On the use of CR-39 PNTD with AFM analysis in measuring proton-induced target fragmentation particles
Artikel i vetenskaplig tidskrift, 2015

In addition to energy loss by ionization process, protons of energy >similar to 50 MeV, such as those used in proton radiotherapy, can undergo nuclear interactions with nuclei of Z > 1, resulting in the production, of short range (<20 gm), high-LET (linear energy transfer) target fragment particles. One of the few methods to detect these short-range particles is by means of CR-39 plastic nuclear track detector (PNTD) analyzed with an atomic force microscope (AFM). However, due to the LET-dependent angular sensitivity of CR-39 PNTD, multiple detectors exposed at a range of incident angles to the primary proton beam, must be analyzed in order to accurately determine the LET spectrum, absorbed dose and dose equivalent. The LET spectrum of 160 MeV proton-induced secondary particles was experimentally measured with CR-39 PNTDs, which were exposed at six different incident angles to take into account the intrinsic sensitivity of the critical angle for track registration. The irradiated detectors were chemically processed to remove a 1 gm thick volume of CR-39 PNTD. The measured LET range of short range tracks was from 15 key/mu m up to 1.5 MeV/mu m. The absorbed dose contribution (D-s/D-p) from secondary particles to primary proton dose was similar to 1%, while the dose equivalent contribution (H-s/D-p) was found to be similar to 20%. Analysis of CR-39 PNTD by AFM yielded similar to 60% higher value for absorbed dose compared to standard optical microscopy analysis.


Proton therapy

Nuclear Track Detector

Target fragmentation

Secondary particles


Biological Effectiveness



S. Kodaira

National Institute of Radiological Sciences

T. Konishi

National Institute of Radiological Sciences

H. Kitamura

National Institute of Radiological Sciences

M. Kurano

National Institute of Radiological Sciences

H. Kawashima

National Institute of Radiological Sciences

Yukio Uchihori

National Institute of Radiological Sciences

T. Nishio

National Cancer Center Tokyo

N. Yasuda

University of Fukui

K. Ogura

Nihon University

Lembit Sihver

Chalmers, Teknisk fysik, Nukleär teknik

E. R. Benton

Oklahoma State University

Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms

0168-583X (ISSN)

Vol. 349 163-168



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