Investigation of Pitch and Jaw Width to Decrease Delivery Time of Helical Tomotherapy Treatments for Head and Neck Cancer

Journal Article · Sat Jan 01 00:00:00 EST 2011 · Medical Dosimetry

DOI:https://doi.org/10.1016/J.MEDDOS.2010.10.001· OSTI ID:22130359

Moldovan, Monica ^[1]; Gibbons, John P. ^[1]; Lee, Tae Kyu ^[1]; Rosen, Isaac I. ^[1]; Fields, Robert S. ^[1]; Hogstrom, Kenneth R. ^[1]

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1. Mary Bird Perkins Cancer Center, Baton Rouge, LA (United States)

Helical tomotherapy plans using a combination of pitch and jaw width settings were developed for 3 patients previously treated for head and neck cancer. Three jaw widths (5, 2.5, and 1 cm) and 4 pitches (0.86, 0.43, 0.287, and 0.215) were used with a (maximum) modulation factor setting of 4. Twelve plans were generated for each patient using an identical optimization procedure (e.g., number of iterations, objective weights, and penalties, etc.), based on recommendations from TomoTherapy (Madison, WI). The plans were compared using isodose plots, dose volume histograms, dose homogeneity indexes, conformity indexes, radiobiological models, and treatment times. Smaller pitches and jaw widths showed better target dose homogeneity and sparing of normal tissue, as expected. However, the treatment time increased inversely proportional to the jaw width, resulting in delivery times of 24 {+-} 1.9 min for the 1-cm jaw width. Although treatment plans produced with the 2.5-cm jaw were dosimetrically superior to plans produced with the 5-cm jaw, subsequent calculations of tumor control probabilities and normal tissue complication probabilities suggest that these differences may not be radiobiologically meaningful. Because treatment plans produced with the 5-cm jaw can be delivered in approximately half the time of plans produced with the 2.5-cm jaw (5.1 {+-} 0.6 min vs. 9.5 {+-} 1.1 min), use of the 5-cm jaw in routine treatment planning may be a viable approach to decreasing treatment delivery times from helical tomotherapy units.

• OSTI ID: 22130359
• Journal Information: Medical Dosimetry, Vol. 36, Issue 4; Other Information: Copyright (c) 2011 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); ISSN 0958-3947
• Country of Publication: United States
• Language: English

Related Subjects

61 RADIATION PROTECTION AND DOSIMETRY
COMPUTERIZED TOMOGRAPHY
CT-GUIDED RADIOTHERAPY
DOSIMETRY
HEAD
JAW
NECK
NEOPLASMS
OPTIMIZATION
PATIENTS
PITCHES
PLANNING
RADIATION DOSES
RECOMMENDATIONS