![]() Paediatric examinations and procedures are of special concern because,Ĭhildren have a higher risk from the detrimental effects of radiation. Įxamination-specific DRLs for various patient groups can provide the stimulus for monitoring practice to promote improvements in patient protection. The objective of DRLs is to help avoiding radiation dose that does not contribute to the clinical purpose of a medical imaging task. Something to guide everyday practice and to improve it continually.ĭiagnostic Reference Levels (DRLs) have been recommended by the International Commission on Radiological Protection (ICRP) as a measure to improve optimization of patient protection and a practical tool to promote the assessment of existing protocols and appropriate development of improved protocols at each CT centre by facilitating the comparison of doses from present practice.Ī DRL is a form of investigational level,Īnd intended for use as a simple test for identifying situations where the levels of patient dose are unusually high or low. These two dose descriptors allow to monitorize radiation dose while performing a CT examination,īut how to know when the dose is too much? A cut-off level is needed, SSDE is not currently displayed on CT scan console,Īlthough SSDE will probably replace CTDI in the near future,Īt the present it is not possible to use it.ĭose-length product (DLP) is a second key patient dose descriptor in CT and it is an indicator of the total radiation dose for an entire CT exam.ĭLP is simply obtained multiplying the CTDI vol value per the scan length as given by the following formula: Taking into consideration the patient’s real size instead than an approximation. ![]() It is clear that such a parameter is better than any other, Where f is the correction factor that takes into account the patient size. The formula to estimate the patient dose for a specific patient size ( Size-Specific Dose Estimate, The American Association of Physicists in Medicine in its Task Group 204 Report (AAPM-TG204) has proposed the calculation of size-specific conversion of CTDI vol in order to get a more accurate descriptor of absorbed dose in patients with a variety of body habitus, It is measured by using a pencil ionization chamber (100 mm length) placed in a standard circular plastic phantom (a 16-cm diameter phantom for adult head and paediatric head and body calculations,Īnd a 32-cm diameter phantom diameter for adult body measurements).Īs the dose distribution in CT is highest at the surface and lowest at the centre of the object,ĬTDI is expressed in terms of CTDI weighted (CTDI w) and it is calculated by taking the properly weighted average of the measured dose at the surface and at the center of the specific phantom.ĬTDI may easily be considered as the radiation dose delivered to the patient during one complete revolution of the tube-detector system with no movement of the CT table (sequential mode).ĭue to the fact the majority of CT scan protocols are now performed in spiral mode,ĬTDI w must be replaced with another CT dose descriptor called CTDI volume (CTDI vol) that takes into account the pitch value of the scan.ĬTDI vol represents the dose within the scan volume from a particular scan protocol for a standardized phantom and it is most suitable descriptor to compare the dose of different CT protocols. ĬTDI is internationally recognized as the most important measure of the radiation output from the CT scanner. Two dose descriptors are commonly used in computed tomography,Ĭomputed Tomography Dose Index (CTDI) and Dose Length Product (DLP). Given the relatively small diameter of the head in comparison with the trunk and the high intrinsic contrast of the evaluated structures,ĬT can be performed in this district with adapted dose parameters depending on the indication.ĭ ose descriptors and paediatric diagnostic reference levels Systemic congenital pathologies like cystic fibrosis and primary ciliary dyskinesia,Ĭomplicated or recurrent acute sinusitis and chronic sinusitis - especially when medical management and/or surgery have failed to control symptoms.Ĭhronic inflammatory diseases account for the major part of CT examinations which add valuable information regarding the extent and severity of inflammation and exquisitely demonstrates sinus anatomy and surgically relevant anatomic variants. Indications for paranasal sinus CT include trauma, Which may not be appreciated on physical examination,Īnd are used to help otolaryngologists to develop a treatment plan for patients. ![]() ĬT scans provide information about patients’ anatomy and disease, Paranasal sinus CT imaging is a fundamental component of caring for paediatric patients with sinonasal and skull base pathology to confirm diagnosis and eliminate the need for unnecessary medication and surgery.
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