breast conservation surgery ( bcs ) followed by whole breast irradiation has become the standard of care for early breast carcinoma [ 14 ] .
however , the duration of treatment remains between 5 to 6 and a half weeks .
the need for whole breast irradiation has been questioned and several centres have evaluated the feasibility and efficacy of accelerated partial - breast irradiation ( apbi ) [ 57 ] . accelerated partial - breast irradiation represents a technique that allows for the delivery of adjuvant therapy after bcs in 1 week or less with multiple techniques being available at this time .
to date , at least seven phase iii trials comparing different techniques of apbi to conventional wbi have been initiated [ 812 ] .
.   demonstrated excellent long - term local tumour control , survival , and cosmetic results with a low - rate of long - term toxicity in a 12 year prospective study using multicatheter interstitial brachytherapy .
currently , the american brachytherapy society recommends proper patient selection for apbi and the current guidelines are for apbi in age ( > 50 years old ) , tumor size ( < 3 cm ) , histology ( all invasive subtypes and ductal carcinoma in situ ) , surgical margins ( negative ) , lymphovascular space invasion not present , and negative nodal status .
the ability to consistently and reproducibly localize and fully irradiate the tumor site is very important in radiation therapy .
patient immobilization has many aspects , ranging from limiting movement of the patient 's body to specific tissue immobilization devices .
the kuske breast applicator ( nucletron , an elekta company , elekta ab , stockholm , sweden ) is currently widely used in multicatheter interstitial brachytherapy as an immobilization device .
it is an adjustable template with integrated guiding plates that are used to compress the breast and guide placement of brachytherapy needles .
another technique that has been used in multicatheter interstitial brachytherapy is the ultrasound guided free hand method , in which ultrasound guided visualisation of the cavity is used to guide catheter insertion into the cavity with needle placement being marked on the skin prior to the insertion . while both techniques have their advantages and remain popular at different centres , there is no published data that compares the two techniques . in this study , we look at both techniques comparing the insertion time , planning time , and the dosimetric outcomes .
between august 2008 and march 2010 , 20 consecutive patients treated with apbi with multicatheter hdr interstitial brachytherapy were included in the study .
all patients underwent lumpectomy and axillary nodal evaluation either by sentinel node biopsy or axillary clearance .
patients were selected as per the criteria of european society of radiotherapy and oncology ( estro ) apbi consensus guidelines , which included : 1 ) tumours of less than 3 cm in size ; 2 ) no lymph node involvement ; 3 ) negative surgical margins ; 4 ) no multicentric disease or extensive intraductal component ; 5 ) patients > 40 years of age with no prior history of cancer .
institutional ethics approval was obtained and informed consent was attained from each patient . within 8 weeks of lumpectomy and axillary nodal evaluation , patients underwent an interstitial implant using either an ultrasound guided free hand method ( non - template ) or a template method .
both methods were performed in the supine position . in the non - template method ,
the target volume was first mapped out on the skin surface with ultrasound visualisation of the lumpectomy cavity ( fig .
needles were placed using the paris system parallel to each other , ensuring adequate coverage of the cavity with generous use of a local anaesthetic mixture .
initially , a deep plane of needles was placed on the pectoralis major fascia with real - time ultrasound guidance .
this was followed by at least one superficial plane resulting in a multiplane implant for adequate geometric coverage of the target volume .
ultrasound localization of the target volume in the free hand technique in the template method , once the cavity was localized , the ipsilateral breast area was surgically prepared under sterile conditions . to avoid injury to the underlying chest wall structures or causing a pneumothorax ,
the overlying breast was pinched and gently lifted off the chest wall before applying the template and securing it .
3 - 5 anchoring needles were then placed in an asymmetric pattern usually involving c-12 .
c-12 was the grid coordinates of the template that corresponded to the center of the template .
the purpose of the asymmetric pattern is to aid easy orientation of the template in reference to the patient 's anatomy , as well as to secure and prevent slipping of the template from the breast ( fig .
these images were then reconstructed on the oncentra planning system ( nucletron , an elekta company , elekta ab , stockholm , sweden ) .
insertion of catheters with the use of a template the planning target volume ( ptv ) was formed by expanding 20 mm from the clinical target volume ( ctv ) , which was determined from the contrast enhanced tumor cavity and any surrounding surgical clips .
the ptv - eval was formed by excluding the 5 mm skin rind , as well as the underlying chest wall muscle layer .
the skin was also contoured on the sagittal slice depicting the largest breast contour ( usually the slice showing the nipple ) , and the most anterior chest wall surface was also contoured .
the images were then reoriented in oncentra to depict the  template view  to determine the location of the remaining catheters .
