4.

Pabmaz

JC,

Windeler

Atherosclerotic

SA,

rabbit

intraluminal

Garcia

grafting.

expanding endovascular mental atherosclerosis.

F, et al.

aortas:

expandable

Radiology

1986; 8.

Duprat Wallace expanded gy

6.

Irving

162:276-278.

Putnam

JS,

Uchida

BT,

Antonovic

9.

R,

Rosch J. Superior vena cava syndrome associated with massive thrombosis: treatment

with

expandable

ogy 1988; Rousseau

7.

wire

stents.

JD,

Radiol-

C, et al.

Self-

10.

Concave

Charnsangavej

Index terms: Angiography, 91.1299, 95.1299, 951.1299, 952.1299 . Angiography, technology Filters

of angiographic

images

density A wedge

commonly but it may

used create

have filter

limited is the

compensating filtration

efmost

filter, artifacts and,

depending on how much of the filter is placed in the path of the primary beam, it may require in exposure.

A good

compensating

produce ty, cause position, crease in

Texas

a considerable

increase

filter

M.D.

Anderson

Cancer

open-floored concentric

Center,

structed shoulder

ogy, tional

the

Section

Department

of Diagnostic

of Angiography

Radiology,

Box

57,

and the

as M.D. Anderson Cancer Center, combe Blvd. Houston, TX 77030. 30,

1990;

revision

requested

Interven-

University

August

of Tex-

1515 HobReceived May 6; revision

received September 13; accepted September Address reprint requests to C.H.C. c RSNA, 1991

578

Radiology

#{149}

20.

161:295-298. Furui 5, Sawada

5, brie

vena

of two metallic

Dahbke

H, Dociu

genicity

edge hole

and

of the filter was conthe

(eg, same

the outby 2.5 by 6

was

with

used

two

[T;o

of which

Lanex

film

Figure

were

regular

(Eastman

1.

Schematic drawing compensating

floored concave (top) and lateral

peak

made

and

with

was

by

the

and

filter.

In

the

usually

to

tion

x

this

vary

man-

out” of adjusted the

institution, a field to

celiac without

Thus,

angiogra-

the

the

are included

entire

lateral

area

walls

in the field

performed

(25

X

of

of the

in

small patients and excluded in larger patients. The standard exposure factors for celiac angiognaphy are 75 kVp and

size.

time den-

The

filter

collimator.

with

a magnifica-

of 1.3 times and a field of 12 (30 X 30 cm), which may

according

timal

magnifica-

of 10 X 13 inches

include

patient’s the

to liven

size.

The

dand exposure factors used in of both sexes are 75 kVp and station to obtain a small focal duce image unshanpness. To

density. is performed

on

factor 12 inches

loss in den-

ner, the filter prevented “burn the less dense areas while the milliampere second maintained

a given

with an exposure an optimal film

Selective hepatic angiognaphy is performed after catheterization of the hepatic artery or one of its branches. It is

the comkilovolt

adjusted

for the overall

caused

milliam-

at 75 kVp,

second

compensate

an optimum

When used, the

maintained

milliampere

views.

screens

a variable

pene second technique. pensating filter was

(bottom)

of the openfilter. Frontal

Kodak,

for

vessel.

as

microsco14:251-268.

17.7 cm2 of It has an

is centered

abdomen

electron Res 1980;

in

sity

the

Thrombo-

materials

demon-

decreased reduced

were

with

K.

suture

revealed by scanning py. J Biomed Mater

Exposures

cm)

expandable 1990; 176:665-

N, Thurau

of different

mA station will produce

32.5

Hepatic treatment

670.

12.

600 that

tion

T, et al.

obstruction:

types with Gianturco stents. Radiology

Rochester, NY). Selective celiac, hepatic, shoulder, and pelvic angiography was performed with use of the filter.

sity

cava

ex1986;

for Anglography’

wedge,

with

TMH-1

was

prelimi-

5,

diameters thickness

both

equipped

kilovolt

cava:

concave design with a wedge with a slope of 1/3

Conn),

and

vena

of treatment with stents. Radiology

Methods

in the concentric

ton,

of the

assessment pandabbe metallic

inferior

imagems, the General Electric MSI 1250 IV (GE Medical Systems, Milwaukee) and the Philips Poly Diagnost I (Shel-

phy

Radiob-

that,

has

for some applications angiognaphy) with

At our From

a filter

boned through the center (Fig 1). A smaller version

overall 1

Wallace

starting 2.5 cm from the outer terminating in a 5.1-cm radius

peak

should

a radiograph of uniform densino artifacts due to its shape or and require little on no inexposure. At the University of

CH,

was made from stock aluminum.

en and inner cm, and the mm. The filter

is often less than optimal because variations in body density result in aneas of oven- or underexposure within a field. Most filters designed to equalize

radiographic fectiveness.

and

The filter 1.3-cm-thick

slope

178:578-579

quality

11.

Filter

constructed

Materials

HE

C, Carrasco

most of its applications, strated these characteristics.

An open-floored concave compensating filter was designed that produced a radiograph of uniform density, caused no artifacts due to its shape or position, and required little or no increase in exposure in most applications. Selective celiac, hepatic, shoulder, and pelvic angiography was performed with use of the filter; image quality was noticeably improved.

T

R, Dondebinger

Compensating we have

James M. Johnston, RT(R) C. Humberto Carrasco, MD William R. Richli, MD Lee M. Marsh

1991;

A, Dick

175:97-102.

167:727-728. H, Joffre F, Railbat

Open-floored

Radiology

Adam

Stenosis

nary

RF, Lunderquist A, Roche A. Gianturco expandable metallic bibiary stents: results of a European clinical trial. Radiology 1989; 172:321-326. Strecker EP, Liermann D, Barth KH, et al. Expandable tubular stents for treatment of arterial occlusive disease: experimental and clinical results. Radiology 1990;

G Jr. Wright KC, Charnsangavej C, 5, Gianturco C. Flexible balloonstent for small vessels. Radiobo-

1987;

et al.

