radiochemistry, pre-clinical studies and first clinical investigation of 90y-labeled hydroxyapatite...

Nuclear Medicine and Biology xxx (2015) xxx–xxx

Contents lists available at ScienceDirect

Nuclear Medicine and Biology

j ourna l homepage: www.e lsev ie r .com/ locate /nucmedb io

Radiochemistry, pre-clinical studies and first clinical investigation of90Y-labeled hydroxyapatite (HA) particles prepared utilizing 90Yproduced by (n,γ) route

K.V. Vimalnath a, Sudipta Chakraborty a,⁎, A. Rajeswari a, H.D. Sarma b, Jitendra Nuwad c, Usha Pandey a,K. Kamaleshwaran d, Ajit Shinto d, Ashutosh Dash a

a Isotope Production and Applications Division, Bhabha Atomic Research Centre, Mumbai, 400085, Indiab Radiation Biology Health Sciences Division, Bhabha Atomic Research Centre, Mumbai, 400085, Indiac Chemistry Division, Bhabha Atomic Research Centre, Mumbai, 400085, Indiad Nuclear Medicine and PET Services, Comprehensive Cancer Care Centre, Kovai Medical Centre and Hospital, Coimbatore, 641014, India

a b s t r a c ta r t i c l e i n f o

⁎ Corresponding author. Tel.: +91 22 2559 3909; fax: +E-mail addresses: [email protected], sudipta63@red

http://dx.doi.org/10.1016/j.nucmedbio.2015.01.0060969-8051/© 2015 Elsevier Inc. All rights reserved.

Please cite this article as: Vimalnath K.V., et(HA) particles prepared utilizing 90Y produc

Article history:
Received 22 October 2014Received in revised form 8 January 2015Accepted 11 January 2015Available online xxxx
Keywords:Radiation synovectomy (RSV)90Y(n,γ) productionHydroxyapatite (HA)Kit formulation

Introduction: The scope of using no carrier added (NCA) 90Y [T1/2 = 64.1 h, Eβ(max) = 2.28 MeV] obtained from90Sr/90Y generator in radiation synovectomy (RSV) iswidely accepted. In the present study, the prospect of using90Y produced by (n,γ) route in a medium flux research reactor for use in RSV was explored.Methods:Yttrium-90wasproducedby thermal neutron irradiationof Y2O3 target at aneutronfluxof ~1×1014n/cm2.sfor 14 d. The influence of various experimental parameterswere systematically investigated and optimized to arrive atthemost favorable conditions for the formulationof 90Y labeledhydroxyapatite (HA)usingHAparticles of 1–10 μmsizerange. An optimized kit formulation strategywas developed for convenient one-step compounding of 90Y-HA,which iseasily adaptable at hospital radiopharmacy. Thepre-clinical biological evaluationof 90Y-HAparticleswas studiedbycar-rying out biodistribution and bioluminiscence imaging studies in Wistar rats. The first clinical investigation using theradiolabeled preparation was performed on a patient suffering from chronic arthritis in knee joint by administering185 MBq 90Y-HA formulated at the hospital radiopharmacy deploying the proposed strategy.
Results: Yttrium-90 was produced with a specific activity of 851 ± 111 MBq/mg and radionuclidic purity of 99.95 ±0.02%. 90Y-labeled HA particles (185 ± 10MBq doses) were formulated in high radiochemical purity (N99%) and ex-cellent in vitro stability. The preparation showed promising results in pre-clinical studies carried out in Wistar rats.The preliminary results of the first clinical investigation of 90Y-HA preparation in a patient with rheumatoid arthritisin knee joints demonstrated the effectiveness of the formulation prepared using 90Y produced via (n,γ) route in themanagement of the disease.Conclusion: The studies revealed that effective utilization of 90Y produced via (n,γ) route in amedium flux research re-actor coupled with the developed strategy of using HA kits for convenient formulation of 90Y-HA at the hospitalradiopharmacy can contribute to sustainable growth in the clinical utilization of 90Y in RSV in the foreseeable future.
© 2015 Elsevier Inc. All rights reserved.

1. Introduction

The role of radiation synovectomy (RSV) or radiosynoviorthesis as aneffective modality in the treatment of acute and chronic inflammatoryjoint disorders, such as rheumatoid arthritis, needs hardly to be reiterated[1,2]. The procedure essentially consists of intra-articular administration ofparticulates/colloids labeled with suitable therapeutic radionuclide to adiseased joint in which they are phagocytized by the macrophages of theinflamed synovial membrane and deliver selective radiation dose to thesynovium. This leads to necrosis, fibrosis and sclerosis of the proliferatingsynovial tissue and ablation of the inflamed synovial membrane [1–4].Availability of ahost of radionuclideswith attractive therapeutic propertiesand the feasibility of incorporating them into bio-degradable and bio-

91 22 2550 5151.iffmail.com (S. Chakraborty).

al, Radiochemistry, pre-clinicaed by (n,γ) route, Nucl Med B

compatible particulates or colloids of appropriate size has facilitated con-siderable advances in this area. Among the wide variety of beta emittingradionuclides and radiolabeled preparations harnessed for this modalityof treatment, three radionuclides namely, 90Y (90Y-silicate/citrate colloid),186Re (186Re-sulfur colloid) and 169Er (169Er-citrate colloid) aremostwide-ly used for large, medium and small joints, respectively [1,2,5,6]. In light ofthe explicit need to achieve optimum tissue penetration of large-sizedjoints such as knees, the prospect of using 90Y is unmatched owing to itsattractive nuclear decay characteristics. Yittrium-90 decays to stabledaughter product 90Zr with a half-life of 64.1 h by emission of high energyβ− particles (Eβmax = 2.28 MeV, maximum tissue range 11 mm). Thescope of using a radionuclide with a short half life is attractive as it mini-mizes the cumulative radiation dose to non-target tissues because agreater fraction of the radioactive decay occurs prior to leakage fromthe joint. There are several reports demonstrating long-term clinicaleffectiveness of RSV using 90Y-labeled particulates/colloids as a safe

l studies and first clinical investigation of 90Y-labeled hydroxyapatiteiol (2015), http://dx.doi.org/10.1016/j.nucmedbio.2015.01.006

http://dx.doi.org/10.1016/j.nucmedbio.2015.01.006

mailto:[email protected]

mailto:[email protected]


http://www.sciencedirect.com/science/journal/09698051


2 K.V. Vimalnath et al. / Nuclear Medicine and Biology xxx (2015) xxx–xxx

anduseful therapeutic strategy in a large population of patients sufferingfrom a variety of arthritis [6–12].

