s tudy w as carrie d out as part of a com pre h e ns ive proje ct to e s tablis h DRLs for radiological e ..... inh e re nt variations in patie nt radiation dos e value s.
ORIGINAL ARTICLE
DIAGNOSTIC REFERENCE LEVELS (DRLs) FOR CONTRAST RADIOGRAPHY EXAMINATIONS IN NORTH EASTERN NIGERIA Joseph Dlama Zira,1 Christian Chukwuemeka Nzotta,2 Joseph Dimas Skam3 De partm e ntofRadiol ogy, Abubak ar Tafaw a Bal e w a Unive rs ity Te ach ing H os pital , Bauch i, Bauch i State , Nige ria. De partm e ntofRadiograph y and Radiol ogicalScie nce s , Facul ty ofH e al th Scie nce and Te ch nol ogy, Nnam di Az ik iw e Unive rs ity Nne w i Cam pus . 3 De partm e ntofRadiol ogy, Fe de ralM e dicalCe nte r K ats ina, Kats ina State , Nige ria. 1 2
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ABSTRACT BACK GRO UND: Diagnos tic re fe re nce l e ve l s (DRLs ) is an e s s e ntialoptim iz ation toolin radiation m e dicine . Th is s tudy w as carrie d outas partofa com pre h e ns ive proje ctto e s tabl is h DRLs for radiol ogicale xam inations for th e firs t tim e in North Eas te rn Nige ria. O BJECTIVE O F TH E STUDY: To e s tabl is h DRL for contras t radiograph y e xam inations in north e as te rn Nige ria and to com pare it w ith oth e r e s tabl is h e d w ork . M ETH O DO LO GY : Th is s tudy is a pros pe ctive cros s - s e ctionals tudy conducte d in tw o unive rs ity te ach ing h os pital s in north e as te rn Nige ria. Th re e h undre d and Sixty (360) patie nts w e re re cruite d for th e s tudy. Th e rm ol um inis ce ntdos im e te r (TLD) ch ips w e re e xpos e d for e ach e xam ination w h il e Dos e are a product (DAP) m e te r w as us e d in fl uoros copy e xam ination. TLD re adings (e ntrance s k in dos e ) w e re obtaine d atth e Ce ntre for Ene rgy Re s e arch and Training Z aria, K aduna s tate , Nige ria. Stude nt T-te s t w as us e d to de te rm ine th e re l ations h ip be tw e e n th e m e an ESD obtaine d in th e tw o ce nte rs and Pe ars on’s corre l ation w as us e d to de te rm ine th e re l ations h ip be tw e e n th e dos e and anth ropote ch nicalparam e te rs . Statis ticals ignificance w as s e t at P0.05. CO NCLUSIO N: DRLs in th is w ork re corde d l ow e r val ue s com pare d to inte rnationale s tabl is h e d w ork . H ow e ve r, re gul ar dos e optim iz ation te ch niq ue and e tiq ue tte are re q uire d to e ns ure good practice in North Eas te rn Nige ria.