170:773-778.

160:723-726.

5.

stent in expeniRadiology 1989;

density,

the

exposure

time

varies according to the patient’s size. Magnification is not possible in patients with abdomens thicken than 27 cm because the required exposure time exceeds the safety limits of the small focal spot. The filter is positioned so that

a

film

stan-

patients a 160 mA spot to meobtain op-

penior

its

thickest and

lateral

portion portion

is over of

the the

February

su-

liver.

1991

Pelvic

angiography

of selective

nab iliac arteries usual magnification

with

usually

angiognaphy

a field

consists

of both

inter-

or their branches. The factor is 1.3 times

of 13

X

13 inches

(32.5

X

32.5 cm). The standard exposure factors used are 75 kVp and 160 mA to obtain a small focal spot. The exposure time vanies according to the patient’s size. The

concave on

compensating

filter

the collimator. Shoulder angiography

after catheterization tery or its branches. factor of 1.3 times

is performed

and

a.

of the axillary anA magnification with a field of 10 X

12 inches (25 X 30 cm) tam a small focal spot,

of 70 kVp

is centered

is used. exposure

are

sels

used. Exposure time shoulder thickness.

varies according The smaller yen-

sion

compensating

of

the

concave

on the of the lateral of the axilla.

Results

lateral

abdominal

use

of the filter in celiac with abdomicm and whose

walls

were

quired a one-step increase in exposure time; men with similar abdominal thickness required a two-step increase.

required

an increase

exposure en patients, ten of the ed in the ed loss in

time. However, in these langmost of the thicker penimeconcentric wedge was includfield, resulting in an unwantopacity. Thus, in these

patients,

the

did

not

improve

with

similar

abdominal

tients

with

18-20-cm-thick

step

increase

few

patients

2

one

in

im-

in exposure

studied

so the

step

for

with 21a two-

time.

with

thinner,

the filter overlaid while the thicken rays penetrating tissues. In patients

more

In the

abdomens

central

the bony periphery the

of

structures filtered

the soft

in these

sage

patients

of the beam

resulted

through

portions of the filter, which the exposure increase. Shoulder angiography.-Although

smaller

in pas-

the thicker required

the version of the concave compenfilter required an average inof three steps in exposure time, quality

considerably

in shoulder

hepatic, pelvic, the greatest in selective he-

with magnification. large opacity difwithout increase

causing in the

factors was necessary in some and, in those in whom it was

required, the increment was cept in shoulder angiography, it was

relatively

raphy

of large

large.

on

half

In

patients,

improvement in image warrant the relatively exposure time. A similar result can pelvic angiography by fenior

portion

surrounding with abdomens

of celiac, angiognaphy; occurred

within a field artifacts. An

exposure instances,

filter

than 21 cm thick, a one-step expoincrease was required. The larger

sure field

image

Number

and

Pelvic angiography.-The use of the concave compensating filter in patients with 14-21-cm-thick abdomens requimed no increase in exposure factors. The beam was collimated to the small

was

#{149}

men

open-floored concave compenfilter noticeably improved the

ferences filtration

of

livers.

sating

178

for

increase

The sating

patic angiography The filter decreased

Pa-

abdomens

time

Discussion

image quality and shoulder improvement

measuring 24-29 cm thick, a three-step increase in exposure time was necessany. Image quality was improved in all patients except those with very large

crease

Volume

thickness.

an exposure

steps

pelvis

In these patients, the filter noticeably improved image quality (Fig 2). Patients of both sexes with abdomens measuring 20 cm or more in thickness

filter

selective heof male patients abdomens, the use

angiography.-In

angiography 15-17-cm-thick

women. Patients of both sexes 23-cm-thick abdomens required

one step in exposure time. The other factors remained unchanged. Women with 16-18-cm-thick abdomens ne-

age quality.

better.

of the concave compensating filter required an average increase of one step in exposure time. No change in exposure time was necessary for women

two

included

steps

Hepatic

patic with

required

in the field did not require an increase in exposure time. Inclusion of the lateral abdominal walls within the field allows more primary rays to strike the film, causing an increase in its overall blackness. Men with abdomens of simibar thickness required an increase of

of three

is considerably

to

filter

previously described is positioned the collimator and centered on shoulder joint. The periphery filter ovenlies the superior and aspects of the shoulder, the apex lung, and the soft tissues of the

Celiac angiography.-The concave compensating angiognaphy in women nal thickness of 13-15

2. Angiograms of the superior mesentenic artery (instead of celiac angiography in type IX hepatic artery anatomy), arterial phase. (a) Angiogram obtained without filtration. There is considerable overexposure of the lateral aspect of the right lobe of the liver due to differences in tissue density. (b) Angiogram obtained with filtration. The field has a less heterogeneous appearance. The visualization of the lateral aspect of the right lobe and its yes-

To obfactors

a 100 mA station

b.

Figure

the

celiac

the

angiog-

marginal

quality did not large increase in be achieved in using a wedge

collimator

covering

of the pelvis,

thicker portion half filter can

small, exin which

the

with

positioned also be used

in-

the

caudally. A in the same

manner. However, both of these filters require an increase in exposure factors and leave a noticeable filtration artifact. In other uses, such as hepatic angiography, the required increase in exposure

factors

with

wedge

or half

filters

would be large because of their design and position. In addition to its uses in angiography,

the

concave

compensating

has potential applications diography of the shoulder and in barium men. U

studies

filter

in routine and pelvis

of the

ra-

abdo-

angiography

improved.

Radiology

579

#{149}