World Journal of Nuclear Science and Technology, 2011, 1, 1-5 doi:10.4236/wjnst.2011.11001 Published Online April 2011 (http://www.SciRP.org/journal/wjnst) Copyright © 2011 SciRes. WJNST 1 Physical Parameters Related to Quantify Quality of Effectiveness of Charged Particles at Lower Doses Abubaker Ali Yousif, Ismail Bin Bahari, Muhamad Samudi Yasir Nuclear Science Programme, School of Applied Physics, Faculty of Science and Technology, University Kebangsaan Malaysia, Selagor, Malaysia E-mail: alghoul75@yahoo.com Received January 18, 2011; revised March 10, 2011; accepted March 15, 2011 Abstract Quality factors for protons and helium particles has determined for cell inactivation using linear energy transfer. The quality has also been investigated as a function for other physical parameters, such as mean free path and effective charge for protons and helium particles, for a better interpretation to the effectiveness of these charged particles in V79 cells. Explanation of quality is clearly illustrated in terms of the average dis- tance of energy deposition events in biological systems. Keywords: Quality Factor, Inactivation Effect, Physical Parameters 1. Introduction Investigations of the biological effects of low doses io- nizing radiation is important in the application of radio- logical protection. The different types of radiation has different qualities in terms of equal doses, whereby it is necessary to intro- duce quality factors, Q, which are used as a multiplier yields a dose-equivalent, quality factors are allocated va- lues which are exceed the measured RBE’s relevant to end-point [1]. The quality factor from the absorbed dose is to be multiplied in order to obtain a quantity that expresses a common scale for all ionizing radiation qualities. Up to now, Q is related to linear energy transfer, LET, of the radiation. LET is not a good physical quality parameter to quantify the radiation effects, as such representing Q in terms of LET is not an accurate method to quantify the effectiveness of ionizing radiations [2]. The relative biological effectiveness, RBE, will be un- limited quantity if the absorbed dose in of survival cur- ves for mammalian cells approaches the zero point. This problem is normal in radiation protection that involves the low doses. The quality factors are introduced in radi- ation protection because of the fundamental difficulties that relates to RBE [3] and it is also because of the large variations found in many biological systems, quality factors are usually based on the RBE measurements [4]. As the same absorbed dose delivered by radiations th- rough different quality, i.e., linear energy transfer LET that has different effectiveness in causing damages, as such absorbed energy is not appropriate physical quantity for radiation protection at lower doses. On the other hand, RBEs are too complex and it’s also too dependent on ab- sorbed dose, dose rate as well as the biological end-point, and it is to be used in radiation protection [5]. The quali- ty factor Q replaces RBE in radiation protection. While RBEs are measured values, the quality factors are estab- lished on the basis of measured RBEs. The quality factor can be viewed as an average RBE in different doses, dose rates, as well as the endpoints. The probability of a stochastic effect does not only de- pend on the absorbed dose but also on the type and ener- gy of the radiation. Some radiation doses are more effec- tive biologically, compared to other doses. All these are taken into account by weighting the absorbed dose th- rough a factor which is related to the quality of the radia- tion. A radiation weighting factor is a multiplier quantity whereby it is used to place biological effects (risks) from exposure of the different types of general radiation mea- sure [6]. The specification of radiation quality is based on the energy deposition which has a limited value in defining the quality of ionizing radiations in creating damage [7]. The quality of ionizing radiation produces inactivation e- ffect which is more obvious if it interpreted based on the mean free path between the primary ionizations, i.e. by determining the mean free path between the primary io-