open access: Cancer risks associated with external radiation from diagnostic imaging procedures - Linet - 2012 - CA: A Cancer Journal for Clinicians

Blogger's Note: extensive (long) analysis; important to assess individual circumstances and as the research article indicates - risk vs benefit

 

Recommendations for Clinicians

• 1
  Become knowledgeable about the radiation doses for the imaging studies.
• 2
  Consider ultrasound and MRI when these are appropriate alternatives since these procedures do not subject the patient to ionizing radiation.172, 236
• 3
  Do not order a higher radiation dose study if a lower dose study (or an imaging study that does not use ionizing radiation) can provide the clinical information needed.
• 4
  All requests for imaging studies should be justified (eg, when all benefits and risks are considered, the study should be expected to do more good than harm).
• 5
  Available aids for justification, such as the ACR's Appropriateness Criteria and the ACC's Appropriate Use Criteria for Cardiac Computed Tomography, should be utilized to provide guidance for choosing the most appropriate imaging examination.
• 6
  Unnecessary imaging studies (duplicate studies and those that are not medically necessary) should not be performed.
• 7
  In general, neither screening nor elective x-ray examinations should be performed on pregnant women.
• 8
  Refer patients who require imaging studies to a facility that strives to optimize radiation dose, so that imaging is performed with the least amount of radiation necessary to provide adequate image quality.

abstract: Predictors of Long-Term Outcome from Intraperitoneal Radioimmunotherapy for Ovarian Cancer.

"A statistically significant improvement in progression-free survival (p≤0.05) was noted for less bulky disease and younger age. Administration of paclitaxel plus IFN, an immune response, and use of (90)Y showed a favorable nonsignificant trend. Dose escalation of radionuclide did not change risk of progression; thus, this therapy may have therapeutic efficacy at modest dose levels."

abstract: Radiation-Induced Micro-RNA Expression Changes in Peripheral Blood Cells of Radiotherapy Patients

Conclusions

Exposure to ionizing radiation leads to the upregulation of the expression of a considerable proportion of the human miRNAome of peripheral blood cells. These miRNA expression signatures can be used as biomarkers of radiation exposure.

medical news: Protection Against Cell Damage From Antioxidant Formula Prior To Radiation Exposure

"A unique formulation of antioxidants taken orally before imaging with ionizing radiation minimizes cell damage, noted researchers at the Society of Interventional Radiology's 36th Annual Scientific Meeting in Chicago, Ill. In what the researchers say is the first clinical trial of its kind, as much as a 50 percent reduction in DNA injury was observed after administering the formula prior to CT scans.

"In our initial small study, we found that pre-administering to patients a proprietary antioxidant formulation resulted in a notable dose-dependent reduction in DNA injury," said Kieran J. Murphy, M.D., FSIR, professor and vice chair, director of research and deputy chief of radiology at the University of Toronto and University Health Network, Toronto, Ontario, Canada. "This could play an important role in protecting adults and children who require imaging or a screening study," he added.

"Pre-administering this formula before a medical imaging exam may be one of the most important tools to provide radioprotection and especially important for patients in the getting CT scans," said Murphy. The study's data support the theory about a protective effect during these kinds of exposure, he explained....."cont'd

link to abstract:

"Purpose:  

We examine use of the free radical scavengers vitamin C (VC), glutathione (GL) and uric acid (UA) as a pre-medication strategy prior to radiation exposures typical of medical imaging studies. Our intent was to develop a simple cocktail of antioxidants to be taken orally prior to X-Ray exposures that can protect a patient’s DNA against free radical mediated radiation injury"

link to meeting:

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NIH summit to focus on management of radiation dose in computerized tomography, Tuesday, February 1, 2011 News Release - National Institutes of Health (NIH)

Radiation Dose with CT Scan-Mayo Clinic - video

Image-Processing Algorithm Reduces CT Radiation Dose By As Much As 95 Percent (perfusion CT)

