U.S. patent number 3,710,118 [Application Number 05/040,944] was granted by the patent office on 1973-01-09 for radioisotope generator.
This patent grant is currently assigned to Mallinckrodt Chemical Works. Invention is credited to Richard L. Holgate, James R. Montgomery.
United States Patent |
3,710,118 |
Holgate , et al. |
January 9, 1973 |
RADIOISOTOPE GENERATOR
Abstract
A generator is provided for eluting a daughter radioisotope from
a parent radioisotope. The generator is characterized by an
elongate closed vessel having a convergent closed lower end and
containing therein a supply of a parent radioisotope material
spaced from the closed lower end. The vessel is closed at its upper
end with a closure through which extends a first conduit
communicating with the upper end of the vessel for introducing an
eluant into the vessel. Also extending through the closure is a
second conduit communicating with the lower end of the vessel which
provides for passage of eluate from the lower end of the
vessel.
Inventors: |
Holgate; Richard L. (Creve
Coeur, MO), Montgomery; James R. (St. Louis County, MO) |
Assignee: |
Mallinckrodt Chemical Works
(St. Louis, MO)
|
Family
ID: |
21913849 |
Appl.
No.: |
05/040,944 |
Filed: |
May 25, 1970 |
Current U.S.
Class: |
250/432R;
250/432PD; 250/493.1 |
Current CPC
Class: |
G21G
4/06 (20130101); G21G 1/0005 (20130101) |
Current International
Class: |
G21G
4/06 (20060101); G21G 4/00 (20060101); G21h
005/00 () |
Field of
Search: |
;250/16T,16SC,16R,16S |
References Cited
[Referenced By]
U.S. Patent Documents
|
|
|
3564256 |
February 1971 |
Arlman et al. |
|
Primary Examiner: Lawrence; James W.
Assistant Examiner: Willis; Davis L.
Claims
What is claimed is:
1. A generator for eluting a daughter radioisotope from a parent
radioisotope comprising an elongate closed vessel having an
integral convergent closed lower end and containing therein a
supply of a parent radioisotope, means in said vessel spaced from
the lower end thereof for maintaining the supply of the parent
radioisotope spaced from said lower end, a closure for the upper
end of said vessel, a first conduit extending through said closure
and communicating with the upper end of the vessel for introducing
an eluant into the vessel and a second conduit extending through
said closure and said supply and said means and communicating with
the lower end of the vessel for passage of eluate from the lower
end of the vessel.
2. A generator according to claim 1, characterized in that the
vessel comprises a glass tube having a hemispherical lower end, the
closure comprises a stopper in the upper end of the tube, the means
for maintaining the parent radioisotope spaced from its lower end
comprising a filter mounted in the tube above its lower end, the
parent radioisotope being confined between the filter and the
stopper, the first conduit extending down through the stopper and
terminating immediately below the stopper, the second conduit
extending down through the stopper and the filter to the lower end
of the tube.
Description
BACKGROUND OF THE INVENTION
This invention relates to the generation of radioactive isotope
solutions and more particularly to an improved generator for the
generation of a daughter radioisotope from a parent
radioisotope.
The invention is particularly concerned with the preparation in a
sterile closed system of a solution of a daughter radioisotope,
such as technetium-99m, generated from a parent radioisotope, such
as molybdenum- 99. Conventionally, the preparation of a daughter
radioisotope from a parent radioisotope has been carried out using
a generator containing the parent radioisotope and an anion
exchange medium or other medium, such as alumina, having a high
adsorptive capacity for the parent radioisotope but a low
adsorptive capacity for the daughter radioisotope. The desired
daughter radioisotope is eluted by washing with a suitable solvent
or eluant such as a sterile, pyrogen-free isotonic saline solution.
The resulting eluate containing the daughter radioisotope in the
form of a dissolved salt is useful as a diagnostic agent, for
example, and is adapted for intravenous administration.
The generator containing the parent radioisotope adsorption medium
for eluting the daughter radioisotope is frequently referred to in
the art as a "cow", and the elution of the daughter radioisotope
therefrom is generally referred to in the art as "milking the
cow".
