Abstract

IJNM

Indian Journal of Nuclear Medicine

0972-3919

Society of Nuclear Medicine, India

ijnm-20-4-oral002

Oral 2

122004

204100105

ijnm-20-4-oral002-001

Radiation Surveillance Experience at the Medical Cyclotron Facility

Rajashekharrao

KamaldeepKumar

Hemant

PushparajaSharma

Radiation Medicine Centre, Bhabha Atomic Research Centre, Tata Memorial Centre Annexe, Parel, Mumbai-400 012

Abstract

The first Medical Cyclotron (MC) in India (a GE Medical System PETtrace Cyclotron) was established at the Radiation Medicine Centre. The PETtrace, is a vertical, unshielded, fixed energy isochronous cyclotron, capable of accelerating negatively charged hydrogen (H-) or deuterium (D-) to energies of 16.5 MeV and 8.4 MeV respectively. Currently, the MC has been exclusively employed for the production of ¹⁸F and subsequent synthesis of ¹⁸F-fluorodeoxyglucose. The ¹⁸F⁻ ion is produced by the ¹⁸O (p,n)¹⁸F reaction using a silver target cell filled with approximately 1.4 ml or 2.2 ml of enriched [¹⁸O] water. On a typical run, the target is irradiated for 45 minutes with 16.5 MeV protons and an average beam current of 40 mA.

During operation of the MC, the philosophy of radiation protection primarily concerns safety of the staff, public and the environment. As compared to nuclear medicine, where conventionally low to medium energy beta and gamma emissions are handled, the MC brings along with it a special problem of protection against high-energy neutrons and gammas. Therefore, considerable attention is required in the design of the shielding around the unshielded MC to protect against high-energy neutron and gamma radiations. The energies of the neutrons produced in our MC are generally in the range of 6-16 MeV and that of the prompt gammas generated by inelastic scattering of protons from target material is about 6 MeV. The bunker design, several built-in safety features along with the safety interlock system and continuous operational health physics surveillance has been effective in reducing exposures to the staff, public and environment ALARA.

The presentation will highlight the operational radiation safety experiences during; (a) routine production of ¹⁸F and synthesis of ¹⁸FDG (b) accidents and emergencies in ¹⁸FDG synthesis (c) preventive maintenance of the MC (d) in-house transport of ¹⁸FDG and (e) handling of radioactive waste.

Key wordsRadiation SafetyMedical Cyclotron¹⁸FDGMonitoringRadioactive Waste

ijnm-20-4-oral002-002

Assessment of Radiation Doses to Nuclear Medicine Staff during PET Procedures

Rohatgi

Rupali

Tandon

Pankaj

Bhabha Atomic Research Centre, Mumbai-400 094

Abstract

Positron Emission Tomography (PET) is the latest diagnostic modality used for obtaining clinical information in the field of oncology, neurology and cardiology. It gives high resolution, 3-D images of the distribution of radiopharmaceuticals in the specific organs. In PET studies the radionuclides used are cyclotron produced. Presently, in our country the most commonly used radio-nuclide is ¹⁸F labeled with glucose.

PET radionuclides are positron emitters, which after annihilation produces two photons each of 0.51 1MeV. In this paper, we have carried out the dose estimation studies for occupational worker involved in routine PET procedures like dispensing of activity, administration of dosages and scanning of patient. The study was carried out in one of the premier institute of the country where the workload is maximum and for that they have employed two NM physician, and three technologists. In this study, the cumulative whole body dose received by the staff involved in carrying out various nuclear medicine procedures was evaluated using pocket dose rate meter (diode based).

From the results it was observed that, while dispensing 6.84 GBq of FDG, the dose received by the technologist was 7µSv while the dose to NM physician was 25µSv during administration of 4.8GBq to 14 patients. The cumulative dose to technologist who was involved in scintigraphy procedure was 13µSV. It was also observed that the nurse who assisted the physician and helped the patient during administration of activity received 27µSv. The doses received also depend on the work practices followed by the staff and the skill of the occupational workers. The above study concludes that if the workload is shared between three Nuclear Medicine physician and three technologists then it is practically possible to handle a workload of 15 patients/day in order to keep dose within limits as prescribed by the competent authority.

