Analysis of Radiation Impact on White Mice through Radiation Dose Mapping in Medical Physics Laboratory

A study about X-ray radiation impact on the white mice through radiation dose mapping in Medical Physic Laboratory is already done. The purpose of this research is to determine the minimum distance of radiologist to X-ray instrument through treatment on the white mice. The radiation exposure doses are measured on the some points in the distance from radiation source between 30 cm up to 80 with interval of 30 cm. The impact of radiation exposure on the white mice and the effects of radiation measurement in different directions are investigated. It is founded that minimum distance of radiation worker to radiation source is 180 cm and X-ray has decreased leukocyte number and haemoglobin and has increased thrombocyte number in the blood of white mice.


Introduction
Radiation is a emission process of energy in the forms of waves or particles from radiation sources or radioactive particles [1]. X-ray radiation is an external radiation source which is produced by X-ray tube, a radiation source outside of human body. In the external radiation protection, there are three techniques to control radiation exposure to the radiologist such as by minimizing exposure distance, exposure time and using radiation shield [2]. Syahria et al. (2012) reported that scattering radiation exposure amount will decrease as well as the exposure distance increase [1]. Therefore, the exposure distance is necessary to be given more attentions and the radiologist must know the safe points of their working area.
Specifically, the technicians in the Medical Physics must know comprehensively for the risk of radiation exposure. The accepted radiation dose by radiologist depend on their positions. A mapping of radiation dose in the area of medical physical laboratory is required to determine the safe position for the technician so that they will be more cautious when they work around the X-ray instrument. The radiation is emitted isotropically and as the exposure distance decreases the accepted radiation increase as well.
Some radiation exposures will be scattered emissions when they touch matters. This scattered radiation will increase amount of received radiation doses by radiologist. To avoid this risk, the radiation worker can pose a safe distance of radiation sources [3].
The radiation intensity is defined as radiation amount that penetrates area (cm 2 ) per second (s). The radiation intensity (I) of spherical surfaces of radius R1 and R2 each is Where I = Intensity (watt/m 2 ) P = Power A = Area of sphere surface Equation (1) can be subsituted into Equation (2) becomes The ratio of radiation intensities equals to inversely ratio of sphere radius [4]. Radiation exposure can cause genetically cell changes on living creatures. One of these changes is chromosome structure change of blood lymphocite [5]. White mice is one of the most frequently mammals used in the research either in medical, pharmacy or biology [6]. The white mice are often used in the experiment laboratory, especially in the biology laboratory, due to their excellencies such as relatively short life cycle, fastly breeding, easily treated in large scale of farming, high amount of genetic variations, well characterized anatomy and physiology, high number of children per birth, high genetic variation, well characterized anatomy and physiology, easy handle, and production and reproduction like human [7].
In many reports of radioteraphy cases, the amount of leukocyte and erythrocyte of the radioteraphy treated patients decreased [8]. Leukocytes play role in maintaining body immune to foreign objects and againts para antigen. It is wellknown that leukocyte is the most sensitive cell to radiation or highest radiosensitivity [9]. Leukocyte is part of body immune system [10]. This research is aimed to investigate radiation impact on the radiologist in Medical Physics Laboratory.

Radiation Dose Map
The radiation level measurement is done around Medical Physic Laboratory. It is measured using analog surveymeter and the result is mapped in the form of distribution contour of radiation level using Software Surfer 10. There are three surveymeter heights of measured points, namely 50 cm, 75 cm, and 150 cm. Based on the mapping result, it can be identified the safe points for radiologist. The minimum safe distance is distance between safe point with radiation source. This safe point is assumed as a point with radiation level lower than 10 µSv/jam. The radiation dose is measured at every distance of 30 cm up to distance of 180 cm to east and west of radiation source as shown in Figure 1. The measurement result on the each height is mapped in the 2D contour to delineate radiation level distribution.