Despite the huge potential of 90Y-labeled particulates/colloids forthe treatment of rheumatoid arthritis, cost effective availability of clini-cally useful 90Y at hospital radiopharmacy is an issue. While the use of90Sr/90Y generator represent a successful paradigm of obtaining no car-rier added (NCA) 90Y on demand [13], the inherent requirement of anonsite 90Sr/90Y generator at hospital radiopharmacy capable of provi-ding 90Y of adequate purity for clinical use is an impediment towardswide-spread cost effective availability of the radionuclide. This is dueto the fact that none of the 90Sr/90Y generators available today are opti-mally designed for providing 90Y for direct use as radiopharmaceuticalingredient for routine clinical use at hospital radiopharmacy. Majorityof nuclear medicine clinics using 90Y are therefore dependent on ahandful of commercial suppliers who provide 90Y in unit doses. Conse-quently, 90Y suitable for in vivo therapeutic applications is not availableat an affordable cost worldwide, particularly in the developing coun-tries. Alternatively, 90Y can be directly produced by neutron activationof natural yttrium target (yttrium is mononuclidic in 89Y) in a nuclearreactor. The radionuclidic purity of the (n,γ) activated product is ex-pected to be very high. However, depending on the fast neutron fluxin the reactor, detectable levels of 89Sr could be present owing to the(n,p) reaction. Yttrium-90 produced by (n,γ) route is of low specific ac-tivity due to the low neutron absorption cross section (1.28 b) of 89Y[14] and hence not suitable for use in receptor-specific therapeuticagents used in peptide receptor radionuclide therapy (PRRT) andradioimmunotherapy (RIT). On the other hand, radionuclides availablein low to moderate specific activity can be utilized in formulation ofthe therapeutic doses of radiolabeled particulates for RSV. In this pre-mise, assessing the potential utility of 90Y produced by (n,γ) route inRSV is not only an interesting proposition, but may be viewed as a po-tential step forward to expand its scope in several countries operatingmedium flux research reactors. The present work is therefore aimed to-wards developing suitable therapeutic agents for RSV utilizing 90Y pro-duced by (n,γ) route in a medium flux research reactor, which could beeasilymade available to a large population of patients at an affordable cost.

Among the different varieties of particulate carriers proposed for usein RSV, hydroxyapatite (HA) [Ca10(PO4)6(OH)2] particulates hold consid-erable promise mainly due to its excellent biocompatibility and biode-gradability, ease of synthesizing in the desired particle size range as wellas its very high affinity for metal ions mainly lanthanides andpseudolanthanide such as yttrium [15–18]. These favorable propertiesof HA as particulate carrier of radionuclides have led to extensive studieson radiolabeled HA particles with a wide variety of therapeutic radionu-clides including 90Y for their use in RSV which showed encouragingresults in animal models and in human patients [12,15–24].

Although anumber of studies on thepreparation of 90Y-HAusingNCA90Y and its utility for RSV have been reported [12,19,21,25], there is onlyone report byKhalid et al.where 90Y-HAhasbeenpreparedusing 90Ypro-ducedby (n,γ) route in amediumflux research reactor [26]. In this report,authors have used large quantity (40 mg) of HA particles to synthesize90Y-HA with high yield and good in vitro stability. More importantly, nostudies on the assessment of biological efficacy of the products were re-ported. However, to assess the potential utility of 90Y-labeledHA particlesprepared from 90Y produced by (n,γ) route for RSV, a thorough systema-tic study deemed worthy of consideration. In the present article, we de-scribe the formulation 90Y-HA using 90Y produced in a medium fluxresearch reactor, chemical and radiochemical characterization of theradiolabeled preparation, its pre-clinical evaluation in animal model andpreliminary clinical investigation in a human patient suffering fromchronic rheumatoid arthritis of knee joint. Towards achieving successfultranslation of the product from radiochemistry laboratory to clinic, aneffective kit formulation strategy was adapted for its expedient formula-tion at hospital radiopharmacy. The present article, to the best of ourknowledge, is the first report on the clinical use 90Y-labeled agent forRSV formulated by using 90Y produced via (n,γ) route.

Please cite this article as: Vimalnath K.V., et al, Radiochemistry, pre-clinica(HA) particles prepared utilizing 90Y produced by (n,γ) route, Nucl Med B

2. Experimentals

2.1. Materials and equipments

Yttrium oxide (spectroscopic grade, N99.99% pure) used for the pro-duction of 90Ywas procured fromAmerican Potash Inc., USA. Suprapurehydrochloric acid and sodium hydrogen carbonate were purchasedfrom Merck, Germany. Sterile, pyrogen free normal saline and waterfor injection were procured from Ives Drugs, India. All other chemicalsused in the experiments were of AR grade and supplied by reputedchemical manufacturers. MilliQ water (resistivity 18.2 MΩ.cm) wasused for all radiochemical studies. Bis-(2-ethylhexyl)-phosphonic acid(KSM-17) used in the extraction paper chromatography (EPC) was syn-thesized previously at Bhabha Atomic Research Centre, India [27].Whatman 3 mm paper chromatography strips were purchased fromM/s. Whatman, UK.

Curiementor 3 Isotope Calibrator was obtained from PTW Freiburg,Germany. High resolution gamma ray spectrometry was carried outusing an HPGe detector (Canberra Eurisys, France) coupled to a 4 Kmulti-channel analyzer (MCA) system. 152Eu reference source used for energy aswell as efficiency calibration of the detectorwas obtained fromAmersham,USA. All other radioactivity measurements were carried out using a well-type NaI(Tl) scintillation detector obtained from Mucha, Raytest,Germany. A liquid scintillation counter (Hidex, Finland) was used for themeasurement of 90Y and 90Sr radioactivities during EPC studies.

Hydroxyapatite (HA) particles used in the present study were syn-thesized and characterized in our laboratory following the procedurereported earlier [17,19,20,22]. The particle size distribution of HA parti-cles was carried out by using a laser diffraction particle size analyzer(LA-950, HORIBA, Japan). More than 95% of the particles were foundto be in the size range of 1–10 μm,with 4.33 μmbeing themedian of dis-tribution. Microscopic morphology and topography of the synthesizedhydroxyapatite particles as well as yttrium labeled hydroxyapatite par-ticles was observed using Scanning Electron Microscopy (SEM) onAIS2100 SERON Tech. SEM from South Korea. The instrument wasequipped with Energy Dispersive X-ray (EDX) spectrometer (Model:INCA E350 from Oxford, UK) which was used for elemental analysis ofyttrium labeled hydroxyapatite particles.

Complete Freund's adjuvant (CFA) was used for the induction of ar-thritis inWistar rats. The animals were anaesthetized using amixture ofxylazine hydrochloride and ketamine hydrochloride. All relevant na-tional laws relating to the conduct of animal experiments were com-plied while experiments were performed. Bioluminiscence images ofthe animals after administration of the radiolabeled preparation wererecorded using Photon Imager (Biospace Lab, France).

99mTc-MDP used for bone scintigraphy of human patient was pre-pared following standard protocol using MDP kits procured fromAmersham, USA. Scintigraphic images were recorded using a dualhead gamma-camera (Siemens Symbia True Point, Siemens Germany)equipped with a low-energy high resolution collimator.

