Determination of effective atomic numbers from mass attenuation coefficients of tissue-equivalent materials in the energy range 60 kev-1.

Transcription

1 Journal of Physcs: Confrnc Srs PAPER OPEN ACCESS Drmnaon of ffcv aomc numbrs from mass anuaon coffcns of ssu-quvaln marals n h nrgy rang 6 kv-.33 MV To c hs arcl: Noorfan Ada B. Amn al 7 J. Phys.: Conf. Sr Rlad conn - A sudy of phoon nracon paramrs n som commonly usd solvns Tjbr Sngh, Paramj Kaur and Parj S Sngh - Smulaon of phoon anuaon coffcns for hgh ffcv shldng maral Lad-Boron Polyhyn L Zhang, M C Ja, J J Gong al. - Gamma ray shldng characrsc of BZnBo-SLS and PbZnBo-SLS glass Nor Syuhada Ahmad, Iskandar Shahrm Musafa, Ishak Mansor al. Vw h arcl onln for updas and nhancmns. Ths conn was downloadd from IP addrss on /6/8 a 9:3

2 ISMP6 IOP Publshng IOP Conf. Srs: Journal of Physcs: Conf. Srs (7) 8 do :.88/ /85//8 Drmnaon of ffcv aomc numbrs from mass anuaon coffcns of ssu-quvaln marals n h nrgy rang 6 kv-.33 MV Noorfan Ada B. Amn, J Zukh, N. A. Kabr, R. Zanon Oncologcal and Radologcal Scncs Clusr, Advancd Mdcal and Dnal Insu, Unvrs Sans Malaysa, 3 Kpala Baas, Pulau Pnang, Malaysa; School of Physcs, Unvrs Sans Malaysa, 8 Pulau Pnang, Malaysa E-mal: rafdahzanon@usm.my Absrac. Th man am of hs sudy was o sablsh a cos-ffcv ssu-quvaln maral for phanom fabrcaon. Effcv aomc numbrs (Z ff) and ffcv lcron dnss (N ff) wr calculad basd on mass anuaon coffcn valus. Th lnar and mass anuaon coffcns of wo sampls of paraffn wax and NaCl composons wr masurd usng S dcor for NaI (Tl) dcor of.5 rsourcs. Radoacv sourc was placd n fron of dcor and h sampl was placd bwn h sourc and h phoomulplr ub (PMT) of h dcor. Th ral m was s for 6 sconds. Th phoopak, full wdh a half maxmum (FWHM) and n ara of phoopak wr masurd usng Masro sofwar. Th anuaon coffcn valus oband from hs sudy wr usd o calcula Z ff and N ff of paraffn wax and NaCl composons. Th masurd rsuls wr compard wh h horcal valus from XCOM and ICRU Rpor 44. Th rlav prcnag dffrnc of mass anuaon coffcns bwn xprmnal and human ssu for boh paraffn wax and NaCl mxur ar blow 5%, whras h rlav prcnag dffrnc of Z ff and N ff ar abov 5%. Th masurd valus of Z ff and N ff of paraffn wax and NaCl hlp us o sablsh h opmal mxurs o fabrca a cos-ffcv ssu-quvaln maral.. Inroducon Suds on ssu quvaln marals for anhropomorphc physcal phanom fabrcaon ar mporan for radaon dosmry, calbraon and mdcal magng []. Ths ssu-quvaln marals ar bng consrucd from svral chmcals [] ha xacly rprsn h anaomcal shap of human organs [3-4] and hav smlar nracon of onzng radaon o human body. In ordr o b accpd as a ssuquvaln maral, h absorbd and h scard radaons should b as clos as possbl o hos xprncd by h rradad ssu undr smlar condons [5]. To undrsand h physcal proprs of ssu quvaln marals, a sudy of paramrs such as mass anuaon coffcn (μ m), lnar anuaon coffcn (μ l), oal aomc cross-scon (σ ), lcronc cross-scon (σ ), ffcv aomc numbr (Z ff), lcron dnsy (N ff), man fr-pah (λ) ar mporan [6]. Mass anuaon coffcn s dfnd as h masur of a maral s ably o absorb or scar lcromagnc radaon n any form (.g., x-rays, gamma ray, c.) pr un of mass. Th mass anuaon coffcn s hn usd o drv ohr phoon nracon paramrs. Lnar anuaon coffcn (μ l) dscrbs h fracon of a bam of x-rays or γ- rays ha s absorbd or scard pr un hcknss of h absorbr. Th scarng and absorpon of gamma radaons ar Conn from hs work may b usd undr h rms of h Crav Commons Arbuon 3. lcnc. Any furhr dsrbuon of hs work mus manan arbuon o h auhor(s) and h l of h work, journal caon and DOI. Publshd undr lcnc by IOP Publshng Ld

