In Vivo Proton Beam Range Verification Using Spine MRI Changes

Journal Article · Wed Sep 01 00:00:00 EDT 2010 · International Journal of Radiation Oncology, Biology and Physics

DOI:https://doi.org/10.1016/j.ijrobp.2009.11.060· OSTI ID:21436164

Gensheimer, Michael F ^[1]; Yock, Torunn I; Liebsch, Norbert J; Sharp, Gregory C; Paganetti, Harald ^[2]; Madan, Neel; Grant, P Ellen ^[3]; Bortfeld, Thomas ^[2]

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1. Vanderbilt University School of Medicine, Nashville, TN (United States)
2. Department of Radiation Oncology, Massachusetts General Hospital, Boston, MA (United States)
3. Department of Radiology, Massachusetts General Hospital, Boston, MA (United States)

Purpose: In proton therapy, uncertainty in the location of the distal dose edge can lead to cautious treatment plans that reduce the dosimetric advantage of protons. After radiation exposure, vertebral bone marrow undergoes fatty replacement that is visible on magnetic resonance imaging (MRI). This presents an exciting opportunity to observe radiation dose distribution in vivo. We used quantitative spine MRI changes to precisely detect the distal dose edge in proton radiation patients. Methods and Materials: We registered follow-up T1-weighted MRI images to planning computed tomography scans from 10 patients who received proton spine irradiation. A radiation dose-MRI signal intensity curve was created using the lateral beam penumbra in the sacrum. This curve was then used to measure range errors in the lumbar spine. Results: In the lateral penumbra, there was an increase in signal intensity with higher dose throughout the full range of 0-37.5 Gy (RBE). In the distal fall-off region, the beam sometimes appeared to penetrate farther than planned. The mean overshoot in 10 patients was 1.9 mm (95% confidence interval, 0.8-3.1 mm), on the order of the uncertainties inherent to our range verification method. Conclusions: We have demonstrated in vivo proton range verification using posttreatment spine MRI changes. Our analysis suggests the presence of a systematic overshoot of a few millimeters in some proton spine treatments, but the range error does not exceed the uncertainty incorporated into the treatment planning margin. It may be possible to extend our technique to MRI sequences that show early bone marrow changes, enabling adaptive treatment modification.

• OSTI ID: 21436164
• Journal Information: International Journal of Radiation Oncology, Biology and Physics, Vol. 78, Issue 1; Other Information: DOI: 10.1016/j.ijrobp.2009.11.060; PII: S0360-3016(09)03634-7; Copyright (c) 2010 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; ISSN 0360-3016
• Country of Publication: United States
• Language: English

Related Subjects

62 RADIOLOGY AND NUCLEAR MEDICINE
BONE MARROW
COMPUTERIZED TOMOGRAPHY
IN VIVO
NMR IMAGING
PROTON BEAMS
RADIATION DOSE DISTRIBUTIONS
RADIOTHERAPY
VERIFICATION
VERTEBRAE
ANIMAL TISSUES
BEAMS
BODY
DIAGNOSTIC TECHNIQUES
HEMATOPOIETIC SYSTEM
MEDICINE
NUCLEAR MEDICINE
NUCLEON BEAMS
ORGANS
PARTICLE BEAMS
RADIOLOGY
SKELETON
THERAPY
TOMOGRAPHY