Reduction Of Uterus Dose In Clinical Thoracic Computed Tomography

[Use of patient radiation shielding in diagnostic and interventional radiology]

The use of patient contact shielding provides an opportunity to reduce patient radiation exposure. Recently, the use has been the subject of controversy. The Radiation Protection Committee has published a recommendation on the use of patient radiation shields by considering the recent findings on dose savings but also the risks of incorrect use. In this article, a specification for the more frequently used types of X‑ray examination is given, which describes whether and which radiation contact shielding should be used. This is accompanied by a rationale for the use or non-use of patient radiation protection agents. Problems and possible errors are explained, as well as how to deal with special situations such as pregnant women and children.

Systematic literature review on the benefit of patient protection shielding during medical X-ray imaging: Towards a discontinuation of the current practice

PURPOSE

Patient shielding during medical X-ray imaging has been increasingly criticized in the last years due to growing evidence that it often provides minimal benefit and may even compromise image quality. In Europe, and as also shown in a short assessment in Switzerland, the use of patient shielding is inhomogeneous. The aim of this study was to systematically review recent literature in order to assess benefits and appraise disadvantages related to the routine use of patient shielding.

METHODS

To evaluate benefits and disadvantages related to the application of patient shielding in radiological procedures, a systematic literature review was performed for CT, radiography, mammography and fluoroscopy-guided medical X-ray imaging. In addition, reports from medical physics societies and authorities of different countries were considered in the evaluation.

RESULTS

The literature review revealed 479 papers and reports on the topic, from which 87 qualified for closer analysis. The review considered in- and out-of-plane patient shielding as well as shielding for pregnant and pediatric patients. Dose savings and other dose and non-dose related effects of patient shielding were considered in the evaluation.

CONCLUSIONS

Although patient shielding has been used in radiological practice for many years, its use is no longer undisputed. The evaluation of the systematic literature review of recent studies and reports shows that dose savings are rather minimal while significant dose- and non-dose-related detrimental effects are present. Consequently, the routine usage of patient protection shielding in medical X-ray imaging can be safely discontinued for all modalities and patient groups.

Ischaemic heart disease and pregnancy

Although ischaemic heart disease is currently rarely encountered in pregnancy, occurring between 2.8 and 6.2 per 100 000 deliveries, it is becoming more common as women delay becoming pregnant until later life, when medical comorbidities are more common, and because of the higher prevalence of obesity in the pregnant population. In addition, chronic inflammatory diseases, which are more common in women, may contribute to greater rates of acute myocardial infarction (AMI). Pregnancy itself seems to be a risk factor for AMI, although the exact mechanisms are not clear. AMI in pregnancy should be investigated in the same manner as in the non-pregnant population, not allowing for delays, with investigations being conducted as they would outside of pregnancy. Maternal morbidity following AMI is high as a result of increased rates of heart failure, arrhythmia and cardiogenic shock. Delivery in women with history of AMI should be typically guided by obstetric indications not cardiac ones.

The use of out-of-plane high Z patient shielding for fetal dose reduction in computed tomography: Literature review and comparison with Monte-Carlo calculations of an alternative optimisation technique

When performing CT examinations on pregnant patients, great effort should be dedicated towards optimising the exposure of the mother and the conceptus. For this purpose, many radiology departments use high-Z garments to be wrapped around the patient's lower abdomen for out-of-plane organ shielding to protect the fetus. To assess their current protection efficiency, we performed a literature review and compared the efficiencies mentioned in the literature to Monte-Carlo calculations of CT protocols for which the overall scan length was reduced. We found 11 relevant articles, all of them reporting uterus exposure due to CT imaging performed for exclusion of pulmonary embolism, one of the leading causes of peripartum deaths in western countries. Uterus doses ranged between 60 and 660 µGy per examination, and relative dose reductions to the uterus due to high-Z garments were between 20 and 56%. Calculations showed that reducing the scan length by one to three centimetres could potentially reduce uterus dose up to 24% for chest imaging, and even 47% for upper abdominal imaging. These dose reductions were in the order of those achieved by high-Z garments. However, using the latter may negatively influence the diagnostic image quality and even interfere with the automatic exposure control system thus increasing patient dose if positioned in the primary beam, for example in the overranging length in helical acquisition. We conclude that efforts should be concentrated on positioning the patient correctly in the gantry and optimising protocol parameters, rather than using high-Z garments for out-of-plane uterus shielding.

[Practical radiation protection of the patient in radiological diagnostics]

BACKGROUND

The use of radiation protection equipment can reduce the radiation exposure of patients.

OBJECTIVES

The aim was to show which patient shields should be used for the different types of examination.

METHODS

The results of multiple studies were compiled and analyzed and recommendations made for the use of patient shields. The absolute dose values and the protective effect were considered.

RESULTS

Radiological protection should be used in many investigations; particularly in the case of CT investigations, a reasonable dose reduction potential exists due to the higher radiation dose.

CONCLUSIONS

Based on these recommendations, workflow changes in some types of investigation are expected due to the use of additional patient shields.

[Current strategies for dosage reduction in computed tomography]

The potential risks of radiation exposure associated with computed tomography (CT) imaging are reason for ongoing concern for both medical staff and patients. Radiation dose reduction is, according to the as low as reasonably achievable principle, an important issue in clinical routine, research and development. The complex interaction of preparation, examination and post-processing provides a high potential for optimization on the one hand but on the other a high risk for errors. The radiologist is responsible for the quality of the CT examination which requires specialized and up-to-date knowledge. Most of the techniques for radiation dose reduction are independent of the system and manufacturer. The basic principle should be radiation dose optimization without loss of diagnostic image quality rather than just reduction.