CT examination with lowest possible dose

CT examination with lowest possible dose for sufficient image quality

Our aim was to perform a CT examination of facial bones of a 12-year old child, from the chin to the orbits with the lowest possible dose for sufficient image quality.

Case objectives
The aim of the study was to provide a good visualization of the anatomy of the mandibular bone and fossa in a patient affected by a facial dimorphic syndrome that had just undergone several radiological examinations.

Clinical and patient background
Patient is a 12 year old male, affected by Goldenhar Syndrome (I grade), with a great hypoplasia and malformation of the mandible’s right side. The examination was performed for the control of the bone’s growth and for surgical planning.

Silvana Manganelli

Radiographer

Fondazione IRCCS Ospedale Maggiore Policlinico

Italy

Dose management methods and techniques that were used
I considered the two main features available on the equipment that allows a considerable dose management: an iterative reconstruction tool that allows a reduction in mA and kV (ASiR80, that makes irrelevant automatic tube current modulation or noise control), and an effective kernel (HFS) that clearly describes bone structures in the examined anatomy.

Technique used: position supine, head first and slightly extended to exclude the thyroid gland, zero at the external auditory meatus. Scan Type: helical, 0.7 s rotation time, 80 kV, 40 mA, speed 5.62 mm/rot, 0.562:1 pitch, SFOV 25 cm. Acquisition range: from 1cm inferior the mandibular synphysis to 1cm above supraorbital margin, with bone and detail reconstruction’s algorithm. Coronal and sagittal multiplanar reconstructions 1mm*1mm and VR.

My own experience in making concerted effort in
reducing the dose to pediatric patients leads me to consider and increase the use of all the available post processing tools.”

- Silvana Manganelli - Radiographer

Fondazione IRCCS Ospedale Maggiore Policlinico, Italy

Conclusions and results

The resulting dose indexes were: CTDI vol=3.7 mGy, DLP=54 mGy*cm, with an approximated effective dose of 0.2 mSv (CT-EXPO 2.1). The exam maintains an appropriate visualization of soft tissue and bone structure.

Discussion of case outcome(s) and future implications
My own experience in making concerted effort in reducing the dose to pediatric patients leads me to consider and increase the use of all the available post processing tools. This example can be easily replicated, establishing standard protocols on every pediatric patient suffering from facial dimorphic syndrome and other facial diseases (e.g. sinusitis) for diagnosis, monitoring and surgical planning.

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