3 ISMP6 IOP Publshng IOP Conf. Srs: Journal of Physcs: Conf. Srs (7) 8 do :.88/ /85//8 rlad o h dnsy and aomc numbr of ach lmn. For compos maral, s rlad o ffcv dnsy and ffcv aomc numbr. Th knowldg of mass anuaon coffcns s prm mporanc n h drmnaon of ffcv aomc numbr [6]. A sngl numbr of aomc numbr hrfor, canno rprsn h aomc numbr unquly across h nr nrgy rang, snc h paral nracon cross-scons dpnd on dffrn lmn numbrs [7]. Th Z ff of h marals s on of h mos mporan paramr rprsnng radaon nracon, and hs paramr has wdly bn usd n mdcal magng, radohrapy and nuclar mdcn. In hs sudy, h mass anuaon coffcns and ohr phoon nracon paramrs of compos marals, paraffn wax and NaCl sampls wr drmnd a dffrn gamma nrgs. Th masurd valus wr compard wh h valus oband usng sm mprcal rlaons basd on mxur rul, and valus from XCOM and ICRU-44 rpor. Ohr phoon nracon paramrs wr drvd from h mass anuaon coffcn.. Exprmnal Mhod.. Sampl prparaon Two mxurs of paraffn wax and NaCl wr prpard o fabrca sof ssu quvaln marals and bon ssu quvaln maral. Th paraffn wax was mld a 6 o C. Thn, h NaCl was addd quckly no paraffn wax. Th mxurs wr hn pourd no fabrcad mould wh dmnson of 3 cm x 3 cm x.5 cm. Two dffrnc sampls wr prpard o rprsn sof ssu quvaln maral of hyrod and bon ssu quvaln maral of spnal cord. Boh sampls hav dffrnc rao of NaCl addd no paraffn wax... Masurmn of lnar anuaon coffcns of paraffn and NaCl composons Th lnar anuaon coffcns of sof-ssu quvaln and bon ssu quvaln sampls wr masurd for nrgs bwn 88 kv and.33 MV from xponnal anuaon law. Ths nrgy rang was chosn du o hs rang ar usd n mdcal magng, radohrapy and nuclar mdcn dparmn. Th masurmn was prformd usng a NaI (Tl) dcor for gamma spcromry. Th dcor was shldd wh a lad housng o rduc h scard radaon comng drcly from h sourc or from h background. Th anuaon masurmns wr masurd usng mulchannl analysr (MCA). Th sampls wr placd bwn dcor and radaon sourc. Th ral m whch s h oal m aks for a dcor o coun (mayb svral sconds longr han lv-m) was s for 6 sconds. Th phoopak, full wdh a half maxmum (FWHM) and n ara of phoopak wr masurd usng Masro sofwar. Th radoacv sourcs usd o gand dffrncs n gamma nrgs wr Am-4 (87.83KV), Na- (74.53KV), Cs-37 (66.66KV), Mn-54 (834.85KV) and Co- 6 (73.4 KV and 33.5 KV). Th lnar anuaon coffcns of boh sampls wr drmnd from h XCOM sofwar. XCOM sofwar s a wb daabas usd n calculang h phoon cross scons and oal anuaon coffcns for lmn, compound or mxur (Z ) a nrgs from kv o GV.

