Measurement of mass attenuation coefficients of Eremurus–Rhizophora spp. particleboards for X-ray in the 16.63–25.30 keV energy range

Author's Accepted Manuscript

Measurement of mass attenuation coefficients of Eremurus-Rhizophora spp. particleboards for X-ray in the 16.63 – 25.30 keV energy range E.T. Tousi, S. Bauk, R. Hashim, M.S. Jaafar, A. Abuarra, K.S.A. Aldroobi, A.M. Al-Jarrah

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S0969-806X(14)00079-6 http://dx.doi.org/10.1016/j.radphyschem.2014.03.011 RPC6372

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Radiation Physics and Chemistry

Received date: 18 September 2013 Accepted date: 6 March 2014 Cite this article as: E.T. Tousi, S. Bauk, R. Hashim, M.S. Jaafar, A. Abuarra, K.S.A. Aldroobi, A.M. Al-Jarrah, Measurement of mass attenuation coefficients of Eremurus-Rhizophora spp. particleboards for X-ray in the 16.63 – 25.30 keV energy range, Radiation Physics and Chemistry, http://dx.doi.org/10.1016/j.radphyschem.2014.03.011 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Measurement

of

mass

attenuation

coefficients

of

Eremurus-Rhizophora

spp.

particleboards for X-ray in the 16.63 – 25.30 keV energy range

E. T. Tousi a,*, S. Bauk b, R. Hashim c, M. S. Jaafar a, A. Abuarra a, K.S.A. Aldroobi a, A. M. Al-Jarrah a a

School of Physics, Universiti Sains Malaysia, 11800 USM, Penang, Malaysia Physics Section, P.P.P. Jarak Jauh, Universiti Sains Malaysia, 11800 USM, Penang, Malaysia c Division of Bio-resource, Paper and Coatings Technology, School of Industrial Technology, Universiti Sains Malaysia, 11800 USM, Penang, Malaysia b

Corresponding author. Tel.: +60175290481 E-mail address: [email protected] (Ehsan Taghizadeh Tousi)

Abstract: The roots of Eremurus spp. were used as a bio-adhesive in the fabrication of Rhizophora spp. particleboards. The mass attenuation coefficients of Eremurus-Rhizophora spp. particleboard of six samples with two different weight percentages of the Eremurus spp. root (6% and 12%) and three various Rhizophora spp. particle sizes (149 μm, 149 μm to 500 μm and 500 μm to 1000 μm) were determined by using X-ray fluorescence (XRF) photons in 16.63 keV and 25.30 keV of the photon energy range. The results were compared with theoretically calculated mass attenuations using the XCOM computer program for younger-age (breast 1: 75% muscle + 25% fat), middle-age (breast 2: 50% muscle + 50% fat), and old-age (breast 3: 25% muscle + 75% fat) breasts. The results indicated that Eremurus-Rhizophora spp. particleboard is the appropriate suitable phantom in the diagnostic energy region. The mass attenuation coefficient in the low weight percentage of the bio-adhesive and the large Rhizophora spp. particle size were found very close to breast 1. Moreover the mass attenuation coefficient of the sample with high weight percentage of the bio-adhesive and small Rhizophora spp. particle size was found very close to water as a standard material phantom. In addition, the viscosity of dissolved Eremurus spp. root in water could be considerably higher than that of formaldehyde-based adhesives, which affects on some properties such as high strength and high binding.

Keywords: Rhizophora spp., Eremurus spp., Bio-adhesive, Attenuation coefficient

1.

Introduction

Phantoms are simulated systems of the human body that are used in medical physics. Although widely used in clinical dosimetry, water and solid homogeneous phantoms, such as polystyrene and acrylic, are not always feasible (Khan, 2010). Thus, the search for new phantom materials and new methods are still ongoing. Mammography is a technique in medical imaging that is used to detect and diagnose breast cancer or any illness in the breast using low-energy X-ray. Phantoms are especially important in mammography due to their use in the quality control (QC) of mammography equipment. Therefore, the proximity of the dose in the phantom and the real breast tissue ensures high-quality mammography. The mass attenuation coefficient is an important parameter in radiation and medical physics, which is extracted from the Beer-Lambert law in optics science (Beutel et al., 2000). Based on this law, the beams are attenuated exponentially when passing through materials. This attenuation depends on the mass attenuation coefficient, defined as the linear attenuation coefficient (μ) per density (), and is expressed in cm2/g.

Rhizophora spp. is a type of mangrove trees that grow in the coastal areas of the tropics. They are presently used mainly for charcoal and building materials. Studies have been performed in the past two decades to determine the possibility of using Rhizophora spp. as a phantom material. In 1988, the suitability of Rhizophora spp. as phantom material was confirmed for the first time by Sudin et al.. The attenuation coefficient of Rhizophora spp. was investigated at the photon energy of 59.54 keV by Bradly et al. (Bradley et al., 1991), and their results were very close to the values of the attenuation coefficient of water. Tajuddin et al. (Tajuddin et al., 1996) studied the transmission and scattering properties of Rhizophora spp. wood, modified rubber, and water. The scattering and radiographic properties of Rhizophora spp. wood and modified rubber were indicated to be similar to water. The dose distribution in Rhizophora spp. wood and water phantoms were measured

