieved while satisfying the dose constraints to critical structures specified in the intensity modulated radiotherapy (IMRT) plan.
IMRT dose (tumor's point of view)
While the PET oncology tracer market today predominantly consists of FDG, a host of PET tracers are under development to image specific characteristics of tumor biology. Examples include EF5 (Varian), HX4 (Siemens), FMISO and FAZA for hypoxia; FLT and FCH for proliferation; FACBC (GE Healthcare), FET and FDOPA for amino-acid transport; MEL050 for melanoma; Redectane (Wilex) for renal cell carcinoma; FES for ER+ breast cancer; PSCA (ImaginAb) for prostate, bladder and pancreatic cancer; and NaF for fluoride uptake in bone metastases. The RefleXion system will potentially be able to leverage these novel PET oncology tracers to deliver a truly personalized treatment paradigm.
If you are a radiation oncologist, medical physicist or other clinician interested in learning more about our technology please email firstname.lastname@example.org
The RefleXion system has not been cleared by the FDA for commercial use.
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