4 ISMP6 IOP Publshng IOP Conf. Srs: Journal of Physcs: Conf. Srs (7) 8 do :.88/ /85//8 Fgur. Th xprmnal s up of MCA and Na(Tl) dcor o masur mass anuaon coffcn of sampls.3. Comparson bwn masurd mass anuaon coffcns, XCOM sofwar and ICRU-44 rpor Two comparsons wr carrd ou n hs sudy o vrfy h sof-ssu and bon ssu quvaln marals. Th rlav prcnag dffrnc of mass anuaon coffcns of sof-ssu and bon ssu quvaln sampls bwn xprmnal valus and XCOM sofwar valus wr drmnd. Nx, h rlav prcnag dffrnc of mass anuaon coffcns bwn sampls and ICRU-44 wr valuad. Th sof ssu and bon ssu quvaln sampls wr compard wh ICRU-44 sof ssu and ICRU-44 bon ssu rspcvly for h nrgs of h radonucld usd..4. Calculang mass anuaon coffcn, ffcv aomc numbr and ffcv lcron dnsy of paraffn wax and NaCl composons. Drmnaon of mass anuaon coffcns of h sampls wr prformd a dffrnc nrgs basd on Equaon (). I Io xpm () whr I s unanuad phoon nnsy, I s anuad phoon nnsy, μm = μ/ρ (cm /g) s h mass anuaon coffcn and (g/cm ) s sampl mass hcknss (h mass pr un ara) For any chmcal compound or mxur of lmns, h oal mass anuaon coffcn μs gvn by mxur rul shown n Equaon (): m w whr w s h wgh fracon, (μ m) s h mass anuaon coffcn of h lmn. For a maral composd of mul lmns h fracon by wgh s gvn by Equaon (3): n A w n A whr A s h aomc wgh of h h lmn and n s h numbr of formula uns. From μm valus masurd, h oal aomc cross-scon (σ) for marals can b gnrad usng h followng rlaon shown n Equaon (4): mn (4) N whr N n A s aomc mass of marals and NA s h Avogadro s numbr. Toal lcronc cross-scon (σ) for h lmn s xprssd by h followng quaon (5): N A fn Z A m m Z whr f dnos h fraconal abundanc of h lmn wh rspc o h numbr of aoms such ha f+f+f3+f4+..f = Z s h aomc numbr of h lmn Th ffcv aomc numbr (Z ff) of h maral can b calculad usng quaon (6) ff () (3) (5) 3

5 ISMP6 IOP Publshng IOP Conf. Srs: Journal of Physcs: Conf. Srs (7) 8 do :.88/ /85//8 Z ff Th ffcv lcron numbr or lcron dnsy (Nff) (numbr of lcrons pr un mass) can b calculad usng h followng Equaon (7): N A m Nff Zff n N Th phoon man fr pah (λ) whch s h avrag dsanc bwn wo succssv nracons, s calculad by Equaon (8): xp x xp x dz xdx whr μ l s lnar anuaon coffcn and x s h absorbr hcknss. 3. Rsuls and dscusson Th rlav prcnag dffrnc bwn h mass anuaon coffcns of sof-ssu and bon ssu quvaln marals wr valuad bwn xprmnal valus and XCOM sofwar. Th rsuls ar prsnd n Tabl. For boh sampls, a nrgy 88 kv, h rlav prcnag dffrnc ar abov 5%. Th rsuls also shown blow 5% for nrgs bwn 66 kv and.3 MV for boh sampls. Thrfor, h us of sof ssu and bon ssu quvaln marals may b consdrd as a subsu maral for sof ssu and bon ssu for radohrapy and nuclar mdcn uss. Tabl. Absolu prcnag dffrnc of mass anuaon coffcns (cm /g) of sof ssu quvaln and bon ssu quvaln sampls E (KV ) ( cm g ) STE l E STE (%) ) (%) l ( E a ( cm g ) l ( E ) (%) ) (%) l ( E b Δl (Eɣ)sof ssu quvaln(%); Absolu prcnag dffrnc bwn mass anuaon coffcns of xprmnal and smulaon Δl (Eɣ)a (%); Absolu prcnag dffrnc bwn mass anuaon coffcns of XCOM valu and ICRU-44 Th rlav prcnag dffrnc of mass anuaon coffcn bwn masurd valus and ICRU-44 rpor was drmnd for h gamma nrgs of common radonucld usd. Dffrncs blow 5 % ar obsrvd n Tabl for sof ssu quvaln sampl. I shows ha sof ssu quvaln has a good rlaonshp n rspc o sof ssu ICRU-44, xcp n h gamma nrgy of 73 KV whch s 5.%. For bon ssu quvaln maral and ICRU-44, h dffrncs blow.5% wr oband of nrgs rang 66 KV and.3 MV and.5% for nrgy 88 kv. I s clar ha mass anuaon coffcn dpnds on phoon nrgy and chmcal conn. Th mass anuaon coffcn of a maral dcrass du o probably of absorpon rducs wh ncrasng ncdn (6) (7) (8) 4