using LiF thermoluminescent dosimeters (TLDs) around

137

Cs and

192

Ir brachytherapy

sources (Munem, 1999). The results indicated good agreement for both brachytherapy sources between Rhizophora spp. and water phantoms. In addition, the percentage depth dose in the water and Rhizophora spp. wood phantoms were compared at 6 MeV photon beam as well as at 5 MeV and 20 MeV electron beams in 2001 (Banjade et al., 2001). The results showed very good agreement between the two phantoms. In 2009, the mass attenuation coefficient was determined within the photon energy range of 15.77 keV-25.27 keV using an X-ray fluorescent (XRF) beam (Shakhreet et al., 2009). The results of this study confirmed that the mass attenuation coefficient of Rhizophora spp. is close to that of young-age breast (breast 1), as calculated by the XCOM computer program. The “XCOM: Photon Cross Sections Database” is a computer code, which has been issued by the National Institute of Standards and Technology (NIST) (Hussein, 2011). The XCOM computer code can calculate the photon cross sections for various elements and compounds with atomic or effective atomic numbers less than 100, at 1 keV to 100 GeV of the photon energy range for all photon-matter reactions (Berger et al., 1998), which has been widely used by many researchers to compare the mass attenuation coefficients of the standard materials with their experimental results.

The use of Rhizophora spp. raw wood as phantom has some practical limitations. Uniformity in the control of density and other properties throughout the phantom is very difficult. In addition, Rhizophora spp. wood gets slimy with mold growth, while cracks and warps appear with time (Marashdeh et al., 2012). The fabrication of Rhizophora spp. in the form of particleboards has been considered by some researchers as an alternative.

A particleboard can be generally made in two forms: binderless and using adhesives. The mass attenuation coefficient of Rhizophora spp. binderless particleboard at photon energy

from 16.59 keV - 25.26 keV was investigated (Marashdeh et al., 2012). The results showed that the mass attenuation coefficient of Rhizophora spp. binderless particleboard depends on the particle sizes and closer to the calculated XCOM values in water with decreasing particle size. However, the mass attenuation coefficients of Rhizophora spp. binderless particleboard were not very close to the values of the breast tissue in the mammography photon energy range. In addition, its applications are limited by low internal bond and low resistance against water absorption for prolonged time usage in clinical dosimetry (Marashdeh et al., 2011). Rhizophora spp. particleboards using synthetic adhesives (urea formaldehyde, phenol formaldehyde and phenol resorcinol formaldehyde) were investigated by Surani (Surani, 2008) and Tong (Ngu, 2009). Their results did not match with the mass attenuation coefficient of water, which significantly varies with that of breast tissue. Moreover the chemical fumes from the synthetic adhesives that may be possibly released from the phantom with passing time may cause some health concerns for staff and patients ((Hashim et al., 2011; Marashdeh et al., 2012; Marashdeh et al., 2011). In the present study, a completely bio-based adhesive was used as a binder to fabricate Rhizophora spp. particleboards. This bio-adhesive was made from dried and finely powdered roots of Eremurus spp., a genus of perennial flowers that is classified in the Angiosperm phylum, and Monocot clade (Bryan, 1992). Eremurus spp. has been traditionally classified in Liliaceae family but has undergone significant revision in the recent year, based on the Monocot classification. This genus is newly classified in the order Asparagales, family Xanthorrhoeaceae, and subfamily Asphodeloideae (Bremer et al., 2009). It commonly grows on stony slopes and the steppes of mountains, and then blossoms in June. The root of this plant is thick and glazed, which looks like a starfish. The root contains about 30% gum, which makes it a good quality glue (Komarov, 1985).

The viscosity and melting point of powdered Eremurus spp. root were measured. Also, the mass attenuation coefficients of Eremurus-Rhizophora spp. particleboards were determined from six samples of powdered Eremurus spp. root with two different percentages by weight and three different Rhizophora spp. particle sizes using X-Ray Fluorescent (XRF) photons within the energy range of 16.63 keV–25.30 keV. The results were compared with the theoretical calculated mass attenuation coefficients using a photon cross section of the XCOM computer program for young-age (breast 1: 75% muscle + 25% fat), middle-age (breast 2: 50% muscle + 50% fat), and old-age (breast 3: 25% muscle + 75% fat) breasts (Constantinou, 1982).

2.

Materials and Methods

2.1

Determination of the melting point of Eremurus spp. root as a bio-adhesive

The melting point of the Eremurus spp. root plays a very important role in the fabrication of the particleboard. In the present study, differential scanning calorimetry (DSC) was used to measure the melting point of the Eremurus spp. root. DSC is a type of thermal analysis technique that is used to study several characterizations of samples and has various applications in sciences and industries. In the experimental method of DSC, the sample and a known reference are heated with a linear temperature gradient between two defined temperatures and the heat of the sample is measured relative to the reference material. The DSC analysis produces a curve that shows the heat flow by milliwatt (mW) against temperature (°C).

