Absorbed doses from spiral CT and conventional spiral tomography: a phantom vs. cadaver study

Abstract

For several radiological examinations, a clinician can select between conventional and spiral computed tomography. Using both techniques, this study aimed at evaluating the difference in absorbed doses when examining a single lateral jaw segment in a human cadaver head and Rando phantom. The present study involved the placement of thermoluminescent dosimeter (TLD) chips (GR-200) in the thyroid gland, and bilaterally, in the parotid and submandibular glands and the lenses of the eyes in both a human cadaver and a Rando phantom at corresponding locations. Consecutive conventional spiral tomographic examinations were carried out in both the left upper and lower premolar area, using a Cranex TOME multifunctional unit. Each examination consisted of 4 slices with a 2 mm slice thickness and exposure parameters of 57 kV, 56 seconds and 1.6-2.0 mA. Regarding spiral computed tomography (CT), a Somatom Plus S scanner (Siemens, Erlangen, Germany), with a slice thickness of 1 mm with settings at 120 kV and 165 mA, was used on both phantoms and separately in the upper and lower jaw. With conventional tomography, the findings of the present study showed that the parotid and submandibular glands on the side near the X-ray tube received the highest dose, both for the cadaver head (doses ranging from 0.5 to 1.3 mGy) and the phantom (doses ranging from 0.6 to 2.6 mGy). For CT of the upper jaw, the highest doses were delivered to the parotid glands with an average absorbed dose of 9.2 and 10.6 mGy for the cadaver head and phantom, respectively. The submandibular glands received the highest doses during CT examination of the lower jaw with an average of 7.8 and 12.9 mGy for the cadaver head and phantom, respectively. It appears from the present investigation that if small edentulous regions are examined, radiation doses during conventional tomography remain much lower than during CT imaging. However, when multiple tomographic cuts are required, a spiral CT examination can replace a series of conventional examinations, especially in cases such as the rehabilitation of an edentulous upper jaw or a more complex surgery.

Three dimensional comparative measurement of polyurethane milled skull models based on CT and MRI data sets

“…The radiation exposure of additional radiological examinations such as CT is the subject of debate because of the associated theoretical morbidity (Brenner et al, 2001). Especially in the paediatric age group, where it may increase the risk of a significantly higher mutation rate (Frederiksen et al, 1995;Bou Serhal et al, 2001).…”

Parotid-Absorbed Doses: A Comparison Between Spiral Tomography and Panoramic

“…In addition, Bou Serhal et al (2001) (13) found that for spiral tomography in the maxilla, organ doses for both parotid glands were most elevated, and average doses per Avicenna J Dent Res. 2016; 8(4):e24431.…”

“…Indeed, the greatest individual organ doses for any examination are in the salivary tissue (9). Some previous studies have measured the absorbed doses of the radiosensitive organs of the head and neck during imaging modalities (10)(11)(12)(13)(14)(15)(16)(17).…”

Perioperative validation of localisation of the mental foramen

“…CT was chosen for cases of full rehabilitation of the lower jaw. 26,27 Eighteen patients were examined by PAN allowing measurements of all 22 sites. Eight sites in ®ve patients were examined by ST and eight in seven patients by CT. No radiographic examinations supplementary to the standards were required for this study and all examinations formed a part of a routine clinical protocol.…”