next , an overlying photocopy of the template on a transparency was placed on top of the screen and the  template view  template magnification was matched 1 : 1 to the overlaid template transparency ( fig .
the corresponding anchoring needle positions were then marked on the overlaid transparency and the chest wall , and ptv - eval contour were outlined onto the transparency . once done , the catheter placement for the remaining catheters was easily determined .
use of an overlaid transparency to mark the chest wall contour and the cavity in both procedures , the final step required replacing the needles with polyethylene tubing with a hemispheric button at each end .
extra attention was given to make sure that the button on the connector side of the remote afterloader was flush to the skin .
after each catheter was trimmed and numbered , an en face picture of the implant showing the catheter numbers with respect to the breast anatomy was obtained to aid in the reconstruction of the catheters .
ct - based simulation of the patient was performed with the patient in supine position and the images were then transferred to the oncentra ( nucletron , an elekta company , elekta ab , stockholm , sweden ) treatment planning system .
a total of 34 gy in 10 fractions , two fractions per day , 3.4 gy per fraction , separated by at least 6 hours , given on 5 treatment days was delivered via a ir remote afterloader in supine position .
target coverage was  90% of the prescribed dose covering  90% of the ptv - eval ( d90  90% ) .
care was taken to ensure that the skin dose did not exceed the prescription dose . in our study , the dose constraint for the skin was set as less than 100% of the prescribed dose . to assure appropriate dose homogeneity throughout the implant ,
two parameters were used : the volume of tissue receiving higher doses and a dose homogeneity index ( dhi ) .
the actual volume of tissue receiving 150% ( v150 ) and 200% ( v200 ) of the prescribed dose was limited to  70 cc and  20 cc , respectively .
the dhi , as represented by the volume ratio ( 1  v150/v100 ) , will be  0.75 .
( v150 represented the volume of tissue receiving 150% of the prescribed dose , and v100 represented the volume of tissue receiving the prescribed dose ) . the maximum skin dose ( msd ) and maximum chest wall dose ( mcd ) were also recorded for each patient . in addition , < 60% of the ipsilateral whole breast reference volume received  50% of the prescribed dose .
the online breast atlas from the rtog website was used to target the whole breast reference volume .
insertion time was defined as the time taken from start of patient 's clean and drape sterile prep to the time when the ct simulation images were acquired .
planning time was defined from the start of contour voluming to the time of plan approval .
the results were analysed statistically using the stata v11.0 ( statacorp usa ) . the two - sample wilcoxon rank sum ( mann whitney u test )
within 8 weeks of lumpectomy and axillary nodal evaluation , patients underwent an interstitial implant using either an ultrasound guided free hand method ( non - template ) or a template method .
both methods were performed in the supine position . in the non - template method ,
the target volume was first mapped out on the skin surface with ultrasound visualisation of the lumpectomy cavity ( fig .
needles were placed using the paris system parallel to each other , ensuring adequate coverage of the cavity with generous use of a local anaesthetic mixture .
initially , a deep plane of needles was placed on the pectoralis major fascia with real - time ultrasound guidance .
this was followed by at least one superficial plane resulting in a multiplane implant for adequate geometric coverage of the target volume .
ultrasound localization of the target volume in the free hand technique in the template method , once the cavity was localized , the ipsilateral breast area was surgically prepared under sterile conditions . to avoid injury to the underlying chest wall structures or causing a pneumothorax ,
the overlying breast was pinched and gently lifted off the chest wall before applying the template and securing it .
3 - 5 anchoring needles were then placed in an asymmetric pattern usually involving c-12 .
c-12 was the grid coordinates of the template that corresponded to the center of the template .
the purpose of the asymmetric pattern is to aid easy orientation of the template in reference to the patient 's anatomy , as well as to secure and prevent slipping of the template from the breast ( fig .
these images were then reconstructed on the oncentra planning system ( nucletron , an elekta company , elekta ab , stockholm , sweden ) .
the planning target volume ( ptv ) was formed by expanding 20 mm from the clinical target volume ( ctv ) , which was determined from the contrast enhanced tumor cavity and any surrounding surgical clips .
the ptv - eval was formed by excluding the 5 mm skin rind , as well as the underlying chest wall muscle layer .
the skin was also contoured on the sagittal slice depicting the largest breast contour ( usually the slice showing the nipple ) , and the most anterior chest wall surface was also contoured .
the images were then reoriented in oncentra to depict the  template view  to determine the location of the remaining catheters .
next , an overlying photocopy of the template on a transparency was placed on top of the screen and the  template view  template magnification was matched 1 : 1 to the overlaid template transparency ( fig .
were then marked on the overlaid transparency and the chest wall , and ptv - eval contour were outlined onto the transparency .