Introduction Diagnos tic re fe re nce l e ve l(DRL) is de fine d as an inve s tigation l e ve lus e d to ide ntify unus ual l y h igh radiation dos e s for radiol ogicale xam inations .1,2 Th e y are s ugge s te d action l e ve l s above w h ich a facil ity s h oul d re vie w its m e th ods and de te rm ine ifacce ptabl e im age q ual ity can be ach ie ve d atl ow e r dos e s .3 DRLs is an optim iz ation toolto e ns ure patie nts are ade -
q uate l y prote cte d and itis de e m e d to be an im portant m e ch anis m for th e m anage m e nt of patie nt dos e to e ns ure itis com m e ns urate w ith th e m e dicalpurpos e of x-ray e xam ination. 4 In th e re com m e ndation of inte rnationalcom m is s ion of Radiol ogicalprote ction (Re port 103), th e principl e for s e tting DRLs are e num e rate d, th e l ocal , re gionaland nationalobje ctive s is cl e arl y de fine d, incl uding th e de gre e of th e s pe cification of cl inicaland te ch nicalconditions for
Corre s ponde nce : Dr. Jos e ph Dl am a Z ira De partm e ntofRadiol ogy, Abubak ar Tafaw a Bal e w a Unive rs ity Te ach ing H os pital , Bauch i, Bauch i State , Nige ria. Em ail : jos e ph dl am a@ gm ail .com Subm itte d 2 Augus t2017, Acce pte d 21 Se pte m be r 2017
PA K I S TA N J OU R N A L O F R A D IO L O GY
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m e dicalim aging tas k , th e s e l e cte d val ue ofth e DRL is bas e d on th e re l e vantre gional , nationaland l ocal data, th e q uantity us e d for th e DRLs can be obtaine d e ve l s in practicalw ay.5,6,7 Th e conce ptofinve s tigation l for diagnos tic m e dicale xpos ure s w as firs tpropos e d by th e Inte rnationalCom m is s ion of Radiol ogical prote ction (ICRP) in its 19 9 0 re com m e ndations , and furth e r de ve l ope d into diagnos tic re fe re nce l e ve l s (DRL) in 19 9 6 in ICRP publ ication 73.8 Th e num e rical val ue s of diagnos tic re fe re nce l e ve l s are advis ory h ow e ve r;im pl e m e ntation ofth e DRLs conce ptm ay be re q uire d by re gul atory and profe s s ionalbodie s .3,7 Diagnos tic re fe re nce l e ve l s (DRLs ) are optim iz ation tool s us e d as s pe cialtype ofdos e cons traints above w h ich dos e s m us tbe re vie w e d and cons ide re d above acce ptabl e l e ve l s , e s pe cial l y if acce ptabl e im age q ual ity can be ach ie ve d atl ow e r dos e s .9 O ptim iz ing th e prote ction ofpatie nts , and m aintaining appropriate good practice is a priority for al ldiagnos tic radiol ogical e xam inations .9 M any s tudie s carrie d outto m e as ure e ntrance s urface dos e (ESD) in diffe re nt countrie s and th e ir re s ul ts w e re com pare d w ith dos e l e ve l s re com m e nde d by re l e vant organiz ations . Al s o, organiz ations s uch as th e NationalRadiol ogical Prote ction Board (NRPB) and Inte rnationalAtom ic Ene rgy Age ncy (IAEA) re com m e nde d th e us e ofdos e cons traints or inve s tigation l e ve l s to provide guidance 10 for m e dicale xpos ure s . In th e Unite d State s , Gre e ce , Braz iland Bangl ade s h , inve s tigations s h ow e d th at patie nts dos e from com m on x-ray e xam inations w e re be l ow th e re fe re nce l e ve l s s e t by Inte rnational Com m is s ion on Radiol ogicalProte ction.11 In contras t, in Ch ina and Tanz ania re s e arch e rs re porte d th atth e ave rage ESDs w e re com parative l y h igh for x-ray 12 e xam inations . Contras t radiograph y e xam ination is a s pe cial radiograph ic inve s tigation th at e m pl oys th e us e of contras tm e dia to outl ine ce rtain anatom icals tructure s in th e body. Th e s e s tudy incl ude s h ys te ros al pingograph y (H SG) for th e ute rus and fal l opian tube s , intrave nous Urograph y (IVU) for k idne ys ure te r and bl adde r, re trograte ure th rograph y (RUG) and m icturating ure th rogram (M CUG) for th e ure th ra, barium m e alfor th e s tom ach , barium s w al l ow for th e oe s oph agus , barium e ne m a for th e bow e l s , ve nograph y for th e ve ins m os tl yl ow e r l im bs , fis tul ogram for an ope ning conne cting s tructure s (fis tul a) and ge nitogram to ch e ck for re productive organs .