2.2. Production, radiochemical processing and quality control of 90Y

Yttrium-90was produced by irradiation of natural Y2O3 (mononuclidicin 89Y) target at a thermal neutron flux of ~1 × 1014 n/cm2.s for a period of14 d. Aweighed amount of Y2O3 powderwas taken into a quartz ampoule,which was subsequently flame sealed and irradiated after placing insidealuminum can. Following irradiation, the target was dissolved in 0.1 Msuprapure HCl by gentle warming inside a lead-shielded glove box facilityequippedwith remote handling gadgets, after allowing a cooling period of~6 h. The resultant solution was evaporated to near-dryness andreconstituted in de-ionized water. Assay of total activity produced wasascertained using Curiementor 3 IsotopeCalibrator. Total radionuclidic im-purity burden in 90Y with respect to gamma emitting impurities wasascertained by recording theγ ray spectra using anHPGe detector coupledto a 4KMCA system. Energy andefficiency calibration of thedetectorwere



3K.V. Vimalnath et al. / Nuclear Medicine and Biology xxx (2015) xxx–xxx

carried out using a 152Eu reference source prior to the recording of gammaray spectra of samples. Several spectrawere recorded for each batch at reg-ular time intervals. Radionuclidic impurity burden with respect to 89Sr,which couldbe formedvia 89Y(n,p)89Sr routeduring irradiationof 89Y in re-actor, was ascertained by EPC technique as described earlier for determina-tion of 90Sr impurity in 90Y obtained from 90Sr/90Y generator [28]. In brief,10 μL of the reagent KSM-17 was impregnated at a distance of 2 cm fromone end of a Whatman 3 mm chromatography paper (12 × 1 cm) uponwhich 5 μL of 90Y solution (37 MBq/mL) was applied. The paper wasdried, developed in 0.9% saline and the activity in each 1 cm segment ofthe paper was counted using a liquid scintillation counter (LSC). Underthese conditions, any 89Sr impurity, if present, migrates to the solventfront (Rf = 0.9–1.0), while 90Y remains at the point of application (Rf =0). The counts obtained at the solvent front were then compared with thetotal spotted activity to determine the 89Sr content in the 90Y sample.

2.3. Optimization of protocol for preparation of 90Y-HA

In light of the perceived need to perform convenient formulation of90Y-HA at hospital radiopharmacy using ready-to-use kits of HA parti-cles, exploratory studies were carried out to optimize the parametersfor radiolabeling. Radiolabeling was achieved by mixing of 90YCl3 solu-tion (~185 MBq of 90Y) with a suspension of HA particles in 0.1 MNaHCO3 solution such that pH of the reaction medium was ~8 afterthe addition of 90YCl3 solution. The mixture was kept at room tempera-ture under constant stirring. Several experiments were carried out byvarying the reaction parameters such as, concentration of HA particles,pH of the reaction mixture and mixing time etc. in order to obtain theoptimized protocol for maximum radiolabeling yield of 90Y-HA. In a reac-tion volume of 1 mL, the amount of HA used for radiolabeling was variedbetween 1 mg to 10 mg, and the radiolabeling yield was determined ineach case. The effect of variation of pH on radiolabeling yield at room tem-perature was studied by adjusting the reaction mixture to different pHvalues ranging from 2 to 10 using either 1 M HCl or 1 M NaOH solutions.Themixing time required to obtainmaximum labeling yieldwas optimizedby carrying out reactions for different time periods (0, 10, 20, 30, 60 and120 min) at room temperature and determining the yields in each case.

2.4. Determination of yield and radiochemical purity

The radiolabeling yield of 90Y-HA was determined in the followingway. An aliquot (typically, 20 μL) was withdrawn from the supernatantsolution of reactionmixture of 90Y-HA after the precipitation of HA par-ticles and the 90Y activity measured. Same aliquot was withdrawn from‘blank’ (solution having the identical composition of 90Y-HA reactionmixturewithout HA particles) and the 90Y activitymeasured. Percentageradiolabeling yield was determined from the activity data using thefollowing equation:

% Radiolabeling yield ¼ 100 – R=Bð Þ½ � ð1Þ

where, B and R are the background-corrected 90Y activities associatedwith the aliquots withdrawn from the blank and supernatant solutionof the reaction mixture, respectively. The radiochemical purity of theradiolabeled preparation was determined using the same techniquesubsequent to the removal of unlabeled 90Y activity by washing ofradiolabeled HA particles using normal saline.

2.5. Synthesis of cold Y-HA

HA particles of 1–10 μm size range (50mg) were suspended in 4mLof 0.1 M NaHCO3 solution. To this suspension, 1 mL of YCl3 solution in0.01 M suprapure HCl containing 50 mg of yttrium was added andmixed thoroughly at room temperature for 24 h using magnetic stirrer.The pH of themixturewas found to be ~7–8. Subsequently, themixturewas centrifuged and supernatant removed carefully. The precipitated


yttrium labeled HA particles was washed thrice with de-ionized waterand dried under IR lamp. The labeled particles were analyzed by SEMand EDX techniques.

2.6. SEM and EDX analysis

The surface morphology and particle size distribution of yttrium la-beled HA particles were examined using SEM. For SEM analysis powdersamples were spread over mirror polished silicon substrate using ace-tone, dried and tapped to remove any loose particle prior to loadinginto SEM chamber. All themicrographswere recorded at the samemag-nification so as to compare the size and shape of samples. Elementalanalyses were carried out using the same samples by EDX technique.Unlabeled HA particles were also subjected to SEM and EDX analysisalong with the yttrium labeled particles.

2.7. Formulation of hydroxyapatite (HA) kits

Hydroxyapatite kits were prepared based on the optimized parame-ters from the preformulation experiments. To prepare kits, 5.0± 0.2mgof HA particles (1–10 μm size range) were weighed into each of theseveral sterile injection glass vials inside a laminar flow hood whereaseptic environment ismaintained. Subsequently, 8.4±0.3mgof sodiumbicarbonate were weighed and added into each of the glass vials, mixedwith HA particles and sealed. One hundred numbers of such cold kitswere prepared.

2.8. Preparation of clinical dose 90Y-HA using kits

Water for injection (1 mL) was added to the kit vial followed by ad-dition of 185±10MBq of 90Y activity as 90YCl3 solution. The contents ofthe kit vials were mixed thoroughly for 5 min using vortex mixture andsubsequently set aside for 60min at room temperaturewithout any fur-ther agitation. The pH of the reaction mixture was measured to be ~8.Subsequently, the supernatant was carefully separated from the precip-itated 90Y-labeledHAparticulates. The radiolabeledHAparticles obtain-ed as precipitate were washed using 1 mL sterile, pyrogen free saline toensure the removal of unlabeled (or loosely held) 90Y activity. Finally,the radiolabeled particulates were suspended in sterile normal saline,autoclaved and used for animal studies or human clinical applicationsafter measurement of dose. Yields and radiochemical purities of 90Y-HA synthesized were determined by following the method describedin Section 2.4.

