DSA DEEPAK GUPTA
description
Transcript of DSA DEEPAK GUPTA
DSA ITS APPLICATION AND ADVANCEMENT
Moderator:MR. S.R.CHOWDHURYTUTOR,DEPT.OF RADIO-DIAGNOSIS & IMAGING,PGIMER CHANDIGARH
Presented by:DEEPAK GUPTABSc final year Student ,DEPT.OF RADIO-DIAGNOSIS & IMAGINGPGIMER CHANDIGARH
04/11/2023 2
ANGIO?
ANGIO means blood vessel
And angiography is the radiological study of blood vessel in the body after the introduction of iodinated contrast media.
SUBTRACTION?
It is simply a technique by which bone structures images are subtracted or canceled out from a film of bones plus opacified vessels, leaving an unobscured image of the vessels.
04/11/2023 3
"DSA" means "Digital Subtraction Angiography"
WHAT DO YOU MEAN BY DSA
DSA-The acquisition of digital fluoroscopic images combined with injection of contrast material and real-time subtraction of pre- and post contrast images to perform angiography is referred to as digital subtraction angiography
04/11/2023 4
The Portuguese neurologist Egas Moniz,( Nobel Prize
winner 1949), in 1927developed the technique of
contrast x-ray cerebral angiography to diagnose
diseases, such as tumors and arteriovenous
malformations.
HISTORY
The idea of subtraction images was first proposed by the Dutch radiologist Ziedses des Plantes in the 1935, when he was able to produce subtracted images using plain films.With the introduction of the Seldinger
technique in 1953, the procedure became
safer as no sharp devices need to remain
inside the vascular lumen.
04/11/2023 5
HISTORICAL DEVELOPMENT
CONVENTIONAL SUBTRACTION TECHNIQUE
Photographic method used to eliminate unwanted images.No addition of information;only purpose to make diagnostically important information to see.First described by a Dutch radiologist, Zeides des Plantes, 1935.3 conditions:SCOUT FILM ANGIOGRAM FILM-CONTRAST NO MOTION OF HEAD
04/11/2023 6
The principles of subtraction are based on the following:The scout film shows the structural details of the skull and the adjacent soft tissue.Angiogram film shows exactly the same anatomic details, if the patient does not move, plus the opacified blood vessels.If all the information in the scout film could be subtracted from the angiogram film, only the opacified vessel pattern would remain visible.
CONTD.
04/11/2023 7
EQUIPMENTTHE AOT CHANGER:Can change films –6/s or 1/5s Two of these changers can be coupled electronically and mechanically and will operate out of phase or synchronously with each other.
Radiographs in 2 planes simultaneously-one mounted vertically and other horizontal.
04/11/2023 8
LOADING MAGZINE Large steel container.
Inside the container are arranged a no. of strong wire separators.
30 sheets of film.Precautions :each film should slide into position
by it’s own wt.
RECIEVING / LOADING MAGZINE
AOT CONTD.
04/11/2023 9
30 SEPERATING WIRES
EXPOSURE AREA :Rectangular, slightly recessed area at the top of the changer.Defined by heavy metal frame.Within this is a secondary grid.Supported on 4 small helical springs placed cornerwise and to consist of a stout Al plate, to the lower side of which is attached an intensifying screen.
RECEIVING CASSETTE:Shallow,polished metal container.Lid is a sliding section in a side which can be pushed down by firm finger pressure and is retained by central spring loaded catch.
04/11/2023 10
THE ROLL FILM CHANGER:
Mechanically easier to wind roll films.12/s.
04/11/2023 11
DIGITAL SUBTRACTION
ANGIOGRAPHY
HISTORY:Developed in 1970s.University of Wisconsin, University of Arizona,University of Kiel.Commercial systems introduced in 1980.