Some widely used daughter radioisotopes used in medical diagnosis
have relatively short half-lives, e.g., 6 hours, and it is
important therefore that they be generated or prepared shortly
before usage in the hospital, clinic or other place of use. Thus,
there is need, for example, for apparatus enabling generation and
containerization under sterile conditions once a day in a hospital
or clinic of the eluate, also under conditions wherein the user of
the apparatus is afforded maximum protection against radioactive
emission from the generator. Prior apparatus for the purpose, such
as disclosed in U.S. Pat. Nos. 2,942,943, 3,369,121 and in the
copending coassigned U.S. Pat. application of Donald J. Shumate,
Ser. No. 658,872, filed Aug. 7, 1967, now U.S. Pat. No. 3,535,085
entitled Closed System Generation and Containerization of
Radioisotopes, has not been wholly satisfactory, primarily on
account of the necessity for carrying out a number of hand
operations while the shield for the generator is open, thus
exposing the hands and possibly other parts of the operator to
radiation. Since the decay characteristics of most of the
parent-daughter radioisotope combinations presently in large-scale
use require that the generator (the "cow") be "milked" daily, the
use of the above prior devices undesirably involves daily exposure
of the operator to radioactivity during the "milking"
operation.
The most widely used prior art generators are of the column type
which generally consist of a glass tube closed at both ends with
rubber stoppers or closures. In addition to the amount of handling
involved in the use of such generators, the necessity for rubber
closures or seals at both ends of the tube increases the
possibility of fluid leaking, especially with respect to the lower
end closure, and therefore decreases the reliability of such
generators.
SUMMARY OF THE INVENTION
Among the objects of the invention may be mentioned the provision
of an improved generator for the generation of a daughter
radioisotope from a parent radioisotope; the provision of such a
generator which is less subject to leaks occurring at the single
closure therefor; and the provision of a generator of this type
which may be used in connection with either a pressure system or a
vacuum system. Other objects will be in part apparent and in part
pointed out hereinafter.
The present invention is thus directed to a generator for eluting a
daughter radioisotope from a parent radioisotope comprising an
elongate closed vessel having a convergent closed lower end and
containing therein a supply of a parent radioisotope, means in the
vessel spaced from the lower end thereof for maintaining the supply
of the parent radioisotope spaced from the lower end, a closure for
the upper end of the vessel, a first conduit extending through the
closure and communicating with the upper end of the vessel for
introducing an eluant into the vessel and a second conduit
extending through the closure and said means and communicating with
the lower end of the vessel for passage of eluate from the lower
end of the vessel.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective of an apparatus with a generator made in
accordance with this invention, a plastic case of the apparatus
being illustrated as transparent for viewing interior detail;
FIG. 2 is a plan of the FIG. 1 apparatus;
FIG. 3 is a view in elevation of the apparatus, showing a container
in position for receiving the eluate eluted from the generator of
the invention in the case;
FIG. 4 is a vertical section on line 4--4 of FIG. 2;
FIG. 5 is a vertical section on line 5--5 of FIG. 2;
FIG. 6 is a horizontal section on line 6--6 of FIG. 3;
FIG. 7 is an enlarged fragment of FIG. 4 showing a plunger and
tubular needle of the apparatus driven downward with the needle
pierced through the stopper of the container; and
FIG. 8 is an enlarged vertical section of the generator or "cow" of
the invention.
Corresponding reference characters indicate corresponding parts
throughout the several views of the drawings.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The generator according to the instant invention shall be described
in connection with the total apparatus system for eluting a sterile
daughter radioisotope from a parent radioisotope and containerizing
the resultant eluate in an evacuated container, as disclosed in the
copending and coassigned application of James R. Montgomery and
Lloyd G. Struttman, Ser. No. 779,793, filed Nov. 29, 1968, now U.S.
Pat No. 3,655,981 dated Apr. 11, 1972. However, it should be
understood that the generator of the invention is not limited to
use in such apparatus and can be used in various other total
apparatus systems.
Referring to the drawings, a generator or "cow" 1 of the invention
is shown as containing a sterile pyrogen-free supply 3 of a parent
radioisotope. The generator is enclosed in a shield 5 for shielding
the user of the apparatus against radioactive emission from the
generator. At 7 is indicated means for holding a sterile
pyrogen-free supply of an eluant with the eluant under atmospheric
pressure. An eluant conduit 9 extends from means 7 through the
shield and into the generator.
