Tecnologias mn

Tecnicas de Medicina
Nuclear
Bases y fundamentos

Procedimiento de obtención de imágenes médicas
Gammagrafía
Tomografia Computarizada por Emision de Fotones
Simples (SPECT)
Tomografía por Emisión de Positrones . PET

Aprender conceptos básicos sobre cómo se generan
las imágenes de Medicina Nuclear: gammagrafías,
SPECT y PET

La Medicina Nuclear (MN) utiliza sustancias
radiactivas: isótopos (iso = igual; topos = lugar)

Fines: diagnósticos, terapéuticos y de
investigación.

Estassustancias radiactivas (radionúclidos o
trazadores) se introducen (in vivo) en la parte
del cuerpo que se quiere estudiar y se hace la
imagen detectando la radiación que emite.

 Es mínimamente invasiva (inyección).
 Es una técnica funcional: no estudia la
anatomía sino su funcionamiento.
 Abarca en la practica, la totalidad del
organismo.
 El nivel de radiación es similar al de
otras técnicas radiológicas (ej. RX)

INTRODUCCIÓN

Algunos de los elementos más usados en MN:

Radionúclido Energía T(1/2) Estudios
(keV)
99m
Tc 140 6 horas Cerebro, tiroides, riñón, pulmón
131
I 364 8´04 días Tiroides y riñon
67
Ga 39 3´25 días Tumores y abscesos
133
Xe 81 5´3 días Pulmón
201
Tl 30-140 72 horas Estudios cardíacos

Fines diagnósticos:

Renograma isotópico de un
paciente con HTA Imágenes de Medicina nuclear
secundaria, que muestra una normales.
atrofia renal derecha

INTRODUCCIÓN
Diferencias (MN, rayos X):
•MN usa radiación gamma ():
Energías Frecuencias
MN: [104 - 107 eV] [1019 - 1022 Hz]
Rayos X: [10 - 104 eV] [1015 - 1019 Hz]

•En MN la fuente de radiación es interna (en el interior del
cuerpo del paciente), en rayos X es externa.

•Trazador con radiofármaco: permite obtener una representación
morfológica o información funcional o dinámica. (En rayos X
contraste)

Esquema básico de un sistema de
IMN
Sustancia
radiactiva Colimador

Tubo Analizador Contador de
órgano Cristal de
fotomultiplicador
centelleo de amplitud impulsos
seleccionado
Radiación  Gammagrafía

Imágenes en Medicina Nuclear

Uso de Rx, radionucleidos y de
radiofarmacos en obtención de imágenes

Con las imagnes de Medicina Nuclear pueden observarse procesos fisiologicos,
como asimismo de Estructuras anatomicas.
En estas tecnicas se inyectan en los pacientes por via
Intravenosa, drogas radiactivas (Radiofarmacos) que emiten rayos gamma
Una vez que son captados por el tejido, organo o sistema de interes.
La cantidad de radionucleidos inyectados, se encuentran en el orden de
concentraciones
de nano a picomolar, de manera de disminuir los riesgos para los pacientes
Durante el estudio de los procesos fisiologicos delos mismos.

El semiperiodo fisico de estos materiales radiactivos es de solo unos pocos
Minutos a semanas. The time course of the
process being studied and the radiation dose to the target are
considered. The nuclear camera then, in effect, takes a time-exposure
"photograph" of the pharmaceutical as it enters and concentrates in
these tissues or organs. By tracing this blood flow activity, the
resulting nuclear medicine image tells physicians about the biological
activity of the organ or the vascular system that nourishes it. Nuclear
Medicine has a wide variety of uses, including the diagnosis of cancer,
studying heart disease, circulatory problems, detecting kidney
malfunction, and other abnormalities in veins, tissues and organs.

Medicina Nuclear: camara gamma

Radiofarmacos

EtOOC O COOEt
N NH

99mTc

S S

Aplicacion: perfusion cerebral

Imagen nuclear de
Cuerpo completo

SPECT: single photon emission
computerized tomography

SPECT esta basada en una tecnica convencional de imagenes nucleares
Y usando ademas la tecnica y metodos de reconstruccion tomografica.

a
d
b
c

Collimator

Electronics NaI(Ti)
crystal
PMT
Y

Counts/pixel
X

Características de Rendimiento de los
sistemas de imágenes de Medicina Nuclear
Resolución Espacial – Es la medida del grado de detalles provistos por la
imagen final reconstruida y por lo tanto del tamaño de lesiones que
potencialmente pueden ser detectadas. En otras palabras: cual es el grado
de detalle en el cual puede ser Observada una imagen o cuanto puede ser
resuelta o separada.

