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Pediatric interventional radiography equipment: safety considerations.

Strauss KJ - Pediatr Radiol (2006)

Bottom Line: The range of pulse widths must be limited to less than 10 ms in children to properly freeze patient motion.Three focal spots with nominal sizes of 0.3 mm to 1 mm are necessary on the pediatric unit.A second, lateral imaging plane might be necessary because of the child's limited tolerance of contrast medium.

View Article: PubMed Central - PubMed

Affiliation: Radiology Physics and Engineering, Children's Hospital Boston, Harvard Medical School, 300 Longwood Ave., Boston, MA 02115-5737, USA. Keith.Strauss@tch.harvard.edu

ABSTRACT
This paper discusses pediatric image quality and radiation dose considerations in state-of-the-art fluoroscopic imaging equipment. Although most fluoroscopes are capable of automatically providing good image quality on infants, toddlers, and small children, excessive radiation dose levels can result from design deficiencies of the imaging device or inappropriate configuration of the equipment's capabilities when imaging small body parts. Important design features and setup choices at installation and during the clinical use of the imaging device can improve image quality and reduce radiation exposure levels in pediatric patients. Pediatric radiologists and cardiologists, with the help of medical physicists, need to understand the issues involved in creating good image quality at reasonable pediatric patient doses. The control of radiographic technique factors by the generator of the imaging device must provide a large dynamic range of mAs values per exposure pulse during both fluoroscopy and image recording as a function of patient girth, which is the thickness of the patient in the posterior-anterior projection at the umbilicus (less than 10 cm to greater than 30 cm). The range of pulse widths must be limited to less than 10 ms in children to properly freeze patient motion. Variable rate pulsed fluoroscopy can be leveraged to reduce radiation dose to the patient and improve image quality. Three focal spots with nominal sizes of 0.3 mm to 1 mm are necessary on the pediatric unit. A second, lateral imaging plane might be necessary because of the child's limited tolerance of contrast medium. Spectral and spatial beam shaping can improve image quality while reducing the radiation dose. Finally, the level of entrance exposure to the image receptor of the fluoroscope as a function of operator choices, of added filter thickness, of selected pulse rate, of the selected field-of-view and of the patient girth all must be addressed at installation.

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A representative biplane catheterization laboratory setup. Each plane of imaging equipment can be independently rotated laterally and/or in the cranial–caudal direction. The elevating table with a float top allows the patient anatomy of interest to be placed at the isocenter, the common point about which both imaging planes rotate
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Fig4: A representative biplane catheterization laboratory setup. Each plane of imaging equipment can be independently rotated laterally and/or in the cranial–caudal direction. The elevating table with a float top allows the patient anatomy of interest to be placed at the isocenter, the common point about which both imaging planes rotate

Mentions: Because the number of iodine injections during complex interventional studies is severely limited in the child, many pediatric interventional laboratories are equipped for two imaging planes that allow the doubling of recorded information per iodine injection. Figure 4 illustrates a representative biplane setup. Each X-ray tube and image receptor is mounted on opposite ends of a large C-arm, which is either ceiling-suspended on a set of rails or floor-mounted. The C-arm rotates on its arc to provide either lateral or cranial–caudal angulation relative to the patient, depending on the positioning of the C-arm, which can be controlled by the operator. Each of the two imaging planes shares the same isocenter, the point in space about which each imaging plane rotates. Although the focal spot to isocenter distance is fixed, the image receptor to isocenter distance can be adjusted by the operator. State-of-the-art units provide preprogrammed positioning of both planes at the push of a button to facilitate reproducible positioning of the stands without exposing the patient to additional radiation.Fig. 4


Pediatric interventional radiography equipment: safety considerations.

Strauss KJ - Pediatr Radiol (2006)

A representative biplane catheterization laboratory setup. Each plane of imaging equipment can be independently rotated laterally and/or in the cranial–caudal direction. The elevating table with a float top allows the patient anatomy of interest to be placed at the isocenter, the common point about which both imaging planes rotate
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2663646&req=5

Fig4: A representative biplane catheterization laboratory setup. Each plane of imaging equipment can be independently rotated laterally and/or in the cranial–caudal direction. The elevating table with a float top allows the patient anatomy of interest to be placed at the isocenter, the common point about which both imaging planes rotate
Mentions: Because the number of iodine injections during complex interventional studies is severely limited in the child, many pediatric interventional laboratories are equipped for two imaging planes that allow the doubling of recorded information per iodine injection. Figure 4 illustrates a representative biplane setup. Each X-ray tube and image receptor is mounted on opposite ends of a large C-arm, which is either ceiling-suspended on a set of rails or floor-mounted. The C-arm rotates on its arc to provide either lateral or cranial–caudal angulation relative to the patient, depending on the positioning of the C-arm, which can be controlled by the operator. Each of the two imaging planes shares the same isocenter, the point in space about which each imaging plane rotates. Although the focal spot to isocenter distance is fixed, the image receptor to isocenter distance can be adjusted by the operator. State-of-the-art units provide preprogrammed positioning of both planes at the push of a button to facilitate reproducible positioning of the stands without exposing the patient to additional radiation.Fig. 4

Bottom Line: The range of pulse widths must be limited to less than 10 ms in children to properly freeze patient motion.Three focal spots with nominal sizes of 0.3 mm to 1 mm are necessary on the pediatric unit.A second, lateral imaging plane might be necessary because of the child's limited tolerance of contrast medium.

View Article: PubMed Central - PubMed

Affiliation: Radiology Physics and Engineering, Children's Hospital Boston, Harvard Medical School, 300 Longwood Ave., Boston, MA 02115-5737, USA. Keith.Strauss@tch.harvard.edu

ABSTRACT
This paper discusses pediatric image quality and radiation dose considerations in state-of-the-art fluoroscopic imaging equipment. Although most fluoroscopes are capable of automatically providing good image quality on infants, toddlers, and small children, excessive radiation dose levels can result from design deficiencies of the imaging device or inappropriate configuration of the equipment's capabilities when imaging small body parts. Important design features and setup choices at installation and during the clinical use of the imaging device can improve image quality and reduce radiation exposure levels in pediatric patients. Pediatric radiologists and cardiologists, with the help of medical physicists, need to understand the issues involved in creating good image quality at reasonable pediatric patient doses. The control of radiographic technique factors by the generator of the imaging device must provide a large dynamic range of mAs values per exposure pulse during both fluoroscopy and image recording as a function of patient girth, which is the thickness of the patient in the posterior-anterior projection at the umbilicus (less than 10 cm to greater than 30 cm). The range of pulse widths must be limited to less than 10 ms in children to properly freeze patient motion. Variable rate pulsed fluoroscopy can be leveraged to reduce radiation dose to the patient and improve image quality. Three focal spots with nominal sizes of 0.3 mm to 1 mm are necessary on the pediatric unit. A second, lateral imaging plane might be necessary because of the child's limited tolerance of contrast medium. Spectral and spatial beam shaping can improve image quality while reducing the radiation dose. Finally, the level of entrance exposure to the image receptor of the fluoroscope as a function of operator choices, of added filter thickness, of selected pulse rate, of the selected field-of-view and of the patient girth all must be addressed at installation.

Show MeSH
Related in: MedlinePlus