04/11/2023 12
Angiography theory ages
Single shot angiographyManual changerAOT PUCKDSA
04/11/2023 13
EQUIPMENT AND APPARATUS
Both film and digital capabilities are usually present and the fluoroscopy equipment operates in the conventional way.Brief review :
Output phosphorLight intensity
Electrical signal
Input surface Visible light Light detectedamplified
04/11/2023 14
DIGITAL IMAGE PROCESSOR
DIGITIZER DIGITAL ARITHEMATIC UNIT
DIGITAL IMAGE MEMORY
DISPLAY SECTION
COMPUTER MONITOR
DIGITALDISK
STORAGE
MULTIFORMAT CAMERA
X-RAY
CONTROL
SIGNALS
04/11/2023 15
X-Ray Unit
Should be capable of rapid serial exp. @2-8
frames/sec for up to 20 sec.
Near monochromatic beam consistent output.
Isocentre motorized table ,tilt 90-0-90 , up-down,
sliding ,floating capable
Ceiling mounted C-arm with versatile movements
II system with multi field ( 6”,9”,12”,16”)
High resolution TV /CCD camera
Computer with high definition monitor system
04/11/2023 16
High output preferably high frequency
generator
High heat loading capacity ,fast heat
dissipation, high speed anode
Target material
tungsten,rhenium,graphite.
Oil-water close loop cooling
Contd.
04/11/2023 17
In our dept.Siemens polydoros SX 65-80Polystar
04/11/2023 18
GAS , AIR & VACUUM PORTS
Boyle apparatus
NECESSARY EQUIPMENT USED WITH ANGIO(DSA)
04/11/2023 19
BED SIDE MONITOR
INJECTOR
04/11/2023 20
04/11/2023 21
IMAGE INTENSIFIER-CONSTRUCTION
04/11/2023 22
WORKING
04/11/2023 23
Modern DSA systems are based on digital fluoroscopy/fluorography systems, which are equipped with special software and display facilities. Digital subtraction angiography (DSA) was developed to improve vessel contrast. This is a technique that uses a computer to subtract two images, obtained before and after contrast media is injected into the vessels of interest. The anatomical structures that are the same in the two images can be removed and the resulting image shows the vessels only.
04/11/2023 24
The image before the contrast agent is administered is called the mask image. Once the contrast is administered, a sequence of images are taken by a television camera in analog form, which is then digitised by computer.
The DSA processor has two separate image memories, one for the mask and the other for the images with contrast medium. These two image memories are subtracted from one another arithmetically, and the result goes to an image processing and display unit.
04/11/2023 25
Adjust contrast & brightness.Remasking – correcting misregistered images.Pixel shifting.Edge enhancement – edges of the vessels can
be enhanced so that small details can be made more obvious.
Image zoom.land marking – a small amount of original
image is added into the subtracted image.Noise smoothing – operates by reducing the
statistical fluctuations in each pixel by averaging the pixel with it's closest neighbors. The visual prominence of noise has been suppressed by averaging, but resolution is decreased.
IMAGE PROCESSING
04/11/2023 26
Road mapping is useful for the placement of catheters and wires in complex and small vasculature. A DSA sequence is performed, and the frame with maximum vessel opacification is identified;this frame becomes the road map mask. The road map mask is subtracted from subsequent live fluoroscopic images to produce real-time subtracted fluoroscopic images overlaid on a static image of the vasculature
Road Mapping
04/11/2023 27
When a digital subtraction technique is used, patient motion that occurs between acquisition of the precontrast images and acquisition of the postcontrast images will result in artifacts due to misregistration of the two images. If these arti-facts are observed, it is possible to reregister the pre- and postcontrast images by shifting the subtraction mask (precontrast image) with respect to the postcontrast image and resubtracting the two images
04/11/2023 28
VIDICON CAMERA TUBE
• Diameter 1 inch
• Length 6 inch
• Main parts -
• Target section
• Electron gun
• Electromagnetic focusing coil
• Two pair of electrostatic deflecting coil
• A scanning section
04/11/2023 29
Working principle of T.V monitor
Control Grid
No. of e-ns & the brightness of individual
dots
Produce bright area in the TV Picture
Dark Area
Strikes the fluorescent Screen
Emits large no. of light photons
VISIBLE TV IMAGE
Receive Video signal from ccu & regulate
Grid cuts off the e-ns flow almost completely
E-ns is Accelerated
04/11/2023 30
• In the scanning section of tube, externally mounted coil (emitting focusing coil and electrostatic deflecting coil) produce an axial electromagnetic field by means of which-
• The electrons are focused on the target of tube and
• The beam is moved over the target area in an orderly scanning scan
• Two types scanning system
• Sequential scanning pattern and
• Interlaced scanning pattern
SCANNING SECTION/ SYSTEMS
04/11/2023 31
SEQUENTIAL SCANNING PATTERN
• Also called progressive scanning
Disadvantages • Technical• Requires a wide frequency band during
transmission
04/11/2023 32
Interlaced scanning
• Instead of scanning all 625 line
consequently, only the even
no. of lines are scanned the
first half of the frame and only
the odd no. lines are scanned
during second half.