Key wordsPositron Emission Tomographypocket dose rate meterworkload

ijnm-20-4-oral002-003

Development of Adenoviral Mediated [¹⁸F]-FES-hERLIn Vivo PET Tracer-Reporter Gene System for Monitoring of Gene Therapy

Lohith

Furukawa

Takamatsu

Mori

Fujibayashi

Biomedical Imaging Research Center, University of Fukui, Fukui, Japan

Abstract

Recently recombinant adenoviruses are being used for efficient delivery and expression of target genes in many gene therapy trials. Though invasive monitoring of gene expression is possible in animals, a non-invasive approach is preferable in case of humans. Currently, different PET tracer-reporter gene systems possessing varying characteristics are making big strides in non-invasive evaluation of gene therapy. Considering the significance of safer human use, versatile tissue permeability and effective gene expression, we have developed an adenoviral PET ligand-reporter gene system utilizing ¹⁸F-Estradiol (FES) as PET ligand, human estrogen receptor á ligand binding domain (hERL) as reporter gene and human thymidine phosphorylase (hTP) as therapeutic gene model. Thus, recombinant Ad5CMV-TIER and control Ad5CMV-LacZ adenoviruses were constructed.

Cultured Cos-7 (African green monkey kidney) cells were infected with varying titers of recombinant Ad5CMV-TIER virus. ECL Immunoblotting showed increasing hTP and hERL expression levels, corresponding to increased viral titers. An in vitro³H-Estradiol specific binding assay was performed in Cos-7 cells 2 days p.i., with 10 min uptake and the unlabeled ligand at 200-fold concentration of the labeled ligand. With TIER virus, the uptake was 44-fold higher in radioligand only added cells, than in cells treated with both labeled and unlabeled estradiol, indicating high specificity of radioligand to the expressed hERL receptor. The uptake in LacZ expressed radioligand only added cells were 69-fold lower than that of corresponding TIER expressed cells, indicating very low non-specific binding. Radioligand disassociation study performed at three different wash conditions showed uptake in TIER expressed cells decreasing by 26%, whereas in LacZ expressed cells it decreased by 97%, indicating high affinity of the radioligand to the expressed hERL protein. An expression study using plasmid pCI-TIER and recombinant adenoviruses, performed in Cos-7 and MRC-5 (human lung fibroblasts) cells yielded improved expression efficiency in viral transduced cells. A periodic gene expression assay was performed over 7 days post infection (p.i.) of Ad5CMV-TIER virus in Cos-7 and MRC-5 cells. Control virus expression was also done after 2 days p.i. The expression levels of both hERL and hTP remained consistent up to 5 days, there after showing a slight reduction over last two days, thus enabling persistent quantification of therapeutic gene expression. We are currently evaluating our system in mouse and rat models using ¹⁸F-FES digital autoradiography and microPET imaging. Considering the positive results in cell model, we expect successful in vivo data will validate our system for prospective clinical use.

Key words¹⁸F-Estradiol (FES)³H-EstradiolImmunoblottingAutoradiographymicroPET

ijnm-20-4-oral002-004

Opportunity for Dose Reduction Exists in Chest CT-Implication in PET-CT

Pandey

AK*

Sharma

Raju

Gupta

Sharma

*Medical Physics Unit, Dept. of Radiodiagnosis, AIIMS, New Delhi

AbstractIntroduction

PET-CT provides excellent diagnostic information as it combines functional (from PET) and anatomical information (from CT). Due to high radiation dose often delivered by CT it is important to ensure that the required diagnostic information is achieved with the minimum possible dose to the patient. However there is a possibility that patients may receive excessive exposure in PET-CT examination (1), which is avoidable. This paper emphasizes how radiation dose can be minimized if tube current (mAs) is tailored based on patients' weight.