PA K I S TA N J O U R N A L OF R A D I O LO GY
Diagnos tic re fe re nce l e ve l s are us ual l y e s tabl is h e d ity control(QC) is al ong w ith im age q ual ity. 14 Qual norm al l y partofth e QA program and k e y in e ns uring th e accuracy ofdata obtaine d in DRLs inve s tigations . QC te ch niq ue s are th os e te ch niq ue s us e d in th e m onitoring (or te s ting) and m ainte nance ofth e te ch nicale l e m e nts or com pone nts of an x-ray s ys te m . Th e q ual ity controlte ch niq ue s th us are conce rne d dire ctl y w ith th e e q uipm e ntth atcan affe ctth e q ual ity ofth e im age .12 An X-ray s ys te m re fe rs to an as s e m bl age ofcom pone nts for th e control l e d production of diagnos tic im age s w ith x-rays . It incl ude s m inim al l y an x-ray h igh vol tage ge ne rator, an x- ray control de vice , a tube -h ous ing as s e m bl y, a be am -l im iting de vice and th e ne ce s s ary s upporting s tructure s .10,13 Oth e r com pone nts th atfunction w ith th e s ys te m , s uch as im age re ce ptors , im age proce s s ors , autom atic e xpos ure controlde vice s , vie w ing boxe s and dark room s , are al s o parts of th e s ys te m . Th e m ain goal of a QC program is to e ns ure th e accuracy of th e diagnos is or th e inte rve ntion (optim iz ing th e outcom e ) w h il e m inim iz ing th e radiation dos e to ach ie ve th at obje ctive .10,14 Incre as ing conce rns ove r radiation dos e s re ce ive d by patie nts and th e as s ociate d radiation ris k s h ave be com e a m ajor is s ue in re ce ntye ars .13,14 Re ducing radiation dos e in radiol ogicale xam ination is ofutm os t im portance particul arl y in th e l igh tofcontinue d incre as e in th e num be r ofne w m odal itie s and e xam inations arge pe rform e d annual l y.14 In Nige ria, in s pite ofth e l num be r ofe xam inations carrie d outye arl y, th e dos e inform ation avail abl e is gros s l y inade q uate . In addition, th e re are no e vide nce of publ is h e d data indicating th e e s tabl is h m e nt of diagnos tic re fe re nce l e ve l s for 15,16 com m on radiograph ic e xam ination in Nige ria. Diagnos tic Re fe re nce Le ve l s (DRLs ), w h ich is th e re com m e nde d toolin ach ie ving optim iz ation ofdos e s , is ye tto be s e tor unavail abl e for radiol ogy e xam inations and proce dure s in Nige ria.17 Practice s are pre s e ntl y re fe re nce d to Unite d K ingdom radiol ogical practice s tandards , Europe an com m is s ion and Aus tral ian Radiation Prote ction and Nucl e ar Safe ty Age ncy. More s o, IPEM (2004) re com m e nds th ate ve ry country and or facil ity s h oul d h ave or s e tits DRLs , be caus e practice s and advance m e ntin te ch nol ogy varie s from one country to anoth e r and h e nce one country’s DRLs cannot be a good re pre s e ntation of anoth e r.16 Th e aim of th is s tudy w as to e s tabl is h DRL for contras t
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radiograph y e xam inations in north e as te rn Nige ria and to com pare itw ith oth e r e s tabl is h e d w ork .