use of an overlaid transparency to mark the chest wall contour and the cavity in both procedures , the final step required replacing the needles with polyethylene tubing with a hemispheric button at each end .
extra attention was given to make sure that the button on the connector side of the remote afterloader was flush to the skin .
after each catheter was trimmed and numbered , an en face picture of the implant showing the catheter numbers with respect to the breast anatomy was obtained to aid in the reconstruction of the catheters .
ct - based simulation of the patient was performed with the patient in supine position and the images were then transferred to the oncentra ( nucletron , an elekta company , elekta ab , stockholm , sweden ) treatment planning system .
a total of 34 gy in 10 fractions , two fractions per day , 3.4 gy per fraction , separated by at least 6 hours , given on 5 treatment days was delivered via a ir remote afterloader in supine position .
target coverage was  90% of the prescribed dose covering  90% of the ptv - eval ( d90  90% ) .
care was taken to ensure that the skin dose did not exceed the prescription dose . in our study , the dose constraint for the skin was set as less than 100% of the prescribed dose . to assure appropriate dose homogeneity throughout the implant ,
two parameters were used : the volume of tissue receiving higher doses and a dose homogeneity index ( dhi ) .
the actual volume of tissue receiving 150% ( v150 ) and 200% ( v200 ) of the prescribed dose was limited to  70 cc and  20 cc , respectively .
the dhi , as represented by the volume ratio ( 1  v150/v100 ) , will be  0.75 .
( v150 represented the volume of tissue receiving 150% of the prescribed dose , and v100 represented the volume of tissue receiving the prescribed dose ) . the maximum skin dose ( msd ) and maximum chest wall dose ( mcd ) were also recorded for each patient . in addition , < 60% of the ipsilateral whole breast reference volume received  50% of the prescribed dose .
the online breast atlas from the rtog website was used to target the whole breast reference volume .
insertion time was defined as the time taken from start of patient 's clean and drape sterile prep to the time when the ct simulation images were acquired .
planning time was defined from the start of contour voluming to the time of plan approval .
the results were analysed statistically using the stata v11.0 ( statacorp usa ) . the two - sample wilcoxon rank sum ( mann whitney u test )
of the 20 patients in the study , 12 underwent the non - template method and 8 underwent insertion using the template method .
a median of 18 catheters was used per patient ( range 16 - 24 ) and median time to insertion was 2 weeks post surgery .
average breast volume was 846 cm ( range 526 - 1384 ) and the average ptv - eval volume was 256 cm ( range 182 - 416 ) .
there were 16 patients with t1 - 2 breast tumours and 4 patients with dcis treated in our study group .
the average breast size of our patients was 816.5 cc ( range 526.4 - 1384.7 ) .
we found that insertion time and planning time was significantly longer for the non - template method compared with the template method .
the difference was 60 minutes longer on average for insertion and 90 minutes longer for planning .
when we compared dosimetry from the plans , we found that the d95 was 3.13 gy ( 92% of the prescribed dose ) on average with the non - template method , which was significantly lower compared to 3.3 gy ( 97% of the prescribed dose on average ) with the template method ( p value < 0.01 ) .
other dosimetric parameters such as the v200 , msd and dhi were not significantly different between the two techniques . see table 1 . 
 
there were 16 patients with t1 - 2 breast tumours and 4 patients with dcis treated in our study group .
the average breast size of our patients was 816.5 cc ( range 526.4 - 1384.7 ) .
we found that insertion time and planning time was significantly longer for the non - template method compared with the template method .
the difference was 60 minutes longer on average for insertion and 90 minutes longer for planning .
when we compared dosimetry from the plans , we found that the d95 was 3.13 gy ( 92% of the prescribed dose ) on average with the non - template method , which was significantly lower compared to 3.3 gy ( 97% of the prescribed dose on average ) with the template method ( p value < 0.01 ) .
other dosimetric parameters such as the v200 , msd and dhi were not significantly different between the two techniques . see table 1 . 
 
our study shows that using the template had the advantages of saving both planning and insertion time , as well as a dosimetric benefit of superior dose coverage . individually , our results compared well with centres that specialized in either technique . for departments wishing to start multicatheter interstitial breast brachytherapy , we believe that the template approach offers superior dosimetric outcomes and shorter treatment procedure times compared to the non - template approach even in novice hands .
multicatheter interstitial brachytherapy has been gaining popularity as an adjuvant treatment in early breast cancer due to its short time of delivery , good outcomes , and excellent cosmesis [ 21 , 22 ] .
there are many techniques currently in use at different centres . despite this , there are no studies that compare the different techniques and look at the advantages of one technique over another .
while preference of technique is dependent on a large number of factors including staff training , tumour location , and patient breast size , our comparison shows significant gains of the template method in saving time and improving dosimetry . in our centre ,
our radiation oncologists were trained in both techniques giving flexibility in technique selection for each patient .
