Radiopharmaceuticals for nuclear medicine

Transcription

1 Radipharmaceuticals fr nuclear medicine Medical University f Ldz Dr Janusz Kapuściński 1

2 Nuclear Medicine A branch f medicine and medicine imaging, that fr diagnstics and theraphy uses pen surces f radiatin administred t patients. 2

3 Nuclear Medicine Radiactive substances are administered t patients and the radiatin emitted is detected.

4 Nuclear Medicine NM is a part f mlecular imaging it prduces images that reflect bilgical prcesses that take place at the cellular and subcellular level.

5 Nuclear Medicine Nuclear medicine prcedures use radipharmaceuticals pharmaceuticals labeled with radinuclides. A radipharmaceutical cnsists f tw functinal cmpnents: - radiactive - nn-radiactive.

6 Radipharmaceuticals The radiactive cmpnent enables detectin f the radipharmaceutical. It is a radinuclide with apprpriate physical prperties. The nn-radiactive cmpnent is a mlecule with apprpriate pharmac-kinetics. It is accumulated in the target rgan and it determines bilgical behaviur f the radipharmaceutical in the bdy. 6

7 Radipharmaceuticals Sme nuclides can be used "as is". - radiactive idine is absrbed directly by thyrid gland. - radiactive thallium is absrbed directly by heart muscle and can be used t investigate whether parts f heart are functining nrmally. 7

8 Radipharmaceuticals Mst radiactive nuclides must be bund with a carrier mlecule which enables them t bind t cells r prcesses we want t image. Carrier mlecule has an affinity fr a certain type f cell r receptr. These mlecules carry 99mTc r ther radinuclides t the sites in the bdy which we want t image. 8

9 Radipharmaceuticals Prperties f ideal diagnstic RF: pure gamma emitter 100 < gamma energy < 250 kev shrt effective half-life 9

10 Radipharmaceuticals Prperties f ideal diagnstic RF: high target : nn-target rati chemical reactivity inexpensive, easily available maximum efficacy in diagnsis minimum radiatin dse. 10

11 Main advantages f Technetium-99m as radiistpe label Shrt half-life (6.02 hurs - lw radiatin dse) Pure gamma radiatin (absence f alfa and beta emissin - lw radi txicity) Energy f gamma quantum 140 kev (cnvenient fr detectin) Reactive (chemical bunds with varius cmpunds) Inexpensive, easily and instantly available (M/Tc radinuclide generatr) 11

12 Radipharmaceuticals Many radipharmaceuticals use technetium (99mTc) as a raditracer. Different radipharmaceuticals based n 99mTc are used fr imaging and functinal studies f brain, mycardium, thyrid, lungs, liver, kidneys,, gallbladder, skeletn, bld and tumrs. 99mTc is a radiistpe used in ver 85% f nuclear medicine diagnstic prcedures. 12

13 Technetium-99m Since 99mTc has a half-life f nly 6 hurs, it is generated n a just-intime basis frm its parent radiistpe mlybdenum-99, which has a half-life f 66 hurs. 13

14 99M/99mTc radinuclide generatr Generatr is a leadshielded clumn cntaining a resin t which 99M is attached. 99M decays t prduce the shrt-lived 99mTc. T btain 99mTc, physilgical saline (the eluent) is injected int the tp f the clumn. 14

15 99M/99mTc radinuclide generatr The eluent is passed thrugh the clumn and NaTcO4 - sdium pertechnetate, (the daughter f 99Mdecay), is eluted. 15

16 99M/99mTc radinuclide generatr The pertechnetate is cllected in a shielded, evacuated sterile vial and calibrated prir t use. It is referred t as the eluate. 16

17 Technetium labelling 99mTc btained frm M/Tc generatr is in +7 xidatin state and des nt frm cmplexes. The majrity f 99mTc cmpunds emply stannus reductin methd. 17

18 Technetium labelling A reducing agent is therefre required t cnvert the 99mTc int a frm capable f binding t chelating agents. In redx reactins TcO4is reduced t Tc4+ by stannus in (Sn2+). 18

19 Technetium labelling If a vial cntains an agent capable f chelating 99mTc, the reactin ccurs almst immediately. The pharmaceutical agent is thus labelled with the radinuclide. 19

20 Technetium labelling Chemistry f technetium allws it t frm a stable cmplex with a relatively wide range f chemical chelatin agents. Ulrich Abram, Rger Albert: Technetium and rhenium - crdinatin chemistry and nuclear medical applicatins. J. Braz. Chem. Sc. 2006; vl.17 n.8 20

21 Kits fr labeling with Tc-99m Mst widely used kits: MIBI (mycardial perfusin scintigraphy) MDP r HEDP (skeletn scintigraphy) DTPA (renscintigraphy renal functin) EC r MAG3 (renscintigraphy renal functin) MAA (perfusin lung scintigraphy) IDA derivatives (bilary ducts scintigraphy) sulfur cllid (liver and spleen scintigraphy). 21

22 Radipharmacy Typically a radipharmacy has a specialized lab t manufacture, label and stre each different radiactive drug.

23 Radipharmaceuticals preparatin Fr preparatin f sterile radipharmaceuticals the wrking area shuld cmply with apprpriate envirnmental requirements. This may be achieved by the prvisin f a wrkstatin with a laminar flw f HEPA-filtered Grade A air. 23

24 Radipharmaceuticals preparatin In rder t minimize the radiatin risk t the persnnel the wrk area must be adequately shielded. The lead surfaces f the shielding must be cvered (stainless steel). 24