Materials and Methods

We conducted this study in two phases. In the first phase we collected the baseline data of 50 patients in different weight categories undergoing routine chest study with existing protocol and in 2^nd phase twenty-nine patients were scanned on reduced mAs (exposure chart as shown in table-1). The study was conducted on multislice CT scanner (Somatom Volume Zoom, Siemens AG, Germany). Table 1

S. No.		1	2	3	4	5	6	7

Weight	Category	<10	10-25	26-45	46-65	66-85	86-100	>100

	No. of Pts.	1	9	11	19	9	1	0
Baseline	mAs	90	90	90	90	90	90	90
	kVp	120	120	120	120	120	120	120
	No. of Pts.	1	5	5	9	6	1	0
Exposure	mAs	16.1-26.6	26.6-49.7	17.5-22.4	22.4-41.3	41.3-66.5	66.5-88.2	49.7
	kVp	80	80	120	120	120	120	140

Image noise was calculated by placing ROI on homogenous area on ascending, descending aorta and pulmonary artery. Two independent radiologists assessed the scan quality and acceptable noise value was determined. Threshold image noise value for acceptable scan quality was determined for each category. Based on this target noise value, a new exposure chart was drafted. In order to estimate percentage dose reduction, the CTDI value displayed in patient protocol were used.

Result

Although the images were noisier they were diagnostically acceptable. Dose was reduced by 80.11% [base line CTDI value 12.27 mGy (9.59 mGy-12.23 mGy) was reduced to 2.44mGy (0.72mGy-5.62mGy) using the modified protocol]. The image noise in the baseline data varied from 6.26 to 12.7 with an average of 8.33. Using the modified protocol as a part of dose reduction strategy the mean value of measured noise was15.0 (range: 9.3 to 26.8).

Conclusion

A huge opportunity for dose reduction exists if parameter like mAs can be tailored based on patient anthropometrics. Although this study was done on patients undergoing chest CT, the findings have major implication for PET-CT where large areas are scanned.

Key wordstube currentradiation dosepatient weight

References1

Brix

Gunnar

Lechel

Ursula

Glatting

Gerhard

Radiation Exposure of patients undergoing whole body dual modality 18F-FDG PET/CT examination. J. Nucl. Med., 2005, 46(4), 608-613.

Acknowledgements

This work was supported in part by IAEA (contact no. 12383/RD)

ijnm-20-4-oral002-005

Standardization of an HPLC Analysis for the Routine Quality Control of [¹⁸F]FDG

Kar

Mayukh

Rajan

MGR

Soni

Laboratory Nuclear Medicine Section, Radio chemistry & Isotope Group, BARC, c/o TMHAnnexe, Jerbai Wadia Road, Parel, Mumbai-400012

Abstract

HPLC analysis of 2-[¹⁸F]fluoro-2-deoxy-D-glucose (FDG) using sugar columns, viz. (Carbopac PA 10,4mm) and 0.1M NaOH as mobile phase, is already an established method being followed universally in compliance with the protocol stipulated in the European Pharmacopoeia (EuPh) [1]. However, a different HPLC system, viz. column (125mm x 4mm, 3µm, C₁₈) and a mixture of 75 volumes of acetonitrile and 25 volumes of 0.95g/l aqueous solution of toluenesulfonic acid as eluent, is recommended [1] for the determination of concentration of tetrabutyl ammoniumbicarbonate (TBAHCO₃), the phase transfer catalyst. The aim of this study was to standardize a reverse phase radioHPLC method, which can be used for simultaneous determination of concentrations of radiochemical impurities as well as TBAHCO₃ present in FDG solution, so that it can be conveniently adopted as a daily QC procedure.

10µl of FDG solution was analyzed by HPLC using 120-5-C₁₈ Macherey-Nagel column and 70:30 acetonitrile/water as mobile phase with 1ml/min flow rate. The wavelength of the UV detector was fixed at 220 nm and the energy window of the radioactive detector was selected for optimum detection of 511 KeV gamma rays. A single UV peak with retention time (RT) 1.7±0.04 mins and two radioactive peaks with RT 2.65±0.05 mins and 4.07±0.15 mins were observed. The principal peak (>90%, RT = 2.65±0.05 mins) in the radiochromatogram corresponds to FDG whereas the smaller peak (RT = 4.07±0.15 mins) corresponds to its epimer, 2-[¹⁸F]fluoro-2-deoxy-D-mannose (FDM). A standard solution (0.075 M) of TBAHCO₃ was analyzed and it was confirmed that the UV peak with RT 1.7±0.04 mins corresponds to the residual TBAHCO₃. However, the C₁₈ column was not found to be ideal for the separation of unreacted ¹⁸F-as considerable tailing of the peak (RT 4.56 mins) was observed.

