CT Users Group

Gareth Iball

Leeds Teaching Hospitals NHS Trust

Abstract

The purpose of this study was to evaluate and compare organ and effective dose savings that could be achieved using conventional lead aprons and a new, custom designed shield as out-of-plane shielding devices during chest CT scans.

Thermoluminescent dosimeters were used to measure doses throughout the abdomen and pelvis during CT scans of the chest of a RANDO phantom. Dose measurements were made with no shielding, with lead aprons and with the new shield around the abdomen and pelvis in order to quantify the achievable organ and effective dose reductions.

Average dose savings in the 10 phantom sections ranged from 5 - 78% with the highest point dose saving of 93% being found in the mid pelvis. When shielding was used the maximum organ dose reduction that was measured was a 72% dose saving to the testes. Significant dose savings were found throughout the abdomen and pelvis which contributed to an effective dose saving of 4% which is achieved over and above the dose savings obtained through conventional optimisation strategies. This could yield significant population dose savings and reductions in collective radiation risk.

In this study significant organ and effective dose reductions have been achieved through the use of abdominal shielding during chest CT examinations and it is therefore recommended that out-of-plane patient shielding devices should be used for all chest CT scans and potentially for every CT scan, irrespective of body part.

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