2.2

Determination of viscosity of Eremurus spp. root as a bio-adhesive

Viscosity is an important physical property of any adhesives. A Brookfield DV-II+ Pro U.S.A. viscometer was employed to measure the viscosity of Eremurus spp. root. According to the Japanese industrial standard, the spindle of viscometer was utilized with 62.5 rpm speed to measure the powdered Eremurus spp. root dissolved in water at different weight percentage of solid content (6%, 10%, 12%, and 15%) at room temperature (Jis, 2003; Wang et al., 2011). The pascal-second (Pa.s = kg.m-1.s-1) is the unit of viscosity in the SI system. The unit of the viscometer was centi-poise (cp), which the poise (g.cm-1.s-1) is the viscosity unit in the cgs system. So, a cp unit is equal to 0.001 Pa.s. The viscosity of the Eremurus spp. root was compared with that of the tow wide-spread based-formaldehyde adhesives, ureaformaldehyde (UF) and phenol-formaldehyde (PF).

2.3

Particleboard fabrication

Three steps are involved in making the Eremurus-Rhizophora spp. particleboard, as follows: 1) Preparation of Rhizophora spp. particles and Eremurus spp. root as a bio-adhesive 2) Mixing of the Rhizophora spp. particles with bio-adhesive 3) Determination of the appropriate method for making the particleboard The Rhizophora spp. tree trunks were longitudinally cut into the planks (approximately 1 m long, 20 cm wide, and 2 cm to 3 cm thick). Then, the planks were peeled. Based on previous studies (Marashdeh et al., 2011; Mitkar and Dongarge, 2012; Shakhreet et al., 2009), the middle section of the Rhizophora spp. tree trunks were used. The planks were chipped using a wood-shaving machine and the chips were air-dried for days until their moisture contents reached approximately 10%. A hammer mill machine was used to convert the wood chips into wood particles. The Rhizophora spp. particles were classified in three sizes (below 149

μm, between 149 μm to 500 μm and between 500 μm to 1000 μm) by a horizontal screening machine. The roots of Eremurus spp., which were used as a bio-adhesive, were washed, cleaned, and peeled. The roots were then dried in an oven and later ground into fine powder. The moisture content of this powder was approximately 1% to 2%. The addition of water was necessary because of the jelly-like structure of the bio-adhesive from Eremurus spp. roots. Approximately 20% of water was added to the mixture of wood particles and adhesive powder. A two-step method was used to fabricate the EremurusRhizophora spp. particleboard. The first step involved the cold pressing of the mixture at room temperature at a pressure of 1000 kg/cm2 for 15 minutes. The second step was hot pressing that generally included four temperature and pressure regimens. The board was pressed at a pressure 600 kg/cm2 at 100 C for approximately 15 minutes. Then, the pressure was increased to 700 kg/cm2 for approximately 10 minutes as the temperature was increased from 100 C to 150 C. When the temperature was increased up to the maximum value of 180 C (according to the results of DSC for the melting-point of the bio-adhesive), the pressure was at 800 kg/cm2 for 5 minutes. Finally, the pressure was set at 1000 kg/cm2 for 15 minutes at the maximum temperature. During this process, the pressure consecutively removed water from the board. The moisture contents of the Eremurus-Rhizophora spp. particleboards were about 5% to 6%. Six different types of samples with two different weight percentages of bioadhesive and three different particle sizes of Rhizophora spp. particles were prepared. A total of 50 particleboard samples (5 cm × 5 cm × 0.6 cm) were fabricated.

2.4

Determination of the mass attenuation coefficients

XRF was produced when a high-purity metal target was irradiated by a  source. In the present study, an annular 241Am source was used as a 60 keV  source, and the metal targets were niobium (purity: 99.8%; K=16.63 keV), molybdenum (purity: 99.9%; K=17.47 keV), palladium (purity: 99.9%; K=21.26 keV), silver (purity: 99.99%; K=22.17 keV) and tin (purity: 99.999%; K=25.30 keV). Fig. 1 shows the used experimental setup in this study.

The Beer-Lambert law declares that the beam is attenuated exponentially when passing through materials (Beutel et al., 2000).

I

I 0 e  Px

(1)

where I is the transmitted photon intensity, I0 is the primary photon intensity, x is the thickness (cm) of material and μ (cm-1) is the linear attenuation coefficient of the material. Rearranging the linear attenuation coefficient provides:

P

1 § I0 · ln¨ ¸ x © I ¹

(2)

The mass attenuation coefficient is defined as the linear attenuation coefficient (μ) per density () with its unit of measurements in square centimeter per gram.

P U

1 § I0 · ln¨ ¸ Ux © I ¹

(3)

where x is the mass density or mass thickness. The error of the mass attenuation coefficient can be calculated as: §P· V ¨¨ ¸¸ ©U¹ §P· ¨¨ ¸¸ ©U¹

§P· V P V U  Ÿ V ¨¨ ¸¸ P U ©U¹

ª V P V  U º § P · « P  U » u ¨¨ U ¸¸ ¬ ¼ © ¹

(4)

§P· where V ¨¨ ¸¸ is the error in the mass attenuation coefficient, V P is the error in the linear ©U¹ mass attenuation coefficient and V U is the error in the density. V P and V U are given by (Marashdeh et al., 2012; Shakhreet et al., 2009):