M ate rial s and M e th ods M e th od Th e s tudy is pros pe ctive cros s s e ctionals tudy carrie d outin Radiol ogy de partm e nts oftw o Unive rs ity Te ach ing H os pital s l ocate d in North E as te rn part of Nige ria. Th re e h undre d and s ixty patie nts w e re re cruite d for th e s tudy. Th e data in th is s tudy w e re col l e cte d from O ctobe r 2015 to January 2016. Th e ce nte rs w e re ch os e n be caus e th e y m e tth e e l igibil ity crite ria for th e s tudy;h aving al lth e im aging m odal itie s for th e s tudy and Nige rian Nucl e ar Re gul atory Auth ority's Re q uire m e nt for Auth oriz ation and Practice (Lice ns ing) invol ving ioniz ing radiation. Th e e xpos e d TLDs w e re l abe l e d for prope r ide ntification and k e pt in bl ack nyl on aw ay from radiation. A dos e data capture w as drafte d, th e te m pl ate s ort for inform ation s uch as patie nts age , ge nde r, s e x, w e igh t, h e igh t, Body m as s inde x, focus to fil m dis tance and te ch nical param e te rs . Data w e re e nte re d by th e re s e arch e r as s is te d by tw o s e nior Radiograph e rs in e ach facil ity and th e n ch e ck e d by a m e dicalph ys icis t. Th e inform ation obtaine d for th e s tudy incl ude s : (i) Age , to m ak e s ure th at onl y adul t patie nts are re cruite d in th e s tudy. (ii) Ge nde r ofth e patie nts . (iii) Patie nts body re gion e xam ine d (iv) Te ch nicalParam e te rs s uch as tube pote ntial (k Vp), tube curre nt(m As ), s can l e ngth , Fie l d ofvie w , angl e ofrotation, focus to fil m dis tance , ante rior pos te rior th ick ne s s and fl uoros copy tim e for e ach e xam ination and proce dure w h e re appl icabl e. (v) W e igh t (k g), h e igh t (m 2) and body m as s inde x BM I (k g/m 2) Proce dure Dos im e tric M e as ure m e nts Th e rm ol um inis ce ntdos im e te rs and Dos e Are a Product m e te rs w e re us e d for dos e m e as ure m e nt for conve ntionalx-ray, de ntalx-ray, and m am m ograph y and fl uoros copy e xam inations . Th e TLD s w e re anne al e d and re ad at Ce nte r for Ene rgy Re s e arch and Training Z aria, K aduna S tate , Nige ria afte r e xpos ure . Th e TLDs w e re anne al e d be fore tak ing th e
PA K I S TA N J O U R N A L OF R A D I O LO GY
m e as ure m e nts . Th e anne al ing w as done at a h igh te m pe rature of 9 8 de gre e ce ntigrade ;th is proce s s e s s e ntial l y z e roe d th e Th e rm o l um ine s ce ntm ate rial by re l e as ing al ltrappe d e l e ctrons be fore th e TLD is us e d. Aboutte n pe rce nt(10% ) ofth e TLD ch ips us e d w e re s e t as ide as control s in th e various ce nte rs to hel p re cord back ground radiation. Th e controlTLD ch ips are k e pt in a bl ack nyl on aw ay from e xpos ure to irradiation (both prim ary and s e condary be am ). Re adings w e re tak e n dire ctl y from th e DAP m e te rs be caus e itis an ins tantdos im e te r. Afte r col l e ction of th e TLD and DAP re adings , th e col l e ctive val ue s w e re re corde d for e ach e xam ination. Th e m e an and th ird e ) val ue s w e re obtaine d from q uartil e (75th pe rce ntil th e totalre ce ive d. M ate rial s a. Conve ntionalx-ray m ach ine : Th e m ach ine us e d w e re products ofVariant m e dicals ys te m m anufacture d in Ch ina and Unite d s tate s