At 11 is indicated a tubular fitting adapted for attachment thereto
at one end (its lower end) of a tubular needle 13, which may be a
conventional hypodermic needle. The apparatus shown, as will
appear, provides for the sealed sterile containerization of a
sterile pyrogen-free eluate eluted from the parent radioisotope in
a sealed sterile evacuated container or vial 15, shown as
comprising a glass bottle having a neck 17 sealed at its upper end
by a closure 19 adapted to be pierced by the needle 13. Closure 19
may be a conventional rubber stopper, and is shown as having an
aluminum foil cover 21. This cover has a removable circular central
section, shown removed in FIGS. 1 and 7 leaving an opening 23 in
the cover.
Means generally designated 25 is provided for mounting the tubular
fitting 11 (and needle 13) for movement away from the retracted
position of FIG. 3 in the direction of length of the needle to
cause the needle to pierce the closure or stopper 19. An eluate
conduit 27 extends from the generator through the shield and has a
flexible tubing portion 29 connected to the other end (the upper
end) of the tubular fitting 11 permitting the stated movement of
the fitting. At 31 is indicated means associated with the fitting
11 for effecting closure of the eluate conduit when the fitting is
in its retracted position and opening of the eluate conduit when
the fitting is moved downward to cause the needle 13 to pierce the
stopper 19 of the evacuated container 15, with resultant suctioning
of eluant from the eluant supply means 7 into the generator 1 for
eluting a daughter radioisotope from the parent radioisotope in the
generator and suctioning of the resultant eluate from the generator
through the eluate conduit 27, fitting 11 and needle 13 into the
evacuated container 15.
The generator 1, as shown, comprises an elongate cylindric vessel
33 constituted by a glass tube resembling a test tube having an
integral convergent closed lower end 35 of hemispherical form and a
neck 37 at its upper end. A pierceable closure constituted by a
rubber stopper 39 is plugged in the neck to seal the vessel. This
has an aluminum foil cover 41 from which a circular central section
has been removed. A fritted glass filter 43 is mounted in the
vessel just above its hemispherical lower end. The vessel 33 is
necked down as indicated at 45, and the filter is lodged in the
necked-down portion and bonded therein. The space below the filter
constitutes an eluate chamber 49, and the filter serves as means
for maintaining the supply 3 of the parent radioisotope spaced from
the lower end of the vessel, so that chamber 49 is maintained free
of the supply 3.
The filter 43 has a center hole 51. The eluate conduit 27 comprises
a length of relatively small diameter metal tubing 53 (e.g.,
stainless steel tubing) bent to have a vertical leg 55 and a
horizontal arm 57. The lower end of the vertical leg 55 is beveled
as indicated at 59. The vertical leg 55 extends down through the
stopper 39, its beveled lower end 59 permitting it to be pierced
through the stopper, and reaches down through the center hole 51 in
the filter 43 substantially to the bottom of the hemispherical
lower end 35 of the vessel 33. The hole 51 may be of substantially
larger diameter than the leg, and the latter may be sealed in the
hole by a suitable sealant, such as silicone rubber as indicated at
61.
The supply or charge 3 of the parent radioisotope is packed in the
vessel above the filter and surrounds the vertical leg 55 of the
tubing 53, which leg extends down generally centrally of the
vessel. The charge 3 comprises the parent radioisotope adsorbed on
an anion exchange medium, alumina or other suitable medium, in
granular form, and having under suitable conditions, a high
adsorption capacity or affinity for the parent radioisotope but a
low adsorption capacity for the daughter radioisotope. For
generation of technetium-99m, for example, the charge 3 in the
vessel may comprise molybdenum-99, in the form of ammonium
molybdate, as the parent radioisotope, adsorbed on alumina, the
latter constituting a medium having a high adsorption capacity for
ammonium molybdate Mo-99 but a low adsorption capacity for the
daughter technetium-99m compound in the presence of certain known
eluting solutions.
The eluant conduit 9 comprises a length of relatively small
diameter metal tubing 63 (e.g., stainless steel tubing) like tubing
53, bent to have a relatively short vertical leg 65 and a
horizontal arm 67. The lower end of the vertical leg is beveled as
indicated at 69. The vertical leg 65 extends down through the
stopper 39, its beveled lower end 69 permitting it to be pierced
through the stopper, and terminates just below the stopper. The
charge 3 substantially fills the vessel from filter 43 up to the
stopper, and leg 65 may reach down just into the top of the charge.
