medical radiology

Villa Marketing Division

Villa Sistemi Medicali SpA

Guide lines: Medical radiology


• Introduction To Radiology• Key Components

• Work Techniques

• Types Of Exams

• Types Of Devices

Contents


• The radiology is used as diagnostic instrument to visualize anatomical structures, that can not be seen from outside and it is a part of a bigger discipline, called “Diagnostic Imaging”

• The X-rays were discovered accidentally by Wilhelm Conrad Röntgen (German) in 1895

• In the course of the century, technologies, means and materials have become refined and have brought the radiology (or better the Diagnostic Imaging) be a particular branch of the medicine

• A significant evolution of the radiology has been the CT (Computerized Tomography) (Hounsfield et Al, 1972) which still uses collimated X-rays and allows the study of body sections

• Progressively other diagnostic modalities have been improved, as ultrasound, nuclear medicine, magnetic resonance which use different physical principles from X-rays and allow to obtain different information compared to ones given by radiographic images

Introduction To Radiology


• With the progress of knowledge and of technologies, radiologists have developed a strong specialization in their competences

• Thanks to X-rays, specialized products were designed, addressed directly to clinical specialist in different fields: Mammography, Interventistic, Angiography, Mineralometry, etc.

• Each clinical specialty is equipped with devices, which, limiting the application field, increase the diagnostic efficacy of the product

• Radiological competence can be found also in other specializations as, for example, surgeon, cardiologist, breast specialist, dentists, etc. They use radiological images, but each of them with very specific purpose and needs, that must be understood and supported.



• Radiology is based on the use of X-rays, electromagnetic radiations with wave-length of about 10-10 m

• X-rays can easily cross each kind of material: they practically go into the object and come out in the opposite side. When X-rays cross an object, they are attenuated by the object itself: the more dense is an object, the higher is its attenuation

- Air is not very dense: X-rays cross it easily

- Water has a middle density: only a part of X-rays can cross it

- Lead has a very high density: practically X-rays don’t cross it (this is the reason for which the lead is used as protective barrier)

• In the human organism there are: elements that are not very dense (soft tissue, muscles, internal organs) and elements very dense (bones)

Physical principle



• X-rays, after having crossed the body, “go out” and hit a film which is very similar to a normal photographic film

• The radiographic film is not very sensitive to X-ray , but it’s much more sensitive to common light: that’s why it is always positioned inside a “cassette”, which has several purposes:

- Protect the film from the light- Increase the sensitivity of the film, getting it in touch with “screens” that

transform X-rays into visible light- Increase the mechanical resistance

• The X-rays are noxious for the organism so it is necessary to limit the exposure of both patients and operators

• Obviously the relation risks/benefits is very favorable, in fact the radiological technique, even if is a century “old”, continues to be used

Physical principleIntroduction To Radiology


• Introduction To Radiology

• Key Components

• Work Techniques

• Types Of Exams


Contents


• X-rays are the most popular technology for diagnostic imaging in a wide spectrum of application (bucky tables and remote controlled RF systems)

• A radiological system is mainly made up of the following elements:

- Patient positioner - Table

- X-ray source - Tube

- High voltage Generator

- Image receptor - Film, Image Intensifier, DR

• In addition, there are:

- Grid

- Collimator

- High tension cables

Key Components


• The table is the element which is mainly useful for support and the positioning of the patient

• Typically the table is also provided with a column, which supports the X-ray tube and allows its positioning as needed

MoviplanApollo

Table

Tube

ColumnTube

Column

Key Components


The table is equipped with a device to support and position the cassette:• The most simple system is called Cassette Holder and is not used frequently

• A middle system is called Potter Bucky and it is typically used for bone exams (Moviplan, chest stands)

• The most sophisticate system is called Spot Film Device and it is typically used for Gastro-Intestinal exams on R/F tables (Apollo, Vision)

Table

Spot Film Device

Potter Bucky

Key Components


• The X-ray tube is the component which emits the X-rays

• To emit the X-rays, the tube must be supplied with a voltage from 40 to 150 kV

• There are several models of tube, in function of the kind of the system, of the application and of workflow

• The models are different as a function of several parameters:- Power- Focal spot size- Heat storage capacity

Tube

Key Components


• The generator generates the high voltage to be applied to the tube to produce X-rays

• There are several models in function of the power and of the application

• The rad-only generators are used with tables as with Moviplan for bones applications

• The R/F generators are used with remote controlled tables (Apollo) and tilting tables (Vision and Viromatic) in gastro-intestinal (GI) and angiographic applications

• With the console it is possible to set three main parameters:- kV (Kilovolt): from 40 to 150- mA (milliampere): from 10 to 1000- s (seconds): from 0.001 to 20

• Changing those three parameters it is possible to adapt X-ray emission to the organ in exam and to the kind of image that the operator wants to obtain

Generator

Key Components


Image receptor

• The radiographic film, similar to a photographic film, is hit by the X-rays and an image with the crossed tissue density can be obtained