for h os pitalA and B re s pe ctive l y both m anufacture d 2009 . M axim um and m inim um k Vp and m As for th e m ach ine s are 40-150 and 0.5-630 for h os pitalA and 40-200 and 0.5-400 for h os pitalB re s pe ctive l y and inh e re ntfil tration of1.5 m m ALand 0.8 m m AL for h os pitalA and B re s pe ctive l y. b. Fl uoros copy m ach ine : Th e e q uipm e ntis an ove r couch type m anufacture d by Ph il ips in Fe bruary 2010. Th e inh e re ntfil te r is 2.5 m m Alw ith k Vp and m As range of 40-150 and 0.5-850. Fl uoros copy m ach ine us e d w as for h os pitalA. H os pitalB h as no fl uoros copy m ach ine . c. Th e rm ol um ine s ce ntdos im e te rs (TLD): TLD-ch ips 100 Dos im e te rs (cal ibrate d) anne al e d. Th e y are round, s m al l , w h ite in col our and ve ry s e ns itive . Th e y are e ncl os e d in a bl ack l e ath e r and l abe l e d. Th e Th e rm ol um inis ce nt dos im e te r ch ips w e re obtaine d from a re gis te re d Radiation Safe ty Advis e r (RSA), Nige rian Nucl e ar re gul atory Auth ority (NNRA), Abuja, Nige ria. d. Dos e Are a Product (DAP) m e te rs (cal ibrate d): Dos e -are a productm e te r is re l ative l y e as y to m e as ure radiation dos e . DAP m e te rs m e as ure th e radiation dos e to air, tim e s th e are a of th e x-ray fie l d. DAP is e xpre s s e d in gray-cm 2 (Gy-cm 2). Th e
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re ading from a DAP m e te r can be ch ange d by al te ring th e x-ray te ch niq ue factors (k Vp, m A, or tim e ), varying th e are a ofth e fie l d, or both . If th e ch am be r are a is l arge r th an th atofth e col l im ators , as th e col l im ators are ope ne d or cl os e d th e ch arge col l e cte d w il lal s o incre as e or de cre as e in proportion to th e are a ofth e fie l d.
Re s ul ts Examination Mean ESD Mean ESD Mean ESD (mGy) (mGy) (mGy) Hospital A Hospital B Both
DAP (mGy. cm2)
DRL mGy
mGy.cm2
IVU
2.17±1.94 4.61±4.58 3.39±3.26 9.25±1.31
6.68
10.66
HSG
1.41±0.66 2.30±1.45 1.85±1.05 2.97±0.55
2.31
3.67
Barium meal
1.66±0.44 2.61±1.31 2.14±0.88 7.33±1.85
2.66
8.98
Barium enema 10.63±1.05 2.62±1.31 6.63±1.18 16.26±3.23
12.78
20.64
Barium swallow 1.62±0.35 2.62±1.45 2.12±0.90 7.62±2.01
2.73
6.56
Data Anal ys is
RUG
2.05
7.55
Data w as obtaine d and s ave d on a com pute r Micros oft
Ke y: IVU- Intrave nous urograph y, H SG- H ys te ros al pingograph y, RUG- Re trograte -ure th rograph y, ESD- Entrance s k in dos e , DAPDos e are a product
e xce ls pre ad s h e e t and cate goriz e d for e ach e xam ination and im aging m odal ity re s pe ctive l y. It w as inde pe nde ntl y ch e ck e d by a s tatis tician and tw o s e nior
1.18±0.65 1.82±1.19 1.50±0.92 5.91±1.24
Tabl e 1: Me an dos e s re ce ive d and 75 pe rce ntil e (DRLs ) for contras tradiograph ic e xam ination
radiograph e rs . Statis ticalPack age for SocialScie nce s ve rs ion 21.0 w as us e d to anal yz e th e m e an and s tandard de viation of th e anth ropom e tric variabl e s,
Examination
te ch nicalparam e te rs and radiation dos e re ce ive d. Se ve nty fifth (75th ) pe rce ntil e or (3rd q uartil e ) val ue
IVU
of th e totalm e an of th e e xam inations and or proce dure s w e re obtaine d at9 5% confide nce inte rval . Us ing Kol m ogorov - Sm irnov to te s tfor norm al ity of
