Abstract
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.
Keywords
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References
- Conformity index: a review.Int. J. Radiat. Oncol. Biol. Phys. 2006; 64: 333-342https://doi.org/10.1016/j.irobp.2005.09.028
- A novel dynamic arc treatment planning solution to reduce dose to small bowel in preoperative radiotherapy for rectal cancer.Med Dos. 2018; 44: 258-265
Article info
Publication history
Published online: November 07, 2020
Accepted:
October 6,
2020
Received in revised form:
September 25,
2020
Received:
July 1,
2020
Identification
Copyright
© 2020 American Association of Medical Dosimetrists. Published by Elsevier Inc. All rights reserved.
