Optical Fibers as Dosimeter Detectors for Mixed Proton/Neutron Fields—A Biological Dosimeter

Abstract

In recent years, proton therapy has gained importance as a cancer treatment modality due to its conformality with the tumor and the sparing of healthy tissue. However, in the interaction of the protons with the beam line elements and patient tissues, potentially harmful secondary neutrons are always generated. To ensure that this neutron dose is as low as possible, treatment plans could be created to also account for and minimize the neutron dose. To monitor such a treatment plan, a compact, easy to use, and inexpensive dosimeter must be developed that not only measures the physical dose, but which can also distinguish between proton and neutron contributions. To that end, plastic optical fibers with scintillation materials (Gd2O2S:Tb, Gd2O2S:Eu, and YVO4:Eu) were irradiated with protons and neutrons. It was confirmed that sensors with different scintillation materials have different sensitivities to protons and neutrons. A combination of these three scintillators can be used to build a detector array to create a biological dosimeter.

Organic Scintillator-Fibre Sensors for Proton Therapy Dosimetry: SCSF-3HF and EJ-260

“…This difference in sensitivity ratios between the SCSF-3HF and EJ-260 scintillators presents the possibility for proton-neutron discrimination using the two scintillators in a single discriminator detector. This possibility was demonstrated for inorganic sensors in our proposed discriminator detector paper [45], which also takes into account the mixed proton/neutron field used in proton measurements. Table 2.…”

A Multi-Point Optical Fibre Sensor for Proton Therapy

“…Spatial resolution can be improved in the future by choosing smaller scintillator sizes and optical fibre diameters; smaller scintillators would also reduce scintillator over-response. Finally, this multipoint array has potential use in fast particle discrimination in mixed fields resulting from proton irradiation, as described by Niedermeyer et al [51], where multiple different sensors could be employed at once. The ultimate result of these variations is that the scintillator measurements appear higher at a shallower depth as compared to the T1 measurements at that same depth, as shown in Figure 10.…”