A study on the dose distributions near the eye lens and the legs. Part 2 – Interventional radiology

Is eye lens dosimetry needed in nuclear medicine?

INTRODUCTION

The exact level of exposure experienced by nuclear medicine personnel, whose work often requires performing manual procedures involving radioactive isotopes, is associated with the form of radiation source used. The variety of radionuclides and medical procedures, and the yearly increase in the number of patients, as well as the change of the individual dose limit for the lens of the eye from a value of 150 mSv yr^-1 to 20 mSv yr^-1, mean that issues of eye lens routine dosimetry become interesting from the radiation protection point of view.

OBJECTIVE

This paper presents an analysis of the exposure of the eye lenses of nuclear medicine department personnel, as well as those of personnel in the facilities that produce radiopharmaceuticals for the purpose of diagnosis by positron emission tomography, from the viewpoint of the advisability of routine eye lens exposure monitoring, taking into account changes in the dose limit for the lens of the eye.

MATERIALS AND METHODS

The paper considers the two most commonly used radionuclides for diagnostic purposes ^99mTc, ¹⁸F, and-for therapeutic purposes-¹³¹I. Dose measurements were made using thermoluminescent detectors.

RESULTS

The estimated exposure analysis identifies the cases when the maximum annual value of the personal dose equivalent, in terms of Hp(3), exceeds threefold the new limit value (20 mSv yr^-1).

CONCLUSIONS

It is recommended that Hp(3) doses be routinely monitored in the group of radiopharmacists who label pharmaceuticals with the radionuclide ^99mTc and in chemists working in ¹⁸F-FDG quality control departments in production units, where this is carried out manually.

The impact of x-ray tube configuration on the eye lens and extremity doses received by cardiologists in electrophysiology room

The aim of the study was to analyse the influence of the x-ray tube configuration on the radiation doses to eye lens and extremities of cardiologists performing pacemaker implantation procedures in electrophysiology laboratory. The measurements were performed on one, widely used, portable C-arm system, first with x-ray tube mounted above the patient table and image intensifier below it and then on a reinstalled (but essentially the same) system with under-table x-ray tube configuration. Thermoluminescent dosimeters, placed in various positions near the eye lens, on the hands and ankle, were used during every procedure. The comparison of doses received by cardiologists after changing the x-ray tube configuration from over- to under-table shows statistically significant dose reduction (p < 0.009) for the eye lens closest to the x-ray tube, left finger, left wrist, while for the ankle a dose increase is observed. The corresponding over- to under-table x-ray tube median dose ratios are 4.1 for the right eye, 4.8 for the left finger, 3.0 for left wrist and, finally, 0.13 for the right ankle. Systems with under-table x-ray tube are preferable from a radiation protection point of view. The observed significant increase in doses to the legs should be partially compensated by the use of a protective lead curtain.