The eluant conduit 9 further comprises a length of flexible tubing
71 interconnecting the eluant supply means 7 and a fitting 73 on
the end of the arm 67 of tubing 63. As herein shown, the eluant
supply means 7 comprises a plastic bag or transfer pack containing
the eluant, this bag being subject to being squeezed by atmospheric
pressure, the bag having an outlet 75 from which flexible tubing 71
extends to the fitting 73 on the end of arm 67. The eluant may be,
for example, a sterile pyrogen-free saline solution which in the
case of elution of technetium-99m as the daughter radioisotope from
molybdenum-99, results in the daughter radioisotope being present
in the eluate as sodium pertechnetate.
As herein illustrated, the shield 5 for the generator comprises a
relatively thick-walled receptacle, which may be made of lead or
other suitable shielding material, formed to provide a cylindric
chamber 77 extending down from the top of the receptacle, and
formed with supporting legs 79. Chamber 77 has a diameter somewhat
greater than that of the generator 1 and a length (height) somewhat
greater than that of the generator. The receptacle is formed with
two diametrically opposite slots 81 extending down from its upper
end, and is closed, after insertion of the generator therein, by a
closure constituted by a plug 83 made of lead or other suitable
shielding material inserted in the upper end of the chamber. The
generator is inserted in the chamber with arms 57 and 67 of the
metal tubing portions 53 and 63 of the eluant and eluate conduits 9
and 27 extending laterally outward through the slots 81 at the
lower ends of those slots (the generator, in effect, being hung in
the chamber by engagement of arms 57 and 67 with the lower ends of
the slots). The plug has two ears 85 extending outward therefrom
diametrically opposite one another fitting in the slots and bearing
on the arms. The plug may be removably secured to the receptacle
(after insertion of the generator) as by adhesive tape (not shown)
or in any other suitable manner.
The shield 5 with the generator 1 sealed therein and the plastic
bag 7 containing the eluant are supplied in a case generally
designated 87. This case, which may be made of either transparent
or opaque plastic or any other suitable material, comprises a
bottom section 89 and a cover 91. The bottom section 89 has a
circular flat bottom plate 93, an internal cylindric wall 95
extending up from bottom 93 and concentric therewith, and an
external peripheral wall 97 extending up from the margin of bottom
93. Wall 97 is part cylindric, having a gap 99 therein spanning
somewhat less than 90.degree. of arc. Radial partitions 101 and 103
extend from the internal wall 95 to the peripheral wall 97, the
outer ends of these partitions (which lie in planes at right angles
to one another) being joined to the peripheral wall 97 on opposite
sides of the gap 99. Partitions 105 and 107 extend from the
internal wall 95 to the peripheral wall 97 diametrically opposite
partitions 101 and 103. A curved panel 109, convexly curved as
viewed from outside the case, extends between the vertical margins
of the peripheral wall 97 on opposite sides of the gap 99 in wall
97 and butts against the internal wall 95. This curved panel
defines a recess 111 opening inward from the respective side of the
case, bottomed by portion 93a of the bottom plate.
The walls 95 and 97 and partitions 101, 103, 105 and 107 are of
equal height, somewhat less than the height of the shield 5. The
curved panel 109 has an upward extension 113 of reduced width
extending up above the level of the top of walls 95 and 97 and the
partitions. The top of the recess 111 is closed by a horizontal
head plate 115 at the top of extension 113, this plate 115 having
an inner edge curved in correspondence with the curvature of the
panel, and an outer edge 117 curved on an arc centered in the
vertical central axis of the case bottom section 89 of radius
corresponding to the radius of the inside of the peripheral wall
97. Plate 115 has a centrally located vertical opening 119 and an
annular boss 121 extending upward around this opening.
The internal wall 95 has an internal diameter somewhat larger than
the cross section of shield 5 and defines a chamber 123 located
centrally of the case bottom section 89 receiving the shield. The
feet of the latter are confined within a centering ring 125
projecting up from bottom 93 of section 89 within the wall 95.
Partitions 105 and 107 in conjunction with walls 95 and 97 define a
compartment 127 receiving the plastic eluant bag 7.
The cover 91 comprises a cylindric external peripheral wall 129
having the same diameter as wall 97, and a cylindric internal wall
131 having the same diameter as wall 95. Radial partitions 133,
135, 137 and 139 (corresponding to partitions 101, 103, 105 and
107) extend between these walls. The upper rims of walls 129 and
131 are at the same level, but wall 129 extends down somewhat
farther than wall 131. Wall 129 has a relatively wide shallow notch
141 in its lower margin, the width of this notch corresponding to
the width of gap 99. Extending around the inside of wall 129 at the
lower end thereof from adjacent one side of the notch to the other
is a rim 143 which projects down below the lower edge of wall 129
an which has a telescopic sliding fit within wall 97 of the case
bottom section 89. The downwardly projecting portion of this rim
has notches 145 receiving the partitions 103, 105, 107 and 109.
