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Medical physics & LPNR

Medical physics & LPNR. Université Mohammed V-Agdal Faculté des Sciences, Rabat. N uclear P hysics L aboratory, R abat (LPNR) , Faculty of Sciences. Created during the sixties of last century Main equipment: Neutron generator, 14 MeV/ SAMES T-400 (1970)

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Medical physics & LPNR

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  1. Medical physics & LPNR Université Mohammed V-Agdal Faculté des Sciences, Rabat Valencia, 18 -19 november 2010

  2. Nuclear Physics Laboratory, Rabat (LPNR) , Faculty of Sciences • Created during the sixties of last century • Main equipment: • Neutron generator, 14 MeV/ SAMES T-400 (1970) • a, b, g and X spectrometers . Valencia, 18 -19 november 2010

  3. Education at LPNR • Teaching nuclear physics at the undergraduate and graduate courses of university, • Diversification of courses, • Contribution to the development of higher education/ national needs, • Formation through research : • 10 CEA Nuclear Physics, • 1 DESA / Physics and Technology of Radiation • 1 Specialized Master / Medical Physics; • 45 doctorates thesis and • 17 state thesis Valencia, 18 -19 november 2010

  4. Research at LPNR • Main topics (above 40 years) : • Nuclear techniques / applications : • 14 MeV Neutron Activation Analysis, • Cross section measurements (Interaction Nuclear) , • Qualitative or quantitative analysis of samples (industry, geological, biological, archéological …), • Fast neutrons dosimetry, • Natural radioactivity measurements (datation, qualitative / quantitative analyse, ..) Valencia, 18 -19 november 2010

  5. Research at LPNR • Reactor Physics : • Neutron (transport) simulation (anomalies reactors, • High energy physics : • ATLAS collaboration : presampler, test beams, TOP physics • Neutron diffraction analysis :applied to magnetic exchange path in transition elements phosphates • Medical physique: Valencia, 18 -19 november 2010

  6. Medical physics • Why? Request of INO’s radiotherapy department • DESA Radiation Physics and Technology - 2004/2006 • 2 projects DESA 2006 : quality control of radiotherapy treatment apparatus / INO • Professional Master : Medical Physics - 2007/2009 Valencia, 18 -19 november 2010

  7. Medical Physics Professional Master : Medical Physics   • 27 laureates (24 students + professionals medical physicists). • Projects / six months training / hospital : • Radiotherapy departments (19), nuclear medicine departments (7) et radiology department (1) • In Morocco : CHU University hospital centers (Casablanca, Rabat) : 19 projects • Abroad : Argentina: 1, Belgium : 1, Canada: 1 et France: 5  Valencia, 18 -19 november 2010

  8. Professional Master : Medical Physics • Projects of subjects : • Quality assurance • Quality control of treatment or diagnostic apparatus, • Improvement or development of independent programs for dosimetry treatment calculations, • Development and calibration of detection systems (semi-conductor diodes, gafchromiques films, ..), • optimisation of dose patient during medical tests, • Workers radioprotection in a hospital Valencia, 18 -19 november 2010

  9. Validation of a double calculation program with wedge (filtre en coin) [F.Z. Erradi] Wedge Accelerator head Dynamic wedge produced by blade’s movement Wedge moderates isodoses Valencia, 18 -19 november 2010

  10. Validation of a double calculation program with wedge [F.Z. Erradi] • Wedge transmission factor : STT: Segmented Treatment Table, fraction totale du nombre d’unités moniteurs à délivrer en fonction de la position de la mâchoire mobile GSTT: Golden Segmented Treatment Table Y : position de la mâchoire en mouvement θ : angle du filtre en coin Yc : position du centre géométrique du champ ouvert. Ys : position de la mâchoire stationnaire Valencia, 18 -19 november 2010

