Evaluation of a Thermoplastic Immobilization System for Breast and Chest Wall Radiation Therapy

Journal Article · Fri Apr 01 00:00:00 EDT 2011 · Medical Dosimetry

DOI:https://doi.org/10.1016/j.meddos.2010.01.001· OSTI ID:21490063

Strydhorst, Jared H ^[1]; Caudrelier, Jean-Michel ^[1]; Clark, Brenda G ^[1]; Montgomery, Lynn A; Fox, Greg ^[1]

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1. Ottawa Hospital Cancer Centre, Ottawa (Canada)

We report on the impact of a thermoplastic immobilization system on intra- and interfraction motion for patients undergoing breast or chest wall radiation therapy. Patients for this study were treated using helical tomotherapy. All patients were immobilized using a thermoplastic shell extending from the shoulders to the ribcage. Intrafraction motion was assessed by measuring maximum displacement of the skin, heart, and chest wall on a pretreatment 4D computed tomography, while inter-fraction motion was inferred from patient shift data arising from daily image guidance procedures on tomotherapy. Using thermoplastic immobilization, the average maximum motion of the external contour was 1.3 {+-} 1.6 mm, whereas the chest wall was found to be 1.6 {+-} 1.9 mm. The day-to-day setup variation was found to be large, with random errors of 4.0, 12.0, and 4.5 mm in the left-right, superior-inferior, and anterior-posterior directions, respectively, and the standard deviations of the systematic errors were found to be 2.7, 9.8, and 4.1 mm. These errors would be expected to dominate any respiratory motion but can be mitigated by daily online image guidance. Using thermoplastic immobilization can effectively reduce respiratory motion of the chest wall and external contour, but these gains can only be realized if daily image guidance is used.

• OSTI ID: 21490063
• Journal Information: Medical Dosimetry, Vol. 36, Issue 1; Other Information: DOI: 10.1016/j.meddos.2010.01.001; PII: S0958-3947(10)00009-9; Copyright (c) 2011 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; ISSN 0958-3947
• Country of Publication: United States
• Language: English

Related Subjects

62 RADIOLOGY AND NUCLEAR MEDICINE
61 RADIATION PROTECTION AND DOSIMETRY
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ERRORS
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MOTION
PATIENTS
THERMOPLASTICS
WALLS
BODY
GLANDS
MATERIALS
MEDICINE
NUCLEAR MEDICINE
ORGANIC COMPOUNDS
ORGANIC POLYMERS
ORGANS
PETROCHEMICALS
PETROLEUM PRODUCTS
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RADIOTHERAPY
SYNTHETIC MATERIALS
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