What are the factors that affect the dose reference values for CT?4 answersThe factors that affect the dose reference values for CT include the size-specific dose estimates (SSDE) based on the volume CT dose index (CTDIvol). Changes in technology and the use of different computational phantoms also influence the dose coefficients. The concept of diagnostic reference range (DRR) and diagnostic reference levels (DRLs) are used to establish the balance between radiation dose and image quality necessary for accurate diagnosis. In pediatric brain CT, the radiation dose indices (volume CT dose index and dose length product) increase with age and weight, and equations can be derived to estimate age- and weight-dependent standard dose indices. Additionally, the water equivalent diameter (WED) of the examination volume affects the reference dose parameter, which is indirectly proportional to the power of the noise level in the CT image dataset.
What are the differences in radiation doses in mGy.cm² between multislice tomography and cone-beam tomography for use in dentistry?4 answersCone beam computed tomography (CBCT) in dentistry has shown improvements in image quality and reduced radiation dose compared to multislice tomography. CBCT devices have better detectors and extraction algorithms, allowing for enhanced image quality while minimizing radiation exposure. The optimization of reconstruction algorithms and the use of pulsed beams have further reduced the grading dose. In a study measuring patient radiation exposure, CBCT scans using a CS9300 Carestream system resulted in mean Kerma Area Product (KAP) values ranging from 314 to 399 mGycm2, depending on voxel size. Comparatively, literature reports KAP values for CBCT ranging from 210 to 2140 mGycm2. Therefore, CBCT offers reduced radiation doses compared to multislice tomography in dentistry.
What are the radiation safety towards occupational dose in radiologic technology?5 answersRadiologic technologists and ancillary staff who work with or near ionizing radiation face possible short- and long-term effects of occupational radiation exposure. Protection techniques such as time, distance, and shielding can help avoid dangerous exposure levels. Occupational dose limits, dose calculation, and devices used to measure exposure are important for keeping radiation exposure as low as reasonably achievable. Proper radiation protection, increased radiation knowledge, and adherence to safety practices can help prevent overexposure to radiation and its adverse effects. Radiation safety standards and the use of protective accessories like lead aprons and goggles are important for individual protection. Implementing periodic radiation safety training for occupational workers is beneficial for practicing a radiation safety culture.
What are the limitations of x-ray mammography in detecting breast cancer?5 answersX-ray mammography has limitations in detecting breast cancer. The difficult interpretation of mammograms can lead to an increase in missed cancers and misinterpreted non-cancerous lesions, which can affect the accuracy of detection. Additionally, the unequal focus on mass boxes during analysis can result in the network focusing too much on larger masses at the expense of smaller ones, leading to a decrease in accuracy. Furthermore, mammography screening can also lead to overdiagnosis of breast cancer, where some women may be diagnosed with breast cancer that would not have caused harm or required treatment. These limitations highlight the need for improved methods, such as computer-aided diagnosis systems and content-based mammogram retrieval, to assist radiologists in interpreting mammograms and reducing the morbidity and mortality of breast cancer.
What are the challenges of digital breast tomosynthesis reconstruction?2 answersDigital breast tomosynthesis (DBT) reconstruction faces several challenges. One challenge is enhancing the quality of the recovered images, which is still an ongoing research topic. Another challenge is the spatial variation of distances between voxels in the volumetric image, which can affect the accuracy of the reconstruction. Additionally, the rapid adoption of DBT into clinical practice has outpaced the evidence of its clinical and cost-effectiveness, highlighting the need for more research and evidence-based policies. Furthermore, the reconstruction process in DBT involves solving a large-scale inverse problem, which requires efficient computational methods and regularization techniques. Overlapping breast tissue can also be a challenge in DBT, as it can mimic or obscure lesions, leading to unnecessary recalls and missed cancers.
What are the disadvantages of digital breast tomosynthesis?5 answersDigital breast tomosynthesis (DBT) has several disadvantages. One major disadvantage is the increased radiation dose compared to standard 2D mammography. DBT requires the acquisition of multiple low-dose exposures, which results in a higher radiation dose to the breast. Another disadvantage is the lack of defined indications for DBT in breast cancer screening and its role in the diagnosis and staging of breast cancer. Further studies are needed to assess the combined reconstruction of the 2D view using 3D tomosynthesis data, which could potentially reduce patient exposure to radiation. Additionally, DBT is still being implemented in routine clinical breast imaging practice, indicating that it may not be widely available. Overall, while DBT offers advantages in detecting and characterizing breast lesions, it is important to consider these disadvantages when evaluating its use in clinical practice.