V P r>P max  P min / 2@; V U r>U max  U min / 2@

(5)

The percentage error of the mass attenuation coefficient is obtained by (Mitkar and Dongarge, 2012):

%error

( P / U )theo  ( P / U )exp ( P / U )theo

u 100

(6)

where ( P / U ) exp and ( P / U ) theo are the experimental and theoretical mass attenuation

coefficients. Paired-sample t-test was used to evaluate the rate of the equivalence and similarity of the mass attenuation coefficient of six fabricated Eremurus-Rhizophora spp. particleboard in three different Rhizophora spp. particle size and two different weight percentage of Eremurus spp. root with mass attenuation of water and breasts 1, 2 and 3 (Constantinou, 1982). The null hypothesis was evaluated, which means that the mean difference between the mass attenuation coefficient of sample and standard is zero (Hatcher, 2003; Pallant, 2010).

( Null  hypothesis) H 0 : P 2  P1

0 o H 0 : Pd

0

( Experimental  hypothesis) H 1 : P 2  P1 z 0 o H 1 : P d z 0

(7)

where in this study μ1 and μ2 were the mass attenuation coefficient of fabricated Eremurus-

Rhizophora spp. particleboard and standard, respectively. So, for each pair that p-value was bigger than 0.05, H0 was accepted, which means the mass attenuation coefficients of standard and sample were statistically equivalent.

Paired-sample t-test was used for six fabricated Eremurus-Rhizophora spp. particleboard in three different Rhizophora spp. particle size and two different weight percentage of Eremurus spp. root. There were four materials as the standard: water, breasts 1, 2 and 3.

3.

Results and discussion

3.1

Melting point of Eremurus spp. root

The melting point of the powdered Eremurus spp. root was measured by DSC (DSC6

model, Perkin Elmer). Fig. 2 illustrates the curve of the heat flow (mW) against temperature (°C). The peak of the DSC curve determined by the melting point of the Eremurus spp. root was 176.709 °C. Accordingly, 180 °C was chosen as the maximum temperature in the hot pressing of the Erremurus-Rhizophora spp. particleboard fabrication.

3.2

Viscosity measurements

Table 1 shows the viscosities of dissolved Eremurus spp. root in water. The viscosities of two commercial industrial adhesives, phenol-formaldehyde (PF) and urea-formaldehyde (UF) are approximately 0.02 Pa.s to 0.12 Pa.s (Chew et al., 1991; Osemeahon et al., 2007) and approximately 0.23 Pa.s to 6.1 Pa.s (Chew et al., 1991; Haupt and Sellers, 1994), respectively. The viscosity of the dissolved Eremurus spp. root in water could be considerably higher than those of formaldehyde-based adhesives, which affects on some properties such as high strength and high binding. The handling and employment of an adhesive with high viscosity would be difficult (Pan et al., 2005). The percentage of dissolved Eremurus spp. root powder could be a balancing parameter between high strength and comfort of utilization of powdered Eremurus spp. root.

3.3

Densities of fabricated Eremurus-Rhizophora spp. particleboards

Six different types of samples with two different weight percentages of bio adhesive and three different particle sizes of Rhizophora spp. particles were prepared (Table 2). The relative densities of water, breasts 1, 2 and 3 were 1, 1.02, 0.99 and 0.95 g/cm3, respectively (Constantinou, 1982; Shakhreet et al., 2009). The density of breast 1 was the target density with a value of 1.02 g/cm3.

3.4

Measured mass attenuation coefficients

Table 3 shows the linear and the mass attenuation coefficients of six fabricated Rhizophora spp. particleboard with three Rhizophora spp. particle sizes (A and B: 500 μm – 1000 μm; C and D: 149 μm – 500 μm; E and F: 149 μm) bonded with powdered Eremurus spp. root in two weight percentage levels (A, C, and E: 6%; B, D, and F: 12%) in 16.63 keV - 25.30 keV of the XRF photon energy range. The errors V(P) and V(P/U) are also shown in Table 3, which have been determined based on Eq. (4) and (5). The calculated error of the mass attenuation coefficients (V(P/U)) were found to be in the range of 0.03 cm2.g-1 to 0.15 cm2.g-1. The low V(P/U) indicates high accuracy of the measurement of the mass attenuation coefficients of the samples.

The mass attenuation coefficients of the fabricated Eremurus–Rhizophora spp. particleboards as a new phantom material must be compared with those of the standard phantom materials or body tissues. Water has similar density with soft body tissue has been known as the most widely used standard phantom material. On the other hand, there is a wide range of body tissues. The mammography technique uses X-ray photon energy range below 30 keV, approximately. Hence, the mass attenuation coefficients of water, breasts 1, 2 and 3

were calculated by using the XCOM computer program (Berger and Hubbell, 1987) in the 16.63 keV - 25.30 keV photon energy range, which are shown in Table 4. Table 5 shows the calculated percentage error of the mass attenuation coefficients of the fabricated Eremurus-Rhizophora spp. particleboards with respect to XCOM calculated values of the water, breasts 1, 2 and 3, based on Eq. 6 and Tables 3 and 4. The percentage errors of all types of the fabricated Eremurus-Rhizophora spp. particleboards with respect to water or young-age breast tissue (breast 1) are found to be very small for each XRF photon energy in the 16.63 keV - 25.30 keV range. On the other hand, the percentage errors of the mass attenuation coefficients of the Eremurus-Rhizophora spp. particleboards with respect to middle-age (breast 2) and old-age (breast 3) breast tissues show a big difference between the mass attenuation coefficients of the samples and those of breasts 2 and 3. Table 5 gives some information for each XRF photon energies, separately. Paired-sample ttest was used to compare the sets of the mass attenuation coefficients of the samples with those of the water, breasts 1, 2 and 3 in the 16.63 keV - 25.30 keV of the XRF photon energy range. Table 6 shows the results of paired-sample t-test of the fabricated Eremurus-

