de Goeij, J.J.M.

Janssen, Anton G.M.

Wijnhoven, G.P.J.

Witsenboer, A.J.

English

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 An extension set for 81Rb-81mKr solution generators for lungventilation studiesCitation for published version (APA):Janssen, A. G. M., Witsenboer, A. J., de Goeij, J. J. M., & Wijnhoven, G. P. J. (1989). An extension set for 81Rb-81mKr solution generators for lung ventilation studies. Abstract from 7th International Symposium onRadiopharmaceutical Chemistry, Groningen, The Netherlands, Groningen, Netherlands.Document status and date:Published: 01/01/1989Document Version:Accepted manuscript including changes made at the peer-review stagePlease check the document version of this publication:• A submitted manuscript is the version of the article upon submission and before peer-review. There can beimportant differences between the submitted version and the official published version of record. Peopleinterested in the research are advised to contact the author for the final version of the publication, or visit theDOI to the publisher's website.• The final author version and the galley proof are versions of the publication after peer review.• The final published version features the final layout of the paper including the volume, issue and pagenumbers.Link to publicationGeneral rightsCopyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright ownersand it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.            • Users may download and print one copy of any publication from the public portal for the purpose of private study or research.            • You may not further distribute the material or use it for any profit-making activity or commercial gain            • You may freely distribute the URL identifying the publication in the public portal.If the publication is distributed under the terms of Article 25fa of the Dutch Copyright Act, indicated by the “Taverne” license above, pleasefollow below link for the End User Agreement:www.tue.nl/taverneTake down policyIf you believe that this document breaches copyright please contact us at:openaccess@tue.nlproviding details and we will investigate your claim.Download date: 08. Jul. 2024AN EXTENSI0N SET F0R 81Rь-81mкr S0LUTI0N GENERAT0RS F0R LUNG VENTILATI0N STUDIES A. G.M . Janssen1 , A.J. Witsenboer1 , J.J.M. de Goeij 1 •2 , and G.P.J. Wijnhoven1 , IRI-REP0RT 133-88-08 IRI-REP0RT 133-89-06 1) Cyclotron Group, Department of Physics, Eindhoven University of Technology, Р.О. Вох 513, 5600 МВ Eindhoven, The Netherlands; 2) Interfaculty Reactor Institute, Delft University of Technology, Mekelweg 15, 2629 JB Delft, The Netherlands Reprint from: Abstract Book , Seventh International Symposium on Radiopharmaceutical Chemistry {Groningen, The Netherlands , 4 - 8 July 1988), Department of Nuclear Medicine, University of Groningen, Groningen, The Netherlands (1988) page 478. and Journal of Labelled Compounds and Radiopharmaceuticals, 26 (1989) 478-480 . AN EXTENS I ON SET FOR 81Rb- 81mKr SOLUTION GENERATORS FOR LUNG VENTILATION STUDIES. A.G.M. Janssen (1), A.J. Witsenboer (1), J.J.M. De Goeij (2), and G.P.J. Wijnhoven (2). (1) Department of Physics, Eindhoven University of Technology, Р.О.Вох 513, 5600 НВ Eindhoven, The Netherlands, (2) Interuni·,ersity Reactor Institute, Mekelweg 15, 2629 JB Delft, The Netherlands Recently, an increasing number of clinical applications of вimкr has been reported involving intravenous administration of the radionuclide dissolved in an isotonic solution. At present, generators of different design are being used: the so-called "gas generators" for ventilatioв studies a!'ld "solution generators". The former are used for elution with air and the latter with isotonic solutions. The actual situation is that solution generators are practically not suited for elution with air, while gas generators cannot Ье used for elution with solutions. А rnore efficient and economic use of 81 Rb may Ье achieved when solution generators can Ье eluted alternately with an isotonic solution for intravenous administration and with air for ventilation studies. The idea of operating а solution generator with а continuous flow of air appears to conflict with the fulfillroent of two basic requirements to the solution generator. First, а continuous flow of air for prolonged tirnes demands humidified air to prevent the generator from running dry, with the risk of deteriorating the sterile state obtained Ьу aseptic preparation. Second, after elution with air the efficiency of elution with an isotonic solution may become substantially lower, possiЬly due to channel formation. Therefore, we have considered another approach, viz. Ьу operating the solution generator only in the solution mode, thus ensuring its integrity. Gaseous 01 mкr is obtained Ьу stripping the aqueous eluate with а stream of air in а ЬuЬЫе column connected· as an extension set to the solution generator. The generator can now Ье operated alternately in а "perfusion mode" and in а "ventilation mode" and vice versa Ьу simply switching а three-way valve (Fig.1). This study aims at proving the feasibility of this approach based on а prototype and furthermore to get more insight into the parameters of interest for an optimum design of the ЬuЬЫе column and its operating conditions. А theoretical model descriЬing the efficiency of the system, which is mainly lirnited Ьу aqueous phase diffusion of в1mкr, was puЫished elsewhere [1). In Fig.1 the prototype of the bubЫe-column extension set is presented schema-tically. The set consists of three concentric perspex cylinders on а bottom plate, with internal diameters of 60 mm, 80 mm, and 200 mm respectively, each with а height of 180 rnm. At the top they are sealed with а removaЫe lid. The inner cylinder (1) is the ЬuЬЫе column with an air injection plate (6) at the bottom. The solution feeding pipe (3) with 1 mm internal diameter and 200 mm length, ends 10 mm above the bottom plate. The annular space (9) between the middle and outer cylinder serves as waste collection vessel. The annular space between the inner and middle cylinder contains а 3 mm thick lead shielding (2). Inside the ЬuЬЫе column а draught pipe (2) is inserted, consisting of а thin-walled (1 mm thick) perspex cylindrical wall with an inner diameter of 50 mrn and а height of 110 mm. The draught pipe ends 10 mm above the waste di s-charge pipe (10) and 10 mm below the spray trap (7,8). The lower end of the draught pipe is provided with circular holes (5 mm diameter). Insertion of this draught pipe results in а more regular bubЫing pattern and higher gas hold-up enaЫing an improvement of the stripping efficiency. Since water can always flow over the edge of the top of the draught pipe into the annular space, flooding of the ЬuЬЫе column (resulting in water entrainment Ьу air) is suppressed in this way . 