gms | German Medical Science

Objective: Decision making in hydrocephalus patients might be challenging if solely based on clinical assessment. Hence, repeated imaging during life time follow-up is not uncommon. Accumulation of ionizing radiation may result in certain conditions like cataract and might even induce malignancies. We aim to analyze the lifetime radiation exposure of hydrocephalus patients and to identify factors associated with high lifetime radiation accumulation.

Methods: This is a retrospective observational analysis. All patients, who underwent ventriculoperitoneal (VP) shunt implantation in our department from 2012 - 2016 were analyzed. Inclusion criteria were: primary implantation of VP shunt in our department, age ≥ 18 years, follow up > 1 year. Single effective doses of x-ray-, fluoroscopy- and CT-imaging were generated from the respective dose length products (DLPs) and dose area products (DAPs). Lifetime shunt associated radiation exposure was calculated by summing up the respective effective doses. These wereregarded abeing high if they exceed values above 2 fold standard deviation.

Results: 336 patients were included in the study. Median age was 68.1 years. Major indication for VP shunt placement was idiopathic normal pressure hydrocephalus (41.4%), median follow up was 3 years. Mean lifetime radiation exposure was 9.52 mSv (median 7.64 mSv), high accumulation of radiation (>24.98 mSv) occurred in 15 patients (4.5%) and was associated with the number of inpatient (r=0.605; p=0.01) and outpatient (r=0.448; p=0.01) treatments as well as duration of initial operation (r=0.457; p=0.01). Significantly higher effective doses were found when diagnosis of hydrocephalus was not clear (16.53 mSv; ANOVA, p<0.05). Navigation assisted procedures showed significantly higher effective doses (17.25 mSv vs. 6.83 mSv; Welch test, p=0.005). Significant differences were found between patients older (8.15 mSv) and younger than 70 years (10.56 mSv; p=0.003) as well in patients with one or more revision (7.00 vs 16.2 mSv; p=0.001; Welch test).

Conclusion: Lifelong accumulation of radiation exposure lies within the range of other X-ray based studies like cardiac imaging or evaluation of kidney stones. However, subgroups seem to be prone to accumulation of high effective doses. Indication for imaging using ionizing radiation should be rigid. Our data argues for the development of non-invasive tools for the measurement of intracranial pressure and for the implementation of low-dose x-raysystems, e.g. the linear slot-scanning technology.