  11. Validation of a double calculation program with wedge [F.Z. Erradi]  Comparison of wedge transmission factors determined by different methods for X6 energy • EDW factors : measured, ionisation chamber value (same dimension for filtered field or not) for a same monitor unit and a reference depth • Mesureappareil : measured with ionisation chambrer • Calculéclipse: calculated by apparatus code. • Calculmanuel: calculated with theoretical formula Wedge angle Beam dimensions Wedge angle Beam dimensions Valencia, 18 -19 november 2010

  12. Validation of a double calculation program with wedge [F.Z. Erradi] • Validation on water tank • X23 MV energy, 10 cm depth without wedge • X23 MV energy, EDW=15° X et Y : dimension field Valencia, 18 -19 november 2010

  13. Validation of a double calculation program with wedge [F.Z. Erradi] • Validation on patient • Validation performed for the treatment of prostate without wedge Valencia, 18 -19 november 2010

  14. Validation of a double calculation program with wedge [F.Z. Erradi] • Comparative study between independent code and treatment planning system calculations for some medical treatments with wedge Ant : Champs antérieur. Post : Champs postérieur. OAG : Oblique antérieur gauche OPD : Oblique postérieur droit. Lat d : latéral droit. Lat g : latéral gauche Valencia, 18 -19 november 2010

  15. Treatment of hyperthyroidism by iodine 131 [H.Saikouk] • Hyperthyroidism is an increase in thyroid hormones secretion • Aim : Optimizing the dose of iodine administered to patients by applying the simplified method for Marinelli calculating dose M: Thyroid weight F24h: thyroid uptake of iodine after 24 hours Valencia, 18 -19 november 2010

  16. Treatment of hyperthyroidism by iodine 131 [H. Saikouk] • Thyroid mass is determined by ultrasonography. The thyroid is geometrically approximated to two ellipsoids (cm3 ) a: thyroid length b: thyroid width c: thyroid thickness Valencia, 18 -19 november 2010

  17. Traitement de l’hyperthyroïdie par l’iode 131 [H.Saikouk] • Radioprotection • Elaboration d’une fiche informative en langues arabe et française pour les patients traités par I-131 Valencia, 18 -19 november 2010

  18. Treatment of hyperthyroidism by iodine 131 [H. Saikouk] Introduction of two distinctive badges for patients treated with iodine 131 for hyperthyroidism (100 mCi) and those who are in the service for scanning with iodine (3 mCi) • balayage post iratherapieréalisé après 5 joursd’hospitalisation des patients traités pour un cancer de la thyroïde , et inoculation d’uneactivité de 100 mCi, • balayage à l'iode, réalisétrois jour après ingestion d’uneactivité de 3mCi, examen de contrôle après traitementd’unehyperthyroidie. Valencia, 18 -19 november 2010

  19. Currently • Thesis : • 4 radiotherapy (1 brachytherapy) • 2 nuclear medicine • 1 radiology • Subjects : • Quality assurance quality: quality control of treatment or diagnostic apparatus, dosimetry measurements and calculations, medical imaging • Tools : • modelling, simulation, Monte Carlo method, codes (MCNP, Géant4, Gate, EGSnrc code system /BEAMnrc code/DOSXYZnrc/BEAMnrc user codes), experiments Valencia, 18 -19 november 2010

  20. Monte Carlo calculation of beam quality correction factors of clinical electron dosimetry [H.Nassar] Aim : • Monte Carlo simulation of 6MV/18 MV photon beams of INO’s Elekta Precise accelerator • Comparison of measured and calculated dose distributions Experimental measurements • Photon dosimetry performed by diode (PTW 30010) /active volume 0.6 cm³/ 7.1 mm cavity diameter/computer controlled scanning system (OmniPro). • Water tank (Wellhöfer) / 50x50x50 cm³. • Central axis depth-dose and lateral dose profiles / 10x10 cm² field • Uncertainty of measurement less than 2%. Valencia, 18 -19 november 2010

