Evaluation and clinical assessment of the hologic selenia

evaluation and CliniCal assessment 

of the hologiC selenia dimensions 

full field direCt digital 

mammography unit 

NHSBSP Equipment Report 1003 

October 2010

Authors 

South East London Breast Screening Service 

King’s College Hospital 

Breast Radiology Department 

Cheyne Wing 

King’s College Hospital, Denmark Hill 

London 

SE5 9RS 

Tel: 020 3299 1964 

Fax: 020 3299 1966 

Published by 

NHS Cancer Screening Programmes 

Fulwood House 

Old Fulwood Road 

Sheffield 

S10 3TH 

Tel: 0114 271 1060 

Fax: 0114 271 1089 

Email: info@cancerscreening.nhs.uk 

Website: www.cancerscreening.nhs.uk 

© NHS Cancer Screening Programmes 2010 

The contents of this document may be copied for use by staff working in the public sector but may not be copied for any 

other purpose without prior permission from NHS Cancer Screening Programmes. The report is available in PDF format on 

the NHS Cancer Screening Programmes website. 

Typeset by Prepress Projects Ltd, Perth (www.prepress-projects.co.uk) 

Printed by Duffield Printers

CONTENTS 

Hologic Selenia Dimensions Full Field Direct Digital Mammography Unit | iii 

AckNOwlEdgEmENtS v 

1. ExEcutivE SummARy 1 

2. iNtROductiON ANd BAckgROuNd 2 

3. OBjEctivES Of tHE EvAluAtiON 3 

4. SyStEm dEScRiPtiON 4 

4.1 Hologic Selenia dimensions 4 

4.2 Hologic Securview dx reporting workstation 6 

4.3 workflow configuration 6 

5. AccEPtANcE tEStiNg, cOmmiSSiONiNg ANd PERfORmANcE tEStiNg 7 

6. ROutiNE QuAlity cONtROl 8 

7. imAgE QuAlity ASSESSmENt 11 

8. dAtA ON ScREENiNg cONductEd 13 

8.1 clinical dose audit 13 

8.2 clinic organisation and throughput 13 

9. dAtA ON ASSESSmENtS cONductEd 14 

10. EQuiPmENt REliABility 15 

11. mAmmOgRAPHERS’ cOmmENtS ANd OBSERvAtiONS 16 

11.1 Operator’s manual 16 

11.2 training 16 

11.3 Ease of use 16 

11.4 Exposure times 16 

11.5 Setting radiographic views 17 

11.6 Setting the position of the breast support table 17 

11.7 Range of movements 17 

11.8 Effectiveness of brakes and locks 17 

11.9 compression 17 

11.10 comfort level for the women being screened 18 

11.11 Range of controls and indicators 18 

11.12 choice of collimators supplied for spot compression 18 

11.13 time elapsing before the image arrives at the acquisition workstation 18 

11.14 image handling and processing facilities at the acquisition workstation 18 

11.15 Overall image quality at the acquisition workstation 19 

11.16 Ease of image transfer to the reporting workstation and to the hard copy printer 19 

NHSBSP October 2010

iv | Hologic Selenia Dimensions Full Field Direct Digital Mammography Unit 

11.17 level of confidence in the dimensions unit 19 

11.18 Hazards 19 

11.19 Equipment cleaning 19 

11.20 Patient and exposure data and post exposure print out facility 19 

11.21 did the performance of the digital x-ray system limit patient throughput? 20 

11.22 Additional comments on performance 20 

11.23 magnification 20 

11.24 Stereo 20 

12. RAdiOlOgiStS’/film REAdERS’ cOmmENtS ANd OBSERvAtiONS 21 

13. iNfORmAtiON SyStEmS 24 

14. cONfidENtiAlity 26 

15. SEcuRity iSSuES 27 

16. cONcluSiONS ANd REcOmmENdAtiONS 28 

17. REfERENcES 29 

APPENdix: cliNicAl dOSE SuRvEy 30 

NHSBSP October 2010

Hologic Selenia Dimensions Full Field Direct Digital Mammography Unit | v 

ACKNOWLEDgEMENTS 

the valuable contributions to the project of the following colleagues are gratefully acknowledged 

• james clinch and colleagues (king’s Radiation Protection Services, department of medical 

Engineering and Physics, king’s college Hospital NHS foundation trust) 

• david lee, Bob martins and colleagues (Hologic, inc) 

• mammographers, breast radiologists, breast radiology/screening administration staff, and it 

staff of the South East london Breast Screening Programme (king’s college Hospital NHS 

foundation trust) 

• Sarah Sellars (Assistant director, Breast Screening Programme, NHS cancer Screening 

Programmes) 

• Professor ken young and dr jenny Oduko (National coordinating centre for Physics in 

mammography, department of medical Physics, Royal Surrey county Hospital). 

NHSBSP October 2010

vi | Hologic Selenia Dimensions Full Field Direct Digital Mammography Unit 

NHSBSP October 2010

Hologic Selenia Dimensions Full Field Direct Digital Mammography Unit | 1 

1. ExECUTivE SUMMARy 

the Hologic Selenia dimensions full field digital mammography unit was evaluated between late 

2009 and early 2010 to establish its suitability for use in the NHS Breast Screening Programme 

(NHSBSP). the evaluation included the Securview dx reporting workstation. 

the majority (90%) of observations in a subjective assessment of clinical image quality rated the 

dimensions images as ‘the same as’ or ‘better than’ those acquired using the standard local film– 

screen system. 

most (83%) of the users of the mammography unit and acquisition workstation found its ease of 

use either ‘good’ or ‘excellent’. Although two-thirds of users believed that the design of the unit 

did not compromise throughput, a number disliked the fact that they had to wait for an image to 

be displayed and select ‘accept’ on the control screen before positioning for the next acquisition. 

clinical radiation doses were reduced by approximately 29% on average when compared with 

the local film–screen system. Routine (radiographer) quality control measurements showed a high 

degree of system stability with results comfortably within NHSBSP thresholds. 

downtime during the screening evaluation period was 8.8% and some concern was expressed 

about the unit’s reliability. this could be explained partly by the fact that it was the first of its type 

to be installed in the uk and engineering support was initially supplied from Belgium. 

the Securview dx reporting station was well received by film readers, with all scoring its workflow 

as either ‘good’ or ‘excellent’. 

the system was successfully integrated with the department’s it and local PAcS (Picture Archiving 

communication Systems) infrastructure. 

the dimensions acquisition system could accommodate the NHSBSP’s requirement of six-minute 

appointment times and, like the Securview dx, was rated generally user-friendly. 

for these reasons, the overall conclusion of this evaluation and clinical assessment is that the 

Hologic Selenia dimensions and Securview dx are suitable for use in the NHSBSP. 