Since it was reported [2] that small amounts of FDM might be observed especially when the FDG parenteral is subjected to terminal sterilization by heat, this HPLC method holds promise for the determination of concentration of FDM in FDG.

Key wordsHPLCQCFDGFDMC₁₈ column

References1

Nachtrag

Monographie [¹⁸F]fludeoxyglukose Injectionslosung, Ph.-Eur, 2001a, pp. 976-979.2

Meyer

G.J.

Matzke

K.H.

Hamacher

Fuchtner

Steinbach

Notohamiprodjo

Zijlstra

Appl. Radiat. Isotopes, 1999, 51, pp. 37-41.

ijnm-20-4-oral002-006

Preparation and Evaluation of ⁹9mTc-Labeled Folic acid and Methotrexate analogs as Tumor Imaging Agents

Okarvi

Jammaz I.A. Cyclotron & Radiopharmaceuticals Department, King Faisal Specialist Hospital & Research Centre. Riyadh 11211, KSA

AbstractObjectives

It is known that cell-membrane folic acid (FA) receptors are responsible for cellular accumulation of FA and FA analogs, such as methotrexate (MTX), and are overexpressed on several tumor cells. Folate as well as antifolates (i.e. MTX), possess high-affinity for the folate-receptor (FR) positive cells and tissues and were deemed useful for radiodiagnostic applications. This study aimed to develop ^99mTc-labeled FA and MTX analogs using MAG₃ chelator and to compare their radiolabeling and biological characteristics as FR-targeting radiopharmaceuticals.

Methods

For the synthesis of MAG₃-FAandMTX conjugates, FA and MTX were converted to their corresponding active esters in the presence of 1-hydroxybenzotriazole (HOBt) and 1,3-dicyclohexylcarbodiimide (DCC), and then reacted with hydrazine to form the respective hydrazide compounds. MAG₃-HOBt ester (prepared by reacting MAG₃ with HOBt in the presence of DCC), was then condensed with FA-hydrazide or MTX-hydrazide to form the desired compounds. Labeling with ^99mTc was achieved by stannous/tartrate exchange method. In vitro cell-binding and internalization studies were performed on MCF-7 and MDA-MB-231 breast cancer cells and in vivo biodistribution was performed in MCF-7 breast tumor-bearing nude mice.

Results

Both MAG₃-FA and MAG₃-MTX analogs were successfully prepared by using a relatively simple and fast chemistry. MAG₃-FA and MTX conjugates after labeling with ^99mTc by ligand exchange method displayed high in vitro stability in human plasma. In vitro cell-binding and internalization on MCF-7 and MDA-MB-231 cells indicated the affinity and specificity of the radioconjugates towards the human breast cancer cells. In nude mice, both radioconjugates showed rapid clearance from the blood and excretion mainly through the renal/urinary pathway with some elimination via the biliary route. There was no significant accumulation of radioactivity observed in other organs with the exception of the intestines. In vivo uptake in the MCF-7 breast tumor was found to be 1.63 ± 0.47 (for ^99mTc-MAG₃-FA) and 1.06 ± 0.53%ID/g (for ^99mTc-MAG₃-MTX), respectively.

Conclusions

The results suggest that the renal clearance was more pronounced for both radioconjugates but there was some excretion via the hepatobiliary system. The uptake in human breast tumor was moderate in nude mice. These findings could be of potential diagnostic interest in designing and developing FA/MTX-based radiopharmaceuticals for tumor imaging.