• In this pattern the transmission
is easier and cheaper because
the actual picture frequency is
lower
04/11/2023 33
TELEVISION IMAGE QUALITY
The assessment of the quality of TV images is a complex subject but there are a no. of image characteristics relating specifically to TV system
• Resolution • Contrast • Brightness • Image lag• Distortion
04/11/2023 34
Resolution is the process by which something is separated into its component part
The resolution of imaging system refers to the amount of detail which is observable
It may be formulated as the number of pairs of black and white lines which an image forming or image recording device can demonstrate in a length of 1 mm
Vertical resolution is determined by no. of vertical scan lines (e.g. 625).
In recent years the manufactures of radio diagnostic imaging equipment have developed his definition TV system which employ 1249 or even more lines.
Resolution
04/11/2023 35
The contrast of the image on a TV screen clearly depends on the
contrast of the original image focused onto the signal plate of the
pick up tube.
Both camera and monitor affect the contrast of a TV image.
A vidicon camera reduces contrast by a factor of approx. 0.8 and the
monitor enhances by a factor of 2.
Contrast
04/11/2023 36
The term luminance and brightness are often used when discussing the aspect of tv imageLuminance can be defined as light emitted per unit area from a surface. It is measured in candela per square meter (cd/m2)
Brightness
Automatic brightness control (ABC)
• ABC helps to maintain the image intensifier exposure rate based on the subject’s thickness
• It is critical to the patient dose and image quality
04/11/2023 37
The ABC monitors the light output from an area of the face of the image intensifier and it tries to maintain the signal travel within an approximate range of that output and adjust tube potential (kvp) and tube current (mA) a/c to predefined algorithm
It refers to control of x-ray exposure levels
Automatic gain control (AGC)If brightness is controlled by varying sensitivity of
the TV system the term AGC is used.It is fairly simple and inexpensive way to control
image brightness It does not change the x-ray dose rate to the patient
37
04/11/2023 38
Image lag Lag is the term used to describe inability of an
imaging system to follow rapid changes in its input image
Distortion Distortion of the image occur in the image
intensifier or in the optical coupling system which links its output phosphor to the signal plate of the TV pick up tube
38
04/11/2023 39
ArtifactsLagVignetting,Veiling glare Pincushion distortionS distortion.
39
04/11/2023 40
Lag Lag is the persistence of luminescence after x-
ray stimulation has been terminated. Lag degrades the temporal resolution of the dynamic image. Older image intensifier tubes had phosphors with lag times on the order of 30–40 msec. Current image intensifier tubes have lag times of approximately 1 msec.
40
Vignetting
A fall-off in brightness at the periphery of an image is called vignetting. Vignetting is caused by the unequal collection of light at the center of the image intensifier compared with the light at its periphery. As a result, the center of an image intensifier has better resolution, increased brightness, and less distortion.
04/11/2023 41
Veiling GlareScattering of light and the defocusing of photoelectrons within the image intensifier are called veiling glare. Veiling glare degrades object contrast at the output phosphor of the image intensifier. As mentioned, the contrast ratio is a good measure of determining the veiling glare of an image intensifier. X-ray, electron, and light scatter all contribute to veiling glare.
41
Pincushion Distortion• Pincushion distortion is a geometric, nonlinear
magnification across the image. • The magnification difference at the periphery of the
image results from the projection of the x-ray beam onto a curved input surface.
• The distortion is easily visualized by imaging a rectangular grid with the fluoroscope.