2.9. In vitro stability studies

In vitro stability of 90Y labeledHAparticles was studied in normal sa-line. For this, the radiolabeled particles were suspended in 1 mL of nor-mal saline. The suspensions were stored at 37 °C for 10 d (N3 half-livesof 90Y). At the end of different time intervals (4 h, 1 d, 3 d, 5 d, 7 d and 10d post-preparation), the radiochemical purities of the suspended 90Y-HA particles were determined by following the technique described inSection 2.4. The in vitro stability of the radiolabeled particulates wasalso ascertained by DTPA challenge. For this, the radiolabeled formula-tion was suspended in 1 mL of 5 mM aqueous solution of DTPA (pH~6.5) and the mixture stored at room temperature. The percentageradiochemical purity 90Y-HA in presence of strong chelator DTPA wasdetermined at regular time intervals following the same technique asdescribed above.

2.10. In vivo studies in animal model

The pre-clinical biological evaluation of 90Y-HAparticleswas studiedby carrying out biodistribution and bioluminiscence imaging studies inWistar rats affected with arthritis in one of the knee joints. Inductionof arthritis was carried out in male Wistar rats weighing ~300 g using



Fig. 1. Effect of variation of HA concentration on the radiolabeling yield 90Y-HA.

Table 1Percentage radionuclidic impurities of different radionuclide present in 90Y produced atEOI.

Radionuclide Decay properties % Radionuclidicimpurity at EOI

89Sr T½ = 49.5 d, Eβ(max) = 1.49 MeV, No γ 0.052 ± 0.01891Y T½ = 58.5 d, Eβ(max) = 1.54 MeV,

Eγ = 1.21 MeV (0.3%)0.008 ± 0.002

160 Tb T½ = 72.3 d, Eβ(max) = 569 keV,Eγ = 879 keV (28.5%)

0.003 ± 0.001

169Yb T½ = 32.03 d, Eγ = 177 keV (21.4%),197 keV (34.9%)

0.007 ± 0.003


Complete Freund's Adjuvant (CFA) following the procedure reportedearlier [20]. Briefly, the rats were first anaesthetized using a combina-tion of xylazine hydrochloride and ketamine hydrochloride. Subse-quently, the left knee area of the animals were clipped and preparedaseptically for the intra-articular injection. 175 μL of CFA was injecteddirectly into the knee joint above the meniscus. The knee joint wasapproached craniolaterally in between lig. collaterale laterale genus andm. gastrocnemius lateralis, below condulis lateralis osis femoris. Inflam-matory symptoms were noticed within 3–4 days of CFA injection.Biodistribution and imaging studies were carried out within 2–3 daysafter confirming onset of arthritis.

For biodistribution studies, radiolabeled HA particles (~2 MBq)suspended in 100 μL of normal saline was injected intra-articularlyinto the arthritis affected knee joint of each animal. Normal saline(100 μL) was injected into the other joint (control). The animals weresacrificed by CO2 asphyxiation, at the end of 3 h, 24 h and 72 h post-injection (p.i.). Four rats were used for each time point. Blood andsome of the major organs such as, liver, intestine, lung, kidney andspleen were separated, washed with saline, dried, weighed and the ac-tivity associated with each organ/tissue was measured in a flat-typeNaI(Tl) scintillation counter. Distribution of the activity in different or-gans was calculated as percentage of injected activity (dose) (%ID) perorgan and percentage of injected activity per gram of the organ (%ID/g)from these data. Activity accumulated per gram of femurwas consideredfor obtaining the total skeletal uptake assuming skeletal weight to be10% of the total bodyweight [17,18]. The total uptake in blood, skeletonand muscle was calculated by considering that the respective tissueconstitutes 7%, 10% and 40% of the total body weight [17,18]. Thepercentage of activity excreted is indirectly ascertained by subtractingthe activity accounted in all the organs from the total injected activity.For bioluminiscence imaging, 90Y-HA preparation (~10MBq) suspendedin 100 μL of normal saline was injected into the joints. Prior to theacquisition of images, the animals were anesthetized using a combina-tion of xylazine hydrochloride and ketamine hydrochloride. Sequentialwhole-body bioluminiscence imageswere acquired in Photon Imager at30 min, 3 h, 1 d, 3 d and 7 d post-injection.

2.11. Clinical study

Radiation synovectomy using 90Y-HAwas performed on one patient(male, 33 y) suffering from rheumatoid arthritis (RA) of the left kneejoint. RA was proven by measurement of pathological parameters suchas, concentration of the C-reactive protein (CRP), the fibrinogen leveland also by pretherapeutic three-phase bone scintigraphy. The patientwas suffering from persistent pain in the knee joint despite ongoingpharmacotherapy with anti-inflammatory and analgesic drugs. The du-ration of the disease was ~18 months. Intra-articular injection of corti-costeroid was prohibited within 4 weeks before RSV. 3-phase bonescintigraphywas performedwith a dual head gamma-camera (SiemensSymbia True Point, Siemens Germany) equipped with a low-energyhigh resolution collimator after intravenous injection 99mTc-MDP(740 MBq) with detectors positioned over the knee joints in anteriorand posterior projections. The first phase (blood flow phase) was ob-tained immediately after radiotracer administration. Dynamic acquisitionwas performed over a period of 2 min with the time resolution of2 seconds. The second phase (blood pool phase) was carried out 5 minpost radiotracer administration with a 10 min static acquisition. Delayed,static images (the third phase ormetabolic phase)were obtained 4h afterradiotracer administration. Bone scans were routinely evaluated.

RSV was performed under local anesthesia administered with 2%lidocaine-hydrochloride. Prior to the injection of 90Y-HA, synovial fluidof the affected joint was aspirated. Subsequently, 185 MBq of 90Y-HAparticles dispersed in 1mL of sterile, pyrogen free normal salinewas ad-ministered intra-articularly. Aspirationwas performed in order to avoidback flushing due to high hydrostatic pressure. Joint puncture was per-formed under fluoroscopy, and the radiolabeled preparation was


injected once intra-articular needle placement was ensured. After theinjection, the remaining activity in the syringe was measured. Immedi-ately after RSV, the knee was flexed to augment inter articular distribu-tion, and the range of flexion was recorded. An orthopedic bandagewasapplied as a semi rigid splint. The treated joints were immobilized forabout 48 h in order to prevent extra-articular migration of radiolabeledparticles through local lymphnodes. Radionuclide leakages along thenee-dle track or any local and general side effects were not observed. Patientwas released 4 h post injection advised complete rest. Follow-up exami-nations, based on detailed information from the patient, clinical examina-tion and bone scintigraphy were performed for a period of 6 months.

The study was approved by the local institutional ethics committee(Reference No. EC/AP/244/06/2013, Registration No ECR/112/INST/TN/2013), and the patient provided written informed consent.