• The Image Intensifier subsystem is used to operate in fluoroscopy mode to convert x-rays into a bright visible light

• Digital X-ray sensors are used in Digital Radiography, instead of traditional film, and are called Flat Panel Detectors. They can be fixed or portable and contain a layer of scintillator material commonly made by Caesium Iodide (CsI) or Gadolinium oxysulfide (Gadox)

Key Components


• Inside the Potter Bucky or the SFD a component called grid is present and it has the purpose of eliminating the “scattered radiation”, that is a sort of fog generated by the subject in exam, which affect the image quality

• The grid is a sort of filter which cleans the image

Grid

Key Components


The collimator is present on the tube in the point from which X-rays are emitted, and is used to:• Limit the size of the irradiated field • Project on the patient a luminous square which shows the field size. • Reduce the stray radiation in the environment

Collimator

Collimator

Key Components


• The high tension cables (HT) are used to connect the generator with the tube

• Their length must be chosen in function of the system composition (14/16 m cables are the most common ones)

HT cables

Key Components



• Key Components

• Work Techniques• Types Of Exams


Contents


• kV are representative of single photons energy and therefore of their penetration power. A radiation with high kV can cross denser and/or thicker materials

• mA are representative of quantity of emitted X-photons and, under the same kV and object in exam, a radiation with higher mA makes the film darker

• Exposure time (s) can be assimilated to emitted photons quantity: under the same mA, if the exposure time doubles, also the photons quantity doubles

Work TechniquesParameters meaning


• mA and s are therefore comparable in the final effect (film darkening)

• The mAs (milliampere-second) unit, as result of the product mA*s, is often used

• For example, if 25 mAs are necessary to obtain a correct exposure, it is possible to use 25 mA for one second, or it is possible to use 250 mA for 0.1 s

• It is preferable to use high mA and short times to reduce the artifacts due to the movement of the patient or of the organs

Parameters meaning

Work Techniques


• Three points technique: the operator can set independently kV, mA and s values

• Two points technique: the operator can set kV and mAs values. The generator sets the highest possible mA value for the kV value selected

• One point technique: the operator can set only the kV value

• Zero points technique: automatic setting of kV, mA, s

Work Techniques


• Allow to set exposure parameters automatically

• The operator sets the organ to examine, the projection (frontal or lateral) and the patient size

• The system sets the best kV, mA, sec values in function of the exam

Work TechniquesAnatomic programs


• Generator accessory

• Composed of two parts:- AEC interface (it is a board, which is installed into the

generator)- Measure chamber is placed in the potter bucky or in the

SFD immediately above the cassette

• The X-rays, before hitting the cassette, cross the measure chamber, which emits an electrical signal proportional to the rays quantity which has crossed it

Automatic Exposure Control (AEC)

Work Techniques


• The signal is sent to interface board, which elaborates it and informs the generator to interrupt the exposure when the radiation dose emitted is sufficient to give the correct film darkening

• Substantially the parameter on which the AEC acts is the exposure time

• It is called also 1 point technique: the operator can set only the kV value, manually or through an anatomic program (in this case a mixed anatomic technique + AEC is used). The mA value is set automatically with the max possible value for that particular kV value

Automatic Exposure Control (AEC)

Work Techniques


• Conventional generator: the wave-shape of the high tension is directly linked to the 50 Hz mains frequency. The kV have a sinusoidal shape which goes from 0 to 100 kV (in example)

• HF generator: the wave-shape of the high tension is generated by an inverter which works with frequencies of several kHz and it is further “levelled” so that it is almost constant

Conventional and HF generators

t

kV

tt

kV

Conventional X-ray generator

Constant Potential (HF) X-ray generator

X-ray pulses

Work Techniques


• Higher efficiency (under the same application, it is sufficient a lower power)

• Reduction of the patient dose

• Insensitivity to mains voltage fluctuations

• Reduction of “soft rays”, that are the rays generated in the rising and falling portions of the wave. They don’t contribute to the image formation, but are noxious for the patient

Advantages of HF technology

Work Techniques



• Key Components

• Work Techniques

• Types Of Exams


Contents


• Radiography: it is comparable to a photo

• Serial radiography: it is comparable to a sequence of photo taken at very short intervals

• Fluoroscopy: it is comparable to a movie

• Pulsed fluoroscopy: it emits X-ray as a series of short pulses instead of a continuous flow, reducing the patient dose

• Digital radiography or fluoroscopy: it allows to operate in each type of exam in digital way

• Tomography: it make a sectional image by moving an X-ray source and the film in opposite directions during the X-ray exposure

Types Of Exams


• It allows to take static images (chest, bones)

• It puts in evidence fine details

• It is executed on:

- Bucky tables (Moviplan) and chest stands (for chest exams) thanks to the Potter Bucky