04/11/2023 42
S DISTORTION
Electrons within the image intensifier move in paths along designated lines of flux. External electromagnetic sources affect electron paths at the perimeter of the image intensifier more so than those nearer the center. This characteristic causes the image in a fluoroscopic system to distort with an S shape .Manufacturers include a highly conductive mu-metal shield that lines the canister in which the vacuum bottle is positioned to reduce the effect of S distortion.
42
04/11/2023 43
INDICATIONSNon traumatic Subarachnoid Hemorrhage
(SAH).Arterial dissection or lacerationAneurysmPseudoaneurysmThrombosis.Arterio-venous malformation (AVM). Arterio-venous fistula (AVF).Tumor vascularity.Gastrointestinal bleed/Uterine artery bleedTherapeutic.
43
04/11/2023 44
CONTRAINDICATIONSNo absolute contraindication.
Poor renal reserve.
Deranged coagulogram.
Allergic to contrast media.
Recent barium examination –abd.angio
44
04/11/2023 45
Contrast Media
Blood vessels are not normally seen in an x-ray image, because of low tissue contrast.
To increase image contrast, contrast agents, which are dense fluids with elements of high atomic numbers, such as iodine, are injected into a blood vessel during angiography. Because of its higher density and high atomic number, iodine absorbs photons more than blood and tissue.
This creates detailed images of the blood vessels in real time.
The first contrast media used for intravascular injection were called high-osmolar contrast media (HOCM). (osmolality is the measure of the particle concentration in a solution.)
45
04/11/2023 4646
HOCM had osmolarity seven to eight times
higher than plasma. This high osmolarity
caused adverse effects such as pain,
endothelial damage, thrombosis, and
increased pressure in the pulmonary
circulation.
Low-osmolar contrast media (LOCM) were
first developed in the 1970's and these
helped to reduce these side effects.
One of the major risks of modern iodine
contrast media is an allergic reaction to
iodine.
04/11/2023 47
Non ionic Iso-osmolar contrast media.
30-40% dilution with normal saline.
50 ml of diluted contrast media is enough to
do a standard cerebral angiogram with total 8
projections.
Approx. 5-8 ml diluted contrast / injection.
47
04/11/2023 48
Materials used
Catheters
Arterial sheath
Medicut
Guidewires
Contrast
Connector/100
cm.tubing
Surgical blade48
Saline
Disposable
syringes
Local anesthesia
Heparin
Surgical gloves
Elastoplast
04/11/2023 4949
Picard
Pigtail
Sim-1
Cathetars
04/11/2023 5050
VASCULAR SHEATH
MEDICUT
GUIDE WIRES
ELASTOPLAST STRIPS
04/11/2023 51
CONTRAST ANESTHESIA
ANTICOAGULANT
PVA-PARTICLESGEL FOAM
04/11/2023 52
PREPARATION
Appointment time
Nil orally 4-6 hrs.
On trolley
In hospital gown
Groin shave
Records
PTI
52
Should be well
hydrated.
Should void before
procedure.
Peripheral pulses
marked.
I.V line in place.
INFORMED CONSENT
MUST
04/11/2023 5353
DSA
DIAGNOSTIC• Cerebral- 4 vessel• Upper & lower limb • Renal • IVC graphy • Pulmonary • Abdominal - coelic
& branches• -sup.
mesentric A.• - inf.
mesentric A.• Transjugular liver
biopsy• Balloon occlusion test.
THERAPEUTIC
• Embolization • - coil • - gel• - particle• - ballon• Stenting
• TACE
• Vertebroplasty
04/11/2023 54
PROCEDUREGaining arterial access.
Selective arterial catheterization.
Image acquisition.
Closure of arterial access.
Post processing
Hard copy
54
04/11/2023 5555
04/11/2023 56
During angiography, patients may be sedated to reduce anxiety.
Their heart rate and rhythm, breathing, and oxygen saturation are monitored throughout the procedure.
Patient clean draped . A local anesthetic is usually used in the area
where the catheter is to be inserted, most commonly the femoral artery.
First, a small incision given, medicut is inserted into the artery. fluoroscopy is used to guide the needle to the proper position .
The needle is then removed after placing guide wire in the artery and vascular sheath is inserted over the guide wire . The catheter is then inserted along the guide wire through the sheath.
