Читать книгу Industrial and Medical Nuclear Accidents - Jean-Claude Amiard - Страница 20

Croüail and Lefaure [CRO 03a, CRO 03b] proposed a more radiologically realistic scale for classifying incidents and accidents. This scale makes it possible to take into account radiation protection events affecting patients as part of a radiotherapy procedure. This proposed scale was then discussed at the IAEA. English-speaking countries did not want to use a classification based on the number of people exposed. They only partially gave way on this point by downgrading certain events [ASN 04] by one level.

Therefore, since 2007, in France, a specific scale has been created, called the ASN-SFRO scale, which characterizes the severity of radiation protection events. The guide for the application of the new INES for the classification of radiation protection events (excluding patients) relating to radioactive sources and the transport of radioactive materials is currently being developed. Radiotherapy events affecting patients were classified on the ASN-SFRO scale issued by the ASN in July 2008 [ASN 08b, ASN 13]. The criteria for ranking on this scale focus on: (1) the proven consequences of exposure to ionizing radiation; and (2) the potential effects of the events (Table 1.2). Levels 0 and 1 are used to classify events without clinical consequences for the patient. Levels 2 and 3 correspond to events referred to as “incidents”. Levels 4–7 correspond to accidents (Table 1.3).

The IRSN [IRS 16a] provides some examples of incidents, such as the level 1 incident where, on October 31, 2008, a practitioner and two manipulators were contaminated with iodine 131 due to inadequate follow-up of cleaning procedures for objects that came into contact with this radioactive element. For level 2 incidents, the IRSN selected three examples. Following an irradiation zone error during radiotherapy performed on December 4, 2008, a patient was re-irradiated in an area after he had already been treated. According to doctors, his condition is now satisfactory. An overexposure of a patient occurred on December 24, 2008 during external radiotherapy during control exposures before a second treatment stage. According to the medical team, the patient’s condition who is receiving special follow-up is currently satisfactory. On June 15, 2007, when a patient was irradiated, the manipulator was still in the treatment room. Based on the effective dose received (approximately 30 mSv), no health effects were expected for this person.

Table 1.2. The ASN-SFRO classification for radiological accidents (adapted from the ASN [ASN 13]. (1) Common Terminology Criteria for Adverse Event, Cancer Therapy Evaluation Program, August 2006, http://ctep.cancer.gov

	Events (unforeseen, unexpected)	Causes	Consequences (CTCAE V3.0 grade)
5–7 Accidents	Death	Dose (or volume irradiated) much higher than normal resulting in complications or outcomes not compatible with life
4 Accidents	A serious life-threatening event, complication or disabling condition	Dose or volume irradiated much higher than tolerable doses or volumes	Severe, unexpected or unpredictable acute or late reaction, grade 4
3 Incidents	An event causing severe alteration of one or more organs or functions	Dose or irradiated volume greater than tolerable doses or volumes	Severe, unexpected or unpredictable acute or late reaction, grade 3
2 Incidents	An event that causes or is likely to cause moderate impairment of an organ or function	Dose higher than recommended doses or irradiation of a volume that may result in unexpected, moderate complications	Moderate, unexpected or unpredictable acute or late effect, grade 2, minimal or no change in quality of life
1 Event	Event with the dosimetric consequence but no expected clinical consequence	Dose or volume error: for example, dose error or target error during a session that cannot be compensated for over the entire treatment	No symptoms expected
O event	Event without any consequences for the patient	For example, error in identifying a patient treated for the same pathology (compensable)

Table 1.3. Procedure for the classification of an event on the basis of exposures or health consequences related to doses received [ASN 08b, IAE 13]

Event	Number of individuals and final ranking
	Minimum ranking	Number of individuals	Final ranking*
Death or lethal dose received		> 10	6
4	> 1	5
	1	4
Deterministic effect or potential deterministic effect with respect to the dose received		> 10	5
3	> 1	4
	1	3
Exposure greater than 1 Sv or 1 Gy		> 100	6
4	> 10	5
	≤ 10	4
Exposure greater than 100 mSv		> 100	5
4	> 10	4
	≤ 10	3
Exposure of worker(s) to a dose above the annual regulatory limit or of a member of the public to a dose above 10 mSv		> 100	4
2	> 10	3
	≤ 10	2
Exposure of worker(s) to a dose above the annual regulatory limit or of a member of the public to a dose above 10 mSv		> 100	3
1**	> 10	2
	≤ 10	1

* The highest ranking should be selected. ** When a dose limit is exceeded as a result of the accumulation of exposure over a certain period of time, the ASN systematically assigns a level 1 classification for lack of a safety culture.