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DJR 46-2B: Methods to Optimize Conformal Dynamic Arcs in Radiation Therapy Treatment Planning

Course Details

MDCB Credits: 2.50

ARRT Credits: 2.50

Available Until: 6/30/2022

Non-Member Price: $87.50

Member Price: $50.00

Member PLUS Price: $50.00

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Authors: Caroline Kendra, RTT, Lon Marsh, CMD, MBA, FAAMD1, Elaine Bogner, CMD, RTT1, Benjamin Gielda, MD1

Department of Radiation Oncology, Spectrum Health Lakeland, Saint Joseph, MI

Conformal Dynamic Arcs (CDA) can provide a useful alternative in certain clinical situations which require a higher level of 3-dimensional (3D) conformation than shaped static fields but for which modulated fields (fixed or arc) are inappropriate. Due to lack of modulation, the quality of the dose distribution produced by a CDA is highly dependent on the specific patient geometry. The ideal geometry for a CDA, in terms of achievable conformation and uniformity, is a spherical target perfectly centered in a cylindrical medium or body and utilizing a full 360 degree of rotation. This manuscript will provide or review several methods a treatment planner may employ to improve dose distributions produced by CDA as the patient and/or target geometry or degrees of arc rotation vary from the ideal. These include:

  1. Weighting arc segments to improve homogeneity.
  2. Defining asymmetric margins for fitting leaves.
  3. Hybrid static/CDA compensating for CDA with limited degrees of rotations.
  4. Improving conformation in irregular target via use of pseudo-PTV.
  5. Creating concave features via the use of avoidance structures.
  6. Editing CDA multi-leaf collimator (MLC) to remove irregular hot spots.