Testing of X-ray Radiation Impact on the White Mice
This research uses 12 Mus musculus which have weight each ±25 gram and ±2 months old and is divided into four groups, each consists of three white mice. They all are exposed under radiation and detected from different positions as illustrated in Table 1. The exposures on the white mice were done for six days, each once exposure per day. The white mice blood is taken in the Biology Laboratory, Semarang State University. The white mice blood was taken of white mice's eye parts due to they have very small blood vessel so that it's blad could be aspirated using hypodermic needle. The lower part of white mice cornea was stabbed using small needle. The white mice blood flowed through needle and poured in the microtube. The white mice blood was tested using blood analyzer in the Ungaran District's Medical Laboratory. The blood was tested to determine amount of leukocyte, erythrocyte, haemoglobin, and thrombocyte at each white mice group during six days.

Radiation Exposoure Level Mapping
The measured exposure dose on the surveymeter was recorded using digital camera. The used x-ray equipment in measuring radiation level is x-ray instrument (Mednif SF100BY). The exposure factors which used in measurement is 80kV, 32mA, and 0,5s. The radiation level is measured on the different heights, namely 150cm, 75cm, and 50 cm from X-ray instrument. The data is mapped using Surfer 10 Software as depicted in Figures 2, 3 Figure 2. The 2D mapping of radiation exposure level at 150cm height of X-ray instrument tube.
X-ray radiation source poses a coordinate (150,200) cm. In Figure 2, it seems that the further measument distance the lower accepted exposure radiation. The largest of measured radiation exposure is 10.000 /ℎ, under radiation source which is shown with blue, while the lowest one is 0 /ℎ , at a distance of 180cm from radiation source coordinate point (150,0) cm for west direction and for east direction at coordinate (150,350)cm which is shown with green colour.
In Figure 3, it seems that X-ray radiation dose at a height of 75 cm equals to 9500 /ℎ , under radiation source which is shown by red colour in the contour. The lowest radiation dose is found at a distance of 120cm from radiation source point, (150,90) cm, which is shown with light blue. In Figure 4, it appears that the highest radiation exposed area, 900 /ℎ, is shown in scarlet. The detected radiation exposure decreased from 900 /ℎ down to 0 /ℎ which is indicated by the color change of light to dark. The lowest radiation exposure is detected at a distance of 120cm from radiation source (west zone), (150,90) cm, and east zone, (150,300) cm, which is shown in dark blue. In this research the same exposure factors were used, but the heights are different.
The accepted radiation dose decreased as well as the exposure distance increased. The safe distances to radiation source for radiologist are 180cm (to east) and 120cm (to west).
Based on the decree of the Nuclear Energy Regulatory Agency of Indonesia about operational work safety of radiology diagnostic No. 1-P/KA BAPETEN/IV-199, the safe work point is 3m with radiation dose limit equal to 10 μSv/h and 0,5 μSv/h, for radiation worker and public, respectively [11]. The radiation intensity decreased as well as the exposure distance increased in agreement with [12]: Radiation is emitted of radiation source isotropically [3].

Testing of X-ray Radiation Impact on Mus musculus
The testing result of white mice blood is tabulated in Table 2. In Table 2, normal haemoglobin content in blood equals to 13-16 g/dL. Post-exposure of radiation, the haemoglobin in the white mice is divided into four groups, the highest haemoglobin content is found in the highest radiation exposed blood (10.000 /ℎ). The groups II and III have experienced the haemoglobin content in the blood up to under normal condition namely each 6,65 and 8,97 g/dL. Each white mice has

Conclusion
In conclusion, the highest radiation exposure is in nearest position of radiation source, the intensity decreased as well as the the exposure distance increased. It is found that the safe distance of radiation worker to radiation source equals to 180 cm (for measurement from east side) and 120 cm (for measurement from west side). The impact of X-ray radiation to white mice are the leukocyte, erythrocyte and hamemoglobin decreased and inversely the thrombocyte increased.