Optimization of Isocenter Location for Intensity Modulated Stereotactic Treatment of Small Intracranial Targets

Bill J. Salter, Martin Fuss, Vikren Sarkar, Brian Wang, Prema Rassiah-Szegedi, Nikos Papanikolaou, Scott Hollingshaus, Dennis C. Shrieve

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

Purpose: To quantify the impact of isocenter location on treatment plan quality for intensity-modulated stereotactic treatment of small intracranial lesions. Methods and Materials: For 18 patients previously treated by stereotactic-intensity modulated radiosurgery (IMRS) or intensity-modulated radiation therapy (IMRT), a retrospective virtual planning study was conducted wherein the impact of isocenter location on plan quality was measured. Treatment indications studied included six arteriovenous malformations, six acoustic neuromas, and six intracranial metastases, ranging in volume from 0.71 to 3.21 cm3 (mean = 2.26 cm3), 1.08 to 2.84 cm3 (mean = 1.73 cm3), and 0.19 to 2.30 cm3 (mean = 0.79 cm3), respectively. Variation of isocenter location causes the geometric grid of pencil beams into which the target is segmented for intensity-modulated treatment to be altered. The impact of this pencil-beam-grid redefinition on achievable conformity index was quantified for three collimators (Varian Millennium 120; BrainLab MM3; Nomos binary Mimic) and three treatment planning systems (TPS; Varian Eclipse v6.5; BrainLab BrainScan v5.31; Best-Nomos Corvus v6.2), resulting in the evaluation of 3,446 treatment plans. Results: For all patients, collimator, and TPS combinations studied, a significant variation in plan quality was observed as a function of isocenter and pencil-beam-grid relocation. Optimization of isocenter location resulted in treatment plan conformity variations as large as 109% (min = 15%, mean = 51%, max = 109%). Conclusion: Optimization of isocenter location for IMRT/IMRS treatment of small intracranial lesions in which pencil-beam dimensions are comparable to target dimensions, can result in significant improvements in treatment plan quality.

Original languageEnglish (US)
Pages (from-to)546-555
Number of pages10
JournalInternational Journal of Radiation Oncology Biology Physics
Volume73
Issue number2
DOIs
StatePublished - Feb 1 2009

Fingerprint

optimization
pencil beams
Therapeutics
Radiosurgery
grids
collimators
lesions
planning
radiation therapy
Radiotherapy
Crows
relocation
Acoustic Neuroma
Arteriovenous Malformations
metastasis
eclipses
indication
Neoplasm Metastasis
acoustics
evaluation

Keywords

  • IMRT
  • Isocenter optimization
  • pencil beam
  • SRS
  • Stereotactic

ASJC Scopus subject areas

  • Oncology
  • Radiology Nuclear Medicine and imaging
  • Radiation
  • Cancer Research

Cite this

Optimization of Isocenter Location for Intensity Modulated Stereotactic Treatment of Small Intracranial Targets. / Salter, Bill J.; Fuss, Martin; Sarkar, Vikren; Wang, Brian; Rassiah-Szegedi, Prema; Papanikolaou, Nikos; Hollingshaus, Scott; Shrieve, Dennis C.

In: International Journal of Radiation Oncology Biology Physics, Vol. 73, No. 2, 01.02.2009, p. 546-555.

Research output: Contribution to journalArticle

Salter, Bill J. ; Fuss, Martin ; Sarkar, Vikren ; Wang, Brian ; Rassiah-Szegedi, Prema ; Papanikolaou, Nikos ; Hollingshaus, Scott ; Shrieve, Dennis C. / Optimization of Isocenter Location for Intensity Modulated Stereotactic Treatment of Small Intracranial Targets. In: International Journal of Radiation Oncology Biology Physics. 2009 ; Vol. 73, No. 2. pp. 546-555.
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AU - Rassiah-Szegedi, Prema

AU - Papanikolaou, Nikos

AU - Hollingshaus, Scott

AU - Shrieve, Dennis C.

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