NHSBSP October 2010

2 | Hologic Selenia Dimensions Full Field Direct Digital Mammography Unit 

2. iNTRODUCTiON AND BACKgROUND 

the Hologic Selenia dimensions full field digital mammography system (hereafter ‘the dimensions’) 

was evaluated within the South East london Breast Screening Programme (‘the unit’) at king’s 

college Hospital NHS foundation trust. the evaluation was commissioned by the NHSBSP and 

undertaken in accordance with the relevant NHSBSP protocol. 1 the opportunity arose to undertake 

the NHSBSP evaluation after the system had been installed in the unit as part of a research project 

on digital breast tomosynthesis (dBt). the dimensions can be purchased in its primary form for 

standard mammography but can also be upgraded to perform dBt. Although the system under 

evaluation at the unit was enabled for dBt, and certain aspects of this functionality are touched on 

in the report, the evaluation relates only to the standard two-dimensional mammography function. 

the evaluation centre is an NHSBSP unit screening approximately 28 000 women per year before 

the cancer Reform Strategy’s age expansion. the centre meets the relevant national quality 

standards for breast screening and also the eligibility criteria for evaluation centres outlined in the 

NHSBSP protocol. 1 the majority of screening at the evaluation centre is undertaken either on mobile 

units or in a static screening unit separate from the base site. the base site is used primarily for 

assessment, and only a small amount of screening tends to be performed there. However, special 

arrangements were made, including well-attended Saturday sessions, to enable high-throughput 

screening on the system. 

the system was installed by Hologic, inc on a free loan basis for the duration of the evaluation. 

the company agreed to indemnify the equipment for the loan period. the company also provided 

technical support at its own expense. 

the project lead was the centre’s Head of Breast Radiography, initially Patsy whelehan, succeeded 

by vivien Phillips. the centre’s clinical lead and the director of Screening for the South East london 

Breast Screening Programme, dr michael michell, took responsibility for key clinical decisions. ms 

whelehan and dr michell had been members of the NHSBSP steering group for digital technologies 

during its two-year lifespan. there were three further members of the project team, all of them 

highly experienced breast screening radiographers: Sally duke, Rachel Baxter and lizzie Parkyn.* 

*throughout this document the term ‘radiographers’ refers to registered radiographers, while ‘mammographers’ includes 

both registered radiographers and assistant practitioners in mammography. 

NHSBSP October 2010


3. OBjECTivES OF THE EvALUATiON 

the overall aim of the evaluation was to assess the suitability of the dimensions for use in NHSBSP 

mammographic screening, using soft-copy reporting. individual objectives were as follows 

• to make a subjective assessment of clinical image quality by direct comparison with the standard 

local film–screen system, using 

− paired imaging of surgical breast specimens 

− comparison of dimensions images and prior film–screen images of women on annual followup 

mammography 

• to evaluate the impact of user interfaces on workflow, focusing on 

− the mammography unit and acquisition workstation 

− the reporting workstation (the Securview dx) 

• to evaluate the ability of the system to integrate with the department’s it and PAcS infrastructure 

• to assess whether the dimensions acquisition system could accommodate typical screening 

appointment times of six minutes 

• to evaluate the reliability of the system when used in the context of the NHS BSP. 

NHSBSP October 2010


4. SySTEM DESCRiPTiON 

4.1 Hologic Selenia Dimensions 

Figure 1 the Hologic Selenia dimensions acquisition workstation and gantry 

the mammography unit is powered by a 220/240 volt single phase supply and the generator is 

integrated into the gantry. the x-ray tube uses a tungsten target with two standard focal spots: 

large (0.3 mm) and small (0.1 mm). the filter assembly is equipped with rhodium and silver filters 

for two-dimensional imaging; an aluminium filter is available on the system for tomosynthesis. the 

source image distance is 70 cm. 

the amorphous selenium detector, manufactured by Hologic, utilises direct conversion technology. 

the image receptor housing contains a cellular air interspaced antiscatter grid, the high transmission 

cellular (Htc) grid. 

the standard compression paddles are made entirely of plastic and the 18 × 24 cm and 24 × 29 cm 

paddles can be operated using the fully Automatic Self Adjust tilt (fASt) mode. this mode is 

enabled and disabled by a simple mechanical switch. for imaging with the smaller paddle the 

shifting required for mediolateral oblique (mlO) imaging is motorised and the motorisation can be 

automatically controlled when the projection is selected. the paddles are recognised automatically 

when inserted into position. 

the system has the following automatic exposure control (AEc) modes: auto-filter, auto-kv, auto-time 

and manual. the positioning of the AEc cells is achieved automatically, with the system selecting 

the best compromise between the densest breast tissue and the average breast density, based on a 

pre-exposure sample shot. the automatic positioning of the AEc cells can be manually overridden 

by the operator. compression and height adjustment are governed by two foot switches. controls 

for compression, height adjustment and rotation are also available on both sides of the c-arm. 

NHSBSP October 2010


the operator console consists of an integrated colour touch screen display for workflow and 

administrative tasks. Operators can log in through fingerprint recognition or by password using the 

keyboard located in an integral sliding drawer. the console also features a trackball and a rotating 

wheel for scrolling, a barcode scanner for patient selection from the worklist and an integrated 

uninterruptible power supply (uPS). A 3 mP greyscale monitor is mounted on a swing arm for the 

display of images. the radiation protection screen is integrated into the console assembly. 

Geometric magnification 

dimensions includes a carbon fibre magnification platform that can be inserted in two different 

locations on the gantry to provide magnifications of 1.5 × and 1.8 ×. the system adapts focal spot 

selection, grid removal and exposure settings automatically when the magnification platform is 

inserted or removed. 