Wall 131 defines a chamber 146 for the upper end of shield 5, and
has notches 147 at its lower end for passage of arms 57 and 67.
Chamber 146 is closed at the top by a circular top plate 149 spaced
somewhat below the upper end of wall 131 to provide a circular
compartment 151 for holding a supply of needles 13. A plate 153
closes the top of the space bounded by partitions 133 and 135 and
walls 129 and 131, and a plate 155 closes the top of the space
bounded by partitions 137 and 139 and walls 129 and 131, defining
oppositely located downwardly opening chambers 157 and 159. Plates
161 close the bottom of the space bounded by partitions 133 and 139
and the bottom of the space bounded by partitions 135 and 137 and
walls 129 and 131, defining two oppositely located upwardly opening
compartments 163 for holding a supply of evacuated bottles 15.
The means 25 for mounting the tubular fitting 11 includes a tubular
plunger 165 mounted for vertical sliding movement in the opening
119 in the plate 115 and in an aligned opening 167 in the plate 153
of the cover, these plates constituting a portion of the case 87
overhanging the recess 111. An annular boss 169 extends down from
plate 153 around the opening 167, and has an annular groove 171 of
inverted V-section in its lower end. The plunger has a plug 173 in
its lower end, the fitting 11 being received in an axial opening
175 in the plug. The fitting extends down from the plug for
attachment of the needle 13 to the lower end of the fitting with
the needle extending downward from the lower end of the fitting by
applying a ferrule 177 on the upper end of the needle to the lower
end of the fitting. The plunger has a lateral opening 179 (see FIG.
7) spaced from its lower end located between the plates 115 and
153. The flexible tubing portion 29 of the eluate conduit 27
extends through this opening and down through the plunger to a
connection at 181 with the upper end of fitting 11. The plunger has
an annular collar 183 thereon immediately below the opening 179
formed with an upwardly extending annular rib 185 of inverted
V-section matching the V-section groove 171 in boss 169. A coil
compression spring 187 surrounding the plunger reacts from the boss
121 against the collar 183 to bias the plunger upward toward its
raised retracted position in which it is illustrated in FIG. 4. A
knob 189 is provided at the upper end of the plunger. Axially
extending keys 191 on the plunger slide in keyways 193 at opposite
sides of opening 167 to prevent rotation of the plunger about its
vertical axis.
The collar 183 on the plunger 165 constitutes a movable jaw member
which functions in conjunction with boss 169 as a fixed jaw member
to pinch closed the flexible tubing portion 29 of the eluate
conduit where it extends into the opening 179 when the plunger is
biased upward to its raised retracted position by the spring 187
(see FIGS. 1, 3 and 4). The latter exerts sufficient upward force
on the plunger for this purpose. When the plunger is driven
downward against the return bias of spring 187, the pinch of the
tubing portion 29 is released and the eluate conduit is thus opened
for flow of eluate.
In manufacturing the generator of the invention, cylindric vessel
33 is first provided with fritted glass filter 43 as described
above. The center hole 51 in the filter is then covered with a
material such as a silicone rubber compound which is allowed (i.e.,
cure. The rubber stopper 39 is next plugged into the neck of vessel
33, and eluate conduit 27 (i.e., tubing 53) is inserted through
stopper 39 and hole 51 and sealed into the lower end of vessel 33
with its beveled end 59 in the position shown in FIG. 8. Stopper 39
is then pushed up without moving conduit 27 so as to permit loading
of the alumina substrate into vessel 33 through its open top. The
stopper is thereafter pushed down and the aluminum foil cover 41
crimped onto the top of vessel 33. The eluant conduit 9 (i.e.,
tubing 63) is inserted through stopper 39 to complete the assembly
of the generator. An acid solution, for example 0.1N hydrochloric
acid, is then introduced into the generator through eluant conduit
9 and withdrawn through eluate 27, after which a radioactive
ammonium molybdate solution is introduced into the generator
through eluant conduit 9 for adsorption onto the alumina to form
the supply 3 of parent radioisotope, The parent radioisotope may be
washed with hydrochloric acid introduced through eluant conduit 9
and withdrawn through eluate conduit 27 prior to sterilizing the
generator as by autoclaving.
