Total scalp irradiation using helical tomotherapy

Journal Article · Fri Sep 30 04:00:00 EDT 2005 · Medical Dosimetry

DOI:https://doi.org/10.1016/j.meddos.2005.05.002· OSTI ID:20696222

Orton, Nigel ^[1]; Jaradat, Hazim ^[1]; Welsh, James ^[1]; Tome, Wolfgang ^[1]

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1. Department of Human Oncology, University of Wisconsin, Madison, WI (United States)

Homogeneous irradiation of the scalp poses technical and dosimetric challenges due to the extensive, superficial, curved treatment volume. Conventional treatments on a linear accelerator use multiple matched electron fields or a combination of electron and photon fields. Problems with these techniques include dose heterogeneity in the target due to varying source-to-skin distance (SSD) and angle of beam incidence, significant dose to the brain, and the potential for overdose or underdose at match lines between the fields. Linac-based intensity-modulated radiation therapy (IMRT) plans have similar problems. This work presents treatment plans for total scalp irradiation on a helical tomotherapy machine. Helical tomotherapy is well-suited for scalp irradiation because it has the ability to deliver beamlets that are tangential to the scalp at all points. Helical tomotherapy also avoids problems associated with field matching and use of more than one modality. Tomotherapy treatment plans were generated and are compared to plans for treatment of the same patient on a linac. The resulting tomotherapy plans show more homogeneous target dose and improved critical structure dose when compared to state-of-the-art linac techniques. Target equivalent uniform dose (EUD) for the best tomotherapy plan was slightly higher than for the linac plan, while the volume of brain tissue receiving over 30 Gy was reduced by two thirds. Furthermore, the tomotherapy plan can be more reliably delivered than linac treatments, because the patient is aligned prior to each treatment based on megavoltage computed tomography (MVCT)

• OSTI ID: 20696222
• Journal Information: Medical Dosimetry, Journal Name: Medical Dosimetry Journal Issue: 3 Vol. 30; ISSN 0958-3947; ISSN MEDOEJ
• Country of Publication: United States
• Language: English

Related Subjects

62 RADIOLOGY AND NUCLEAR MEDICINE
BEAM POSITION
BRAIN
COMPUTERIZED TOMOGRAPHY
IRRADIATION
LINEAR ACCELERATORS
PATIENTS
PHOTONS
RADIATION DOSES
RADIOTHERAPY
SKIN