Accessories present in the evaluation centre 

• dual function foot switches (conventional, tomosynthesis) 

• face shield 

• magnification platform 

• compression paddles 

− 24 × 29 cm 

− 18 × 24 cm 

− small breast paddle 

− 10 cm contact paddle 

− 7.5 cm spot contact paddle 

− frameless spot paddle 

− 10 cm magnification paddle 

− 7.5 cm spot magnification paddle 

− 15 cm contact paddle 

− 15 cm magnification paddle 

Additional accessories available but not present for the evaluation 

• 10 cm open localisation paddle 

• 15 cm open localisation paddle 

• 10 cm perforated localisation paddle 

• 15 cm perforated localisation paddle 

Localisation kit 

An optional localisation kit is available for the system but was not installed until the end of the 

evaluation period. the kit consists of a 10 cm open localisation paddle (contact), a 10 cm open 

localisation paddle (magnification) and localisation crosshair assemblies (contact, magnification). 

Stereotactic add-on 

the dimensions system is biopsy-ready. the newly-designed biopsy device was not available at 

the time of the evaluation but is due for release in late 2010. 

NHSBSP October 2010


4.2 Hologic SecurView DX reporting workstation 

Figure 2 the Securview dx reporting workstation 

the Securview dx reporting workstation was installed, with two 5 mP lcd greyscale monitors and 

a dedicated mammography workflow keypad. A third, smaller, monitor connected to the Securview 

dx was used to display either the trust’s radiology information system (HSS cRiS † ) or National 

Breast Screening System (NBSS). the Securview dx was connected to the trust PAcS, enabling 

dicOm Query Retrieve functionality. 

4.3 Workflow configuration 

the evaluation centre has implemented a digital mammography workflow, which is based on the 

trust’s standard radiology workflow and uses the main trust PAcS. However the workflow for breast 

radiology differs from the trust standard in certain respects. for details and a workflow diagram 

see Section 13, information systems. 

† Healthcare Software Systems, Radman House, 3 Banbury Office village, Banbury, Oxfordshire Ox16 2SB. 

NHSBSP October 2010


5. ACCEPTANCE TESTiNg, COMMiSSiONiNg 

AND PERFORMANCE TESTiNg 

installation of the system took place over five days and was completed on schedule. this included 

integration with the trust PAcS. 

Acceptance and commissioning tests were administered from 20 to 24 October 2008 and conducted 

in accordance with NHSBSP guidance by the local physics service, king’s Radiation Protection 

Services. 2‡ in addition, the system was subjected to a thorough technical evaluation by staff from 

the National coordinating centre for the Physics of mammography (NccPm). § the clinical evaluation 

began only once this technical evaluation was concluded and a formal recommendation to 

proceed was received from the NccPm. 

After two days of applications training at the end of October 2008, the unit went into normal operation 

in week beginning 3 November 2008. it was initially used for symptomatic imaging and for 

tomosynthesis within an NHS Research Ethics committee approved research project. the specimen 

imaging required for the first stage of the NHSBSP evaluation was conducted during this period, 

after which assessment imaging was introduced. the primary screening phase of the evaluation 

began in late October 2009 and ran for approximately three months. 

‡ 

department of medical Engineering and Physics, king’s college Hospital NHS foundation trust, denmark Hill, london 

SE5 9RS. 

§ the Royal Surrey county Hospital NHS foundation trust, Egerton Road, guildford gu2 7xx. these findings will be 

published by the NHSBSP. 

NHSBSP October 2010


6. ROUTiNE QUALiTy CONTROL 

Routine quality control (Qc) was undertaken in accordance with the relevant NHSBSP guidelines 3 

and the results for the screening phase of the user evaluation. the mean weekly tORmAm score 

was 79. Other results are shown in figures 3–7. 

in accordance with the guidelines, the remedial levels are set at 20% above and below a baseline. 

this baseline is derived following commissioning, and updated after any significant service interventions, 

by performing a group of 10 successive tests and taking the mean results. 

Figure 3 daily signal-to-noise ratio (SNR) 

the second half of the daily 4 cm signal-to-noise ratio (SNR) graph should be seen as representative. 

this is because during the first half of the evaluation period there was frequent user error when the 

region of interest was placed on the image to enable the system to calculate the SNR. this illustrates 

the importance of effective digital Qc training and competency monitoring by departments. these 

errors were responsible for the erratic and generally lower SNR readings. By contrast, the second 

half of the graph shows a good degree of stability, with the SNR consistently within the permitted 

levels of variability. the graphs in figures 4–7 also show excellent stability. 

NHSBSP October 2010


Figure 4 weekly multi-thickness signal-to-noise ratio (SNR) 

Figure 5 weekly contrast-to-noise ratio (cNR) 

NHSBSP October 2010


Figure 6 weekly multi-thickness contrast-to-noise ratio (cNR) 

Figure 7 weekly detector uniformity 

NHSBSP October 2010


7. iMAgE QUALiTy ASSESSMENT 

image quality was monitored as part of the routine Qc regime, using the leeds tORmAm test 

object. the mean score was 79. 

clinical image quality was compared with the local film–screen system by undertaking paired imaging 

of surgical specimens or comparing pairs of sequential annual mammograms performed first on 

film–screen and then on the dimensions. Six radiologists/film readers each scored the 25 sets of 

paired images, producing a total of 150 observations. these included a range of mammographic 

features. the images generated by the dimensions system were scored ‘the same as’, ‘better than’ 

or ‘worse than’ the corresponding film–screen images. the results are set out in figure 8. they 

show that the image quality on the dimensions was classified as ‘the same as’ or ‘better than’ local 

film–screen in a large majority (90%) of observations. in two specimen cases, where three readers 

classified the digital image as worse than film, two observers in each case commented that the 

digital images appeared to have been incorrectly exposed. Only after this satisfactory subjective 

clinical comparison had been undertaken was the dimensions used for screening mammography. 