56
04/11/2023 57
When the catheter is in the correct position, the wire is pulled out and dye is injected through the catheter.
Images are acquired during contrast injection. Injections can be made directly into the artery of interest (selective arteriography)
Complications from an arteriogram are very rare, but there is some risk. Most problems that occur can be detected at the time of the procedure or immediately after the procedure. The artery may be injured at the puncture site or along the artery where the catheter is passed.
57
04/11/2023 58
COMPLICATIONS0.16% major complication rate.Local complications: hematoma,
vessel laceration, dissection, peudoaneurysm, AV fistula.
Systemic complications: contrast reactions, fever, sepsis, dehydration, death.
CNS complication: aggravation of preexisting complaints, neurological deficit.
58
04/11/2023 59
POSTPROCEDURAL CARE
After the catheter is removed compression is applied to the puncture site.The patient is asked for bed rest for a minimum of 4 hoursDuring rest patient is monitored and vital sign like peripheral pulse like distal to Puncture are regularly The extremity is also checked for warmth, color, numbness to ensure circulation has not been disrupted.
04/11/2023 60
Oral fluid is given and analgesics are given if required.Special care should be given in case of children and geriatric patient since additional Patience is required. They have given warming blanket to keep the body temp. Normal. Geriatric patient also frequently feel nervous and afraid of falling off the Table ,reassurance and additional care from the technologist will enable the Patient to feel secure and comfortable.
04/11/2023 61
Digital subtraction techniques
DSA has many techniques
Mask subtraction
Dual energy subtraction
• Time interval differencing
Temporal filtering
04/11/2023 62
Mask subtractionThe mask image is
subtracted from the
image with dye to
reveal just the vessels
uncontaminated by
overlying bone
structures.
PRE CONTRAST POST CONTRAST
SUBTRACTED ENHANCED
04/11/2023 63
Dual energy subtraction
2 images are taken within a very short period (no pt. movement ).
One at low KVp & other at high KVp.
K EDGE HYBRID
04/11/2023 64
K edge subtractionIodine attenuates diagnostic x-rays almost
entirely by P.E.E.One method for achieving high iodine
contrast is removal of all x-rays from the beam except those that lie below the k-shell B.E of ‘I’.
An x-ray filter made of rare earth named cerium can do this well, since B.E = 40 KeV.
Thick filter will remove most of the x-rays above 40 KeV.
The image to be subtracted should contain few
x-rays.
04/11/2023 65
Hybrid subtraction
High KVp & low KVp image pair is collected.
No pt. movement – soft tissues cancel properly. but bone
edges cause severe artifact.
Consider the subtracted images to consist of only 2 atomic
no. materials (iodine & bone).
The hybrid subtraction produces 2 sets of subtracted images.
The same bone & iodine structures are present on both sets.
D.E.S can now be used to eliminate bone leaving only iodine.
The final image – more noise.
Mask subtraction + dual energy subtraction
04/11/2023 66
Time interval differencing
In simple mask subtraction, an early image is
used as a mask.
TID – a new mask for each subtraction.
Each subtracted image is the difference b/w the
images separated by some fixed interval of time.
04/11/2023 67
Temporal filtering
Temporal filters are used.
This filter generates one final image by
adding & subtracting some of the
original images together, & then shifting
& repeating to form the next image.
04/11/2023 68
ADVANCEMENTSIN OUR DEPARTMENTPhilips Allura Xper FD 20/10 and interventional tools
The Allura Xper FD20/10 is a biplane flat
detector system with integrated 3D for
intricate neurovascular procedures.
Combining the proven stable geometry with
'real-time' Allura
3D- reconstructions,
Xper CT,
SPECTRA BEAM
3D Roadmapping,
and multi-modality information integration,
04/11/2023 6969 69
04/11/2023 70
the Allura Xper FD20/10 balances
superb image quality with excellent
dose safety. The flat detector's
unique distortion-free imaging chain
redefines image clarity and captures
information at a resolution four
times greater than conventional X-
ray systems.