  21. Monte Carlo calculation of beam quality correction factors of clinical electron dosimetry [H.Nassar] Monte Carlo simulation : • BEAMnrc code based on the EGSnrc Monte Carlo system. BEAMnrc  modelling of radiotherapy external beam treatment units  used to build the accelerator • Simulated head model : • target, primary collimator, flattening filter, ion chamber, backscatter plate, mirror, multi-leaf collimator MLC, Jaws in X and Y directions and Mylar screen. • PEGS4 data cross sections of components • the flattening filters different for 6 MV and 18 MV • Accurate data of accelerator provided by Elekta Company, Crawley, United Kingdom. Valencia, 18 -19 november 2010

  22. Monte Carlo calculation of beam quality correction factors of clinical electron dosimetry [H.Nassar] Valencia, 18 -19 november 2010

  23. Monte Carlo calculation of beam quality correction factors of clinical electron dosimetry [H.Nassar] Results 1. Photon spectra • BEAMDP (BEAM Data Processor) used to analyze the phase-space of electron and photon beams generated using BEAMnrc. • Photon spectra calculated with of 0.1 MeV wide bin for 10x10 cm² field. Photon spectral distribution for 6 MV beam : number of photons per MeV per incident electron Valencia, 18 -19 november 2010

  24. Monte Carlo calculation of beam quality correction factors of clinical electron dosimetry [H.Nassar] 2. Depth dose curves and lateral dose profiles • Mean energy : 6 MeV • FWHM of the radial intensity distribution : 1mm. • The gamma index was used for distribution dose comparison with Dmax= 1 % and Zmax= 2 mm. Comparison of the calculated and measured depth dose curves for 6MV photon beam and 10x10 cm². The depth dose curves are normalized to the maximum dose. Valencia, 18 -19 november 2010

  25. Monte Carlo calculation of beam quality correction factors of clinical electron dosimetry [H.Nassar] Comparison of the calculated and measured lateral dose profile for 6MV photon beam /10x10 cm² field. The lateral dose profiles are normalized to the maximum dose. Valencia, 18 -19 november 2010

  26. Monte Carlo calculation of beam quality correction factors of clinical electron dosimetry [H.Nassar] Comparison of average energy of 6 MV and 18 MV photon beams with other works Valencia, 18 -19 november 2010

  27. Monte Carlo calculation of beam quality correction factors of clinical electron dosimetry [H.Nassar] Next steps : • Dosimetric evaluation of the models with a large field on the basis of experimental measurements and calculated dose distribution. • Establishing of a Monte Carlo models for electrons beams • Verification of the electron models with comparing the measured and calculated dose distributions. Valencia, 18 -19 november 2010

  28. Evaluation of some features of the gamma camera using the software GATE [H.Saikouk] • In the previous presentation, Rabat october 2010: • Description of the simulation components • The geometry of SPECThead • The procedure of the validation by an experience in the Nuclear Medicine department of Ibn Sina Hospital in Rabat Valencia, 18 -19 november 2010

  29. Evaluation of some features of the gamma camera using the software GATE [H.Saikouk] Modifications introduced in the simulation • Add aluminium wrap (in red) contouring the crystal  taking into account attenuation of gamma rays in the alumina • dimensions: 59.1x0.36x44.5 cm3 • Add the perspex part to take into account the photomultipliers and the electronics card • Dimensions: 59.1x6x44.5 cm3 Valencia, 18 -19 november 2010

  30. Evaluation of some features of the gamma camera using the software GATE [H.Saikouk] • Adding the real dimensions of the phantom and considering the source to be a point source • Radius : 1.5 cm • Height: 3.9 cm Valencia, 18 -19 november 2010

  31. Evaluation of some features of the gamma camera using the software GATE [H.Saikouk] Preliminary result • The sensitivity: calculated in counts/second/MBq • It’s value: 73 kcounts.s-1.MBq-1 Corresponds to 22.3% Next steps • Measuring the spatial resolution • Validating the simulation by a real experience • Simulating the gamma camera in tomographic mode and validation • Image reconstruction in the gamma camera Valencia, 18 -19 november 2010

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