Intensity-modulated radiotherapy of nasopharyngeal carcinoma: a comparative treatment planning study of photons and protons.

Abstract

BACKGROUND:

The aim of this treatment planning study was to investigate the potential advantages of intensity-modulated (IM) proton therapy (IMPT) compared with IM photon therapy (IMRT) in nasopharyngeal carcinoma (NPC).

METHODS:

Eight NPC patients were chosen. The dose prescriptions in cobalt Gray equivalent (GyE) for gross tumor volumes of the primary tumor (GTV-T), planning target volumes of GTV-T and metastatic (PTV-TN) and elective (PTV-N) lymph node stations were 72.6 GyE, 66 GyE, and 52.8 GyE, respectively. For each patient, nine coplanar fields IMRT with step-and-shoot technique and 3D spot-scanned three coplanar fields IMPT plans were prepared. Both modalities were planned in 33 fractions to be delivered with a simultaneous integrated boost technique. All plans were prepared and optimized by using the research version of the inverse treatment planning system KonRad (DKFZ, Heidelberg).

RESULTS:

Both treatment techniques were equal in terms of averaged mean dose to target volumes. IMPT plans significantly improved the tumor coverage and conformation (P < 0.05) and they reduced the averaged mean dose to several organs at risk (OARs) by a factor of 2-3. The low-to-medium dose volumes (0.33-13.2 GyE) were more than doubled by IMRT plans.

CONCLUSION:

In radiotherapy of NPC patients, three-field IMPT has greater potential than nine-field IMRT with respect to tumor coverage and reduction of the integral dose to OARs and non-specific normal tissues. The practicality of IMPT in NPC deserves further exploration when this technique becomes available on wider clinical scale.

• Authors: Zahra Taheri-Kadkhoda, Thomas Björk-Eriksson, Simeon Nill, Jan J Wilkens, Uwe Oelfke, Karl-Axel Johansson, Peter E Huber, Marc W Münter
• Journal: Radiation oncology (London, England) (Radiat Oncol) Vol. 3 Pg. 4 (Jan 24 2008) ISSN: 1748-717X [Electronic] England
• PMID: 18218078 (Publication Type: Comparative Study, Evaluation Study, Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Protons

Topics

• Algorithms
• Computer Simulation
• Humans
• Nasopharyngeal Neoplasms (radiotherapy)
• Photons (therapeutic use)
• Proton Therapy
• Radiotherapy Dosage
• Radiotherapy Planning, Computer-Assisted
• Radiotherapy, Intensity-Modulated (adverse effects, methods)