3. Results

The primary objective of this study is to assess the utility 90Y pro-duced in amediumflux research reactor by (n,γ) route in RSV by formu-lation of a suitable radiolabeled agent, which can be convenientlyformulated at hospital radiopharmacy. In order to realize the objective,a systematic study was pursued diligently.

3.1. Production of 90Y

Irradiation of natural Y2O3 target at a thermal neutron flux of ~1 × 1014

n/cm2.s for a period of 14 d yielded 90Y with a specific activity of 851 ±111 MBq/mg (23 ± 3 mCi/mg) (n = 6) at the end of irradiation (EOI).The radionuclidic purity of 90Y produced was found to be 99.93 ± 0.03%(n= 6) at EOI, with 89Sr, 91Y, 160 Tb and 169Yb being the radionuclidic im-purities detected. Table 1 gives the percentage radionuclidic impurity bur-den of these radionuclides in 90Y at EOI. While all the gamma photonemitting radionuclides, namely, 91Y, 160 Tb and 169Yb were detected and



Fig. 2. Scanning electron micrograph of Y-labeled HA particles.


analyzed by gamma ray spectrometry; 89Sr, being a pure β− emitter, wasanalyzed by EPC technique.

3.2. Optimization of radiolabeling protocol

With an aim to arrive at the optimum conditions for the radiolabelingof HA particles utilizing (n,γ) produced 90Y, a detailed study on the

Fig. 3. ED spectrum of (a) HA particle


influence of various experimental parameters on the radiolabeling yieldwere carried out. The effect of variation of the concentration of HA parti-cles used in radiolabeling on the yield of 90Y-labeledHA is shown in Fig. 1.Radiolabeling yield of 95.2± 0.4%was obtained using 1mg of HA in 1mLof reaction volume,which increased to 99.3±0.2%when 5mg of HAwasused. Consequently, 5mg/mLwas considered as the optimum ligand con-centration for further studies. In all the cases reactionswere carried out atpH ~8 for 30min at room temperature using ~185MBq of 90Y containing0.5 mg of yttrium. Variation of pH of the reactionmixture between 2 and10 showed that the pH did not have any significant effect on theradiolabeling yield within the range of 4–8. Below pH 4, the radiolabelingyield was found to be poor. Beyond pH 8, slight decrease in theradiolabeling yield was observed. The optimum pH for radiolabelingwas therefore considered to be ~7–8, which is advantageous as it is sim-ilar to the physiological pH. Further, it was found that when theradiolabeling is carried out in 0.1 M NaHCO3 medium, the pH was auto-matically adjustedwithin 7–8when 90YCl3 solutionwas added to the sus-pension of HA particles. When radiolabeling yield were determined atdifferent time points during the reaction, it was observed that the yieldgradually increasedwith reaction time and reached N99%when the reac-tants were mixed for 30 min of incubation at room temperature.

3.3. SEM and EDX analysis

A typical scanning electron micrograph of yttrium labeled HA parti-cles is shown in Fig. 2. The SEM result reveals that the hydroxyapatite

s and (b) Y-labeled HA particles.



Table 3Biodistribution pattern of 90Y-HA inWistar rats with one of the knee joints affected witharthritis.

Organ %ID in organ/tissue(% ID/g of organ/tissue)

3 h 24 h 72 h

Blood 0.01 ± 0.01 0.01 ± 0.01 0.00 ± 0.000.00 ± 0.00 0.00 ± 0.00 0.00 ± 0.0

Liver 0.28 ± 0.08 0.18 ± 0.08 0.19 ± 0.030.03 ± 0.02 0.02 ± 0.02 0.02 ± 0.01

Intestine 0.07 ± 0.03 0.04 ± 0.02 0.02 ± 0.010.00 ± 0.00 0.00 ± 0.00 0.00 ± 0.00

Kidney 0.02 ± 0.00 0.01 ± 0.01 0.00 ± 0.000.01 ± 0.00 0.00 ± 0.00 0.00 ± 0.00

Stomach 0.00 ± 0.00 0.00 ± 0.00 0.00 ± 0.000.00 ± 0.00 0.00 ± 0.00 0.00 ± 0.00

Heart 0.00 ± 0.00 0.00 ± 0.00 0.00 ± 0.000.00 ± 0.00 0.00 ± 0.00 0.00 ± 0.00

Lungs 0.06 ± 0.03 0.04 ± 0.01 0.03 ± 0.020.04 ± 0.03 0.02 ± 0.01 0.02 ± 0.01

Spleen 0.05 ± 0.02 0.04 ± 0.02 0.04 ± 0.010.08 ± 0.03 0.07 ± 0.03 0.07 ± 0.01

Muscle 0.02 ± 0.01 0.00 ± 0.00 0.00 ± 0.000.00 ± 0.00 0.00 ± 0.00 0.00 ± 0.00

Skeleton 0.06 ± 0.03 0.04 ± 0.03 0.04 ± 0.020.00 ± 0.00 0.00 ± 0.00 0.00 ± 0.00

Injected knee 98.68 ± 0.29 98.41 ± 0.38 98.36 ± 0.82Control knee 0.05 ± 0.03 0.03 ± 0.02 0.03 ± 0.02Excretiona 0.68 ± 0.12 1.21 ± 0.18 1.31 ± 0.32

% ID/of organ/tissue are shown in the figures in italics.‘±’ represents standard deviation.At every time point 4 animals have been used.

a Excretion has been calculated by subtracting the activity accounted in all the organsfrom the total activity injected.


scaffolds has a porous architecture throughout the matrix. The poroussurface has an advantage because it can facilitate the diffusion of Y foradsorption on the internal surface of HA. The particle sizes were nearlyuniform and ranged from 2 to 10 μm.

To verify the elemental composition and ensure the incorporation ofY into HA matrix, an EDX profile of HA and Y adsorbed HA have alsobeen recorded as shown in Fig. 3(a) and (b), respectively. The EDX spec-trumof HA [Fig. 3(a)] confirms the presence of Ca, O, and P ions. HApre-pared is thus found to be free from any other chemical impurities. TheEDX spectrum of Y-HA [Fig. 3(b)] shows the presence of Na, Ca, Y, O,P, and Cl confirming the incorporation of yttrium in HA particles. Theadditional Na and Cl peaks observed are attributed from theNaHCO3 so-lution and YCl3 solution thatwere used in the formulation. The chemicalcomposition of HA and Y-HA surface were determined from the intensityof the peak pertaining to different elements and the quantification ofresults as weight percentage is given in Table 2.

3.4. Preparation of clinical dose 90Y-HA using kits

Based on the results of the optimization studies, HA kits convenientfor easy preparation of 90Y-HA doses at hospital radiopharmacy wereformulated. Addition of 1 mL of water for injection into the kit vialsand subsequent thorough mixing result in a suspension of HA particlesin 0.01M NaHCO3 solution with a concentration of 5 mg of HA particlesper mL. The pH of the mixture was observed to be ~7–8 after the addi-tion of 185± 10MBq of 90Y activity as 90YCl3 solution (typically 100 μL,containing 0.5 mg of yttrium). The yield of 90Y-HA prepared using kitswas found to be 98.5 ± 1.1% (n = 25), while the radiochemical purityof the labeled particles subsequent to washing with normal saline was99.5 ± 0.2% (n = 25).

