ICRP Publication 129
Radiological Protection in Cone Beam Computed Tomography (CBCT)
Recommended citation
ICRP, 2015. Radiological Protection in Cone Beam Computed Tomography (CBCT). ICRP Publication 129. Ann. ICRP 44(1).
Authors on behalf of ICRP
M.M. Rehani, R. Gupta, S. Bartling, G.C. Sharp, R. Pauwels, T. Berris, J.M. Boone
Abstract - The objective of this publication is to provide guidance on radiological protection in the new technology of cone beam computed tomography (CBCT).
Publications 87 and 102 dealt with patient dose management in computed tomography (CT) and multi-detector CT. The new applications of CBCT and the associated radiological protection issues are substantially different from those of conventional CT. The perception that CBCT involves lower doses was only true in initial applications. CBCT is now used widely by specialists who have little or no training in radiological protection. This publication provides recommendations on radiation dose management directed at different stakeholders, and covers principles of radiological protection, training, and quality assurance aspects.
Advice on appropriate use of CBCT needs to be made widely available. Advice on optimisation of protection when using CBCT equipment needs to be strengthened, particularly with respect to the use of newer features of the equipment. Manufacturers should standardise radiation dose displays on CBCT equipment to assist users in optimisation of protection and comparisons of performance. Additional challenges to radiological protection are introduced when CBCT-capable equipment is used for both fluoroscopy and tomography during the same procedure. Standardised methods need to be established for tracking and reporting of patient radiation doses from these procedures.
The recommendations provided in this publication may evolve in the future as CBCT equipment and applications evolve. As with previous ICRP publications, the Commission hopes that imaging professionals, medical physicists, and manufacturers will use the guidelines and recommendations provided in this publication for implementation of the Commission’s principle of optimisation of protection of patients and medical workers, with the objective of keeping exposures as low as reasonably achievable, taking into account economic and societal factors, and consistent with achieving the necessary medical outcomes.
© 2015 ICRP. Published by SAGE.
Keywords: Cone beam CT; C-arm CBCT; ICRP recommendations; Dose management CBCT; Interventional CBCT; CT fluoroscopy.
AUTHORS ON BEHALF OF ICRP M.M. REHANI, R. GUPTA, S. BARTLING, G.C. SHARP, R. PAUWELS, T. BERRIS, J.M. BOONE
Key Points
The guidelines and recommendations on radiological protection in cone beam computed tomography (CBCT) are important because CBCT extends the use of computed tomography (CT) to areas that were not typically associated with CT imaging in the past, e.g. surgery, dental and otolaryngology [ear/nose/throat (ENT)] clinics, angiography suites, radiotherapy treatment vaults, and orthopaedic polyclinics.
The manufacturers of CBCT scanners have invested considerable effort into meeting the electrical and mechanical safety requirements of the users. Similar diligence is needed for issues related to radiation dose and radiological protection.
This publication provides a basis to develop informed decisions and to direct the use of CBCT for optimising the trade-off between clinical benefit and radiation risk.
The International Commission on Radiological Protection (ICRP) emphasises that protection should be optimised not only for whole-body exposures, but also for exposures to specific tissues, especially those of the lens of the eye, the heart, and the cerebrovascular system.
Equipment used for both fluoroscopy and CBCT should provide aggregate dose indices for individual patients throughout the procedure through electronic display on the operator console and a radiation dose structured report.
Optimisation of both patient and worker doses, particularly when workers have to be near the machine, is important when monitoring of doses becomes an essential tool. Recording, reporting, and tracking of radiation dose for a single patient should be made possible in a consistent manner across vendors.
Low-dose protocols may be sufficient to answer diagnostic questions focused on high contrast structures, such as lung, bones, dental and maxillofacial scans, ENT scans (paranasal sinuses, skull, temporal bone), interventional material, and contrastenhanced vessels (angiographic interventions).
Higher-dose protocols should only be selected if visualisation of soft tissue structures, such as intracranial haemorrhage, soft tissue tumours, or abscesses, is the primary focus.
Most interventional and intraprocedural C-arm CBCT systems can scan an angular range spanning 180–240° plus the cone angle of the x-ray beam. Localised critical organs, such as the thyroid, eyes, female breasts, and gonads, should be on the ‘detector side’ of the arc whenever possible.
