Characterization of the optical properties and stability of Presage™ following irradiation with photons and carbon ions

Figures & data

Figure 1. Co-60 irradiation of Presage™ detectors. The samples of Presage™ mounted for irradiation with γ-photons from a Co-60 source with a farmer-type ionization chamber.

Table I. Overview of irradiated Presage™ samples. An overview of the number of cuvettes irradiated with different particles and doses. The table also includes the number of “blanks” that were used to estimate the background throughout each experiment. *Eight cuvettes were irradiated in the dose range from 50 to 10 kGy. The actual doses can be seen in Figure 4. **From the series of irradiations performed at HIT.

	γ-photons		Carbon ion
	Gammatron (Co-60)	Gammatron (Co-60)	Plateau 400 MeV/u	SOBP 400 MeV/u
0	5	2	5	3
1	2	1	2
5	2	1	2	2
10	2	1	2+2^b	2
20		1	2^b	2
50,…, 10 kGy		8^a

^aEight cuvettes were irradiated in the dose range from 50 to 10 kGy. The actual doses can be seen in Figure 4.

^bFrom the series of irradiations performed at HIT.

Figure 2. Presage™ detectors irradiated from 0 to 10 kGy. Twelve Presage™ samples irradiated with γ-photons from a Co-60 source in the dose range from 0 (left) to 10 kGy (right).

Figure 3. Optical setup. The laser setup used for determination of the optical density of the irradiated samples.

Figure 4. Optical spectrum of Presage™ detectors postirradiation. The optical spectrum of Presage™ following irradiation with γ-photons from a Co-60 source in the dose range from 0 to 10 kGy.

Figure 5. Presage™ detector dose response. The optical density change at 633 nm is plotted for Co-60 irradiated Presage™ samples. The dose response is found to be linear up to approximately 100 Gy.

Table II. Dose response of Presage™ detectors. The dose response of Presage™ following irradiation with carbon ions (plateau, 400 MeV/u) and γ-photons from Co-60. Carbon I and Carbon II are two different data sets and are therefore presented separately. The same applies for Co-60 I and Co-60 II. A lower slope is expected for high LET irradiation. Rˆ2 – linear correlation coefficient squared.

	Carbon I	Carbon II	Co-60 I	Co-60 II
ΔOD/Gy	0.011 ± 0.002	0.013 ± 0.002	0.014 ± 0.002	0.012 ± 0.002
R^2	0.996	0.983	0.987	0.999
LET	10.94 keV/μm	10.94 keV/μm	0.2 keV/μm	0.2 keV/μm

Figure 6. Presage™ detector carbon ion dose response. The dose response of Presage™ dosimeters after irradiation with carbon ions in the Plateau and the SOBP at HIT. The response is found to be linear despite the difference in LET.

Table III. Detector response following SOBP and Plateau carbon ion irradiation. The slope of the dose response for Presage™ following irradiation with carbon ions both in the plateau and the SOBP. *The high energy deposition in and around the SOBP creates carbon ions with a variety of different energies and other particles all with different LET.

	SOBP	Plateau
ΔOD/Gy	0.015 ± 0.001	0.012 ± 0.001
R^2	0.9966	0.956
LET	> 10.94 keV/μm*	10.94 keV/μm