Rhizophora spp. particleboards with water, breasts 1, 2 and 3 calculated by the SPSS-16 computer program. According to Eq. 7, the p value less than 0.05 indicates a significant difference between two sets of the mass attenuation coefficients. Therefore, the mass attenuation coefficients of the fabricated Eremurus-Rhizophora spp. particleboards are not similar to those of the middleage (breast 2) and old-age (breast 3) breast tissues. In addition, Table 7 shows the statistical equivalent of samples with standards based on the results of calculating paired-sample t-test. Samples A and C are similar to soft tissue of young-age breast, and samples B, E, and F are

similar to standard water phantom, statistically. The similarity of two data sets raises with bigger p value. Therefore, samples C and F are closer to breast 1 and water, respectively. Figure 3 shows the comparison between the mass attenuation coefficients of sample C, natural Rhizophora spp. raw wood (Shakhreet et al., 2009), Rhizophora spp. binderless particleboard (Marashdeh et al., 2012), and breast 1 calculated by XCOM computer program.

The mass attenuation coefficients of sample C for each XRF photon energies were found to be approximately on the mass attenuation coefficient line of breast 1, calculated by the XCOM computer program. Therefore, the mass attenuation coefficient of sample C was found to be more similar to that of breast 1 compared with natural Rhizophora spp. raw wood (Shakhreet et al., 2009) and Rhizophora spp. binderless particleboard (Marashdeh et al., 2012). Likewise, Figure 4 shows the mass attenuation coefficient of sample F compared with those of natural Rhizophora spp. raw wood (Shakhreet et al., 2009), Rhizophora spp. binderless particleboard (Marashdeh et al., 2012), and the calculated XCOM value of water. The mass attenuation coefficient of natural Rhizophora spp. raw wood (Shakhreet et al., 2009) was very far from that of water. The mass attenuation coefficient of sample F was in good agreement with that of the Rhizophora spp. binderless particleboard (Marashdeh et al., 2012), which has been approximately on the line of the mass attenuation coefficient of water calculated by XCOM computer program.

3.5

Effect of the Rhizophora spp.the XCOM computer program mass attenuation coefficient

The Rhizophora spp. particle sizes ranged from 500 μm to 1000 μm for samples A and B; 149 μm to 500 μm for samples C and D; and 149 μm for samples E and F. According to Table 6, the largest p values of the mass attenuation coefficients of the couple sample-water are found for samples E and F with the smallest Rhizophora spp. particle size (149 μm). As well as, samples E and F had the smallest p values of the couple sample-breast 1. On the other hand, the mass attenuation coefficients of the samples A and C with the Rhizophora spp. particle size 149 μm were found similar to that of breast 1. Also, the lowest p value of the couple sample-water was related to the samples A, B, and D. Therefore, the mass attenuation coefficient was found closer to that of breast 1 with the Rhizophora spp. particle size 149 μm. On the other hand, the mass attenuation coefficients of the fabricated

Eremurus-Rhizophora spp. particleboard was found more similar to that of water with the Rhizophora spp. particle size 149 μm. Therefore, the mass attenuation coefficient of the fabricated Eremurus-Rhizophora spp. particleboard becomes to closer than that of water with the reduced Rhizophora spp. particle size. The increasing of the Rhizophora spp. particle size caused to be more similar to young-age breast tissue (breast 1).

3.6

Effect of bio-adhesive weight percentage on the mass attenuation coefficient

The weight percentage of bio-adhesive was another parameter that effected on the mass attenuation coefficient. The adhesive treatment levels were 6% for samples A, C and E; and 12% for samples B, D and F. The p value of the couple sample-water increased with the raised adhesive treatment level. As well as, the p value of the couple sample-breast1 increased with decreased adhesive treatment level. Therefore, the mass attenuation coefficient of the fabricated Rhizophora spp. particleboard was closer to that of breast 1 with the lower

weight percentage of Eremurus adhesive. Likewise, the mass attenuation coefficient of the fabricated Rhizophora spp. particleboard was more similar to water in high Eremurus spp. root percentage level.