Clinical need permitting, every effort should be made by users to ensure that the volume of interest is fully incorporated in the field of view (FOV) provided by the CBCT scanners, while radiosensitive organs should be placed outside the FOV.
The aim of CBCT should be to answer a specific diagnostic or intra-operative question vis-à-vis other imaging modalities, and not to obtain image quality that rivals multi-detector CT (MDCT). The decision by the referring practitioner to use CBCT should be made in consultation with an imaging professional.
There is a need to provide checks and balances, such as dose check alerts implemented in CT in recent years, to avoid high patient doses compared with locally defined reference values.
Methods that provide reliable estimates of dose to the eye under practical situations should be established and used.
The user of CBCT in interventions can influence the radiation dose imparted to the patient significantly by judicious use of a ‘low-image-quality or low-dose’ scan instead of a ‘high-image-quality or high-dose’ scan.
In radiotherapy, justified use of CBCT has potential at different stages of therapy such as: pretreatment verification of patient position and target volume localisation; evaluation of non-rigid misalignments, such as flexion of the spine or anatomical changes in soft tissue; and during or after treatment to verify that the patient position has remained stable throughout the procedure. Low-dose CBCT protocols should be used for pretreatment alignment of bony structures.
Many machines were only capable of fluoroscopy initially, but can now also perform CBCT. Due to the improved clinical information in CBCT and its ability to remove overlying structures, the user may be tempted to over-use the CBCT mode. The CBCT mode should be used judiciously.
In orthopaedics, justified use of CBCT can help in assessing the position of fractures and implants with respect to the bony anatomy, especially in situations where fluoroscopy alone is insufficient, and thus can help in patient dose management.
In urology, low-dose CBCT protocols should be used when imaging high-contrast structures, such as calcified kidney stones.
Dental and maxillofacial CBCT scans should be justified, considering alternative imaging modalities. Once justified, they should be optimised to obtain images with minimal radiation dose without compromising the diagnostic information.
The level of training in radiological protection should be commensurate with the level of expected radiation exposure.
All workers intending to use CBCT for diagnostic purposes should be trained in the same manner as for diagnostic CT, and those intending to perform interventional CBCT should be trained in the same manner as for interventional CT.
Executive Summary: Not included in this publication
ICRP, 2015. Radiological Protection in Cone Beam Computed Tomography (CBCT). ICRP Publication 129. Ann. ICRP 44(1).
Authors on behalf of ICRP
M.M. Rehani, R. Gupta, S. Bartling, G.C. Sharp, R. Pauwels, T. Berris, J.M. Boone
Abstract - The objective of this publication is to provide guidance on radiological protection in the new technology of cone beam computed tomography (CBCT).
Publications 87 and 102 dealt with patient dose management in computed tomography (CT) and multi-detector CT. The new applications of CBCT and the associated radiological protection issues are substantially different from those of conventional CT. The perception that CBCT involves lower doses was only true in initial applications. CBCT is now used widely by specialists who have little or no training in radiological protection. This publication provides recommendations on radiation dose management directed at different stakeholders, and covers principles of radiological protection, training, and quality assurance aspects.
Advice on appropriate use of CBCT needs to be made widely available. Advice on optimisation of protection when using CBCT equipment needs to be strengthened, particularly with respect to the use of newer features of the equipment. Manufacturers should standardise radiation dose displays on CBCT equipment to assist users in optimisation of protection and comparisons of performance. Additional challenges to radiological protection are introduced when CBCT-capable equipment is used for both fluoroscopy and tomography during the same procedure. Standardised methods need to be established for tracking and reporting of patient radiation doses from these procedures.
The recommendations provided in this publication may evolve in the future as CBCT equipment and applications evolve. As with previous ICRP publications, the Commission hopes that imaging professionals, medical physicists, and manufacturers will use the guidelines and recommendations provided in this publication for implementation of the Commission’s principle of optimisation of protection of patients and medical workers, with the objective of keeping exposures as low as reasonably achievable, taking into account economic and societal factors, and consistent with achieving the necessary medical outcomes.
© 2015 ICRP. Published by SAGE.
Keywords: Cone beam CT; C-arm CBCT; ICRP recommendations; Dose management CBCT; Interventional CBCT; CT fluoroscopy.