HSG
data dis tribution itw as ve rifie d th at, for 9 5% ofconfide nce l e ve l , th e re w as a norm aldis tribution. Th e re -
FSD
ESD Vs Technical Parameters R-value p-value 0.534 0.002
Technical Parameters
DAP Vs Technical Parameters 0.077
0.686
kVp
-0.317
0.088
-0.209
0.268
mAs
-0.067
0.726
-0.469**
0.009
FSD
0.171
0.367
-0.096
0.613
kVp
0.250
0.183
-0.071
0.708
mAs
0.012
0.949
-0.132
0.488
0.671
0.000
FSD
-0.235
0.211
fore , w e us e d a param e tric te s tth atw as s uitabl e for
kVp
-0.153
0.420
0.485
0.007
th e s e t of data and anal ys is . Pe ars on’s corre l ation
mAs
0.213
0.259
-0.010
0.956
FSD
0.386
0.035
0.390*
0.033
radiation dos e and w e igh t at s tatis ticals ignificance
kVp
-0.086
0.650
-0.199
0.292
ofp0.05
0.383
p>0.05
2.110
ESD
3.17±1.02
6.61±2.00
p>0.05
2.654
DAP
9.25±0.00
10.26±2.00
p>0.05
0.875
Examination
ARPANSA DRL mGy DAP
EC, DRL
UK, DRL
DRL This work mGy DAP
mGy
DAP
mGy
DAP
IVU
--
16
--
14
10
14
6.68
10.66
HSG
--
4
--
2
2
4
2.31
3.67
Barium meal
--
13
--
12
5.0
12
2.66
8.98
Barium enema
--
31
--
23
15
21
12.78
20.64
KVp
66.90±5.00 76.63±4.00
p>0.05
2.632
mAs
25.67±10.00 40.80±10.00
p>0.05
1.853
Barium swallow
--
11
--
3.4
4
7.5
2.73
6.56
--
13
--
7
15
7
2.05
7.77
ESD
1.41±0.91
2.30±0.88
p>0.05
1.207
RUG
DAP
2.97±0.00
3.44±0.40
p>0.05
2.035
KVp
74.67±3.00 79.33±10.00
p>0.05
0.773
mAs
34.83±10.00 39.60±10.00
p>0.05
0.584
Fl uoros copy tim e is be tw e e n 2 - 15 s e conds w ith m e an tim e of 8.12±1.03 m inute s . DAP - dos e are a productin m Gy.cm 2. ECEurope an com m is s ion, UK - Unite d Kingdom , ARPANSA-Aus tral ian radiation prote ction and nucl e ar s afe ty age ncy
ESD
1.18±1.00
1.82±0.80
p>0.05
0.866
DAP
5.91±0.00
7.14±1.00
p>0.05
2.130
KVp
78.50±10.00 86.00±2.00
p>0.05
1.274
mAs
32.00±10.00 29.67±10.00
p>0.05
0.285
ESD
10.63±4.00 2.62±0.00*
P0.05
2.390
KVp
66.97±6.00 86.00±2.50*
P0.05
0.643
ESD
0.34±0.20
0.55±0.20
p>0.05
1.286
DAP
7.33±0.00
7.90±1.00
p>0.05
0.987
**. Corre l ation is s ignificantatth e 0.01 l e ve l(2-tail e d), *. Corre l ation is s ignificantatth e 0.05 l e ve l(2-tail e d). IVU- Intrave nous urograph y, H SG- H ys te ros al pingograph y, RUGRe trograte ure th rograph y, ESD- Entrance s k in dos e , DAP-Dos e are a product, k Vp- k il o vol tpe ak , m As - m il l i am pe re s e conds . Tabl e 3: Com paris on ofpatie nt’s m e an radiation dos e and te ch nical param e te rs for contras t radiograph ic e xam ination for h os pitalA and H os pitalB
Dis cus s ion Th e s tudy e s tabl is h e d diagnos tic re fe re nce l e ve l s for contras t radiograph ic e xam ination in tw o s e l e cte d unive rs ity te ach ing h os pital s in North e as te rn Nige ria. Th e h os pital s s tudie d w e re divide d into tw o A and B re s pe ctive l y. Th e re are th re e unive rs ity te ach ing h os pital s in North Eas te rn Nige ria as at th e tim e of th e s tudy. H ow e ve r, h os pital s A and B w e re ch os e n be caus e th e y m e tth e incl us ion crite ria for th e s tudy h aving th e ne ce s s ary functionalim aging facil ity. A
PAK I S TA N J O U R N A L OF R A D I O LO GY
Tabl e 4: Com paris on ofDRLs for contras tradiograph ic e xam ination in th is w ork w ith Europe an Com m is s ion, Unite d K ingdom and Aus tral ian radiation prote ction and nucl e ar s afe ty age ncy DRLs .