the current radiation therapy oncology group trial rtog 04 - 13 technical guidelines for interstitial brachytherapy are a target coverage of (  90% dose received by  90% target volume , v150 < 70 cm , v200 < 20 cm and dose homogeneity index  0.75 ) and skin dose volume histogram parameters ( maximum 100% of prescribed dose ) .
we compared the results of our non - template technique and our template technique with the results from the university of wisconsin   and tufts university , respectively .
comparison of our results with other institutions personal communication with dr patel as technique selection was not randomised in this study , there were some patients in whom the non - template technique was used because of small breast size or because the tumour cavity was located very medially or laterally .
apbi in the technically difficult patient is a field of further study and development that we are researching . in this study ,
only 16 patients were recruited as this is a pilot study comparing two different techniques .
subsequent studies into apbi should compare various techniques of catheter insertion and dose delivery , as well as planning techniques to decrease planning and insertion time .
current developments in other breast brachytherapy techniques include multilumen balloon catheters ( contura , senorx corp , usa ) , which do not require a template and may be suitable in certain patients . the apbi program in our centre
was introduced 5 years ago and since then we have treated over one hundred patients in the program using either technique , but predominately favouring the template approach .
we have no local recurrences or grade 3 toxicity in our patients and the cosmesis of this procedure at our centre remains excellent .
our experience shows that adequate training of staff , exposure , and use of various techniques in brachytherapy can allow diversity in a centre and allow comparisons between techniques .
as technique selection was not randomised in this study , there were some patients in whom the non - template technique was used because of small breast size or because the tumour cavity was located very medially or laterally .
apbi in the technically difficult patient is a field of further study and development that we are researching . in this study , only 16 patients were recruited as this is a pilot study comparing two different techniques .
subsequent studies into apbi should compare various techniques of catheter insertion and dose delivery , as well as planning techniques to decrease planning and insertion time .
current developments in other breast brachytherapy techniques include multilumen balloon catheters ( contura , senorx corp , usa ) , which do not require a template and may be suitable in certain patients . the apbi program in our centre
was introduced 5 years ago and since then we have treated over one hundred patients in the program using either technique , but predominately favouring the template approach .
we have no local recurrences or grade 3 toxicity in our patients and the cosmesis of this procedure at our centre remains excellent .
our experience shows that adequate training of staff , exposure , and use of various techniques in brachytherapy can allow diversity in a centre and allow comparisons between techniques .
compared to the non - template approach , the template approach offered significantly shorter insertion and planning times with improved dosimetric ptveval coverage without significantly compromising organs at risk .
this template approach should form the starting point for any department wishing to commence multicatheter interstitial breast brachytherapy .
 purposecurrently , there are two described methods of catheter insertion for women undergoing multicatheter interstitial accelerated partial breast irradiation ( apbi ) . 
 these are a volume based template approach ( template ) and a non - template ultrasound guidance freehand approach ( non - template ) . 
 we aim to compare dosimetric endpoints between the template and non - template approach.material and methodstwenty patients , who received adjuvant multicatheter interstitial apbi between august 2008 to march 2010 formed the study cohort . 
 dosimetric planning was based on the rtog 04 - 13 protocol . for standardization , 
 the planning target volume evaluation ( ptv - eval ) and organs at risk were contoured with the assistance of the attending surgeon . 
 dosimetric endpoints include d90 of the ptv - eval , dose homogeneity index ( dhi ) , v200 , maximum skin dose ( msd ) , and maximum chest wall dose ( mcd ) . 
 a median of 18 catheters was used per patient . 
 the dose prescribed was 34 gy in 10 fractions bid over 5 days.resultsthe average breast volume was 846 cm3 ( 526 - 1384 ) for the entire cohort and there was no difference between the two groups ( p = 0.6 ) . 
 insertion time was significantly longer for the non - template approach ( mean 150 minutes ) compared to the template approach ( mean : 90 minutes ) ( p = 0.02 ) . 
 the planning time was also significantly longer for the non - template approach ( mean : 240 minutes ) compared to the template approach ( mean : 150 minutes ) ( p < 0.01 ) . 
 the template approach yielded a higher d90 ( mean : 95% ) compared to the non - template approach ( mean : 92% ) ( p < 0.01 ) . 
 there were no differences in dhi ( p = 0.14 ) , v200 ( p = 0.21 ) , msd ( p = 0.7 ) , and mcd ( p = 0.8).conclusionscompared to the non - template approach , the template approach offered significant shorter insertion and planning times with significantly improved dosimetric ptv - eval coverage without significantly compromising organs at risk dosimetrically . 