AUTHORS ON BEHALF OF ICRP M.M. REHANI, R. GUPTA, S. BARTLING, G.C. SHARP, R. PAUWELS, T. BERRIS, J.M. BOONE
Key Points
The guidelines and recommendations on radiological protection in cone beam computed tomography (CBCT) are important because CBCT extends the use of computed tomography (CT) to areas that were not typically associated with CT imaging in the past, e.g. surgery, dental and otolaryngology [ear/nose/throat (ENT)] clinics, angiography suites, radiotherapy treatment vaults, and orthopaedic polyclinics.
The manufacturers of CBCT scanners have invested considerable effort into meeting the electrical and mechanical safety requirements of the users. Similar diligence is needed for issues related to radiation dose and radiological protection.
This publication provides a basis to develop informed decisions and to direct the use of CBCT for optimising the trade-off between clinical benefit and radiation risk.
The International Commission on Radiological Protection (ICRP) emphasises that protection should be optimised not only for whole-body exposures, but also for exposures to specific tissues, especially those of the lens of the eye, the heart, and the cerebrovascular system.
Equipment used for both fluoroscopy and CBCT should provide aggregate dose indices for individual patients throughout the procedure through electronic display on the operator console and a radiation dose structured report.
Optimisation of both patient and worker doses, particularly when workers have to be near the machine, is important when monitoring of doses becomes an essential tool. Recording, reporting, and tracking of radiation dose for a single patient should be made possible in a consistent manner across vendors.
Low-dose protocols may be sufficient to answer diagnostic questions focused on high contrast structures, such as lung, bones, dental and maxillofacial scans, ENT scans (paranasal sinuses, skull, temporal bone), interventional material, and contrastenhanced vessels (angiographic interventions).
Higher-dose protocols should only be selected if visualisation of soft tissue structures, such as intracranial haemorrhage, soft tissue tumours, or abscesses, is the primary focus.
Most interventional and intraprocedural C-arm CBCT systems can scan an angular range spanning 180–240° plus the cone angle of the x-ray beam. Localised critical organs, such as the thyroid, eyes, female breasts, and gonads, should be on the ‘detector side’ of the arc whenever possible.
Clinical need permitting, every effort should be made by users to ensure that the volume of interest is fully incorporated in the field of view (FOV) provided by the CBCT scanners, while radiosensitive organs should be placed outside the FOV.
The aim of CBCT should be to answer a specific diagnostic or intra-operative question vis-à-vis other imaging modalities, and not to obtain image quality that rivals multi-detector CT (MDCT). The decision by the referring practitioner to use CBCT should be made in consultation with an imaging professional.
There is a need to provide checks and balances, such as dose check alerts implemented in CT in recent years, to avoid high patient doses compared with locally defined reference values.
Methods that provide reliable estimates of dose to the eye under practical situations should be established and used.
The user of CBCT in interventions can influence the radiation dose imparted to the patient significantly by judicious use of a ‘low-image-quality or low-dose’ scan instead of a ‘high-image-quality or high-dose’ scan.
In radiotherapy, justified use of CBCT has potential at different stages of therapy such as: pretreatment verification of patient position and target volume localisation; evaluation of non-rigid misalignments, such as flexion of the spine or anatomical changes in soft tissue; and during or after treatment to verify that the patient position has remained stable throughout the procedure. Low-dose CBCT protocols should be used for pretreatment alignment of bony structures.
Many machines were only capable of fluoroscopy initially, but can now also perform CBCT. Due to the improved clinical information in CBCT and its ability to remove overlying structures, the user may be tempted to over-use the CBCT mode. The CBCT mode should be used judiciously.
In orthopaedics, justified use of CBCT can help in assessing the position of fractures and implants with respect to the bony anatomy, especially in situations where fluoroscopy alone is insufficient, and thus can help in patient dose management.
In urology, low-dose CBCT protocols should be used when imaging high-contrast structures, such as calcified kidney stones.
Dental and maxillofacial CBCT scans should be justified, considering alternative imaging modalities. Once justified, they should be optimised to obtain images with minimal radiation dose without compromising the diagnostic information.
The level of training in radiological protection should be commensurate with the level of expected radiation exposure.
All workers intending to use CBCT for diagnostic purposes should be trained in the same manner as for diagnostic CT, and those intending to perform interventional CBCT should be trained in the same manner as for interventional CT.
Executive Summary: Not included in this publication