3.5. In vitro stability studies

Yttrium-90-labeled HA particles showed excellent in vitro stabilityup to a period of 10 d (N3 half-lives of 90Y) in normal saline at 37 °C.The radiochemical purity of the preparation was found to be retainedto the extent of N99% during the entire study period. In the DTPA chal-lenge study, it was observed that the radiochemical purity of 90Y-HAgradually degraded in 5 mM DTPA solution most likely due to leachingof yttrium ions from HA particles and formation of 90Y-DTPA complex(Fig. 4). However, it is pertinent tonote that despite the gradual leachingof yttrium from HA matrix in presence of strong challenging agent(DTPA), the radiochemical purity of the radiolabeled particulates wasfound to be retained to the extent of 76.2±1.8%evenafter 72hof storage.This indicates fairly strong association of yttrium with HA particles.

3.6. In vivo studies in animal model

The results of the biodistribution studies carried out in normalWistar rats after loco-regional administration of 90Y-HA into one of

Table 2Chemical composition of the surface ofHA particles and Y-labeledHA particles as obtainedfrom EDX analysis.

Element Intensity Corrn. Weight percentage

HA particlesOxygen 0.4280 60.06 ± 1.06Phosphorus 1.2625 16.65 ± 0.45Calcium 0.8827 23.30 ± 0.70

Y-labeled HA particlesOxygen 0.4287 52.67 ± 1.24Sodium 0.4008 1.27 ± 0.22Phosphorus 1.2797 11.43 ± 0.39Chlorine 0.6628 1.66 ± 0.17Calcium 0.9396 19.27 ± 0.53Yttrium 0.8134 13.72 ± 0.73


the knee joint cavities of the animals are summarized in Table 3. Theresults showed retention of N 98% of the injected activity within thejoint cavity even after 72 h p.i.. Activity detected in blood and othermajor organ/tissue was insignificantly low, which indicated that therewas almost no leakage of injected activity from the joint cavity. Thepercentage of injected activity excreted was also found to be very less(1.31 ± 0.32 at 72 h p.i.).

The sequential whole-body bioluminescence images of theWistar ratacquired 3 h, 24 h, 72 h and 168 h post-injection of 90Y-HA preparationinto one of the knee joints are shown in Fig. 5(a) to (d), respectively. Itis evident from the figures that almost all the injected activity remainedlocalized in the synovium even at 168 h post-administration. No activitycould be detected in any other organs/tissue thereby confirming thatpractically no leakage of instilled particles had occurred. This observationhas been corroborated with the results of the biodistribution studies.

Fig. 4. Variation of radiochemical purity of 90Y-HA at different time intervals when storedin 5 mM DTPA solution at room temperature.



ig. 6.Representative 99mTc-MDPbonescan(anterior)of apatient recorded1weekprior to theY-HA therapy showing increased uptake of the radiotracer in the arthritis affected knee joint.

Fig. 5.Whole bodybioluminiscence images ofWistar rats at (a) 3h, (b) 24h, (c) 72hand (d)168hafter intra-articular administrationof 90Y-HApreparation into the arthritis inducedknee joint.


3.7. Clinical studies

Results of the preliminary clinical investigations, carried out on a pa-tient suffering from acute RA of knee joint, showed that the adminis-tered 90Y-HA activity was retained completely within the knee jointcavity as no leakage of 90Y activity into any other non-target organscould be visible in the serial whole body scans recorded up to 7 dpost-administration of 90Y-HA. Fig. 6 shows the representative 99mTc-MDP bone scan of the patient recorded 7 d prior to the 90Y-HA therapyshowing increased uptake of the radiotracer in the knee joints. The rep-resentative scan of the treated knee joint of the same patient recorded24 h post-administration of 90Y-HA recorded using Bremsstrahlung ra-diation from 90Y is shown in Fig. 7. The scan indicates excellent localiza-tion of the radiolabeled particulates in the joint cavity with almost noextra-articular leakage. Preliminary assessment of treatment efficacycarried out over a period of 6 months based on the information fromthe patient showed substantial improvement in the disease conditionssuch as, reduction in joint effusion, local pain and improvement in therange of motion. The patient reported a 50% decrease in joint pain andstiffness along with 40% improvement in mobility scores over a periodof 6 months. A comparison of pre-therapy, 3 months post-therapy and6 months post-therapy 99Tc-MDP scans of the knee joint region of thepatient [Fig. 8(a) to (c), respectively] clearly demonstrates significantreduction of synovial inflammation as a direct evidence of therapeuticefficacy of 90Y-HA. Long-term treatment efficacy based on quantitativedata obtained from clinical and pathological examinations are beingworked out, and the data will be published in the future.

4. Discussions

No-carrier-added 90Y available from 90Sr/90Y generator is one of thepivotal radionuclide in therapeutic nuclear medicine, especially for usein targeted tumor therapy using peptides and antibodies as thetargeting vector. The separation of high purity 90Y from 90Sr amenable


F90



Fig. 7. Bremsstrahlung image of the knee joints (anterior) of the patient recorded 24 h post-administration of 90Y-HA into the arthritis affected joint showing excellent localization andretention of instilled radioactivity in joint cavity.


for clinical application, however, requires an elaborate complex radio-chemical separation process. The limit for the 90Sr impurities permissi-ble in 90Y is very low, and extensive quality control tests are essential toascertain the purity and certify compliance formedical use. On the otherhand, the prospect of clinical utilization of 90Y produced in nuclear reac-tor via neutron activation of naturally mononuclidic (in 89Y) yttriumtarget is hardly explored so far. While the specific activity of 90Y pro-duced via (n,γ) route is not suitable for its use in targeted tumor thera-py, it is shown adequate for the preparation of 90Y labeled particulateamenable for use inRSV, provided irradiations are carried out inmoderateto high thermal neutron flux (preferably 1 × 1014 n/cm2.s) or higher.The IAEA database shows that there are 251 research reactors currentlyin operation worldwide [29] and ~50 of these research reactors havethermal neutron flux capabilities 1 × 1014 n/cm2.s or higher. Many of

Fig. 8. (a) Pre-therapy, (b) 3months post-therapy and (c) 6months post-therapy 99Tc-MDP scademonstrating significant reduction of synovial inflammation as a direct evidence of therapeut


these research reactors could be used for the production of 90Y for clini-cal use by the direct (n,γ) production route as setting up of processingfacilities is realistic and implementable in a very short timeframe be-cause simple target dissolution capabilitieswill suffice. This is a sustainableand affordable option and the least intricate route to access 90Y withadequate radionuclidic purity acceptable specific activity for use inRSV, where the 90Sr/90Y generator is not available.

