Evaluation of thyroid radiation dose during abdominal Computed Tomography procedures and dose reduction effectiveness of thyroid shielding

INTRODUCTION

During abdominal Computed Tomography (CT) studies, vicinity organs receive a dose from scatter radiation. The thyroid is considered an organ at greater risk due to high radiosensitivity.

METHODS

The primary objective of this study was to determine the entrances surface dose (ESD) to the thyroid during abdominal CT studies and to evaluate the efficiency of dose reduction by lead shielding. The calibrated thermoluminescence dosimeter (TLD) chips were used to measure the ESD during 180 contrast-enhanced (CE) and non-contrast-enhanced (NC) abdominal CT studies in the presence and absence of lead shielding.

RESULTS

Thyroid shielding reduces the ESD by 72.3% (0.55 mGy), 86.5% (2.95 mGy) and 64.0% (2.24 mGy) during NC, 3-phase and 4-phase abdominal CT scans. Also, the patient height was identified as a parameter that inversely influenced the thyroid dose, proving that the taller patients receive less dose to the thyroid. Regardless, the scan parameters such as time and display field of view (DFOV) positively impact the thyroid dose.

CONCLUSION

Lead shielding can prevent the external scatter reaching the thyroid region by 64%-87% during the non-vicinity scans such as abdomen CT. However, the actual dose saving lies between 0.2% and 0.4%, compared to the total effective dose of the whole CT procedure.

IMPLICATIONS FOR PRACTICE

The thyroid shield can effectively reduce external scatter radiation during abdominal CT procedures. However, the dose saving is insignificant compared to the total effective dose from the whole examination. Therefore, the use of thyroid shielding should be carefully evaluated during CT abdomen procedures.

Perceptions on radioprotective garment usage and underlying reasons for non-adherence among medical radiation workers from public hospitals in a middle-income Asian setting: A qualitative exploration

Background

Radioprotective garments protect medical radiation workers from exposure to radiation at workplace. However, previous studies have found poor adherence to the use of radioprotective garments.

Objectives

We explored the perceptions and practices related to the use of radioprotective garments among medical radiation workers in public hospitals, and sought to understand the reasons for non-adherence.

Design and setting

A qualitative approach was applied by conducting face-to-face in-depth interviews with 18 medical radiation workers from three university hospitals using a semi-structured interview guide.

Results

Five themes emerged with respect to perceptions on the use of radioprotective garments: (i) the dilemmas in practising radiation protection, (ii) indication of workers' credibility, (iii) physical appearance of radioprotective garments, (iv) practicality of radioprotective garment use, and (v) impact on workflow. Actual lack of radioprotective garment use was attributed to inadequate number of thyroid shield and other garments, radioprotective garments' unsightly appearance including being dirty and defective, impracticality of using radioprotective garments for some nuclear medicine procedures, disruption of workflow because of workers’ limited movements, attitudes of workers, and organisational influences.

Conclusion

Medical radiation workers demonstrated a definitive practice of using radioprotective aprons, but often neglected to use thyroid shields and other garments. Availability and hygiene are reported as the core issues, while unclear guidelines on practical use of radioprotective garments appear to lead to confusion among medical radiation workers. To the best of our knowledge, this is the first qualitative study of its kind from a middle-income Asian setting.