Key wordsFolic acidMethotrexateTc-99mradiolabelingtumor imaging agent

Acknowledgment

This work was supported by KACST grant #M-S-72.

ijnm-20-4-oral002-007

A Retrospective Evaluation of theAccuracy and Clinical Impact of a Derived Plasma Volume Determination

Vorster

Warwick

Ellmann

Nuclear Medicine, University of Stellenbosch, Cape Town, South Africa

AbstractIntroduction

Blood volume determinations are important for the further management of patients with a raised hemoglobin and/or hematocrit. The plasma volume can be determined directly using a more accurate and expensive method, or can be derived from the red cell volume and haematocrit using a cheaper and more readily available method. The aim of this study was to determine the accuracy and clinical value of the derived plasma volume determination.

Methology

Aretrospective analysis was performed on patients who had both red cell volume (determined using Tc-99m labeled red cells) and plasma volume studies (determined using I-125 HS A) during the period August 1997 till December 2004. Derived plasma volume values were obtained from the measured red cell volume and venous haematocrit and compared with directly measured plasma volume values which were used as gold standard. The clinical impact of the use of the derived method was also determined by comparing the differences, if any, in the management of the patients with the usage of the different techniques.

Results

The study included 32 patients with a mean age of 55 years. In all cases the two studies were performed within a month of each other. There was a reasonable correlation between the directly determined and derived plasma volumes (r = 0.71). There would however have been no difference in the clinical management of the patients using the results of either of the two different techniques.

Discussion

Only a reasonable correlation was found between actual values obtained using the two different techniques. We did however find that the usage of only the derived plasma volume did not cause a change in the clinical management of the patients compared to the direct method. Although the use of a directly determined plasma volume is ideal, the use of a derived plasma volume is an acceptable alternative method if the direct method is not possible due to its cost or unavailability.

Key wordsPlasmavolumedeterminationdirectderived

ijnm-20-4-oral002-008

Technetium Labeling of Biotin: “A Model for Rhenium Labeling”

Hazra

Gupta

Garg

Hazra

P Khanna

Gangwar

Sharma

Nuclear Medicine Unit, S.N. Medical College & Boston Medical Centre, Agra-282005

AbstractObjective

Pretargeting is considered to be very crucial for enhancing tumour/non target ratios for delivery of therapeutic radionuclides through biological molecules. Avidin-Biotin interaction is one of the principal methods of such pretargeting. Yttrium biotin labeling has been standardized, but since Rhenium is a promising isotope for therapy, We have proposed Rhenium labeling of biotin. In order to develop this methodology we are describing here our comparison of two different protocols for labeling biotin with technetium. These methods had earlier being developed for biotin derivatives which are expensive as compared to native biotin and we therefore wished to determine how far technetium can be similarly used to label native biotin. In addition as oxalate has been found to enhance the Rhenium labeling of antibody, we wanted to find whether oxalate would have a beneficial effect on biotin labeling.

Methods

Two protocols were evaluated each with or without oxalate. In the Ist protocol Biotin in alcoholic solution is reduced with tin, K⁺ N^a+ tartrate and then labeled with technetium. In the 2^nd protocol biotin in alkaline aqucous solution is reduced with stannous chloride and sodium citrate with or without oxalate.

Protocol-1

900 mgm biotin dissolved in 1ml. equi-volume solution of EtOH/H20 (PH=7.5). 500 mlofK⁺N^a+ tartrate (160 mg/10 ml distilled water) and 10 ml (0.1%) solution of Sncl₂ and 40ml (0.1 %) solution of sodium oxalate was added to it. Finally 1ml Tc-generator eluate (aprox. 5mCi activity) was added to above reaction mixture and allowed to incubate at room temperature for 15 minutes.

Protocol-2

900 m gm biotin dissolved in 1ml. bi-carbonate buffer solution of PH=10.5. To 100 ml of this biotin buffer solution added 10 ml (0.1 %) Sncl₂ 40ml (0.1%) sodium oxalate and 200ml (0.1%) sodium citrate solution. Finally 1ml Tc-generator eluate was added (aprox. 5mCi activity).