totalofth re e h undre d and s ixty (360) patie nts w e re cons ide re d in th is s tudy. Itis re com m e nde d th atth e e ntrance s k in dos e m e as ure m e nts be m ade on s tatis tical l y s ignificants am pl e ofpatie nts (m inim um 10) w h os e w e igh ts are ne ar th e s tandard adul tpatie nts of ave rage w e igh t 70±10 k g as a m ajor s te p to e s tabl is h s tandardiz e d patie nts for our popul ation.8,18,19 Th is s tudy com pl ie d w ith th e re com m e ndations and th e re fore th e e s tim ate of ESDs for th e various e xam inations coul d be cons ide re d s ufficie ntl y as a re pre s e ntative val ue for s pe cific protocol s and e xam ination. Th is corroborate s w ith oth e r s tudie s by ARPANSA, UK , EC and IPEM , 2005.8 Th e m ain factors affe cting patie nt’s dos e in contras t radiograph ic e xam ination are e xpos ure factors , fil tration, and s ource to s k in dis tance , col l im ation path ol ogy and patie nt s iz e . M inor variations w e re obs e rve d am ong patie nt’s popul ations in te rm s ofage w e igh t h e igh t, BMIand th ick ne s s . Th e e s tabl is h e d diagnos tic re fe re nce l e ve l s for intrave nous urograph y, h ys te ros al pingograph y, barium m e al , barium e ne m a, barium s w al l ow and re trograde ure th rograph y are 6.68 m Gy and 10.66 m Gy.cm 2, 2.31m Gy and 3.67 Gy.cm 2, 2.66 m Gy and 8.9 8 Gy.cm 2, 12.78 m Gy and 20.64 Gy.cm 2, 2.73 m Gy and 6.56 Gy.cm 2, 2.05 m Gy and 7.55 Gy.cm 2 re s pe ctive l y. Th e re w e re variations in th e m e an dos e s as note d in (Tab. 2), th e variations in th e data re corde d de m ons trate th e im portance ofcre ating aw are ne s s by th e radiograph ic s taff on q ual ity as s urance and s tandardiz ation ofprotocol s to e ns ure s atis factory y s tandards and optim iz e d radiation dos e to patie nts and s taff, th is concurs w ith anoth e r s tudy.4,15 Th e variations e ncounte re d m igh th ave aris e n
PJR January - March 2018; 28(1)
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from th e diffe re nce s in s am pl e s iz e s as w e l las th e inh e re nt variations in patie nt radiation dos e val ue s for diffe re nt type s of e xam ination. Th e variations in patie nt dos e are re l e vant in th e proce s s of dos e 8 optim iz ation. Th e inh e re nt variations in dos e s am ong th e inve s tigate d popul ation are e xpe cte d to be tak e n into cons ide ration w h il e s e tting up th e tol e rance and l im iting val ue s to actas trigge r l e ve l s and guidance m e ch anis m for e s tabl is h ing DRL publ is h e d by Ins titute of Ph ys ics and Engine e ring in M e dicine .16 Re s ul t from IVU e xam ination in (Tab. 2) s h ow s th at th e re w as s tatis ticals ignificantre l ations h ip (p0.05) w ith ESD. During H SG e xam ination th e re w as s tatis ticals ignificantre l ations h ip (p0.05). Th e re w as s tatis ticals ignificantre l ations h ip (p
