Medical Neutron Science

Size: px

Start display at page:

Download "Medical Neutron Science"

Amberlynn Fletcher
6 years ago
Views:

1 Medical Neutron Science 03 Neutron Activation Analysis

2 The use of NAA techniques for medical applications was first reported in 1964 for measurement of sodium in the body J. Anderson, SB S.B. Ob Osborn, RW R.W. Tomlinson, D. Newton, J. Rundo, L. Sl Salmon, and J.W. JW Smith, Neutron Activation Analysis in Man in Vivo. a New Technique in Medical Investigation, Lancet 2, , (Dec ).. Na 23 + n Na 24 ( 1.37; 2.75 MeV)

3 Between 1968 and 1972, Chamberlain reported the measurement of body calcium and sodium in the body and described techniques for whole-body NAA and pulsed NAA. 48 Ca + n 49 Ca + (3.1 MeV ) M.J. Chamberlain, J.H. Fremlin, D.K. Peters, and H. Philip, Total body calcium by whole body neutron activation: new technique for study of bone disease, Br. Med. J. 2, 581 3, Jun

5 Cohn and Dombrowski reported the measurement of calcium, sodium chlorine, nitrogen, and phosphorus in the human body through in vivo NAA. Since then, NAA and PGNAA have been used for a variety of applications, such as the measurement of nitrogen, carbon and oxygen, cadmium, and manganese in the body and in trace element research to identify cancerous tissue.

6 Inelastic neutron scatter analysis (INSA) using fast neutrons use 14 MeV neutrons from a (d,t) sealed-tube neutron generator to determine whole body carbon content as a measure of energy expenditure in the body. K. Kyere, B. Oldroyd, C.B. Oxby, L. Burkinshaw, R.E. Ellis, and G.L. Hill, The feasibility of measuring total body carbon by counting neutron inelastic scatter gamma rays, Phys. Med. Biol. 27, (Jun 1982).

8 The use of nuclear resonance scattering (NRS) is used for detection of iron in the liver and in the heart using an indirect method of nuclear excitation by gamma rays generated through neutron capture (INSA). Recently, 14 MeV neutrons has been used for in vivo measurement of liver iron through h INSA and NRS.

9 Neutron Stimulated Emission Computed Tomography: A New Technique for Spectroscopic Medical Imaging g

10 Radiation therapy activation analysis

11 2002 Prompt gamma spektroskopi (PGS) Mätning av infångningsgamma utsända från bor och väte i patient under bestrålning med epitermiska neutroner. n + p D 2 + gamma

12 2002 Prompt gamma spektroskopi (PGS) MCA+Dator Mätning av infångningsgamma utsända från bor och väte i patient under bestrålning Räknehastigheten h t i detektorn för linjerna 1000 kan relateras lt till 100 borkoncentrationen in vivo. 10 Coun nts HPGe-detektor Energi [kev]

13 Tidigare resultat med PGS Mättider kring 3 min. Borkoncentrationer kring 5 ppm. Vid homogen borfördelning blir noggranheten 3% (1 SD).

14 Neutron stimulated emission computed tomography (NSECT), was pioneered at Duke University in 2003 by the late Dr. Carey E. Floyd Jr. for the purpose of diagnostic medical imaging. g

16 A neutron incident on a sample travels freely along its projected path until it collides with an atomic nucleus of an element present in the sample. If the collision with the atomic nucleus results in inelastic scatter, the nucleus can get excited to one of its quantized higher-energy states. The excited nucleus is often unstable and will rapidly decay to a lower energy state, emitting a gamma-ray a photon with energy equal to the difference of the two states. These energy states are well established for most elements and isotopes and are mostly unique for the elements commonly found in the body. Therefore, the energy of the emitted gamma photon can be treated as a unique signature of the emitting element. Tomographic detection and analysis of gamma lines in the emitted spectrum provide quantitative information about the spatial distribution of the element in the sample

18 Spectrum for Fe with the sample out spectrum subtracted from the sample in spectrum.

19 Geometry of the phantom imaged in the tomography experiment. The vertical outer bars represent copper while the diagonal inner (gray) bars represent iron. Each bar measures 0.6 cm by 6 cm by 2.5 cm Reconstructed image from the NSECT acquisition of the sample. The vertical outer regions represent copper while the diagonal inner region represents iron. Each element was reconstructed separately and then combined

20 56 Fe 63 Cu 56 Fe 63 Cu Gamma energy spectrum from the iron copper phantom showing spectral lines from six transitions in 56 Fe and 63 Cu: 1. 63Cu from 1st excited state to ground state; energy 660 kev 2. 56Fe from 1st excited state to ground state; energy 847 kev 3. 63Cu from 2nd excited state to ground state; energy 962 kev 4. 56Fe from 3rd to 2nd excited state; energy 1239 kev 5. 56Fe from 4th to 2nd excited state; energy 1811 kev 6. 63Cu from 6th to 1st excited state; energy 1864 kev

of a benign breast sample showing elements malignant breast sample showing

21 6 MeV Neutron Stimulated Emission 6 MeV Neutron Stimulated Emission Computed Tomography NSECT spectrum of a Computed Tomography NSECT spectrum of a benign breast sample showing elements malignant breast sample showing identified through gamma spectroscopy. elements identified through gamma spectroscopy.

23 The Dose analysis can be summarized in the following three steps: (a) () a Monte Carlo simulation is used to estimate two parameters for an incident neutron beam the number of neutrons that interact in the volume of interest and the average energy deposited per interacting neutron, (b) the resulting energy deposited in the volume is converted from MeV to J/kg using the knownmass of the volume to give the absorbed energy in Gray (Gy), And (c) the absorbed energy is multiplied by the quality factor for neutrons (10) and the weighting factor for the organ of interest to give the effective dose equivalent in Sieverts (Sv).

24 Patient dose was calculated for each gamma spectrum obtained and was found to range from between 0.05 and msv depending on the number of neutrons. This simulation demonstrates that NSECT has the potential to noninvasively detect breast cancer through h five prominent trace element energy levels, at dose levels comparable to other breast cancer screening techniques.

25 NSECT represents an exciting new imaging modality that has the potential for application in both medical and biological research. At the department of Medical Radiation Physics in Lund we already have a lot of expertise in the different field of knowledge necessary to establish Neutron Stimulated Emission Computed Tomography NSECT in practice. What we are missing are laboratories for neutron Exposure. A prototype of the NSECT acquisition system has been developed and built at Duke University using a Van de Graaff accelerator and HPGe detectors. That would be able to establish in Lund as well, in collaboration with our friends at Nuclear Physics. For furthe establishment at ESS The use of nano particles of iron or other elements labelled with biologically active molecules or antibodies or lymphocytes y labelled with nanoparticles in combinations with Neutron Stimulated Emission Computed Tomography NSECT opens up for a completely new field of Nano Nuclear medicine. This could be one important leg for establishing Medical Neutron Beam at ESS

Nuclear Spectroscopy: Radioactivity and Half Life

Nuclear Spectroscopy: Radioactivity and Half Life Particle and Spectroscopy: and Half Life 02/08/2018 My Office Hours: Thursday 1:00-3:00 PM 212 Keen Building Outline 1 2 3 4 5 Some nuclei are unstable and decay spontaneously into two or more particles.