Figure 8 dimensions and local film–screen images: subjective image quality comparison 

in seven of the 25 cases, at least one observer commented that they had felt the need to adjust 

the contrast at the workstation or that the digital image had lower contrast than the film–screen 

image. this highlights the need for the radiologists and film readers in each department to reach a 

consensus during installation when selecting the baseline appearance of images. the dimensions 

has a tungsten target, which will tend to produce a relatively high energy beam with lower radiation 

doses and lower contrast than other commonly used target materials. However the dimensions also 

has a range of contrast settings that can be configured by the engineer. low contrast settings had 

been selected on the grounds that Hologic images were thought to tend towards particularly high 

NHSBSP October 2010


contrast. Notwithstanding observers’ comments on the need to adjust contrast, it was decided to 

retain these low settings. Although there is some empirical evidence that different manufac turers’ 

image processing algorithms can lead to variation in the visibility of microcalcifications on full field 

digital mammography (ffdm) systems, 4 evidence for the specific effect of contrast on clinical 

performance is lacking. the decision on preferred contrast settings for ffdm units such as the 

dimensions therefore remains a matter of subjective clinical judgement. it is recommended that 

the installation engineers are asked to demonstrate the settings available before readers reach 

their decision. 

despite the opinions on contrast, an observer commented in relation to one case that the microcalcifications 

were more easily visible on the digital images. in another case, two observers commented 

that the dimensions images demonstrated the glandular tissue more effectively than did 

film in a particularly dense, nodular breast. 

NHSBSP October 2010


8. DATA ON SCREENiNg CONDUCTED 

8.1 Clinical dose audit 

the exposure data from 100 screened women were entered into the NccPm dose survey software. 5 

the results are summarised at Appendix 1. in brief, the mean glandular dose (mgd) was 

• 1.35 mgy for the craniocaudal (cc) view, for a mean thickness of 58 mm 

• 1.37 mgy for the mlO view, for a mean thickness of 61 mm 

• 1.01 mgy for the mlO in the 50–60 mm breast, for a mean thickness of 55 mm. 

the evaluation centre has adopted the national dose diagnostic reference level (dRl) of 3.5 mgy 

per image for the 50–60 mm breast. 6 the dose survey results for the dimensions system show it 

to be well below this level, with an average mgd per examination for a two-view mammogram of 

2.71 mgy. 

for the purpose of comparison, the evaluation centre carried out a clinical dose survey using the 

kodak min-R Ev film–screen combination. the film density for a phantom of 40 mm Plexiglas 

(polymethylmethacrylate, PmmA) was 1.69 and the mgds were as follows 

• 1.76 mgy for the cc view, for a mean thickness of 52 mm 

• 1.96 mgy for the mlO view, for a mean thickness of 55 mm 

• 1.96 mgy for the 50–60 mm breast, for a mean thickness of 55 mm 

• 3.70 mgy for a two-view mammogram. 

the clinical dose for two views was thus found to be 26.8% lower in this sample when using the 

dimensions than it was with the local film–screen combination. 

8.2 Clinic organisation and throughput 

the unit was sited in an assessment centre where normally only a small amount of screening is 

scheduled. in addition the centre is located in an inner city area with low uptake. in order to screen 

the required 500 women the evaluation period ran from late October 2009 to early february 2010. 

Special clinics were arranged with appointment intervals designed to compensate for the anticipated 

low uptake. 

in one clinic, of the 82 women invited only 54 attended. Of these, 37 were x-rayed on the dimensions 

while 17 were screened using another digital unit, in order not to keep clients waiting unnecessarily. 

Appointments were booked at four-minute intervals: for example, 23 were screened between 09.04 

and 12.16 hours. Although this equates to an average of 8.3 minutes per examination, it reflects 

the fact that the women undress and dress in the x-ray room because of the configuration of the 

assessment centre and the working practices employed there. No calculation was made of whether 

any room time was unnecessarily lost for other reasons during the session. 

An individually-timed session was also conducted, with the clock starting on the woman’s entry into 

the x-ray room and stopping at the point when she was asked to dress again. this demonstrated 

an average time of 5.85 minutes per examination, which is within the six-minute interval expected 

by the NHSBSP. Some of the times recorded were as low as five minutes. 

carestream Health inc, 150 verona Street, Rochester, Ny 14608. 

NHSBSP October 2010


9. DATA ON ASSESSMENTS CONDUCTED 

the amount of traditional assessment imaging carried out during the evaluation was limited by the 

concurrent clinical research study of tomosynthesis. direct prospective investigation of any reduction 

in the need for standard assessment views in the presence of a tomosynthesis examination was 

not an aim of the research; nevertheless an effect was observed. As a result far fewer traditional 

assessment views were performed than had been the norm without tomosynthesis. However the 

mammographers did feel able to comment on the magnification accessories and function, and 

these comments are presented in Sections 11.12 and 11.23. Neither stereotaxis nor perforated or 

alphanumeric plate localisation formed part of the evaluation. this was because the equipment was 

so new to the market when it took place that these accessories were not yet available. 

NHSBSP October 2010


10. EQUiPMENT RELiABiLiTy 

during the evaluation period (26 October 2009 to 9 february 2010), 500 women were screened 

using the dimensions. Seven NHSBSP Equipment fault Report forms were completed and additional 

comments were recorded in the x-ray room’s communication book. 

in total 80 days were available for screening, 77 of which were during the normal working week, 

from 09.00 to 17.00 hours with an hour’s break for lunch. the remaining three days were Saturdays, 

from 09.00 to 15.45 hours with a 45-minute break. this gave a total of 557 hours available 

for screening over the evaluation period. Seven days of equipment downtime were recorded during 

the evaluation period, giving a total uptime of 91.2%. this figure partly helps to explain some mammographers’ 

impression that, although they enjoyed using the unit, it could be unreliable. it should 

be borne in mind, however, that the unit was only cE marked in October 2008 and this was the 

first installation in the uk. in addition, the unit was on loan for the evaluation directly from Hologic, 

while engineering support was based in Belgium. there was no service level agreement in place 

for maintenance because the equipment had not been purchased; in the circumstances response 

times for an engineer to attend might be expected to be longer than those within a uk maintenance 

contract. Although this seems likely to have had an adverse effect on downtime, insufficient detailed 

data were collected to quantify its impact. 

Although 10 engineer’s report sheets were logged, only seven NHSBSP Equipment fault Report 

forms were completed. this suggests either that more than one issue was recorded on a fault report 

form on occasions or that the engineer attended more than once for the same fault. in one instance 

the company twice sent an incorrect side switch for raising and lowering the gantry, although this did 

not lead to any downtime. in another instance the face guard was replaced because of dislodged 

screws, although, again, this did not cause any downtime. 

