Radiation Safety Concerns Related to PET/Computed Tomography Imaging for Assessing Pediatric Diseases and Disorders.

The Image Gently Nuclear Medicine Working Group published a 10-year update in 2019. One of the future goals of this working group is to continue the efforts started in 2014 to harmonize the North American guidelines with the European Association of Nuclear Medicine pediatric dosing guidelines, continuing to publicize the use of the North American guidelines. The update also acknowledged the need for standardization of CT parameters in hybrid imaging and also will seek to tackle this issue as one of its future goals.

Radiation dose reduction using novel size 1 and size 0 rectangular collimators in pediatric dental imaging.

Objectives: Commercial intraoral rectangular collimators are available for collimating to size 2 image receptor. The benefits of reducing the x-ray beam to match the area of the image detector in adult intraoral radiography are endorsed internationally. However, in pediatric dentistry the image receptor can be further decreased to size 1 and 0.

Assessment of dental radiation dose reduction utilizing mathematical pediatric phantom models: applications in clinical practice.

Objectives: Replacing conventional round intraoral collimators with rectangular collimators provides a considerable radiation dose reduction in adult patients. This study aimed to determine the radiation dose reduction via mathematical phantom when converting from round to appropriately sized rectangular collimation in children ages 5 to 15 years.

Method And Materials: Virtual full mouth series (FMX) were simulated using a commercially available radiation dose software.

Kerma area product (KAP) and scatter measurements for intraoral X-ray machines using three different types of round collimation compared with rectangular beam limiter.

Objectives:: The objective of the study was to determine the radiation dose reduction achieved when rectangular collimation was used on various round collimators. In addition, we evaluated the tissue doses imparted to various head and neck organs.

Methods:: To evaluate the variation in radiation output based on the variable geometric configurations, the kerma area product (KAP) was measured using a commercially available KAP-meter with an internal ion chamber capable of detecting both radiation dose (µGy) and the primary X-ray beam area.

METHOD FOR OCCUPATIONAL SKIN DOSE ESTIMATION IN UPPER EXTREMITY 131I-MIBG CONTAMINATION.

This study examines upper extremity skin contamination of nuclear medicine and radiation safety staff during 131I-Metaiodobenzylguanidine (MIBG) therapy. Utilizing retrospective data, a methodology for performing a rapid assessment of the radiation dose to the skin of the upper extremities is presented. Using the skin contamination measurements and calculated skin dose for each contamination incident at our facility, a conversion factor (XE) was derived that estimates skin dose (DE) based on the initial contamination measurement.

Investigation of dental cone-beam CT pixel data and a modified method for conversion to Hounsfield unit (HU).

Objectives: To investigate the relationship in dental cone-beam CT (CBCT) between the manufacturer-reported image pixel data and a modified conversion to CT number densities in Hounsfield unit (HU).

Methods: A standardized CT phantom was imaged using typical clinical parameters on CBCT from three manufacturers (Carestream 9300, Carestream Health, Rochester, NY; J Morita 3D Accutomo, J. Morita Mfg.

Female gonadal shielding with automatic exposure control increases radiation risks.

Background: Gonadal shielding remains common, but current estimates of gonadal radiation risk are lower than estimated risks to colon and stomach. A female gonadal shield may attenuate active automatic exposure control (AEC) sensors, resulting in increased dose to colon and stomach as well as to ovaries outside the shielded area.

Objective: We assess changes in dose-area product (DAP) and absorbed organ dose when female gonadal shielding is used with AEC for pelvis radiography.

Intussusception reduction: Effect of air vs. liquid enema on radiation dose.

Background: Both air and radiopaque liquid contrast are used to reduce ileocolic intussusception under fluoroscopy. Some suggest air lowers radiation dose due to shorter procedure times. However, air enema likely lowers radiation dose regardless of fluoroscopy time due to less density over the automatic exposure control cells.

THE EFFECT OF RADIATION SHIELDS ON OPERATOR EXPOSURE DURING CONGENITAL CARDIAC CATHETERISATION.

Cardiac catheterisation personnel are exposed to occupational radiation and its health risks. Little data exist regarding the efficacy of radiation-protective equipment from congenital catheterisation laboratories (CLs). The authors retrospectively reviewed data in which CL operators wore a radiation dosemeter during catheterizations on patients of >20 kg.

Computation of thyroid doses and carcinogenic radiation risks to patients undergoing neck CT examinations.

The aim of the study was to investigate how differences in patient anatomy and CT technical factors in neck CT impact on thyroid doses and the corresponding carcinogenic risks. The CTDIvol and dose-length product used in 11 consecutive neck CT studies, as well as data on automatic exposure control (AEC) tube current variation(s) from the image DICOM header, were recorded. For each CT image that included the thyroid, the mass equivalent water cylinder was estimated based on the patient cross-sectional area and average relative attenuation coefficient (Hounsfield unit, HU).

Technical note: estimating absorbed doses to the thyroid in CT.

Purpose: To describe a method for estimating absorbed doses to the thyroid in patients undergoing neck CT examinations.

Methods: Thyroid doses in anthropomorphic phantoms were obtained for all 23 scanner dosimetry data sets in the ImPACT CT patient dosimetry calculator. Values of relative thyroid dose [R(thy)(L)], defined as the thyroid dose for a given scan length (L) divided by the corresponding thyroid dose for a whole body scan, were determined for neck CT scans.

CT effective dose per dose length product using ICRP 103 weighting factors.

Purpose: To generate effective dose per unit dose length product (E/DLP) conversion factors incorporating ICRP Publication 103 tissue weighting factors.

Methods: Effective doses for CT examinations were obtained using the IMPACT Dosimetry Calculator using all 23 dose data sets that are offered by this spreadsheet. CT examinations were simulated for scans performed along the patient long axis for each dosimetry data set using a 4 cm beam width ranging from the upper thighs to top of the head.

X-ray tube current modulation and patient doses in chest CT.

The aim of the study was to investigate how patient effective doses vary as a function of X-ray tube projection angle, as well as the patient long axis, and quantify how X-ray tube current modulation affects patient doses in chest CT examinations. Chest examinations were simulated for a gantry CT scanner geometry with projections acquired for a beam width of 4 cm. PCXMC 2.

Patient doses and projection angle in cone beam CT.

Purpose: To investigate how x-ray tube projection angle affects organ and effective doses to patients undergoing a CT examination on a cone beam scanner.

Methods: The authors investigated two cone beam CT systems that use a flat panel detector to capture the x-ray pattern transmitted through patients. One system had the flat panel detector and x-ray tube mounted on a conventional CT gantry (gantry CT), whereas the other CT scanner had the x-ray tube and flat panel detector mounted on a C-arm apparatus (C-arm CT).