Sensibilidad, tiempo muerto – describe de que manera y con que eficiencia
se Detectan los decaimientos radiactivos y la distribucion del trazador, para
Formar finalmente la imagen.

Una fuente isotropica irradia en forma igual hacia todas las direcciones del
espacio. Los detectores, recolectan parte del total de los decaimientos,
dentro de un angulo Solido limitado por los colimadores.
Algunos de estos eventos se pierden debido a que el sistema necesita de
un tiempo de procesamiento entre la deteccion de un evento y el siguiente.
(dead time o Tiempo Muerto).

Signal to Noise ratio (SNR) - The relative strength of the information
and the noise. If the lesion is small compared with the spatial resolution
the contrast is reduced because the high lesion activity blurred into the
neighborhood by the detector response.

Uniformity, Linearity - The image of an object should be independent
of its position in the field of view. This is not true in real systems.

This can be assessed in calibration measurements to derive correction
factors. This reduces non-uniformity from 10% to 3%.

The conventional nuclear medicine imaging process.
Typical radionuclides used are 140 KeV Tc-99m and 70 KeV photons
from Tl-201.

The gamma ray photons emitted from the radiopharmaceutical
penetrate through the patient body and are detected by a set of
collimated radiation detectors. The emitted photon experience
interaction within the body by the photoelectric effect which stops
their emergence from the body or compton scattering which
transfers part of the energy to free electrons and the photon is
scattered into a new direction. These photons are also detected
by the camera and cause blurring of the image if un-treated with
image reconstruction and processing tools.

q
Pixel I
Activity ai
Intersected area fi

r

P(r,q)

In 2-D tomographic imaging, the 1D detector array rotates around
the object distribution f(x,y) and collects projection data from various
projection angles q. The integral transform of the object distribution
to its projections is given by:


Ç
p' (t ,q )  ct I 0 exp[  z

 ( x , y )ds]

Which is called the Radon transform. The goal of image
reconstruction is to solve the inverse Radon transform. The solution
is the constructed image estimate f(x,y) of the object distribution
f(x,y).
The measured projection data can be written as the integral of
radioactivity along the projection rays.

The measured projection data can be written as the integral of
radioactivity along the projection rays.

z

p(t ,q )  ce  ( x , y )ds

In SPECT attenuation coefficient is not so important, so it can
be considered as constant in the body region under inspection.

z

p(t ,q )  ce  ( x , y ) exp[  l ( x, y )]ds


l(x,y) is the pathlength between the point (x,y) and the edge of the
attenuator (or patient’s body) along the direction of the projection
ray.
The image reconstruction problem is further complicated by the non
stationary properties of the collimator detector and scatter response
functions and their dependence on the size and composition of the
patient’s body.

PROCEDIMIENTO DE OBTENCIÓN DE IMÁGENES MÉDICAS

Cristal de centelleo (Yoduro de sodio con talio-
C INa(Ta))
Transductor de energía  en energía luminosa.

 El cristal está acoplado a un conjunto de
fotomultiplicadores de sección exagonal.
Transductor de energía luminosa en electrones.

 Salida del fotomultiplicador: impulsos eléctricos
amplitud proporcional a la energía de la
radiación 
y número proporcional a la actividad del
elemento radiactivo en el punto analizado.

 Llevando estas señales a un circuito de
posicionamiento, obtenemos las coordenadas X e
Y, que indican la posición donde se ha detectado
el fotón.

PROCEDIMIENTO DE OBTENCIÓN DE IMÁGENES MÉDICAS

Colimador tipo pinhole.
Colimadores de múltiples
La imagen es invertida y el orificios paralelos,
tamaño dependiente dela convergentes y divergentes
distancia al plano objeto.