Our interest on the use of (n,γ) produced 90Y for RSV was drivenmainly by two considerations: (i) suitable nuclear properties of 90Y foruse in RSV and (ii) straight forward production of 90Y in required quantityand specific activity via (n,γ) route leading to its cost effective availabilityon demand. Several batches of 90Ywere producedwith specific activity ofN740MBq/mg and radionuclidic purity of N99.9% by irradiation of naturalY2O3 target in a medium flux research reactor of ~1 × 1014 n/cm2.s

ns of the knee joint region (posterior blood pool) of the patient treatedwith 90Y-HA clearlyic efficacy of 90Y-HA.




thermal neutron flux for 14 d. The co-produced radionuclide impurities,mainly 89Sr [T1/2 = 50.5 d, Eβ(max) = 1.49 MeV] and 91Y [T1/2 = 58.5 d,Eβ(max) = 1.54 MeV, Eγ = 1.21 MeV (0.3%)] are in very low levels(Table 1) and consequently, the overall dose burden from these impuri-ties to the patient administeredwith ~185MBq of 90Ywould be insignifi-cantly small. The irradiation duration of 14dwas found to be optimum forthe production of 90Y with adequate specific activity for RSV whilekeeping the level of co-produced radionuclide impurities within theacceptable limit.

Successful utilization of (n,γ) produced 90Y in RSV not only demandsthe radionuclide of desired quantity and purity but also a suitable particu-late carrier used as vehicle for 90Y. The scope of usingHAparticles of appro-priate size distribution is enticing as it is themajor inorganic component ofnatural bone and known for its biocompatible, biodegradable, non-toxic,non-inflammatory, non-immunogenic properties [15–17]. Other appealingattributes of HA are ease of synthesizing in the desired particle size rangeand capability to bind a wide variety of metal ions, mainly lanthanidesand pseudolanthanide such as yttrium [15–20,22,25,26]. Hydroxyapatiteparticles were synthesized in required quantity in our laboratory; particlesof 1 to 10 μm size range were segregated and characterized. The use of HAparticles between 1 and 10 μmseems to be logical as they are small enoughto ensure homogenous distribution of radiolabeled particle throughout thejoint to deliver uniform radiation dose to the inflamed synovium and at thesame time large enough to prevent the leakage from the synovial cavitythrough lymphatic drainage. Moreover, the binding between the 90Y andthe HA particle is required to be strong to preclude the dissociation ofactivity from the particles throughout the course of the treatment. Ourin vitro and in vivo experimental results clearly demonstrated the suitabilityof 90Y-HAparticles forRSV.Useof thedevelopedkit type labelingprocedureis found to be an effective strategy to achieve a ready and convenient for-mulation of 90Y-labeled HA particles. Preparation of 90Y-HA in 200 ±30 MBq dose with high yield, radiochemical purity and reproducibilitywas accomplished using the developed HA kits. The strategy was found tobe simple and easily adaptable for nuclear medicine technologists athospital radiopharmacy.

Having successfully completed the in vitroand in vivo studies, transitionof 90Y-labeled HA particles from radiopharmacy to clinical investigationwas considered worthwhile pursuing. Preliminary clinical investigationwas carried out in one patient suffering from rheumatoid arthritis inknee joint by intra-articular administration of 185 MBq dose 90Y-HA intothe joint cavity and follow up studies carried out for a period of6 months. Based on the post-therapy imaging studies using Bremsstrah-lung radiation from 90Y, near-complete intra-articular retention of instilledradiolabeled particulates was observed up to 7 d post-therapy. Significantimprovement in the disease conditionswas reported in terms of joint effu-sion, local pain and range ofmotionwhich persisted up to 6months followup period. Further follow up investigations are being carried out. No un-wanted side effects from the treatment were observed. The data on thepreliminary clinical investigations using the administered dose of 90Y-HArevealed its promise in the treatment of rheumatoid arthritis of knee jointsand the utility of convenient kit type radiolabeling strategy followed athospital radiopharmacy. However, systematic investigations in a largerpopulation of patients, detailed study on dosimetry etc. are warranted be-fore proposing the agent as a viable radiopharmaceutical for RSV. The pur-pose of the present report is to demonstrate the suitability of 90Y obtainedfrom neutron activation production route for RSV, which the authors be-lieve would create interest among the scientific community and cliniciansleading to further developments in this field.

The discussions put forth in this article are not meant to denouncethe need for, or merits of NCA 90Y obtained from 89Sr/90Y generator inthe therapeutic nuclear medicine; only a case has been advocated forthe use of (n,γ) produced 90Y-labeled HA particles as a viable and costeffective alternative to the existing options in RSV. The developedmethodology can be pursued in a significant number of countries acrossthe world which have operating medium flux research reactors havingthermal neutron flux of ~ of ~1 × 1014 n/cm2.s or higher.


5. Conclusion

The utility of 90Y obtained from neutron activation production route forthe formulation of clinical doses of 90Y-labeledHA particles using ready-to-use single vial kits of HA particles at the hospital radiopharmacy set up hasbeen successfully demonstrated. The single-vial kits, provided a convenientand reproducible method for facile preparation of 90Y-labeled HA particles(185 ± 10 MBq) with high yield (N98%) and radiochemical purity(N99%) in a clinical setting. The radiolabeled particulates prepared usingkit formulation strategy showed promising results in biodistribution andimaging studies in Wistar rats with knee joints affected with arthritis. Pre-liminary clinical studies carried out on a single patient suffering from rheu-matoid arthritis in one of the knee joints demonstrate the effectiveness of90Y-HA in terms of pain control, functional improvement and prevention ofdisease progression. Development of a kit formulation strategy for the facilesynthesis of 90Y-HA using 90Y produced by (n,γ) route and its subsequentpreliminary clinical translation represents apotential step forward to realizetheir therapeutic potential in themanagement of patientswith rheumatoidarthritis. The important details available from this investigationwould be ofconsiderable value to stimulate scientists, researchers andcliniciansof otherinstitutions planning to pursue 90Y-labeled particulates/colloids for thetreatment of rheumatoid arthritis.

Statement of conflict of interest

The authors declare that they have no conflict of interests, financial,scientific or otherwise with other people or organizations in the publi-cation of this article.

Acknowledgement

Research at the Bhabha Atomic Research Centre is part of the ongoingactivities of theDepartment of Atomic Energy, India and is fully supportedby government funding. The authors express their sincere thanks toDr. V. Sudarshan, Chemistry Division, Bhabha Atomic Research Centre,for EPC analysis and SEM and EDAX analysis, respectively. The authorsalso gratefully acknowledge the help rendered by Dr. S. V. Thakare andShri K. C. Jagadeesan in arranging for the irradiation of Y2O3 targets inDhruva research reactor.

References

[1] Schneider P, Farahati J, Reiners C. Radiosynovectomy in rheumatology, orthopedics,and hemophilia. J Nucl Med 2005;46:48S–54S.

[2] Deutsch E, Brodack JW, Deutsch KF. Radiation synovectomy revisited. Eur J Nucl Med1993;20:1113–27.

