A new brain positron emission tomography scanner with semiconductor detectors for target volume delineation and radiotherapy treatment planning in patients with nasopharyngeal carcinoma.

Abstract

PURPOSE:

We compared two treatment planning methods for stereotactic boost for treating nasopharyngeal carcinoma (NPC): the use of conventional whole-body bismuth germanate (BGO) scintillator positron emission tomography (PET(CONV)WB) versus the new brain (BR) PET system using semiconductor detectors (PET(NEW)BR).

METHODS AND MATERIALS:

Twelve patients with NPC were enrolled in this study. [(18)F]Fluorodeoxyglucose-PET images were acquired using both the PET(NEW)BR and the PET(CONV)WB system on the same day. Computed tomography (CT) and two PET data sets were transferred to a treatment planning system, and the PET(CONV)WB and PET(NEW)BR images were coregistered with the same set of CT images. Window width and level values for all PET images were fixed at 3000 and 300, respectively. The gross tumor volume (GTV) was visually delineated on PET images by using either PET(CONV)WB (GTV(CONV)) images or PET(NEW)BR (GTV(NEW)) images. Assuming a stereotactic radiotherapy boost of 7 ports, the prescribed dose delivered to 95% of the planning target volume (PTV) was set to 2000 cGy in 4 fractions.

RESULTS:

The average absolute volume (±standard deviation [SD]) of GTV(NEW) was 15.7 ml (±9.9) ml, and that of GTV(CONV) was 34.0 (±20.5) ml. The average GTV(NEW) was significantly smaller than that of GTV(CONV) (p = 0.0006). There was no statistically significant difference between the maximum dose (p = 0.0585) and the mean dose (p = 0.2748) of PTV. The radiotherapy treatment plan based on the new gross tumor volume (PLAN(NEW)) significantly reduced maximum doses to the cerebrum and cerebellum (p = 0.0418) and to brain stem (p = 0.0041).

CONCLUSION:

Results of the present study suggest that the new brain PET system using semiconductor detectors can provide more accurate tumor delineation than the conventional whole-body BGO PET system and may be an important tool for functional and molecular radiotherapy treatment planning.

• Authors: Norio Katoh, Koichi Yasuda, Tohru Shiga, Masakazu Hasegawa, Rikiya Onimaru, Shinichi Shimizu, Gerard Bengua, Masayori Ishikawa, Nagara Tamaki, Hiroki Shirato
• Journal: International journal of radiation oncology, biology, physics (Int J Radiat Oncol Biol Phys) Vol. 82 Issue 4 Pg. e671-6 (Mar 15 2012) ISSN: 1879-355X [Electronic] United States
• PMID: 22245187 (Publication Type: Comparative Study, Evaluation Study, Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: Copyright © 2012 Elsevier Inc. All rights reserved.

Chemical References

• Radiopharmaceuticals
• Germanium
• Fluorodeoxyglucose F18
• bismuth germanium oxide
• Bismuth

Topics

• Adult
• Aged
• Bismuth
• Brain (diagnostic imaging)
• Carcinoma
• Female
• Fluorodeoxyglucose F18
• Germanium
• Humans
• Male
• Middle Aged
• Multimodal Imaging (instrumentation, methods)
• Nasopharyngeal Carcinoma
• Nasopharyngeal Neoplasms (diagnostic imaging, radiotherapy)
• Positron-Emission Tomography (instrumentation, methods)
• Radiopharmaceuticals
• Radiotherapy Planning, Computer-Assisted (instrumentation, methods)
• Tomography, X-Ray Computed
• Tumor Burden