Problems that did result in downtime were 

• failure of the exposure switches (two days) 

• difficulty with automatic recognition of compression paddles (1.5 days) 

• loss of power to the gantry resulting from fusing problems (2.5 days) 

• loss of gantry c-arm movement (one day). 

NHSBSP October 2010


11. MAMMOgRAPHERS’ COMMENTS AND 

OBSERvATiONS 

mammographers’ opinions were collected using form number 6 from the NHSBSP equipment 

evaluation protocol. 1 Eighteen forms were returned, although not every question was answered by 

every respondent. Responses are summarised below. 

11.1 Operator’s manual 

this was provided as two large manuals: a user manual and a quality control manual. it was considered 

to be good (5), satisfactory (4) or poor (2). Seven mammographers did not use it. those 

who commented said that the manual was of limited value: it contained inaccuracies, was not 

especially user-friendly, and changes associated with upgrades were poorly documented. Hologic 

advised that a shortened version of the manual could not be supplied, for regulatory reasons. An 

in-house version was developed, however, and was used extensively. 

11.2 Training 

the clinical applications specialist spent two days in the department training a core team of six 

radiographers, who cascaded this information. they were trained in pairs for 1.5 days each, and 

found the training satisfactory, although it was felt that more time was needed. 

Of those who responded to the question on training, nine had not received formal training from 

the applications specialist. those who did receive it rated it satisfactory (2), good (4) or excellent 

(2). One commented that ‘the applications specialists were helpful and approachable; they were 

willing to return as often as was needed’. 

Although Hologic readily sent back the applications specialist when asked, users would have benefited 

more from routine update training following significant software upgrades. 

11.3 Ease of use 

this was classified as excellent (6), good (9) or satisfactory (3). the dimensions’ help in minimising 

fatigue was rated excellent (5), good (10) or satisfactory (3), with one radiographer commenting 

that the motorised movements were very helpful. the two exposure buttons are located under the 

lip of the workstation console on either side. Although the level of force required is not high, both 

buttons have to be squeezed simultaneously to make the exposure, which limits changes to hand 

positions. it is now possible to adapt the system for one-switch operation, however, subject to 

local radiation rules. 

11.4 Exposure times 

All mammographers found the exposure times acceptable, rating them excellent (2), good (8) or 

satisfactory (7). 

NHSBSP October 2010


11.5 Setting radiographic views 

the support arm can be rotated via a switch on either side of the c-arm or another located on the 

underside of the c-arm. the rotation of the support arm was rated excellent (2), good (14), satisfactory 

(1) or poor (1). three mammographers commented on the sensitivity of the rotation, noting that 

the angle of rotation was too sensitive and the speed of the movement made it difficult to set an 

exact angle. Several mammographers would have preferred a single touch function to set the angle, 

as with other equipment in the evaluation centre. Although this function does not strictly comply 

with British Standard BS 5724-2-45:2001, 7 our mammographers found it helpful and believed the 

risk to be minimal. Autorotation now features in the Hologic 1.3 software upgrade, subject to the 

trust approving a disclaimer. 

the visibility of the set angle was found to be generally acceptable, scoring excellent (2), good (8), 

satisfactory (6) and poor (2). the dimensions displays the angle at the top of the gantry, on each 

side. it was noted that the angle display can be obscured by the tube head when it is being rotated 

towards the operator. 

11.6 Setting the position of the breast support table 

the facility for positioning the height of the breast table was rated excellent (4), good (13) or satisfactory 

(1). the height can be altered by the foot pedals or via a hand switch on either side of the 

c-arm. the height adjustment pedals are clearly marked, to differentiate them from the compression 

pedals. 

11.7 Range of movements 

All mammographers believed that the dimensions offered an adequate range of movements, rating 

it excellent (4), good (10) or satisfactory (4). two respondents noted that the speed of the movements 

made it difficult to make small adjustments to angles. 

11.8 Effectiveness of brakes and locks 

All mammographers found that the brakes worked well, rating them excellent (3), good (11) or 

satisfactory (2). there were no problems reported with backlash or movement. 

11.9 Compression 

the compression can be applied with the compression plate either in a fixed flat position or in a 

flexible mode, which evens out the pressure over the varying thickness of the breast. All mammographers 

routinely used the flexible mode. 

the effectiveness of the compression system was rated excellent (4), good (13) or satisfactory (1). 

One mammographer commented that the compression force ‘could be quite fearsome’. 

the compression paddles are available in two sizes. changing the paddle can be awkward. However 

the 18 × 24 cm paddle is automatically offset when the machine is rotated for the oblique and 

lateral views. this was found to be particularly useful when positioning a patient. 

NHSBSP October 2010


the visibility of the applied compression force was considered excellent (2), good (11), satisfactory 

(2) or poor (3). the reading is displayed on either side of the compression device and those who 

rated the visibility as ‘poor’ commented that it was difficult to see the reading when the unit was 

in the oblique position. 

there have been problems with compression plate errors and these are detailed in Section 10, 

Equipment reliability. 

11.10 Comfort level for the women being screened 

women were not asked formally to assess the comfort or otherwise of the dimensions. mammographers’ 

ratings are therefore based on their own perceptions of it and any comments volunteered by 

individual women. the comfort level was rated excellent (3), good (12) or satisfactory (3). women’s 

favourable comparisons with previous experience of mammography (most probably film–screen 

mammography) suggested that the compression this time was more readily tolerated. mammographers 

also formed the opinion that the flexible (fASt) compression was less uncomfortable than 

a fixed paddle mode. client expectation may also have played a part in reducing discomfort, as 

most were aware that this unit was ‘state of the art’ equipment. 

11.11 Range of controls and indicators 

All the expected controls were present. most were easy to find and use and they were rated collectively 

as excellent (3), good (12) or satisfactory (3). Each is clearly marked and no instances of 

confusion were reported. 

11.12 Choice of collimators supplied for spot compression 

mammographers who had used spot compression rated the choice of collimators as excellent (1), 

good (9), satisfactory (5) or poor (1). One would have preferred a greater choice and felt that they 

did not cone down the field of vision sufficiently; however this was later found to be a training issue. 

11.13 Time elapsing before the image arrives at the acquisition workstation 

this was rated excellent (2), good (8), satisfactory (4) or poor (3). Six of the 17 responses mentioned 

the perceived delay between exposure, acquisition and acceptance of the image. However this 

was probably a retrospective response to the initial installation, since when the delay has been 

addressed with software upgrades. 