4

Conclusion

The viscosity of dissolved Eremurus spp. root in water could be considerably higher than that of formaldehyde-based, which affects on some properties such as high strength and high binding. The percentage of dissolved Eremurus spp. root powder could be a balancing parameter between high strength and comfort of utilization of powdered Eremurus spp. root. The mass attenuation coefficient within the photon energy range of 16.63 keV - 25.30 keV for the lowest weight percentage of bio-adhesive and the large Rhizophora spp. particle size (sample A and C) was very close to that of breast 1. Moreover, the results of sample F, with higher weight percentage bio-adhesive (Eremurus spp. root) and smallest Rhizophora spp. particle size, are nearest to that of water. The mass attenuation coefficient of Eremurus-Rhizophora spp. particleboard was found very close to that of breast 1 with an increase in the Rhizophora spp. particle size and a decrease in the weight percentage of bio-adhesive. The mass attenuation coefficient of

Rhizophora spp. binderless particleboard was close to that of water (Marashdeh et al., 2012). Thus the addition of bio-adhesive has affected on the relationship between the mass attenuation coefficient and the Rhizophora spp. particle size. Moreover, the mass attenuation coefficient of the Eremurus-Rhizophora spp. particleboard was very close to that of water by a decrease in the Rhizophora spp. particle size and an increase in the weight percentage of the bio-adhesive. These results demonstrate that Eremurus-Rhizophora spp. particleboard is an appropriate phantom in diagnostic radiation.

Acknowledgement

The authors acknowledge the financial support provided by the research grant no. 1001/PFIZIK/845019 from the Universiti Sains Malaysia. Our appreciation goes to Mohammad Javad Sadeghi Fard and Wan Noor Aidawati binti Wan Nadhari for their useful discussion.

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Hatcher, L., 2003. Step-by-step basic statistics using SAS: student guide. SAS Institute, New York. Haupt, R.A., Sellers, T.J., 1994. Characterizations of phenol-formaldehyde resol resins. Industrial & engineering chemistry research 33, 693-697. Hussein, E.M.A., 2011. Computer Radiation Imaging: Physics and Mathematics of the Forward and Inverse Problems. Elsevier, Waltham, Massachusetts, USA. JIS, 2003. JIS A 5908: Particleboards. Japanese Standard Association, Japan. Khan, F.M., 2010. The physics of radiation therapy. Lippincott Williams & Wilkins, Philadelphia. Komarov, V.L., 1985. Flora of the USSR. Koeltz Scientific Books, Germany. Marashdeh, M.W., Bauk, S., Tajuddin, A.A., Hashim, R., 2012. Measurement of mass attenuation coefficients of Rhizophora spp. binderless particleboards in the 16.59–25.26 keV photon energy range and their density profile using x-ray computed tomography. Applied Radiation and Isotopes 70, 656-662. Marashdeh, M.W., Hashim, R., Tajuddin, A.A., Bauk, S., Sulaiman, O., 2011. Effect of particle size on the characterization of binderless particleboard made from Rhizophora spp. Mangrove wood for use as phantom material. BioResources 6, 4028-4044. Mitkar, S.R., Dongarge, S.M., 2012. To study the linear and mass attenuation coefficient of alcohol soluble compound for gamma rays at energy 662 KeV. Journal of Chemical and Pharmaceutical Research 4, 3944-3949. Munem, E.M.E.A., 1999. Radiation dose distribution measurements around brachytherapy sources in water and Rhizophora spp phantom. M.Sc. Thesis, Universiti Sains Malaysia, Penang, Malaysia. Ngu, K.T., 2009. Fabrication of 1.0 g/cm3 Rhizophora spp. particleboard and determination of their mass attenuation coefficient. M.Sc. Thesis, Universiti Sains Malaysia, Penang, Malaysia. Osemeahon, S., Barminas, J., Aliyu, B., 2007. Effect of urea formaldehyde viscosity on some physical properties of a composite from reactive blending of urea formaldehyde with natural rubber. International Journal of Physical Sciences 2, 242-248. Pallant, J., 2010. SPSS survival manual: A step by step guide to data analysis using SPSS. Open University Press, Buckingham, UK. Pan, Z., Cathcart, A., Wang, D., 2005. Thermal and chemical treatments to improve adhesive property of rice bran. Industrial Crops and Products 22, 233-240.

Shakhreet, B.Z., Bauk, S., Tajuddin, A.A., Shukri, A., 2009. Mass attenuation coefficients of natural Rhizophora spp. wood for X-rays in the 15.77–25.27 keV range. Radiation Protection Dosimetry 135, 47-53. Surani, B.T., 2008. The suitability of PF, UF, and PRF resins in term of structure and attenuation properties to be used in Rhizophora Spp. particleboard phantom. M.Sc. Thesis, Universiti Sains Malaysia, Penang, Malaysia. Tajuddin, A.A., Sudin, C.W.a.C.W., Bradley, D.A., 1996. Radiographic and scattering investigation on the suitability of Rhizophora spp. as tissue-equivalent medium for dosimetric study. Radiation Physics and Chemistry 47, 739-740. Wang, Q., Kashiwagi, N., Apaer, P., Chen, Q., Wang, Y., Maezono, T., 2011. Study on coal recovery technology from waste fine Chinese coals by a vegetable oil agglomeration process, in: Brebbia, C.A. (Ed.), The Sustainable World. Wit press, Southampton, UK, p. 331.