 Gammagrafía
 SPECT
 PET

 Es la técnica mas simple.
 Su funcionamiento es similar al de las
radiografías, una sola imagen por
volumen.
 Varios tipos dependiendo de la zona:
› Osea (tumores de hueso)
› Pulmonar (trombos en las arterias
pulmonares)
› Tiroidea (nódulos en la tiroides)
› Renal (función de los riñones)

Renograma isotópico de un
Gammagrafía de un
paciente con HTA secundaria,
adenoma suprarrenal
que muestra una clara atrofia
causante de hipertensión
renal derecha. La pequeña
arterial secundaria
cantidad de contraste isotópico
que se observa ha llegado por
vía del pedículo suprarrenal.

 Gammacámara que puede
realizar movimientos de rotación
alrededor del cuerpo del paciente
o anillo.
 Imagen de la distribución del
trazador en 3D utilizando la
combinación de imágenes
obtenidas desde diversas
orientaciones. Pueden obtenerse
imágenes de cortes axiales,
sagitales, coronales.
 Mediante los algoritmos de
retroproyección, similares a los TC,
se puede reconstruir la imagen.

Ejemplo de un escáner de SPECT

fotón  Positrón

fotón 

Detectores de
radiación 

Detección de positrones mediante dos gammacámaras

Tipos de cámaras PET:
a) un par
b) un anillo hexagonal giratorio alrededor del paciente
c) Anillo circular que rodea al paciente

 PET generates images depicting the
distributions of positron-emitting nuclides in
patients
 In the typical scanner, several rings of
detectors surround the patient
 PET scanners use annihilation coincidence
detection (ACD) instead of collimation to
obtain projections of the activity distribution
in the subject

 Positrons emitted in matter lose most of their
kinetic energy by causing ionization and
excitation
 When a positron has lost most of its kinetic
energy, it interacts with an electron by
annihilation
 The entire mass of the electron-positron pair
is converted into two 511-keV photons,
which are emitted in nearly opposite
directions

 If both annihilation photons interact with
detectors, the annihilation occurred close
to the line connecting the two interactions
 Circuitry within the scanner identifies
interactions occurring at nearly the same
time, a process called annihilation
coincidence detection
 Circuitry of the scanner then determines the
line in space connecting the locations of
the two detector interactions

 ACD establishes the trajectories of the
detected photons, a function performed by
collimation in SPECT systems
 Much less wasteful of photons than
collimation
 Avoids degradation of spatial resolution
with distance from the detector that occurs
when collimation is used to form projection
images

 A true coincidence is the simultaneous
interaction of emissions resulting from a
single nuclear transformation
 A random coincidence, which mimics a
true coincidence, occurs when emissions
from different nuclear transformations
interact simultaneously with the detectors
 A scatter coincidence occurs when one or
both of the photons from a single
annihilation are scattered, but both are
detected

 Scintillation crystals coupled to PMTs are
used as detectors in PET
 Signals from PMTs are processed in pulse
mode to create signals identifying the
position, deposited energy, and time of
each interaction
 Energy signal is used for energy
discrimination to reduce mispositioned
events due to scatter and the time signal is
used for coincidence detection

 Early PET scanners coupled each
scintillation crystal to a single PMT
› Size of individual crystal largely determined
spatial resolution of the system
 Modern designs couple larger crystals to
more than one PMT
 Relative magnitudes of the signals from the
PMTs coupled to a single crystal used to
determine the position of the interaction in
the crystal

 Material must emit light very promptly to
permit true coincident interactions to be
distinguished from random coincidences
and to minimize dead-time count losses
at high interaction rates
 Must have high linear attenuation
coefficient for 511-keV photons in order
to maximize counting efficiency

 Most PET systems use crystals of bismuth
germanate (Bi4Ge3O12, abbreviated BGO)
› Light output 12% to 14% that of NaI(Tl), but
greater density and average atomic number
give it higher efficiency at detecting 511-keV
photons
 Other inorganic scintillators being
investigated: lutetium oxyorthosilicate and
gadolinium oxyorthosilicate – faster light
emission than BGO produces better
performance at high interaction rates

 Energy signals sent to energy discrimination
circuits which can reject events in which
the deposited energy differs significantly
from 511 keV to reduce effect of photon
scatter in patient
 Energy window may be adjusted to include
part of the Compton continuum, increasing
sensitivity but also increasing the number of
scattered photons detected

 Time signals of interactions not rejected by
the energy discrimination circuits are used
for coincidence detection
 When a coincidence is detected, the
circuitry or computer of the scanner
determines a line in space connecting the
two interactions
› PET system collects data for all projections
simultaneously
 Projection data used to produce transverse
images of the radionuclide distribution as in
x-ray CT or SPECT