11.14 Image handling and processing facilities at the acquisition workstation 

the image handling and processing facilities at the acquisition workstation were rated excellent (2), 

good (8), satisfactory (7) or poor (3). there is a touch screen display and one radiographer commented 

that the ‘busy looking screen can be confusing and slow to react’. 

NHSBSP October 2010


11.15 Overall image quality at the acquisition workstation 

this was rated excellent (5), good (10) or satisfactory (2). 

11.16 Ease of image transfer to the reporting workstation and to the hard copy 

printer 

All mammographers found it easy to transfer images to the reporting workstation, rating it excellent 

(1), good (13) or satisfactory (4). there had initially been instances of images backing up, but this 

was caused by a specific workflow configuration issue and has since been resolved. One mammographer 

commented that the procedure for sending images to the hard copy printer ‘was not 

intuitive’. 

11.17 Level of confidence in the Dimensions unit 

this was graded excellent (1), good (11), satisfactory (5) or poor (1). most mammographers agreed 

that the machine produced good results. Some dissented, however, with two finding it too sensitive, 

with ‘quite a few error logs recorded’ and ‘it often broke down’. it may be that these more critical 

comments reflect the mammographers’ earlier experience of the unit, during the tomosynthesis 

pilot study, when more teething problems were encountered. it was evaluated for screening at a 

later date, however, by which time its performance had been enhanced by software upgrades. (See 

Section 10, Equipment reliability.) 

11.18 Hazards 

No potential hazards were identified by the 15 mammographers who answered this question. 

11.19 Equipment cleaning 

All users reported that the machine was easy to clean, rating it good (16) or satisfactory (1). there 

are cleaning instructions in the manual and they were found by three users; the remainder had not 

referred to the manual, on the grounds that they had received verbal instruction from the applications 

specialist or from a colleague. One mammographer pointed out that the ‘hidden’ exposure 

buttons are not easy to clean, which may have implications for infection control. 

11.20 Patient and exposure data and post exposure print out facility 

the mammographers who completed this section rated these excellent (1), good (5) or satisfactory 

(5). their responses may reflect some lack of focus in the question, however, and perhaps relate to 

the display of patient and exposure data on images. the dimensions control panel has a colourcoded 

dose level indicator that shows, after each exposure, whether the dose to the detector was 

in the target range. there is currently no facility for users to download exposure data files for audit, 

although this feature is now under development. 

NHSBSP October 2010


11.21 Did the performance of the digital x-ray system limit patient throughput? 

Eight respondents answered ‘no’ to this question, and four ‘yes’. those answering ‘yes’ thought 

that throughput was compromised by the machine’s unreliability and, to a lesser degree, by the 

time taken for the image to be acquired and accepted. throughput performance is discussed in 

Section 8.2. 

11.22 Additional comments on performance 

most of the mammographers who responded generally enjoyed using this machine. Among their 

comments were 

• very easy and user-friendly (3) 

• easy to operate (4) 

• user-friendly and produces good images (4). 

However, several respondents noted that it was ‘unreliable’ (3) with a ‘high level of error codes’ (3). 

11.23 Magnification 

Some respondents had had limited clinical experience with the magnification equipment, although 

all had the opportunity to become familiar with its use. the ease with which the equipment could 

be attached or removed was rated excellent (1), good (3), satisfactory (3) or poor (7). Several mammographers 

commented on the difficulty of attaching and removing the magnification table; three 

noted that ‘it gets stuck’, particularly when inserted into the 1.5 × magnification slots, and the paddles 

were stiff to slot into and out of position. 

the ease with which the magnification breast support table could be used was graded good (3), 

satisfactory (8) or poor (5). Hologic has advised that a new carbon fibre magnification platform is 

now available. 

the range of collimators was rated good (5), satisfactory (5) or poor (4). the collimation is matched 

automatically to the paddle fitted. 

11.24 Stereo 

the stereotactic device was not available at the time of the evaluation. 

NHSBSP October 2010


12. RADiOLOgiSTS’/FiLM READERS’ 

COMMENTS AND OBSERvATiONS 

form number 9 from the NHSBSP equipment evaluation protocol 1 was used to collect the views of 

eight radiologists and film readers on the Hologic Securview dx workstation. while all eight questionnaires 

were returned, not all questions were answered. As can be seen from the table below, 

the most frequent response to the evaluation questions was ‘good’. Overall satisfaction with the 

workstation was classified ‘good’ by six observers and ‘excellent’ by two. 

Table 1 Radiologists’/film readers’ comments and observations 

How good was the 

operator’s manual? 

(State if N/A) 

How good was the training 

provided by the supplier? 

How easy is it to adjust 

the height and angle of the 

reporting monitors to suit 

the user? 

How easy is it to adjust 

the height and angle of the 

database monitor to suit 

the user? 

How do you rate the ease 

of use of the workstation 

controls? 

complete any applicable 

excellent good satisfactory poor 

1 1 

2 3 1 1 

2 4 2 

2 4 1 

2 4 1 

a) mouse 2 5 1 

b) keyboard 2 6 

c) keypad 2 6 

How to you rate the image 

handling tools (zoom, etc.) 

Rate visibility and usability 

of on-screen icons 

separately 

How do you rate the 

post processing image 

manipulation (window and 

level)? 


reading/reporting flow 

pattern? 

1 6 1 

2 5 1 

2 4 2 

1 4 2 

Comments – include 

all specific 

difficulties (n/a, not 

applicable) 

N/A: 5 

Not seen, wasn’t 

given one for the 

reporting station: 1 

N/A: 1 

didn’t receive much 

training: 1 

Haven’t needed to 

try: 1 

Haven’t tried: 1 

N/A: 1 

N/A: 2 

didn’t actually read 

on it: 1 

NHSBSP October 2010


Table 1 continued 

if there was a choice of 

hanging protocols, how 

easy was it to set these? 

within a hanging protocol, 

how easy was it to display 

a different choice of image, 

ie images performed 

beyond the standard four? 


time taken between an 

image being selected and 

appearing on the screen? 