Figure captions:

Fig. 1. Schematic experimental setup for the determination of the attenuation coefficients of the fabricated Eremurus-Rhizophora spp. particleboards. Fig. 2. DSC spectra of the powdered Eremurus spp. root. Figure 3. The compared mass attenuation coefficients for sample C with those of natural

Rhizophora spp. raw wood (Shakhreet et al., 2009), Rhizophora spp. binderless particleboard (Marashdeh et al., 2012), and calculated XCOM value for breast 1. Figure 4. The compared mass attenuation coefficients for sample F with those of natural

Rhizophora spp. raw wood (Shakhreet et al., 2009), Rhizophora spp. binderless particleboard (Marashdeh et al., 2012), and calculated XCOM value for water.

Tables

Table 1. Viscosities of four different dissolved Eremurus spp. root in water in Pa.s, at room temperature (25 °C to 30 °C).

% weight of powdered 6% Eremurus spp. root Viscosity Pa.s 0.853

10%

12%

15%

8.800

14.400 36.867

Table 2. Eremurus-Rhizophora spp. samples with different weight percentages of Eremurus spp. root, particle size of Rhizophora spp. and measured densities. Sample A B C D E F

%weight Eremurus spp. root 6 12 6 12 6 12

Particle size Rhizophora spp. (μm) 500-1000 500-1000 149-500 149-500 149 149

Max 1.07 1.09 1.10 1.10 1.08 1.08

Density (g/cm3) Min Average 0.94 1.00 0.97 1.00 0.99 1.00 1.00 1.01 0.96 1.01 0.91 0.99

() 0.07 0.06 0.05 0.05 0.06 0.09

Energy (keV)

Sample A Sample B Sample C μ/ (μ/) Avrerage (μ) μ/ (μ/) Avrerage (μ) μ/ (μ/) Avrerage (μ) -1 -1 -1 -1 -1 -1 μ (cm ) ±(cm ) (cm²/g) ±(cm²/g) μ (cm ) ±(cm ) (cm²/g) ±(cm²/g) μ (cm ) ±(cm ) (cm²/g) ±(cm²/g) 16.63 1.11 0.02 1.11 0.10 0.02 1.22 0.10 0.01 1.13 0.07  1.2  1.13 17.47 0.99 0.02 0.99 0.09 0.04 1.04 0.10 0.02 1.03 0.08  1.04  1.03 21.26 0.66 0.03 0.66 0.07 0.01 0.69 0.05 0.01 0.65 0.04  0.69  0.66 22.17 0.52 0.07 0.59 0.12 0.62 0.02 0.62 0.06 0.59 0.01 0.59 0.04 25.3 0.48 0.01 0.48 0.04 0.01 0.50 0.04 0.00 0.47 0.03  0.50  0.47   Sample E Sample F Sample D Energy μ/ (μ/) Avrerage (μ) μ/ (μ/) Avrerage (μ) μ/ (μ/) Avrerage (μ) (keV) μ (cm-1) ±(cm-1) (cm²/g) ±(cm²/g) μ (cm-1) ±(cm-1) (cm²/g) ±(cm²/g) μ (cm-1) ±(cm-1) (cm²/g) ±(cm²/g) 16.63 1.21 0.02 1.2 0.08 1.24 0.05 1.23 0.12 1.23 0.02 1.24 0.12 17.47 1.08 0.03 1.07 0.09 0.01 1.09 0.07 0.02 1.11 0.11  1.09  1.10 21.26 0.67 0.00 0.66 0.04 0.01 0.68 0.05 0.01 0.73 0.07  0.69  0.72 22.17 0.63 0.02 0.62 0.05 0.01 0.63 0.05 0.10 0.64 0.15  0.63  0.64 25.3 0.49 0.02 0.48 0.05 0.52 0.01 0.51 0.04 0.50 0.02 0.50 0.06 Sample A: Rhizophora spp. particle size (RPS) 500 μm – 1000 μm, Percentage adhesive treatment level (Adh) 6%; Sample B: RPS 500 μm – 1000 μm, Adh 12%; Sample C: RPS 149 μm – 500 μm, Adh 6%; Sample D: RPS 149 μm – 500 μm, Adh 12%; Sample E: RPS 149 μm, Adh 6%; Sample F: RPS 149 μm, Adh 12%

Table 3. Linear and mass attenuation coefficients of the Eremurus-Rhizophra spp. particleboards.



Table 4. Mass attenuation coefficients of water, breasts 1, 2 and 3 calculated by the XCOM computer program (Berger and Hubbell, 1987).

Energy (keV) 16.63 17.47 21.26 22.17 25.30

μ/ from XCOM (cm²g-1) Water breast1 breast2 breast3 1.27 1.16 0.99 0.85 1.12 1.02 0.88 0.76 0.71 0.65 0.57 0.51 0.65 0.60 0.53 0.47 0.50 0.47 0.42 0.38



