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P253. Cumulative ionizing radiation to image the small bowel: Are we really exceeding the safety limits?

P. Ellul1,2, N. Azzopardi1,2, M. Borg3,2, M. Vassallo1,2

1Gastroenterology Department, Malta, Malta; 2Mater Dei Hopsital, Msida, Malta; 3Radiology Department, Malta, Malta

Introduction: Radiation exposure from diagnostic imaging of the small bowel is common in Crohn`s disease (CD) patients. Increased risk of malignancy has been associated with radiation exposure. For solid cancers this follows a linear-no-threshold model. Current data (BEIR VII) demonstrates that exposure to 100 mGY to population of mixed ages, the life time attributable risk (LAR) of solid organ malignancy is 8 per 1000 of exposed persons for males and 13.1 per 1000 for females. This varies according to age of exposure – exposure to 100 mGY at age 10 confers a risk of 1.33% for males (2.53% for females); at age 30 this is 0.6% for males (1% for females) and at age 50 it is 0.51% for males (0.68% for females).

100 mGY exposure confers a LAR (in a linear-quadratic model) for leukaemia of 1 per 1000 for males and 0.72 per 1000 for females. This varies from 1.2 per 1000 exposed males at age 10 (0.86 for females) to 0.84 per 1000 males exposed at age 30 (0.49 for females). The risk remains the same for males aged 50 and decreases to 0.30 per 1000 females exposed aged 50.

Aim and Method: Aim: To determine the cumulative ionizing radiation exposure in mGY secondary to non-acute small bowel (SB) imaging in CD patients. Method: Patients were identified from our database. Their SB investigations were extracted. Radiation exposure for the procedures was obtained from the Physics division of the radiology department.

Results: 80 CD patients (males – 42 patient) were identified. The time since the diagnosis of CD varied from 41 years to 5 months (mean – 8.6 years). 56 patients (30 males) were exposed to ionizing radiation to image the SB.

Table 1 denotes the total number of exposures per age group and gender.

15 male and 5 female patients had SB stricturing disease. 2 female patients had fistulising SB disease.

Table 2 demonstrates cumulative ionizing radiation secondary to non-acute small bowel imaging.

Conclusions: 70% of the CD patients were exposed to diagnostic ionizing radiation as to image the small bowel. This radiation exposure reached more than 50 mGY in 15% of patients and more than 100 mGY in 8.75% our Study group. These results demonstrate the high ionizing radiation with the possible consequences that CD patients are exposed to throughout their lifetime. Thus we suggest that efforts should be done to image the small bowel by non-ionizing radiation such as MRI. In places where this is not available the request for ionizing radiation should only be done by specialists in close liason with the radiologists.

Table 1
Age groupNumber of exposures
<20 years51
20–30 years2916
30–40 years1313
40–50 years43
50–60 years24
>60 years02
Table 2
Cumulative ionizing radiationNumber of patients
<50 mGy201838
100–150 mGy426
>150 mGy011