13 G· ,, 18 -.--.-ь:r~~~---t=-=~~ ,i ~--t-10 solution 9E!nerator f>lfnsion set ou,ous 81 m Kr Figure 1. Schematic presentation of the combination of solution generator and extension set ; (1) ЬuЬЫе column ; (2) lead shielding; (3) solution feeding pipe ; (4) and (5) air in/out tubes, 4 mm ID ; (6) ЬuЬЫе injection plate, with 32 orifices of 0.3 mm , (7) and (8) spray trap; (9) solution waste collection; (10) solution discharge pipe from ЬuЬЫе column to waste; (11) channel for pressure discharge of waste compartment; (12) draught tube, 50 mm ID; (13) sterile 5% glucose solution bag; (14) peristaltic pump for glucose solution (15) solution generator ion exchange column; (16) lead shieldi11g; (17) sterile filter; (18) sterilised three-way valve, connected to sterilised 0.8 mm ID polyethylene tubing conveying solution; (19) air pump, operated at 2-4 L min- 1 • Measured and theoretical overall yields ar~ presented in Fig. 2; the separate points denote the experirnental values, while the solid curves refer to the theoretical values. Both experimental and theoretical data involve the following conditions: air flow rates between 0.5 and 4 L min- 1 in the presence as well as in the absence of the draught pipe. А ЬuЬЫе injection plate with 0.3 mm orifices was used. The curves III and IV involve а temperature of 20 °С, while curve V (with associated pointsi involves а temperature of 50 °С. At flow rates corresponding to superficial gas velocities (i.e. the ratio of flow rate to cross section area) higher than са .022 m s- 1 , water entrainment and coa-lescence of bubЫes tend to occur. 50 ~ .> 30 о >-10 air flo1,· r а le, L min·' 1 1 1 1 1 .. 1 2 R • 50mm 2R-60mm : , 1 1u•0.022m.s· 1 1 Figure 2. Measured overall 01 mкr recovery yields from the combination of the solution generator and the extension set as а function of the applied air flow rate. О: 60 mm internal column diameter, О: 50 mm internal column diameter, + : 50 mm internal column diameter at а solution temperature of 50 °С. _The solid curves III, IV, and V were calculated. Air flow rates corresponding to а superficial gas velocity of 0.022 m s- 1 are indicated for the 60 mm and the 50 mm column diameters . The maximum overall yield obtained for а temperature of 20 °С of the solution in the ЬuЬЫе column amounts to са 41% at an air flow rate of 2. 5 L min- 1 , using а column diameter of 50 mm (draught pipe inserted) and а ЬuЬЫе injection plate with orifice diameter of 0.3 mm. According to the theoretical model, at these conditions the relative losses in the separate compartments are as follows: 15% in the solution generator, 8. 0% in the connecting tubing due to decay, 39% in the ЬuЬЫе column due to incomplete stripping, 0.8% due to spill-over, and 14% in the gas phase of the ЬuЬЫе column due to decay. Thus, the main factor reducing the overall yield is the low stripping efficiency (61%). The stripping efficiency is limited Ьу the transfer via diffusion of в 1 mкr dissolved in water to the gas phase. This process, being relatively slow, causes substantial decay of вimкr in the water phase. The most effective way of improving the overall yield must Ье sought in increasing the availaЫe interfacial surface area Ьу increasing the volumetric gas fraction or decreasing the ЬuЬЫе diameter (for instance Ьу stirring), or Ьу increasing the diffusion rate Ьу operating the extension set above room temperature. With the combination of а 81 Rb/ 01 mкr solution generator and the prototype of the extension set for production of gaseous 81mKr, an overall yield of са 41% may Ье achieved, provided (i) minimum volumes are used for the connecting tubing to the feeding solution generator, (ii) the inner diameter of the ЬuЬЫе column is matched with the desired air flow rate to obtain а superficial air velocity close to 0.02 m s- 1 , and (iii) adequate ЬuЬЫе injection orifices are applied. Furtherrnore, improvement of the overall yield to at least 60% appears feasiЫe Ьу an increase of the temperature of the aqueous phase in the ЬuЬЫе column and particularly Ьу stirring, possiЫy in combination with addition of electrolytes. When using the extension set in combination with а 740 MBq (20 mCi) solution generator, an equivalent of а ventilation generator output of 305 MBq (8.2 mCi) is achievaЫe. Since the yield of ventilation generators is usually between 90 and 95%, this output corresponds to а nominal ventilation generator strength of 320 to 340 MBq (8.6-9.1 mCi). This compares well with the activity range of 220-440 MBq (6-12 mCi) of the usual ventilation generators. Thus, the simple extension set rnay Ье а useful and inexpensive enlargement of the clinical possibilities, viz.for measurement of ventilation/perfusion ratios with only а single generator system. 1. Janssen, A.G.M., Witsenboer, A.J., and De Goeij, J.J.M., Appl.Radiat.Isot., J1, 87 (1988) 

An extension set for 81Rb-81mKr solution generators for lung ventilation studies

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An extension set for 81Rb-81mKr solution generators for lung ventilation studies

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