The results of the reactions were analysed by thin layer chromatography in Normal Saline, Acetone as well as mixture of H₂O : Ethanol: NH₄ OH (5): (2): (1) in order to evaluate the extent of labeling.

Results

Successful labeling was observed with both protocols, but better with protocol 2. The addition of oxalate enhanced labeling.

Conclusion

It appears that Tc-99m can label biotin, but the stability of this labeled biotin under physiological conditions and its bio-distribution needs to be evaluated. It successful this could be a model for labeling biotin with Rhenium for therapy.

Key wordsBiotinTechnetiumRadio-immunotherapy

ijnm-20-4-oral002-009

Development of a Novel Carrier for Radiolabelling Inhalation Aerosol Formulations for Scintigraphic Studies

Soni

¹Bajaj

³Pandit

³Korde

²Choudhary

²Khanolkar

¹BRIT/BARC c/o TMC Annexe, Jerbai Wadia Road, Parel, Mumbai-400 012²Isotope Group, Radiopharmaceutical Division, BARC.³C. U. Shah College of Pharmacy, SNDT, Women's University, Mumbai-400 049

Abstract

Inhalation aerosols, as a mode of administration represent a valuable means of targeting the medicinal agents to pulmonary tract. However, it is difficult to predict the exact dose delivered through these devices and to determine the amount of drug deposition and the distribution pattern of the inhaled drugs in the lungs. It has been observed that ^99mTc-pertechnatate is rapidly absorbed in to the systemic blood circulation and has a low retention time in the lungs. This makes it difficult to quantify the deposition of the radiolabel drugs. Thus the aim of the study was to radiolabel Calcium Hydroxy Apatite (CHA) [Ca₁₀ (PO₄)₆(OH)₂] with ^99mTcO₄⁻ and study the invitro deposition pattern through a Dry Powder Inhaler (DPI). Radiolabelling of CHA particles was carried out in presence of reducing agents. ^99mTc in saline was added to CHA solution and labeled radionuclide was separated by centrifugation. Effect of temperature and pH on radiolabelled product was studied. The free pertechnetate content, radionuclide purity and radiochemical purity of generated particles were determined by chromatographic technique. ^99mTc labelled CHA particles were incorporated in salbutamol DPI formulations. The formulations were characterized by Anderson Cascade Impactor for in-vitro deposition pattern and particle size distribution (AMAD; GSD). The safety and retention of CHA particles in pulmonary region was confirmed using Albino Wistar Rats. The animals inhaled the radiolabelled formulation and the toxicity was predicted based on histopathological studies. The pulmonary retention of CHA particles was determined on Rabbits. Pulmonary scintigrams were taken for period upto 150 min after inhalation of radiolabelled formulations. The CHA particles radiolabelled with ^99mTc had the desired radionuclide purity and low free pertechnetate content. The radiolabelled formulations showed comparable invitro deposition pattern and particle size distribution (AMAD 2.0 mm; GSD 2.5) compared to unlabelled formulations (1.9 mm; 2.4) indicating that the radiolabelling process did not modify the particle size distribution of the drug. The histopathological observation proved the ^99mTc-CHA carrier to be safe for administration. The scintigraphic scans demonstrated the uniform distribution of the radiolabelled ^99mTc-CHA particles even upto peripheral region of lungs. ^99mTc-CHA particles were retained in the lungs for longer periods of 150 min as compared to ^99mTc pertechnetate when used alone. A rapid, convenient radiolabelling procedure using CHA particles has been developed to prepare a novel radiopharmaceutical carrier for pulmonary drug delivery systems.