04/11/2023 71
Xper ctWith XperCT clinicians can access CT-like imaging right on the angio system so that they can assess soft tissue, bone structure and other body structures before, during or after an interventional procedure. The XperCT reconstruction is created from a rotational acquisition performed on the Allura Xper system. This reconstruction can be overlaid with the 3D vascular image.
IT Bring 3D soft tissue imaging to your angio suite
3D soft tissue imaging supports diagnosis, planning, interventions and treatment follow-up, XperCT can be combined with Allura 3D-RA images to visualize soft tissue and vascular anatomy on one image. Using CT-like imaging for a post-procedural check can help reduce delays and improve patient comfort.
04/11/2023 72
XperCT overlay on both the internal carotid and vertebral arteries
04/11/2023 7373 73
04/11/2023 74
Spectra Beam
It is basically a selectable copper beam filtration
The combination of SpectraBeam with the MRC- tube allows increased X-ray output with better filtration of soft radiation. SpectraBeam offers filters of 200, 500 and 1000 microns thickness Cu equivalent to provide a high level of radiation protection regardless of the projection or patient absorption. This reduces patient X-ray dose for cardiac and vascular applications, while maintaining the same image quality.
04/11/2023 7575 75
When the acquisition sequence is initiated, the C-arm rotates from left
to right for 220o at 40o per second but
dataacquisition is accomplished at the
range Of 200o, acquiring at 8.8 frames per
second
for 5 seconds resulting in 44mask images
The gantry then rotates back to the starting position. When the C-arm returns to the starting position, the Power injector is initiated according to the injector delay protocol, which is Mask-to-Image delay of 1.1 seconds and Injector-to-Image delay of 1.1 seconds.The Power injector injects 18
milliliterof Visipaque 280 at the rate of 3.6ml/second for Internal Carotid Artery(ICA). The gantry repeats the maskacquisition path and acquires
another44 images with contrast. Real timesubtraction angiographs are
displayedon post processing screen.
04/11/2023 7676
System components
GeneratorsX-Ray TubesII/Flat detectorImaging ChainPatient Table
04/11/2023 7777
Generator characteristicsX-ray generators High powered x-ray generators to provide
almost constant potential power supply to the tube.
Two Velara CVFD microprocessor-controlled 100 kW high-
frequency converter generators.
Minimum exposure time of 1 ms.
Voltage range: 40 kV to 125 kV.
Max current:
- MRC-GS 04-07: 802 mA at 80 kV.
- MRC-GS 05-08: 1062.5 mA at 80 kV.
Automatic kV and mA control for optimal image quality prior
to run to reduce dose.
77
04/11/2023 7878
Generator characteristics cont. Max continuous power for fluoroscopy: 2.4 kW for 0.5 hour
and 2 kW for 8 hours.Nominal power (highest electrical power): 100 kW (1000
mA at 100 kV)Reference loading conditions: 110 kV, 18 mA continuous. Pulsed X-ray of 3.75, 7.5, 15 and 30 frames/sec. in
monoplane and biplane mode for pulsed fluoroscopy. Pulsed X-ray of 0.5 to 6 frames/sec. for digital subtracted
acquisition in monoplane and biplane mode.Pulsed X-ray up to 6 frames/sec. for digital acquisition in
monoplane and biplane mode. 15 and 30 frames/sec. Noise < 55 dB(A).
78
04/11/2023 7979
X-Ray Tubes
79
The high performance metal ceramic tubes .Most relevant feature is support of the rotor anode in a spiral groove bearingThe spiral groove bearing glides on a thin film of liquid metal to maximize heat dissipation allowing virtually unlimited X-ray sessions without forced cool down delays.• The MRC tube runs silently offering a more comfortable patient environment.• Another secret of the MRC tube is the enormous heat storage capacity of its 200 mm diameter anode, eliminating waiting times.• And, the MRC X-ray tube can image the heaviest patients even at steep angles, while maintaining image quality.
04/11/2023 8080 80
Tube Specifications
04/11/2023 8181 81
Tube Specifications …
04/11/2023 8282
DetectorsMore recently, however,
the image intensifier/CCD combination has been replaced by an advanced flat detector imaging device.
The flat detector converts the light generated by the absorbed X-ray energy in the scintillation layer directly into a digital electrical signal.