[3] Mödder G. Radiation synovectomy. In: Biersack HJ, Freeman LM, editors. ClinicalNuclear Medicine. Berlin Heidelberg: Springer Verlag; 2007. p. 512–8.

[4] Wang SJ, Lin WY, ChenMN, Chen JT, HoWL, Hsieh BT, et al. Histologic study of effects ofradiation synovectomy with Rhenium-188microsphere. Nucl Med Biol 2001;28:727–32.

[5] Clunie G, Fisher M. EANM procedure guidelines for radiosynovectomy. Eur J NuclMed Mol Imaging 2003;30:BP12–6.

[6] van der Zant FM, Boer RO, Moolenberg JD, Jahangier ZN, Bijlsma JWJ, Jacobs JWG.Radiation synovectomy with 90Yttrium, 186Rhenium and 169Erbium: a systematicliterature review and meta-analysis. Clin Exp Rheumatol 2009;27:130–9.

[7] Spooren PFMJ, Rasker JJ, Arens RPJH. Synovectomy of the knee with 90Y. Eur J NuclMed 1985;10:441–5.

[8] Franseen MLAM, Boerbooms AMTH, Karthaus RP, Buijs WCAM, van de Putte LBA.Treatment of pigmented villonodular synovitis of the kneewith yttrium-90 siclicate:prospective evaluations by arthroscopy, and 99mTc pertechnetate uptake measure-ments. Ann Rheum Dis 1989;48:1007–13.

[9] Will R, Laing B, Edelman J, Lovegrove F, Surveyor I. Comparison of two yttrium-90regimens in inflammatory and osteoarthropathies. Ann Rheum Dis 1992;52:262–5.

[10] Stucki G, Bozzone P, Treuer E, Wassmer P, Felder M. Efficacy and safety of radiationsynovectomy with yttrium-90: a retrospective long-term analysis of application in82 patients. Br J Rheumatol 1993;32:383–6.

[11] Kampen WU, Voth M, Pinkert J, Krause A. Therapeutic status of radiosynoviorthesisof the knee with yttrium [90Y] colloid in rheumatoid arthritis and related indications.Rheumatology 2007;46:16–24.

[12] Thomas S, Gabriel MC, De Souza SAL, Gomes SC, Assi PE, Pinheiro Perri ML, et al.Haemophilia 2011;17:e985–9.

[13] Chakravarty R, Dash A, Pillai MRA. Availability of Yttrium-90 from Strontium-90: anuclear medicine perspective. Cancer Biother Radiopharm 2012;27:621–41.


http://refhub.elsevier.com/S0969-8051(15)00018-9/rf0005













































[14] Atlas of neutron capture cross sections. Vienna, Austria: IAEA Nuclear Data Section;1997.

[15] Chinol M, Vallabhajosula S, Goldsmith SJ, Klein MJ, Deutsch KF, Chinen LK, et al.Chemistry and biological behaviour of Samarium-153 and Rhenium-186-labeledhydroxyapatite particles: potential radiopharmaceuticals for radiation synovectomy.J Nucl Med 1993;34:1536–42.

[16] ClunieG, LuiD, Cullum I, Edwards JCW, Ell PJ. Samarium-153-particulatehydroxyapatitefor radiation synovectomy: biodistribution data for chronic knee synovitis. J Nucl Med1995;36:51–7.

[17] Unni PR, Chaudhari PR, Venkatesh M, Ramamoorthy N, Pillai MRA. Prepration andbioevaluation of 166Ho labeled hydroxyapatite (HA) particles for radiosynovectomy.Nucl Med Biol 2002;29:199–209.

[18] Chakraborty S, Vimalnath KV, Rajeswari A, Shinto A, Radhakrishnan ER, Dash A.Radiolanthanide-labeled HA particles in the treatment of rheumatoid arthritis:ready-to-use cold kits for rapid formulation in hospital radiopharmacy. J RadioanalNucl Chem 2014;302:875–81.

[19] Pandey U, Mukherjee A, Chaudhary PR, Pillai MRA, Venkatesh M. Preparation andstudies with 90Y-labelled particles for use in radiation synovectomy. Appl RadiatIsot 2001;55:471–5.

[20] Chakraborty S, Das T, Banerjee S, Sarma HD, Venkatesh M. Preparation and prelimi-nary biological evaluation of 177Lu labeled hydroxyapatite as a promising agent forradiation synovectomy of small joints. Nucl Med Commun 2006;27:661–8.

[21] Pandey U, Bapat K, Sarma HD, Dhami PS, Naik PW, Samuel G, et al. Bioevaluation of90Y-labeled particles in animal model of arthritis. Ann Nucl Med 2009;23:333–9.


[22] Chakraborty S, Das T, Chirayil V, Lohar SP, Sharma HD. Erbium-169 labeled hydroxy-apatite particulates for use in radiation synovectomy of digital joints – a preliminaryinvestigation. Radiochim Acta 2014;102:443–50.

[23] Chakraborty S, Vimalnath KV, Rajeswari A, Shinto A, Sarma HD, Kamaleshwaran K,et al. Preparation, evaluation and first clinical use of 177Lu-labeled hydroxyapatite(HA) particles in the treatment of rheumatoid arthritis: utility of cold kits for conve-nient dose formulation at hospital radiopharmacy. J Label Compd Radiopharm 2014;57:453–62.

[24] Calegaro JU, Machado J, Furtado RG, de Almeida JS, de Vasconcelos AV, de BarbozaMF, et al. The use of 185 MBq and 740 MBq of 153-samarium hydroxyapatite forknee synovectomy in haemophilia. Haemophilia 2014;20:421–5.

[25] Davarpanah MR, Khoshhosn HA, Harati S, Nosrati SA, Zoghi M, Mazidi M, et al. Op-timization of fundamental parameters in routine production of 90Y-hydroxyapatitefor radiosynovectomy. J Radioanal Nucl Chem 2014;302:69–70.

[26] Khalid M, Mushtaq A. Preparation and in vitro stability of (n, gamma) yttrium-90hydroxyapatite. Appl Radiat Isot 2005;62:587–90.

[27] Marwah UR. Synthesis of organophosphorus extractants for solvent extraction ofmetals. Proc. National Symposium on Organic Reagents Synthesises and use inextraction metallurgy. Mumbai, India: BARC; 1994. p. 23.

[28] Pandey U, Dhami PS, Jagesia P, Venkatesh M, Pillai MRA. A novel extraction paperchromatography (EPC) technique for the radionuclidic purity evaluation of 90Y forclinical use. Anal Chem 2008;80:801–7.

[29] International Atomic EnergyAgency. Operation research reactors in theworld. [data-base] www.naweb.iaea.org/napc/physics/research_reactors/database.






























































http://www.naweb.iaea.org/napc/physics/research_reactors/database


radiochemistry, pre-clinical studies and first clinical investigation of 90y-labeled hydroxyapatite...

Documents