 In 2D (slice) data acquisition, coincidences
are detected and recorded within each
detector ring or small groups of adjacent
detector rings
 PET scanners designed for 2D data
acquisition have thin annular collimators
(typically tungsten) to prevent most
radiation emitted by activity outside a
transaxial slice from reaching the detector
ring for that slice
 Fraction of scatter coincidences reduced
because of the geometry

 Coincidences within one or more pairs of
adjacent detector rings may be added to
improve sensitivity
 Data from each pair of detector rings are
added to that of the slice midway between
the two rings
 Increasing the number of adjacent rings
used in 2D acquisition reduces the axial
spatial resolution

 In 3D (volume) data acquisition, axial
collimators are not used and
coincidences are detected between
many or all detector rings
 Greatly increases the number of true
coincidences detected; may permit
smaller activities to be administered to
patients

 For the same administered activity, the
increased interaction rate increases
random coincidence fraction and dead-
time count losses
› 3D acquisition may require less activity to be
administered
 Scatter coincidence fraction is much larger
and number of interactions from activity
outside the FOV is increased
› Activity outside the FOV causes few true
coincidences, but increases rate of random
coincidences and dead-time count losses

 3D acquisition may be most useful in low-
scatter studies, such as pediatric and
brain studies
 Some PET systems are equipped with
retractable axial collimators, permitting
them to perform 2D or 3D acquisition

 For 2D data acquisition, image
reconstruction methods are similar to SPECT
 For 3D data acquisition, special 3D analytic
or iterative reconstruction techniques are
required
 In PET, the correction for nonuniform
attenuation can be applied to the
projection data before reconstruction; in
SPECT, the correction for nonuniform
attenuation is intertwined with and
complicates the reconstruction process

 Whole-body PET systems achieve a spatial
resolution slightly better than 5 mm FWHM in
the center of the detector ring
 Spatial resolution limited by:
a) intrinsic spatial resolution of detectors
b) distance traveled by positrons before annihilation
c) the fact that annihilation photons are not emitted in
exactly opposite directions from each other
 Intrinsic resolution of detectors most significant

 Spatial resolution of PET is best in the center
of the detector ring and decreases slightly
with distance from the center
 This occurs because of detector thickness
and inability to determine the depth in the
crystal where an interaction occurs
 Uncertainty in depth of interaction causes
uncertainty in the line of response for
annihilation photons that strike the
detectors obliquely

 Distance traveled by positron before
annihilation also degrades the spatial
resolution
 Distance is determined by maximal positron
energy of the radionuclide and density of
the tissue
 Radionuclide that emits lower energy
positrons yields superior resolution
 Activity in denser tissue yields higher
resolution than activity in less dense tissue

 Although positrons lose nearly all of their
momentum before annihilation, the positron
and electron possess some residual
momentum when they annihilate
 Conservation of momentum predicts that
the resultant photons will not be emitted in
exactly opposite directions
 This causes a small loss of resolution, which
increases with the diameter of the detector
ring

 Point source of positron-emitting radionuclide in air
midway between two identical detectors
 True coincidence rate is
RT  2 AG 2

where A is the activity of the source, G is the
geometric efficiency of either detector, and  is the
intrinsic efficiency of either detector
 Because the rate of true coincidences detected is
proportional to the square of the intrinsic efficiency,
maximizing the intrinsic efficiency is very important

 Differs in PET from SPECT, because both
annihilation photons must escape the
patient to cause a coincidence event to
be registered
 Probability of both photons escaping the
patient without interaction is the product
of the probabilities of each escaping:
e ) e
 x   d  x )
) e  d

 For a 20-cm path in soft tissue, the chance
of both annihilation photons of a pair
escaping the tissue without interacting is
about 15%
 Attenuation causes a loss of information
and, because the loss is not the same for all
lines of response, causes artifacts in the
reconstructed transverse images
 Loss of information also contributes to
statistical noise in the images

 Some PET systems provide one or more
retractable positron-emitting sources to
measure the transmission of annihilation
photons through the patient
› Gamma-ray emitting source (Cs-137) may be
used
 Sources revolve around the patient so
attenuation is measured along all lines of
response through the patient
 Attenuation correction cannot
compensate for increased statistical noise;
increases imaging time