82
04/11/2023 8383
Flat detector frontalSize of housing 42x52 cmMaximum field view 30x38cmImage matrix
2480x1920 pixel at 14 bit heightDetector zoom fields
30x30cm,22x22cm, 16x16cm,13.5x13.5cm,
11x11cm formats Pixel size 154x154 μm Detective Quantum Efficiency
(DQE): >73% at low spatial frequencies
83
04/11/2023 8484
Flat detector lateral
• Size of housing 28x28 cm
• Maximum field view 18x18cm
• Image matrix 1024x1024 pixel at 14 bit height
• Detector zoom fields 14.5x14.5cm, 11x11cm formats
Pixel size 184x184 μm Detective Quantum Efficiency
(DQE): 75%84
04/11/2023 8585
Patient supportAngioDIAGNOST 5
Length: 303 cm (119.3 inch). Metal-free overhang: 125 cm
(49.2 inch). Width: 50 cm (19.7 inch).Longitudinal float: 100 cm (39.4
inch). Transverse float: 36 cm (14.2
inch). Height adjustment (without
pivot option): 76 to 104 cm (29.9 to 40.9
inch). Maximum levelling speed (height
adjustment):- 2 cm/s (0.8 inch/s).Table tilt:L-arc position Angulation
(degrees) Rotation (degrees)Head-end of table 45 Caudal to 45
cranial 27 RAO to 115 RAO85
04/11/2023 8686
Examination lightLight intensity: 30,000 Lux.
Colour temperature: 4300° K.
Focusable light field size: 14 - 25 cm (5.5
- 9.8 inch).
Working distance: 70 -140 cm (27.6 -
55.1 inch).
Light intensity at 30,000 Lux: 114 W/m2.
Lamp type: halogen 22.8 / 24 V 50 W.
Mains power: 220/240 V.
86
04/11/2023 87
Quality Assurance
Weekly 3D calibration is carried out. The calibration data is valid for only 14 days (7 days pre- and post- acquisition).
The calibration is to rectify S-distortion as well as pin cushion distortion.
S-distortion is caused by geo- magnetic field s on moving electrons within the Image Intensifier and pin cushion distortion is caused by the curvature of the input phosphor of the Image Intensifier.
04/11/2023 8888
Radiation Protection- Dose reductionDoseWise is active throughout at every level of system
- from spectra beam, pulsed fluoroscopy to syncratouch. It ensures every possible opportunity to
reduce dose, while maintaining image quality.
DoseWise includes three highly effective strategies for dose management:
Spectra Beam technology to remove unwanted ‘soft’ radiation and minimize scatter radiation, automatically. Spectra Beam filters during fluoro and exposures remove unwanted soft radiation, i.e. those X-rays that hit the patient but do not have enough energy to reach the image detector. In this way, filtering significantly reduces patient dose and scattered radiation for staff while maintaining a high image quality.
88
04/11/2023 8989
Advantages Dose reduction3-D road mappingXper CTBolus ChaseQuantitative analysis packages
89
04/11/2023 90
DIS-ADVANTAGES OF DSA
Mis-registration .
Poor resolution compared to conventional
angiography. User dependent success rate. Risk of emboli may reaching to healthy
tissue. Not suitable for everyone.
04/11/2023 9191
ConclusionDespite recent advances in CT angiography and MR
angiography, digital subtraction angiography (DSA) remains the standard imaging technique for evaluation of the cerebral vasculature .
Three-dimensional (3D) reconstruction of the dataset acquired during rotational DSA represents the latest development in the neurovascular imaging armamentarium.
This technique combines the anatomic resolution of DSA with the 3D visualization abilities previously offered by only CT or MR angiography and provides more detailed information than does DSA alone in the evaluation of neurovascular lesions, such as cerebral aneurysms .
3D-DSA has taken a prominent role in treatment planning by enabling better appreciation of the morphology of complex vascular lesions before endovascular or surgical management.
It is also superior in the performance of sophisticated tasks such as aneurysm volume measurement
On the other hand, the inability of 3D-DSA to simultaneously image osseous and vascular structures is noted as a weakness of this technique compared with CT angiography .
91
04/11/2023 92
THANK
YOU
92