- Remote controlled tables (Apollo) thanks to under-table SFD

- Tilting tables (Vision, Viromatic) thanks to under-table potter bucky

Radiography

Types Of Exams


• It is used typically for dynamic GI (gastro-intestinal) study

• More images (from 2 to 6), called divisions, at intervals of 0.5-1 sec. each other, are taken on the same film

• It is executed on R/F (Radio/Fluoro) tables, tilting or remote controlled, through the SFD

Serial radiography

Types Of Exams


• It allows to take pictures of dynamic events (gastro-Intestinal)

• It is not useful to put in evidence details, but to see the evolution of a phenomenon

• It is executed on R/F (Radio/Fluoro) tables, tilting or remote controlled and on surgical C-arm

• The image is taken by TV Chain, made up of an II (Image Intensifier) and a CCD camera, and is visualized on the monitor

Fluoroscopy

Types Of Exams


• Study of dynamic phenomenon/district with middle/high speed (up to 25 img/s)

• It is used typically for digestive and vascular apparatus study

• It allows to execute angiographic examination with DSA (Digital Subtraction Angiography)

• The system is based on a I.I, a high resolution CCD camera and a digital processing system (DIVA-D)

Digital fluoroscopy

Types Of Exams


• It is used to take internal organs sections

• It is based on the principle of “cancellation” of structures which are outside the slice layer

• The cancellation is obtained with an defocussing procedure, thanks to a relative movement between the film and the structures which are not interesting

• For example it is used for kidney, liver and other exams

• It is often replaced by Computed Tomography and Magnetic Resonance

Tomography

Types Of Exams


The effect of “cancellation” of the structures which are outside the focal layer is obtained through the movement in opposite directions of the source and the film respect to the organ.

Tomography

Film/screen

Table surface

Patient body

X-ray source movement

Cassette movement

Focal plane

Types Of Exams


• It can be executed on:

- Remote controlled tables (standard)

- Tilting tables, through optional tomographic column

- Bucky table through optional tomographic column

• The simplest systems use a mechanical bar which synchronizes the tube and the potter movement

• The most sophisticated systems use an electronic system without bar (electronic tomography)

Tomography

Types Of Exams


Types Of ExamsExposure parameters

Parameter Radiography, serialRadiography, digital

Fluoroscopy

kV 40 – 150 40 – 120

mA 10 – 1000 0,5 – 10

Times 1 ms – 10 sec From few seconds to some

minutes



• Key Components

• Work Techniques

• Types Of Exams


Contents


Types Of Devices

• Remote controlled tables

• Conventional titling tables

• Bucky tables

• Chest stands

• Ceiling tubestands

• Mobile units

• Surgical “C” arms

• Mammographic units

• U-arm Digital Radiographic Systems


• It is the device which allows to execute the widest number of R/F and RAD exams

• The control console is positioned in a separate room

• It is typical of Italian and French schools

• It allows to make the best of digital acquisition systems

Remote controlled tables

Types Of Devices


• It allows to execute R/F exams

• To execute RAD exams, an under-table potter bucky and a second tube on column or ceiling tubestand are needed

• The controls are on the table itself

• It is typical of Anglo-Saxon school

Conventional tilting tables

Types Of Devices


• It is a simple device which allows to execute a wide number of exams

• The tabletop is “floating” to allows a fast and precise manual positioning

• It is often coupled with a chest stand to make a general radiography room (general rad)

• It is often provided with vertical movement thanks to a lift, which allows to lower the tabletop to about 50 cm from floor, to facilitate the access of patients with motion difficulties (elders or with extremities problems) since the device is often used for first study of casualty ward

Bucky tables

Types Of Devices


• It is an accessory which completes a radiological system (generally based on Moviplan or Vision/Viromatic, sometimes with remote control)

• It is used to execute chest and spinal column exams with standing patients

• It can also be used for loaded lower extremities studies

Chest stands

Types Of Devices


• Useful in casualty wards to have 4-side access to the bucky table, without the floor column

• For lateral projections on remote control tables

Ceiling tubestands

Types Of Devices


• Mobile units: mobile radiographic systems used in trauma and surgery rooms, at patient’s bed and also as backup unit in general diagnostic

• Surgical “C” arms: radiographic and fluoroscopy systems used in general and vascular surgery, traumatology and orthopedics thanks to their positioning flexibility

• U-arm Direct Digital Radiographic Systems: systems based on flat panel detectors that can cover virtually all the applications of a modern radiological room assuring flexibility

• Mammographic units: analog or digital, are available ready for biopsy

Other devices

Types Of Devices


Radiological tables and applicationsKind RAD

R/FModel Villa

Applications

Remote control R/F Apollo BonesGastrointestinal (GI)Angiography TomographyChest

Conventional Tilting

R/F VisionViromatic

BonesGastrointestinal (GI)Angiography (limited)Tomography

Bucky Table RAD Moviplan BonesTomography

Chest stand RAD Chest stand

ChestSpinal column Under load inf. extremities

Types Of Devices


Thank you for your attention!

Villa Sistemi Medicali Sales & Marketing Team

medical radiology

Health & Medicine