 SPECT with high-energy collimators or
multihead SPECT cameras with
coincidence detection capability
› Less acceptable for brain imaging or evaluation
and staging of neoplasms
 Dedicated PET systems that are less
expensive than those with full rings of BGO
detectors, but which provide better
coincidence detection sensitivity than
double-head scintillation cameras

 PET scanner more efficient than scintillation
camera due to use of annihilation
coincidence detection instead of
collimation; also yields superior spatial
resolution
 Spatial resolution in SPECT deteriorates from
edge toward center; PET is relatively
constant across transaxial image, best at
center
 Attenuation less severe in SPECT; accurate
attenuation correction possible in PET (with
transmission source)
 Cost: SPECT ~US$500,000; PET ~US$1M - $2M

 Main factors limiting availability of PET are
the relatively high cost of a dedicated PET
scanner and, in many areas, the lack of
local sources of F-18 FDG
 Multihead SPECT cameras with coincidence
circuitry and SPECT cameras with high-
energy collimators provide less expensive,
although less accurate, alternatives for
imaging FDG

PET enables physicians to assess chemical or physiological changes
related to metabolism. Since the origins of many diseases are
biochemical in nature, these functional changes often predate or exceed
structural change in tissue or organs. PET imaging utilizes a variety of
radiopharmaceuticals, called "tracers," to obtain images. PET tracers
mimic the natural sugars, water, proteins, and oxygen found in our
bodies. These tracers are injected into a patient and collect in various
tissues and organs. The PET system takes a time-exposure of the tracer
and generates a "photo" of cellular biological activities. PET images
can be used to measure many processes, including sugar metabolism,
blood flow and perfusion, receptor-ligand binding rates, oxygen
utilization and a long list of other vital physiological activities.

PET scanning uses artificial
radioactive tracers and
radionuclides. Their lifetime is
usually rather short, thus they
need to be produced on site.

Some examples of such materials are:

Radionuclide Half life Application
Carbon-11 20.3 min Positron emitter for metabolism studies
Copper –64 12.8 hours clinical diagnostic agent for cancer and
metabolic disorder
Iodine –122 3.76 min Positron emitter for blood flow study
Iodine –131 8.1 days Diagnose thyroid disorders including cancer
Iron - 52 8.2 hours Iron tracer for PET bone marrow imaging
Nitrogen – 13 9.9 min Positron emitter used as 13NH for heart
perfusion studies
Strontium – 85 64 days Study of bone formation metabolism
Oxygen – 15 123 sec Positron emitter used for blood flow
Technetium – 99m 6 hours The most widely used radiopharmaceutical
In nuclear medicine

PET has a million fold sensitivity advantage over MRI in tracer study
and its chemical specificity, PET is used to study neuroreceptors in
the brain and other body tissues. It is efficient in the nanomolar range
where much of the receptor proteins in the body. Clinical studies
include tumors of the brain, breast, lung, lower GI tract. Additional
study of Alzheimer’s disease, Parkinson’s disease, epilepsy and
coronary artery disease affecting heart muscle metabolism and flow.

PET studies has immeasurably added to the understanding of oxygen
utilization and metabolic changes that accompany disease.

PET imaging starts with the injection of metabolically active tracer – a biologic
molecule that carries with it a positron emitting isotope. Over a few minutes the
isotope accumulates in an area of the body for which the molecule has an affinity.
i.e. glucose labeled with 11C or glucose analogue labeled with 18F, accumulates in the
brain or tumors, where glucose is used as the primary source of energy. The
radioactive nuclei then decay by positron emission. In positron (positive electron) ,
a nuclear proton changes into a positive electron and a neutron. The atom maintains
its atomic mass but decreases its atomic number by 1. The ejected positron combines
with an electron almost instantaneously, and these 2 particles undergo the process of
annihilation. The energy associated with the masses of the positron and electron
particles is 12.022MeV in accordance with E=MC2 . This energy is divided equally
between 2 photons which fly away from one another at 1800 angle. Each photon has
an energy of 511 keV. These high energy gamma rays emerge from the body in
opposite directions and recorded simultaneously by pair of detectors.

