ASN Report 2015

1. MEDICAL AND DENTAL

RADIODIAGNOSIS INSTALLATIONS

1.1 Presentation of the equipment

and inventory

Medical diagnostic radiology is based on the principle

of differential attenuation of X-rays by the organs and

tissues of the human body. The information is most often

collected on digital media allowing computer processing

of the resulting images, and their transfer and filing.

Diagnostic X-ray imaging is one of the oldest medical

applications of ionising radiation; it encompasses all the

methods ofmorphological explorationof the humanbody

using X-rays produced by electric generators. It occupies

an important place in the field of medical imaging and

comprises various techniques (conventional radiology,

radiologyassociatedwithinterventionalpractices,computed

tomography, mammography) and a very wide variety of

examinations (radiography of the thorax, chest-abdomen-

pelvis computed tomography scan, etc).

The request for a radiological examinationby the physician

must be part of a diagnostic strategy taking account of the

patient’s known medical history, the question posed, the

expectedbenefit for the patient, the exposure level and the

possibilities offeredby other non-irradiating investigative

techniques. Aguide intended formedical doctors (

Guide to

goodmedical imaging examinationpractices

) updated in2013

indicates the most appropriate examinations to request

according to the clinical situations (see point  5.5).

1.1.1 Medical radiodiagnosis

Conventional radiology

Conventional radiology (producing radiographic images, or

radiographs), if considered by the number of procedures,

represents the largemajority of radiological examinations

performed.

The examinations mainly concern the bones, the thorax

and the abdomen. Conventional radiology can be carried

out in fixed facilities reserved for diagnostic radiology or,

in certain cases, using portable devices if justified by the

clinical situation of the patient.

Angiography

This technique, used for exploring blood vessels, involves

injectingaradio-opaquecontrastagentintothevesselswhich

enables the arterial (arteriography) or venous (venography)

tree tobe visualised. Angiography techniques benefit from

computerised imageprocessing (suchas digital subtraction

angiography).

Mammography

Given the composition of the mammary gland and the

fineness of the details thatmust be seen inorder todiagnose

mammary pathologies, specific devices (mammography

units) areused. Theyoperate at lowvoltage andprovidehigh

resolution and high contrast. They are used in particular

in the national breast cancer screening programme.

The use of a new three-dimensional imaging technique

called “tomosynthesis”, which involves reconstruction of

or more than a century now,

for both diagnostic and therapeutic purposes,

medicine hasmade use of ionising radiation produced either by electric generators

or by radionuclides in sealed or unsealed sources. The benefits and usefulness

of these techniques have long been proven, but they nevertheless contribute

significantly to the exposure of the population to ionising radiation. They effectively

represent the second source of exposure for the population (behind exposure to natural

ionising radiation) and the leading source of artificial exposure (see chapter 1).

Protection of the staff working in facilities using ionising radiation for medical purposes is

regulated by the provisions of the Labour Code. The medical facilities and devices emitting

ionising radiation, including sealed and unsealed sources, must satisfy technical rules and

procedures defined in the Public Health Code (see chapter 3).

The protection of patients undergoingmedical imaging examinations or receiving therapeutic

treatments involving ionising radiation is regulated by specific provisions of the Public Health

Code (see chapter 3). The principles of justification of procedures and optimisation of the

doses delivered are the basis of these regulations. However, contrary to the other applications

of ionising radiation, the principle of dose limitation does not apply to patients due to the

need to adapt the dose delivered to each individual patient according to the therapeutic

objective or to obtain an image of adequate quality to make the diagnosis.

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CHAPTER 09:

MEDICAL USES OF IONISING RADIATION

ASN report on the state of nuclear safety and radiation protection in France in 2015