NHSBSP October 2010 

excellent good satisfactory poor 

2 2 2 N/A: 1 

2 3 2 

1 2 3 

a) new patient selection 2 3 3 

b) in-exam change 2 3 3 

did the database or PAcS 

software allow for recording 

findings under NHSBSP 

reading protocols? 

How easy was it to record 

findings? List any specific 

difficulties in the comments 

section. 

How much of a problem 

was light from the database 

screen raising ambient 

lighting around the 

reporting monitors? 

did you identify any 

hazards associated with the 

workstation or its use? 

describe any additional or 

unusual features or quirks 

of the system. 

what is your overall level 

of satisfaction with the 

reporting workstation? 

yES or NO 

Comments – include 

all specific 

difficulties (n/a, not 

applicable) 

yes: 1 

No: 4 

N/A: 3 

1 N/A: 4 

3 1 

yES or NO No: 7 

Not a problem: 1 

Not too bad: 1 

too slow at retrieving from PAcS. Not good enough at comparing with 

previous examinations: 1 

2 6


the majority thought training by the supplier was ‘good’ or ‘excellent’. However it appears that 

six of the eight respondents were unaware of the existence of the operator’s manual, despite the 

fact that a hard copy was available in the department. it may be that more should be done during 

applications training to highlight the existence of the manual and encourage its use. in general, 

anyone who had trouble operating a particular function of the workstation was more likely to ask 

a colleague or a representative of the supplier for help than to consult a manual. with this in mind, 

the unit plans to develop at least one ‘super user’ for each electronic system in the department to 

serve as a source of expertise. 

the Securview dx native database does not permit the recording of NHSBSP results and this functionality 

would not normally be required, as screening results are entered directly into NBSS. At the 

time the evaluation took place, the department was in the process of implementing its overarching 

PAcS and mammography reporting system for both screening and symptomatic work. this, and 

the fact that desktop synchronisation between the Securview dx and NBSS had been demonstrated 

in the department, may explain why one respondent answered ‘yes’ to the question ‘did 

the database or PAcS software allow for recording findings under NHSBSP reading protocols?’. 

the Securview dx was reliable and, overall, the film readers found it user-friendly. it was networked 

to the department’s kodak 8610 dryview laser imager and the radiography staff found the printing 

function valuable and simple to use. 

NHSBSP October 2010


13. iNFORMATiON SySTEMS 

the evaluation of the dimensions overlapped with the implementation of a fully integrated screening 

and symptomatic mammography PAcS workflow system in the Breast Screening unit. the dimensions 

was incorporated into the trust and departmental systems in the same way as any other modality, 

as shown in the workflow diagram (figure 9). the department operates an integrated system: 

screening cases are identified by NHS number and symptomatic cases are identified primarily by 

hospital number (although they usually also bear the NHS number in a secondary dicOm id field) 

and both types of case reside in a single trust PAcS. the dimensions operated in this environment: 

it received a modality worklist feed from the PAcS broker, incorporating both screening (NBSS) and 

symptomatic (cRiS) appointments, and successfully sent images to the PAcS. 

the Securview dx did not form part of the main screening workflow because mammography PAcS 

workstations had been purchased from another supplier and set up for screen reading. it was part 

of the standard workflow used for symptomatic mammography, however, and (like the department’s 

own mammography workstations) was connected to the trust PAcS via the PAcS virtual local area 

network. Screening and symptomatic mammograms could be displayed on the Securview dx 

once they had been sent from the modalities, which was done either via the departmental server 

or directly. images could also be called from the PAcS to the Securview dx, by performing dicOm 

query/retrieve operations. 

the display of images on the Securview dx could be driven either by cRiS, if symptomatic, or by 

Hologic’s own software. the first tended to be used for symptomatic reporting sessions and the 

second for ad hoc image viewing, for example during diagnostic clinics. users had little difficulty 

operating the Hologic database software for finding and displaying images or performing dicOm 

query/retrieve operations. desktop synchronisation with cRiS required each operator’s user name 

and password to be identical in cRiS and in the Hologic database software. Although this gave rise 

to some administrative inconvenience (eg when a cRiS password expired) changing the password 

on the Hologic software was straightforward. 

the department’s mammography PAcS enables reporting workstations to recognise both screening 

and symptomatic images from the same person as belonging to a single individual. this enables 

workstations to call up details automatically of either type of examination (via the auto prefetch 

facility) on receiving new images for that person, and to display sequential mammograms from either 

database system as a single patient. this was not possible on the Securview dx; its software did 

not recognise screening and symptomatic images as belonging to the same person unless a manual 

operation was performed on the workstation to merge the two episodes in a single patient entity. 

However we did observe successful Securview dx desktop synchronisation with NBSS and know 

that a screening workflow would be possible in a screening-only environment, or where screening 

and symptomatic images are managed in separate PAcS. moreover once the planned workflow 

is fully implemented, the auto prefetch will be handled by the departmental server rather than by 

workstations. in a well-designed and comprehensive PAcS workflow configuration workstations 

would not normally be required to include auto prefetch. despite this the inability of a workstation to 

recognise the NBSS and cRiS episodes, where relevant, as relating a single patient has implications 

for the optimal display of sequential images from the two different database systems. Although we 

understand that it might be possible to resolve this with further development, the evaluation team 

had no reason to pursue it. 

NHSBSP October 2010

Figure 9 workflow diagram 


NHSBSP October 2010


14. CONFiDENTiALiTy 

the clinical evaluation complied fully with NHS cancer Screening Programmes’ Confidentiality and 

Disclosure Policy, in conformity with Section 251 of the Health and Social care Act 2006. # Each 

member of Hologic staff who had contact with patient-identifiable information was asked to read 

the local policy and sign the Patient Advisory and information group (PiAg) agreement. ** they were 

also required to sign the trust’s it security declaration. 

# this has since been updated in Section 251 of the NHS Act 2008, administered by the National information governance 

Board for Health and Social care. See http://www.nigb.nhs.uk/. 

**PiAg was established to provide advice on issues involving the use of patient information and to oversee arrangements 

created under Section 251 of the NHS Act 2006 (originally enacted under Section 60 of the Health and Social care Act 

2001). it was replaced by NigB in 2008. See above and http://www.dh.gov.uk/ab/PiAg/index.htm. 