Key wordsImaging techniquesPulmonary deliveryCalcium HydroxyapatiteDrugsCarriers

ijnm-20-4-oral002-010

Studies on Samarium phosphate [³²P] Colloidal suspension (SMPC) for possible synoviorthesis applications

Prabhakar

¹Sachdev

¹Umamaheswari

¹Sivaprasad

¹Chaudhari

¹Radiopharmaceuticals Programme, BRIT; Navi Mumbai²Laboratory Nuclear Medicine Section, BARC, Mumbai

Abstract

Therapeutic use of radiocolloids is presently emerging as promising application through local instillation approaches, for example, synoviorthesis and intra tumoral therapy. The radio colloids of pure beta emitters such as ³²P, ⁹⁰Y and beta, gamma emitters such as ¹⁵³Sm, ¹⁶⁶Ho, and ^186/188Re have shown promising utility for therapeutic applications, namely colloidal chromic phosphate -³²P suspension for pleural and peritoneal effusions secondary to primary malignancy, ⁹⁰Y-silicate/citrate colloid, ¹⁵³Sm-hydroxy apatite, ¹⁸⁶Re-sulphide for treatment of rheumatoid arthritis of joints of different sizes. In view of the well proven safety and efficacy of ³²P-phosphate for bone pain palliative treatment, reasonably satisfactory radiation characteristics, the development work ³²P-samarium phosphate colloidal suspension was taken up, as a corallary of the product development work of ¹⁵³Sm -samarium phosphate colloidal (SMPC) suspension.

The method of preparation involves the reaction of carrier SmCl₃ with phosphoric acid doped with ³²P-H₃PO₄, followed by the addition of 3.5% gelatin (Haemaccel) solution to have true colloidal dispersion. Near quantitative yields of SMPC were obtained (RC yields ~90%). Pure product recovered by dialysis was formulated in isotonic saline solution, dispensed and sterilized by heating in an autoclave, under aseptic conditions. The Radiochemical Purity was not less than 98% as assessed by paper chromatography. The product retained its radiochemical integrity throughout the stability study period of 7 days.

Particle size evaluation was carried out on cold samples of SMPC, using laser diffraction particle size analyser. 70 % of the particles were in the range of 1-5µM, ideally suitable to the radiation synovectomy applications.

The product was evaluated for its biological efficacy with 0.1ml of ³²P-samarium phosphate colloid (~ 1mCi) instilled into the rabbit knee joint. The joint was immobilized and images of the joint were acquired. Complete retention of the instilled product at the knee joint and absence of leakage in to systemic circulation was observed throughout the study period of 96h. Simultaneously aliquots of blood were drawn at 0h, 3h, 24h, 72h, 96h, 120h and 144h post instillation and the radioactivity leaked out into blood was estimated in comparison with an aliquot of standard representing the injected dose and found that the radioactivity in blood was indistinguishable from the background. Multicentric clinical trails in humans are in progress.

Key wordsP-32 radiocolloidSynovial inflammationRadiosynoviorthesisRheumatoid arthritisHaemophilia

ijnm-20-4-oral002-011

Performance and Evaluation of CTI - Siemens RDS 111 Cyclotron for Production of Positron Emitting Isotopes

Phani

A Raju

Gada

Atul

Naresh

Anjaneyulu

Kumar

Prasanna

Apollo Gleneagles, Hyderabad, India

AbstractObjective

To assess and quantify the yield of CTI -Siemens RDS-111 Cyclotron for the production of F¹⁸.

Background

F¹⁸ is produced by RDS 111 Eclipse 1 1MeV negative ion Cyclotron using enriched O¹⁸ water as target material from either of the targets Eclipse HP or RD. The former target consumes 2.4mL of O¹⁸ water and the later target consumes 1.2mL of O¹⁸ water.

Target selection and Cyclotron run duration is based on number of patients and the schedule. Prior to bombardment, a set of pre and post initialization checks are executed and the target material is loaded in the selected target. Then the production follows. F¹⁸ is delivered to the chemistry unit after the required time is elapsed.

Materials and Methods

The yield of F¹⁸ was measured and calculated using pre-calibrated CRS-15 Capintec dose calibrator. Effective yields were analyzed for 45 runs on HP and 33 runs on RD target. The results were tabulated and analyzed.

Conclusion

According to the F¹⁸ yield specifications of CTI-Siemens 76% of the yield was accomplished on HP target and 60% on RD target. The variable yields are attributed to fluctuations in cyclotron parameters, quality of the target material and mechanical failures.

The efficiency of our unit is fulfilling the CTI-Siemens specifications.