The generator 1, containing the sterile pyrogen-free supply 3 of
the parent radioisotope, and itself being made sterile and
pyrogen-free (as by heating) is placed in chamber 77 in the lead
shield 5, and the latter is closed by the plug 83. The shield 5 and
the plastic bag 7 containing the supply of sterile pyrogen-free
eluant are placed in the bottom section 89 of the case 87, tubing
71 is connected to fitting 73, and tubing 29, extending from
fitting 11 out of the plunger 165 through opening 179, is connected
to a fitting 195 on the end of arm 57. The metal tubing and
flexible tubing portions of the eluant and eluate conduits and
fitting 11 are all in sterile and pyrogen-free condition, and it
will be understood that the needles 13 are supplied in sterile
pyrogen-free condition. The cover 91 of the case 87 is applied to
the bottom section 89, and secured thereto in any suitable manner,
as by adhesive tape, or by use of a solvent for the plastic of the
case and cover to cause them to become bonded together. The
containers or vials 15, as initially supplied, are sterile and
pyrogen-free and evacuated of air. They may have graduations marked
thereon for indicating volume of eluate drawn thereinto.
In the use of the apparatus, an evacuated container or vial 15,
held in a lead cup 197, is placed in the recess 111 of the case 87
with the stopper 19 of the vial in line with the needle 13 on the
lower end of the fitting 11. The plunger 165 is then manually
pushed downward against the upward return bias of spring 187 to
cause the needle 13 to pierce through the stopper 19 of the vial
(see FIG. 7) and simultaneously to effect release of the flexible
tubing portion 29 of the eluate conduit 27 by the jaw member 183 so
as to open the eluate conduit. This results in suctioning of the
eluant from the eluant supply bag 7 (which is under atmospheric
pressure) through the eluant conduit 9 into the generator 1 for
eluting the daughter radioisotope from the parent radioisotope in
the generator. The resultant eluate passes down through the filter
43 into the eluate chamber 49 at the lower end of the generator,
and is suctioned upward through leg 55 of metal tubing 53 and
thence through flexible tubing portion 29 of the eluate conduit 27,
and fitting 11 and needle 13 into the evacuated vial 15. The
plunger 165 is held down until the desired amount of eluate has
been suctioned into the vial, and then released to be returned to
its raised retracted position by the spring 187, resulting in
pinching of the flexible tubing portion 29 of the eluate conduit 27
to cut off further flow as might otherwise occur due to siphoning
action. The filled vial is then taken away for ultimate use, and
the apparatus is ready for the next "milking" operation.
It will be observed that the "milking" operation is carried out
without opening of the shield 5, hence does not involve any
exposure of the operator to radiation from the generator 1. The
latter at all times remains essentially sealed within the shield,
which is made of lead or other suitable material for shielding
against radioactive emission from the generator. After the first
"milking" operation, there will be some eluant in the eluant
conduit 27 from the shield to where the flexible tubing portion 29
of the eluant conduit is pinched between jaw members 183 and 169,
but radiation from this amount of eluant is minor.
While, as above described, the elution is by use of an evacuated
container 15 and suctioning of the eluant into the generator and
the eluate out of the generator (i.e., a vacuum system), the
principles of the invention are also applicable to a pressure
system, as distinguished from a vacuum system, using a nonevacuated
container or vial, and in which the eluant supply would be under
pressure above atmospheric pressure or adapted for flow by gravity
through the generator into the vial, and a vent would be provided
in the stopper of the vial.
As can be seen from the above, the provision of a vessel integrally
closed at one end eliminates one stopper closure and hence one
possible source of leaks of radioactive solution from the
generator. The generator of the invention also eliminates one
possible source for loss of sterility of the system. Further, the
arrangement of the eluant and eluate conduits, even if not
connected to a completely closed system as described above reduces
the amount of handling necessary in using the apparatus.
Similarly, although the vessel has been described above as
vertically disposed with its open end up, it should be apparent
that other orientations of the vessel are possible and within the
scope of the instant invention.
In view of the above, it will be seen that the several objects of
the invention are achieved and other advantageous results
attained.
As various changes could be made in the above constructions without
departing from the scope of the invention, it is intended that all
matter contained in the above description or shown in the
accompanying drawings shall be interpreted as illustrative and not
in a limiting sense.
* * * * *