Comparison of linac based fractionated stereotactic radiotherapy and tomotherapy treatment plans for skull-base tumors

Emilie T. Soisson, Wolfgang A. Tome, Gregory M. Richards, Minesh P. Mehta

Research output: Contribution to journalArticle

46 Citations (Scopus)

Abstract

Background and purpose: To compare and evaluate helical tomotherapy and linac based fractionated stereotactic radiotherapy (FSRT) techniques in the treatment of skull-base tumors. Patients and methods: Ten patients diagnosed with skull-base tumors, originally planned for optically guided FSRT to prescribed doses of 50.4-54 Gy were replanned for treatment with clinically deliverable helical tomotherapy. All original CT scans, MR-CT fusion defined target and normal structure contours, and PTV margins were used for helical tomotherapy planning. Linac based plans utilized one of the following FSRT planning techniques: non-coplanar or coplanar intensity modulated radiation therapy (IMRT), multiple non-coplanar conformal arcs, and non-coplanar conformal radiation therapy (CRT). These plans were used as the standard to which the subsequent tomotherapy plans were compared, using the following criteria: prescription isodose to target volume (PITV) ratios, an inhomogeneity index (II), equivalent uniform dose (EUD) for PTV volumes, mean normalized total doses (NTD mean) for critical structures, and size of 10, 20, and 30 Gy isodose volumes. Results: Use of both linac based FSRT techniques and helical tomotherapy generated highly conformal treatment plans. Tomotherapy plans, which are predominantly coplanar in nature, compared to non-coplanar linac based plans exhibited increased PITV ratios, variable change in II, similar EUD values, and generally comparable NTD mean values for organs at risk. When compared to non-coplanar field arrangements, deliverable (as opposed to idealized) tomotherapy plans also resulted in 13-540% increases in low dose isodose volumes. All criteria except for the II, which was generally improved with tomotherapy, were found to be similar when coplanar linac based plans were compared to helical tomotherapy plans. Conclusions: Results show a distinct advantage in using non-coplanar beam arrangements for treatment of skull-base tumors. In the case where disease spreads far inferiorly, limiting the ability to use non-coplanar arrangements, helical tomotherapy can be used to generate a comparable treatment plan, with potentially superior homogeneity.

Original languageEnglish (US)
Pages (from-to)313-321
Number of pages9
JournalRadiotherapy and Oncology
Volume78
Issue number3
DOIs
StatePublished - Mar 2006
Externally publishedYes

Fingerprint

Intensity-Modulated Radiotherapy
Skull Base
Radiotherapy
Stereotaxic Techniques
Neoplasms
Prescriptions
Therapeutics
Planning Techniques
Organs at Risk

Keywords

  • Base of skull
  • EUD
  • IMRT
  • Tomotherapy
  • Treatment planning

ASJC Scopus subject areas

  • Oncology
  • Radiology Nuclear Medicine and imaging
  • Urology

Cite this

Comparison of linac based fractionated stereotactic radiotherapy and tomotherapy treatment plans for skull-base tumors. / Soisson, Emilie T.; Tome, Wolfgang A.; Richards, Gregory M.; Mehta, Minesh P.

In: Radiotherapy and Oncology, Vol. 78, No. 3, 03.2006, p. 313-321.

Research output: Contribution to journalArticle

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abstract = "Background and purpose: To compare and evaluate helical tomotherapy and linac based fractionated stereotactic radiotherapy (FSRT) techniques in the treatment of skull-base tumors. Patients and methods: Ten patients diagnosed with skull-base tumors, originally planned for optically guided FSRT to prescribed doses of 50.4-54 Gy were replanned for treatment with clinically deliverable helical tomotherapy. All original CT scans, MR-CT fusion defined target and normal structure contours, and PTV margins were used for helical tomotherapy planning. Linac based plans utilized one of the following FSRT planning techniques: non-coplanar or coplanar intensity modulated radiation therapy (IMRT), multiple non-coplanar conformal arcs, and non-coplanar conformal radiation therapy (CRT). These plans were used as the standard to which the subsequent tomotherapy plans were compared, using the following criteria: prescription isodose to target volume (PITV) ratios, an inhomogeneity index (II), equivalent uniform dose (EUD) for PTV volumes, mean normalized total doses (NTD mean) for critical structures, and size of 10, 20, and 30 Gy isodose volumes. Results: Use of both linac based FSRT techniques and helical tomotherapy generated highly conformal treatment plans. Tomotherapy plans, which are predominantly coplanar in nature, compared to non-coplanar linac based plans exhibited increased PITV ratios, variable change in II, similar EUD values, and generally comparable NTD mean values for organs at risk. When compared to non-coplanar field arrangements, deliverable (as opposed to idealized) tomotherapy plans also resulted in 13-540{\%} increases in low dose isodose volumes. All criteria except for the II, which was generally improved with tomotherapy, were found to be similar when coplanar linac based plans were compared to helical tomotherapy plans. Conclusions: Results show a distinct advantage in using non-coplanar beam arrangements for treatment of skull-base tumors. In the case where disease spreads far inferiorly, limiting the ability to use non-coplanar arrangements, helical tomotherapy can be used to generate a comparable treatment plan, with potentially superior homogeneity.",
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N2 - Background and purpose: To compare and evaluate helical tomotherapy and linac based fractionated stereotactic radiotherapy (FSRT) techniques in the treatment of skull-base tumors. Patients and methods: Ten patients diagnosed with skull-base tumors, originally planned for optically guided FSRT to prescribed doses of 50.4-54 Gy were replanned for treatment with clinically deliverable helical tomotherapy. All original CT scans, MR-CT fusion defined target and normal structure contours, and PTV margins were used for helical tomotherapy planning. Linac based plans utilized one of the following FSRT planning techniques: non-coplanar or coplanar intensity modulated radiation therapy (IMRT), multiple non-coplanar conformal arcs, and non-coplanar conformal radiation therapy (CRT). These plans were used as the standard to which the subsequent tomotherapy plans were compared, using the following criteria: prescription isodose to target volume (PITV) ratios, an inhomogeneity index (II), equivalent uniform dose (EUD) for PTV volumes, mean normalized total doses (NTD mean) for critical structures, and size of 10, 20, and 30 Gy isodose volumes. Results: Use of both linac based FSRT techniques and helical tomotherapy generated highly conformal treatment plans. Tomotherapy plans, which are predominantly coplanar in nature, compared to non-coplanar linac based plans exhibited increased PITV ratios, variable change in II, similar EUD values, and generally comparable NTD mean values for organs at risk. When compared to non-coplanar field arrangements, deliverable (as opposed to idealized) tomotherapy plans also resulted in 13-540% increases in low dose isodose volumes. All criteria except for the II, which was generally improved with tomotherapy, were found to be similar when coplanar linac based plans were compared to helical tomotherapy plans. Conclusions: Results show a distinct advantage in using non-coplanar beam arrangements for treatment of skull-base tumors. In the case where disease spreads far inferiorly, limiting the ability to use non-coplanar arrangements, helical tomotherapy can be used to generate a comparable treatment plan, with potentially superior homogeneity.

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