NHSBSP October 2010


15. SECURiTy iSSUES 

All electronic patient data were stored on NBSS, cRiS and gE PAcS. Access to each of these 

systems is restricted to authorised users by password protection. Although images are held on 

the acquisition workstation and the reporting workstation for a period of time, the primary record 

is on gE PAcS and thereafter on the long-term image archive. gE PAcS is therefore checked after 

every examination to ensure that all images have arrived safely. if images are stored outside their 

electronic folder on PAcS (ie they are ‘unspecified’), this is corrected by routine housekeeping 

procedures. if a network or other failure prevents safe arrival, images can be re-sent to PAcS from 

the acquisition workstation. Similarly if images fail to arrive at the reporting workstation for any 

reason they can be either re-sent from the acquisition workstation or retrieved from PAcS. that 

would not be possible if images were sent to the gE PAcS via the departmental server, however, 

rather than being sent in parallel to the gE PAcS and the reporting workstations via that server, 

although the option to re-send them from the modality would remain (see figure 9). Parallel image 

routing thus provides extra security but at the cost of greater network loading and more elements 

to investigate if the image transfer fails. 

Access to the dimensions acquisition workstation is controlled by either fingerprint login or typing 

a username and password. Access to the Securview dx is also password protected. the images 

on the workstation were not the primary permanent record and the workstation’s own software 

was not used to record any reports. with this in mind the department allowed a group login to be 

used alongside individual passwords. 

NHSBSP October 2010


16. CONCLUSiONS AND 

RECOMMENDATiONS 

the evaluation team found the Hologic Selenia dimensions suitable for screening use in the NHSBSP. 

Over the course of the evaluation it was shown to meet the key requirements for clinical image quality 

and radiation dose, system stability, integration with it infrastructure, workflow and throughput. 

the screening downtime during the evaluation was a source of concern. Since the end of the 

evaluation period, however, the dimensions has been more reliable and an increase in the number 

of trained engineers has led to faster response times. 

the Securview dx reporting workstation performed effectively and was well liked by users. No 

conclusion can be drawn as to its screen reading throughput, however, because departmental 

circumstances prevented its use for this purpose. 

image quality compared very well with the local film–screen system. However purchasers and 

installation engineers should ensure as far as possible when setting up the dimensions, and ffdm 

systems in general, that contrast levels reflect local preferences. 

NHSBSP October 2010


17. REFERENCES 

1. Guidance Notes for Equipment Evaluation: Protocol for User Evaluation of Imaging Equipment for Mammographic 

Screening and Assessment. NHS Cancer Screening Programmes, 2007 (NHSBSP Equipment Report 0703). 

2. Commissioning and Routine Testing of Full Field Digital Mammography Systems, 3rd edition. NHS Cancer Screening 

Programmes, 2009 (NHSBSP Equipment Report 0604). 

3. Routine Quality Control Tests for Full Field Digital Mammography Systems. NHS Cancer Screening Programmes, 2007 

(NHSBSP Equipment Report 0702). 

4. Zanca F, jacobs j, van Ongeval C et al. Evaluation of clinical image processing algorithms used in digital 

mammography. Med Phys, 2009, 36: 765–775. 

5. National Coordinating Centre for the Physics of Mammography. Patient Dose Software v2.1. Available from Patient 

Dose (http://www.nccpm.org/patient_dose.htm). Accessed 08.09.2010. 

6. Quality Assurance Guidelines for Mammography Including Radiographic Quality Control. NHS Cancer Screening 

Programmes, 2006 (NHSBSP Publication No 63). 

7. British Standards institution. Medical Electrical Equipment, Particular Requirements for Safety – Specification for 

Mammographic X-ray Equipment and Mammographic Stereotactic Devices (BS 5724-245:2001, iEC 60601-2- 

45:2001). London: British Standards institution, 2001. 

NHSBSP October 2010


APPENDix: CLiNiCAL DOSE SURvEy 

Survey No: 20 

Centre: KING'S COLLEGE HOSPIT 

Date of first exam: 

Date of last exam: 

X-ray make Hologic 

Model: Selenia Dimensions 

Local id: 

Installation: 

kV mode: 

standard kV: 0 

Routine/age trial: 

24x30 cassettes available: 

Block mAs: 

Block density: 

physics service 

Physicist 

Count of films 

Average doses for main films 

NHSBSP October 2010 

3 

2.5 

2 

MGD (m Gy) 1.5 

1 

0.5 

Average doses per screening examination 

No of 

women 

NHSBSP Breast Dose Survey 

min 

MGD 

(mGy) 

max 

MGD 

(mGy) 

mean 

MGD 

(mGy) 

Processor make: 

Processor ID: 

Developer: 

Fixer: 

Dev Temp (deg C): 

Proc time (s): 0 

Cassette make: 

Film make: 

Screen make: 

MGD to standard breast 

auto/manual kV: 

auto/AEC setting: 

0 

0 20 40 60 80 100 120 

view main films Extra films 

CC 218 

OB 217 

view 

No of films 

min 

MGD 

(mGy) 

breast thickness (mm) 

max 

MGD 

(mGy) 

mean 

MGD 

(mGy) 

mean 

thickness 

(mm) 

CC 218 0.76 2.44 1.35 58 

OB 217 0.72 2.28 1.37 61 

Two view 

109 1.59 4.34 2.71 

Average dose for 50-60mm thick breasts 

View No of mean 2 mean 

films MGD s.e.m. thickness 

(mGy) 

(mm) 

OB 62 1.39 0.07 56 

kV set: 28 

target: Mo 

filter: Mo 

No of 

films 

160 

140 

120 

100 

80 

60 

40 

20 

0 

PMMA thickness: 

MGD mAs: 

HVL: 

MGD: 

film density: 

Dose histogram 

0 1 2 3 4 5 6 7 8 9 10 

MGD (m Gy) 

Summary of X-ray factors selected 

Anode Filter kV films 

W 

W 

W 

W 

W 

W 

W 

W 

W 

W 

W 

W 

Rh 

Rh 

Rh 

Rh 

Rh 

Rh 

Rh 

Rh 

Rh 

Rh 

Rh 

Rh 

25 1 

26 16 

27 10 

28 71 

29 65 

30 108 

31 92 

32 59 

33 7 

34 4 

35 2 

36 1

Evaluation and clinical assessment of the hologic selenia

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