The Pipeline

Don’t sacrifice image quality in the name of low dose

Matthew Morrill, Service Line Strategy Advisor

For years, radiologists and imaging managers have focused on an enduring issue: lowering radiation dose for CT and nuclear imaging exams to reduce long-term cancer risk for patients. However, what are the risks of focusing exclusively on dose and not image quality?

Negligible impact on cancer risk

A single CT scan is unlikely to dramatically increase a patient’s risk of cancer. In fact, not performing a CT or performing a CT with suboptimal image quality is often riskier for the patient than radiation exposure. That said, some patient populations are at higher risk than others and should be the focus of dose reduction efforts:

  • Pediatric patients
  • Patients who require repeat CT or PET exams
  • Patients who receive cardiac and/or perfusion imaging
  • Bariatric patients

Dose optimization approaches

Instead of low dose, the conversation should focus on the right or optimal dose for the patient, a concept known as ALARA (As Low As Reasonably Achievable). There are a few strategies to achieve this:

  • Iterative reconstruction software reduces image noise during the processing phase, allowing clear images to be taken at lower radiation doses. Most CT scanners 64-slice and above come standard with this software. Additionally, sub-64-slice scanners may be retrofitted with dose reduction software; however, dose reduction is most pertinent for cardiac exams (performed on 64-slice CT scanners and above) due to the high inherent radiation doses.

  • Dose optimization involves protocols that tailor dose according to patient characteristics. For instance, obese and female patients may require higher radiation doses than other patients. Having accessible protocols in place helps the technologists integrate dose optimization into their workflows, and many vendors offer a consulting solution to help hospitals integrate these methods.

  • Dose tracking helps avoid excessive radiation exposure from repeat exams. Using IT tools, some institutions track patients’ cumulative radiation exposure over time. Patients who have received excessive radiological testing in the past may be candidates for non-irradiating modalities such as MRI or ultrasound, if appropriate.

A strong dose optimization program helps prove an institution’s commitment to the health of its local population.

Technology developments another path to dose optimization

Aside from CT, another modality exposing patients to radiation is PET. Patients with low grade cancers often receive many follow-up PET scans, which pose a particular risk to pediatric patients. However, researchers at Stanford University demonstrated use of a novel contrast agent to detect malignancies using MRI, a technique that does not expose the patient to radiation. 

Though still experimental, the method produced comparable results to PET/CT scans in 22 patients. If evidence mounts, the MRI-based technique could translate to a significant risk reduction among pediatric patients in populations.

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