@misc{oai:repo.qst.go.jp:00076948,
 author = {楠本, 多聞 and 小平聡 and Fromm, Michel and Omar, Norhan and 長谷川純崇 and 小川原亮 and 小西輝昭 and 甲斐健師 and Kusumoto, Tamon},
 month = {Sep},
 note = {Background and Objectives
Recently, radiation therapies have been recognized as effective candidates for the cancer treatment. Among them, the targeted radioimmunotherapy using radiolabeled copper (Ⅱ) (diacetyl-bis N4-methylthiosemicarbazone) (64Cu-ATSM) is underdevelopment as a new generational cancer treatment 1). 64Cu decays by emission of β- (0.573 MeV), β+ (0.656 MeV) and electron capture (41%) with half-life of 12.7 h. The specific feature of 64Cu is the emission of auger electrons, which has been expected to be effective to kill cancer cells. The therapeutic effectiveness of 64Cu-ATSM for hypoxic cancer cells has been demonstrated so far but the absorbed dose from 64Cu has not been quantitatively evaluated. To establish a dose evaluation method of electrons, we, in the first step, have conducted the dosimetry of 64Cu. 

Experiments
Fluorescence Nuclear Track Detector (FNTD) (Landauer, Ltd.) with a thickness of 90 μm was employed for the dosimetry. The fluorescence intensities were measured using confocal laser scanning microscope (FV-1000, Olympus Co.). FNTD was excited by a laser with a wavelength of 635 nm and then we read the luminescence intensity at 668 nm.
An aqueous copper nitrate solution (FUJIFILM), which was labeled by 64Cu, was used as an electrons source. The radioactivity was 684 kBq at 10:30 on December 20th, 2018. We removed aqueous copper nitrate solution at 13:00 on January 28th, 2019. 

Results and Discussion
Figure 1 shows the depth dependence of relative fluorescence intensity, that is proportional to the absorbed dose. Inset photos are confocal microscopic images of FNTD. The fluorescence intensity at deeper layer could be darker due to the optical light absorption of both excited and emitted lights. The changes in the intensity are calibrated by gamma exposures. The relative intensity decreases monotonically with increasing the depth. At 0 μm in depth, the high absorbed dose is predominantly attributed to auger electrons, characteristic X-rays, β- and β+. Furthermore, the continuous slowing down approximation range of β- in FNTD is 0.85 cm calculated by E-STAR program2). This implies that we should consider the influence to the normal tissues by β- and β+.

Conclusion
We clarified depth dependence of fluorescence intensity measured by FNTD. We are addressing to evaluate the 60Co equivalent dose in water at each depth. Additionally, the results obtained present work will be compared to that using a Monte Carlo simulation., 19th International Conference on Solid State Dosimetry},
 title = {Dose estimation of electrons and positrons from 64Cu using fluorescence nuclear track detector},
 year = {2019}
}