The annihilation event that gave rise to them must have occurred somewhere
along the line connecting the detectors. Of course if one of the photons is scattered,
then the line of coincidence will be incorrect. After 100,000 or more annihilation
events are detected, the distribution of the positron-emitting tracer is calculated by
tomographic reconstruction procedures. PET reconstructs a 2 dimensional image
from the one dimensional projections seen at different angles. 3-D reconstructions
can be done using 2D projections from multiple angles.

Tagged Positron
metabolic annihilation
activity -
photons (1800
+
N 0.250)
P
11C nucleus

Lead
shield

Scintillator
Tungsten
septum

 Detector crystal width
 Anger logic
 Photon noncolinarity
 Positron range
 Reconstruction algorithm

Acquisition

Calibration data
Sinogram
Correction data

Counts/ray
Reconstruction

Image

• Blood volumes
• Oxygen consumption
• Perfusion
• Glucose consumption

CENTELLEADOR

FOTOMULTIPLICADOR
RADIOISÓTOPOS
β+ DE
ELECTRÓNICA
VIDA CORTA

2 RAYOS γ
COLINEALES

CICLOTRÓN Radioisótopo Inyección
Radioisótopos + al
β+ Trazador Paciente

Reconstrucción Detección Decaimiento β+
de la de y
Imagen Coincidencias Aniquilación (2γ)

IMAGEN FUNCIONAL:

DISTRIBUCIÓN DEL TRAZADOR
EN EL ORGANISMO

APLICACIONES:

-DETECCIÓN DE TUMORES
- FUNCIÓN CEREBRAL

-EFICIENCIA DEL DETECTOR
- SENSIBILIDAD DEL SISTEMA
- RESOLUCIÓN TEMPORAL
- RESOLUCIÓN ESPACIAL
- RITMO DE RECUENTO

Punto
Paralelepípedo

Esfera
¿Dentro No
de Esfera?
Sí
PROGRAMA DE
Rayo
Θ,φ SIMULACIÓN
n veces

Intersección
Detectores-Rayo MÉTODO
MONTECARLO

Detector
¿Dentro
de No
Sí
planos?

Numeración
Detectores

Guardar datos

DETECTOR IDEAL
LOR
2γ COLINEALES

EJE Y

Datos

EJE X

υxr
F1

y υy
υxr
EQUIVALENTES
F2
f(x,y) φ
υx
x


  2i xr xr    2i xr xr 
f ( x, y )     d xr e  xr W ( xr )  dxr e
 p( xr , ) d

0    

φ

φ

0
xr

Transformada de Radon 0 xr


P( xr ,  )    f ( x, y) ( x cos   ysen  x )dxdy

r

PROYECCIÓN RETROPROYECCIÓN

Sobremuestreo en el Tipos de Filtros
origen de frecuencias

υy

Δφ

Filtro rampa
υx

Δυxr Ventana Hamming

0 υ

p(xr,φ) p·cos

xr xr

cos(2 N xr )

4

2
xr = x·cosφ +y·senφ

  2i xr xr    2i xr xr 
f ( x, y )     d xr e  xr W ( xr )  dxr e
 p( xr , ) d

0    
1
3

5
φ
(x, z)
υxr
3
xr
1 4

2 5

CORREGIDA
POR
NORMALIZACIÓN

CONCLUSIONES:

- Simulación de la Emisión y Detección de
Gammas en P.E.T.

- Reconstrucción de Imágenes con FBP en
Modo 2D.

- Estudios Realizados: Resolución,
Normalización, Filtros.

Imágenes PET de un cerebro activo en varios estados, tras inyección
intravenosa de 18F, con deoxy-glucosa. (de Shung-92)

Low Pet Scan of Patient.
The Positron Emission Tomography
Lab at Mount Sinai Medical
Center is located in New York City.
We are dedicated to the study of
Alzheimers, Schizophrenia and
general questions regarding how
the brain changes with age. This
research is accomplished through
the co-registration of PET and MRI
modalities. We have developed
software in order to better aid in
this research

http://neurosurgery.mgh.harvard.edu/pet-hp.htm
 Parkinson's Disease

http://neurosurgery.mgh.harvard.edu/pet-hp.htm
 Huntington's disease

 Sitio caliente: sala de preparación de
radiofármacos
 Sala de pacientes
 Sala de exploraciones
 Sala de almacenamiento de residuos
radiactivos
 Equipo humano: Especialista y técnico

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