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Table 5. Percent error of the mass attenuation coefficient of the Eremurus-Rhizophora spp. particleboards related to the calculated XCOM values of water (w.), breast 1 (b. 1), breast 2 (b. 2), and breast 3 (b. 3). Energy A B (keV) b. 1 b. 2 b. 3 w. b. 1 b. 2 b. 3 w. 16.63 4.00 12.37 31.32 12.32 4.89 22.78 43.48 4.20 17.47 3.37 11.88 30.03 12.00 2.23 18.36 37.56 6.90 21.26 1.34 14.91 30.07 6.41 6.26 20.49 36.38 1.87 22.17 0.87 11.85 25.86 8.09 2.98 16.20 30.75 4.52 25.30 3.39 14.45 26.13 3.06 7.70 19.21 31.38 0.98 Energy C D (keV) b. 1 b. 2 b. 3 w. b. 1 b. 2 b. 3 w. 16.63 2.46 14.17 33.43 10.91 3.64 21.31 41.77 5.34 17.47 0.84 16.75 35.70 8.16 5.24 21.84 41.62 4.16 21.26 0.32 13.76 28.76 7.35 1.76 15.39 30.61 6.02 22.17 1.31 11.36 25.31 8.50 3.99 17.34 32.03 3.58 25.30 0.72 11.49 22.87 5.56 3.06 14.08 25.73 3.37 Energy E F (keV) b. 1 b. 2 b. 3 w. b. 1 b. 2 b. 3 w. 16.63 6.06 24.15 45.09 3.12 6.88 25.11 46.21 2.38 17.47 6.48 23.28 43.29 3.03 8.97 26.17 46.64 0.76 21.26 4.65 18.66 34.31 3.36 11.90 26.88 43.61 3.34 22.17 5.12 18.60 33.46 2.54 7.47 21.26 36.45 0.36 25.30 10.10 21.90 34.35 3.26 7.99 19.53 31.73 1.25 Sample A: Rhizophora spp. particle size (RPS) 500 μm – 1000 μm, Percentage adhesive treatment level (Adh) 6%; Sample B: RPS 500 μm – 1000 μm, Adh 12%; Sample C: RPS 149 μm – 500 μm, Adh 6%; Sample D: RPS 149 μm – 500 μm, Adh 12%; Sample E: RPS 149 μm, Adh 6%; Sample F: RPS 149 μm, Adh 12% 

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Table 6. The results of paired-sample t-test of samples with water, breast 1, breast 2, and breast 3 calculated by SPSS code.

p value of sample-standard pair A B C D E F water 0.042 0.081 0.020 0.012 0.117 0.812 breast1 0.368 0.007 0.536 0.023 0.004 0.003 breast2 0.002 0.008 0.010 0.014 0.008 0.007 breast3 0.005 0.009 0.011 0.013 0.010 0.008 Sample A: Rhizophora spp. particle size (RPS) 500 μm – 1000 μm, Percentage adhesive treatment level (Adh) 6%; Sample B: RPS 500 μm – 1000 μm, Adh 12%; Sample C: RPS 149 μm – 500 μm, Adh 6%; Sample D: RPS 149 μm – 500 μm, Adh 12%; Sample E: RPS 149 μm, Adh 6%; Sample F: RPS 149 μm, Adh 12%

Standard



24 



Table 7. The statistically equivalent of samples with standards based on the results of calculated paired-sample t-test.

Sample A B C D E F

Rhizophora spp. particle size (μm) 500 – 1000 500 – 1000 149 – 500 149 – 500 149 149

%weight Eremurus spp. root 6 12 6 12 6 12





25 

Standard Breast 1 Water Breast 1 ××× Water Water



Highlight  ¾ Rhizophora spp. particleboard bonded with Eremurus spp. root as a new phantom. ¾ Mass attenuation coefficient of particleboard was measured in16.63–25.30keVrange. ¾ Mass attenuation coefficient particleboard was affected by particle size & %glue. ¾ Mass attenuation coefficient of particleboard was close to water and young breast. ¾ ViscosityofEremuruswassignificantlyhigherthanthoseofsyntheticadhesives.

26 



Figures

Metal plate

 rays Annular 241Am source

Lead (Pb)

XRF beam Sample

Collimator (Pb)

Detector

Fig. 1. Schematic experimental setup for the determination of the attenuation coefficients of the fabricated Eremurus-Rhizophora spp. particleboards.

27 

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65

Fig. 2. DSC spectra of the powdered Eremurus spp. root.

2



Mass Attenuation Coefficient (cm²/g)

1.5

Sample C Rhizophora spp. Binderless particleboard (Marashdeh et al., 2012) Natural Rhizophora spp. raw wood (Shakhreet, et al., 2009) breast 1 (XCOM)

1.2

0.9

0.6

0.3 15

17

19 21 Energy (keV)

23

25

Figure 3. The compared mass attenuation coefficients for sample C with those of natural

Rhizophora spp. raw wood (Shakhreet et al., 2009), Rhizophora spp. binderless particleboard (Marashdeh et al., 2012), and calculated XCOM value for breast 1.

29 

Mass Attenuation Coefficient (cm²/g)



1.5

Sample F

1.2

Rhizophora spp. Binderless particleboard (Marashdeh et al., 2012) Natural Rhizophora spp. raw wood (Shakhreet, et al., 2009) water (XCOM)

0.9

0.6

0.3 15

17

19 21 Energy (keV)

23

25

Figure 4. The compared mass attenuation coefficients for sample F with those of natural

Rhizophora spp. raw wood (Shakhreet et al., 2009), Rhizophora spp. binderless particleboard (Marashdeh et al., 2012), and calculated XCOM value for water.

30