Computer-based system automatically tracks radiation dose exposure in patients receiving CT scan

"Computer-based-system-automatically-tracks-radiation-dose-exposure-in-patients-receiving-CT-scan. "The fact that Valkyrie works with older CT equipment is important. This is an immediate solution for almost all hospitals, many of which may not be able to upgrade their CT technology in the short or medium term," said Shih."

open access - free: Imaging in Radiation Oncology: A Perspective -- The Oncologist

Note: not specific to ovarian cancer; paper addresses the importance of imaging techniques (ie; MRI/PET) while planning radiation therapies.  
some excerpts:
- Shortly after the discovery of the x-ray in 1895, the potential therapeutic benefits of the x-ray and possible toxicities were realized. More than a century later, we continue to struggle with how to balance the intensity of cancer treatment toward increasing the chance of cure with the potential for normal tissue toxicity. Imaging has improved our understanding of the complexities of cancer biology, cancer diagnosis, staging, and prognosis, and it is an essential component of present-day radiation oncology practice. Progress in radiation oncology has occurred in parallel to advances in imaging.
- The primary decisions that radiation oncologists make daily are to decide who to treat, what to treat, what to avoid, and how to deliver the intended doses safely. Imaging is considered in each of these decisions. Although the steps described in sequence below often occur simultaneously, they feed back to each other. Predictions about uncertainties and response in a specific patient can be made from experience in treating a population of similar patients or as more is learned about the patients themselves (e.g., with imaging obtained during therapy).
- How to define the gross tumor volume and volumes at risk for containing microscopic disease (clinical target volumes [CTVs]) is not an easy task. Different imaging tools demonstrate inherently different representations of the tumor

Radiation recall dermatitis triggered by multi-targeted tyrosine kinase inhibitors: sunitinib and sorafenib

Note: other treatments such as Gemzar/Gemcitabine have been noted in radiation recall

Accurate accumulation of dose for improved understanding of radiation effects in normal tissue

Int J Radiat Oncol Biol Phys. 2010 Mar

Jaffray DA, Lindsay PE, Brock KK, Deasy JO, Tomé WA.
Princess Margaret Hospital, Department of Radiation Oncology, University of Toronto, Toronto, Ontario, Canada. david.jaffray@rmp.uhn.on.ca

Abstract:
The actual distribution of radiation dose accumulated in normal tissues over the complete course of radiation therapy is, in general, poorly quantified.  
Differences in the patient anatomy between planning and treatment can occur gradually (e.g., tumor regression, resolution of edema) or relatively rapidly (e.g., bladder filling, breathing motion) and these undermine the accuracy of the planned dose distribution. Current efforts to maximize the therapeutic ratio require models that relate the true accumulated dose to clinical outcome. The needed accuracy can only be achieved through the development of robust methods that track the accumulation of dose within the various tissues in the body. Specific needs include the development of segmentation methods, tissue-mapping algorithms, uncertainty estimation, optimal schedules for image-based monitoring, and the development of informatics tools to support subsequent analysis. These developments will not only improve radiation outcomes modeling but will address the technical demands of the adaptive radiotherapy paradigm.
The next 5 years need to see academia and industry bring these tools into the hands of the clinician and the clinical scientist.

Use of CT Scans Linked to Cancer Risk, Studies Say | netReturns | e-Newsletter

"There is considerable disagreement in the scientific community about the validity of these models," notes Rosaleen Parsons, M.D., chair of the department of diagnostic imaging at Fox Chase Cancer Center. "And some scientists believe the radiation dose from these CT scans may not lead to any increased risk of cancer."

In the second study, conducted at the University of California-San Francisco, researchers compared CT scan use at four San Francisco Bay area facilities. They found that the amount of radiation from a CT scan may be up to four times greater than estimated in previous studies. In addition, they noted significant differences among different institutions and, in some instances, within the same institution, when looking at the radiation dose associated with CT scans.