6 ISMP6 IOP Publshng IOP Conf. Srs: Journal of Physcs: Conf. Srs (7) 8 do :.88/ /85//8 phoon nrgs whch rsuls n h ncras n h ransmsson of phoons hrough. Th oal xprmnal uncrany of mass anuaon coffcn valus dpnd on h uncrans of pak ara valuaon, mass hcknss masurmns, xprmnal sysm, counng sascs, and ffcncy rrors. Th ohr paramrs such as lnar anuaon coffcn (μ l), oal aomc cross-scon (σ ), lcronc cross-scon (σ ), ffcv aomc numbr (Z ff), lcron dnsy (N ff), man fr-pah (λ) wr calculad usng mass anuaon coffcn for boh sampls a dffrn phoon nrgs. Th rsuls wr dsplayd n Tabls and 3. Th phoon man fr pah (λ) for sof-ssu and bon ssu quvaln marals ncrass wh h phoon nrgy (Fgur ). Ths s du o dcras n h probably of nracon of phoons n h maral wh h ncras n nrgy. A low nrgs, oal aomc cross-scon (σ ) and lcronc cross-scon (σ ) dcrass whn nrgs ncrass (Fgurs 3 and 4). Howvr, only a low nrgs, σ and σ h dpndnc of phoon nrgy s domnan. Th Z ff and h N ff rman consan and ar found o b ndpndn of phoon nrgy for a compound xcp for nrgy 6 KV whch s slghly hghr. Boh ffcv aomc numbr and lcron dnsy hav clos rlaons o ach ohr and hus hav h sam qualav nrgy dpndnc. Th agrmn bwn h calculad valus from sm mprcal rlaons, XCOM and xprmnal rsuls s good. In a ral pracc, h unformy of NaCl n h paraffn wax wr vard as h mxur of hs wo lmns ar nhomognous, ha a chang n chmcal surroundngs and dsoron. Ths facor may affc h mass anuaon coffcn valu gand from xprmn. Howvr hs facors ar no consdrd whn h valus of mass anuaon coffcn wr compud by XCOM and mprcal rlaons. Hnc h xprmnal valus for h mass anuaon coffcns of sof ssu quvaln and bon ssu quvaln sampls dffr from h calculad valus. Ths dffrnc n valu bwn xprmnal and calculad (XCOM valu) mgh ars n h valus of μ m oband from xprmn and calculaon du o xprmnal s up and s counng ffcncy rrors. Tabl. μ l, μ m, σ, λ,σ, Z ff and N ff valus for sof ssu quvaln sampl a dffrnc gamma nrgs. Enrgy(KV) ɥ l (cm - ) ɥ m(cm /g) λ(cm) (x 3 ) barn/aoms (x 5 ) barn/aoms Z ff (lcrons) N ff (x 3 ) lcrons/z Tabl 3. μ l, μ m, σ, λ,σ, Z ff and N ff valus for bon ssu quvaln sampl a dffrnc gamma nrgs. Enrgy(KV) ɥ l (cm - ) ɥ m(cm /g) λ(cm) (x 3 ) barn/aoms (x 5 ) barn/aoms Z ff (lcrons) N ff (x 3 ) lcrons/z

7 Elcronc cross scon ( -5 ) barn/aom Toal aomc cross barn/aom Man fr-pah (cm) ISMP6 IOP Publshng IOP Conf. Srs: Journal of Physcs: Conf. Srs (7) 8 do :.88/ /85// Enrgy (Kv) Fgur. Man fr-pah agans phoon nrgy STE Enrgy (KV) STE Fgur 3. Elcronc cross scon agans phoon nrgy scon ( 3 ) Enrgy (KV) Fgur 4. Toal aomc cross scon agans phoon nrgy STE 4. Concluson Th abov xprmnal sudy wr carrd ou o drmn h mass anuaon coffcns and ohr rlad phoon nracon paramrs for sof ssu quvaln and bon ssu quvaln sampls. In h nracon of phoon wh mar, h μ m valus ar dpndn on h physcal and chmcal composon of h lmns n h sampl.th μ m valus of boh sampls dcras wh ncras n phoon nrgy. Boh sof ssu quvaln and bon ssu quvaln sampls hav mass anuaon coffcn valus clos o human ssu, wh prcnag dffrnc blow 5%. Th Ơ and Ơ dcrass as h phoon nrgy ncrass bu h nflunc domnan a low nrgs. I can b concludd ha h mass anuaon coffcns can b usd o gnra and drmn h Zff and Nff and ohr phoon nracon paramrs for sof ssu quvaln of hyrod and bon ssu quvaln of spnal cord. Th Z ff and N ff ar ndpndnc on phoon nrgy. Howvr, h Z ff and N ff calculad ar abov 5% of s prcnag dffrnc whn compar o Z ff and N ff human ssu. All phoon nracon paramrs of sof ssu quvaln and bon ssu quvaln oband n hs sudy wll nhanc h undrsandng on how h mass anuaon coffcns chang wh varaon of h aomc and lcronc numbr for dffrnc amoun of NaCl addd no paraffn wax. Ths sudy also amd o sablsh sof ssu quvaln and bon ssu quvaln as ssu quvaln marals for phanom fabrcaon. 5. Rfrnc [] SM Nadr, S Sna, M Karmpoorfard, F Lofalzadh, M Enzarmahd, H Morad and R Faghh. 5. Radaon Procon Dosmry,pp. 6. [] H Hasanzadh, A Abdlah.. Journal pf Pramdcal Scncs (4):

8 ISMP6 IOP Publshng IOP Conf. Srs: Journal of Physcs: Conf. Srs (7) 8 do :.88/ /85//8 [3] Wh, D. R Radaon Procon Dosmry 49 (/3), [4] Crqura, R. A. D. and Maa, A. F. 4. Rada. Phys. Chm 95, [5] L.S. Dl Lama, L.D.H. Soars al. 4. Nuclar Insrumns and Mhods n Physcs Rsarch 784 (5) [6] A.S. Madhusudhan Rao, A Gachw. 5. Inrnaonal Journal of Advanc Rsarch In Scnc And Engnrng 4(), [7] Sngh, N., Sngh, K.J., Sngh, K. and Sngh, H., 6. Rada. Mas. 4, pp [8] Inrnaonal Commsson on Radaon Uns and Masurmns ICRU. 99. ICRU Rpor 48, 96. [9] M Kurudrk. 4. Appld Radaon and Isoops 94 (4), -7. [] H Yücl, E Güllüoğlu, Ş Çubukçu and Yğ Al Ü. 6. Journal of Physcal Scnc, 7 (), 8 [] Chaudhar L. M and Raj D. V. 3. Journal of Chmcal, Bologcal and Physcal Scncs 3 () 54-5 [] A. Hrmoslla, G. Dı az London o, M. Garcı a, F.Ruı z, P. Andrad and A. P rz. 4. Radaon Procon Dosmry 6 (4), [3] Parsa Akhlagh, Hashm Mr Hakmabad, Lalh Rafa Moavall. 5. Radaon Physcs and Chmsry (5), [4] C C Frrra, R E Xmns, C A B Garca, J W Vra, A F Maa.. Journal of Physcs: Confrnc Srs 49 () 9 Acknowldgmns Th auhors would lk o acknowldg h fnancal suppor from Mnsry of Hghr Educaon hrough Fundamnal Rsarch Gran Schm (FRGS). 7