Dosimetric analysis and clinical implementation of 6 MV X-ray radiosurgery beam

S. Guru Prasad, K. Parthasaradhi, Colleen Des Rosiers, William D. Bloomer, Michael A. Lacombe

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


The dosimetric data on tissue maximum ratios (TMR), output factors, off axis ratios and beam profiles are presented for small circular fields of diameters ranging from 12.5 to 40 mm for 6 MV radiosurgery beam. It is noticed that d(max) increases as the collimator field size increases. Comparison of our data with the published TMR and output factors of similar small circular fields shows that our values are higher than those data. Similarities in trend are noticed with the published isodose volumes for 1-5 and 10 arcs. Not much variation is seen beyond two arcs for 80% isodose volumes for all the field sizes. The variation is small in 20% isodose volumes beyond three arcs. Variations are noticed in 5% isodose volumes for 12.5 mm diameter collimated beam. Our experience has been exclusively with malignant neoplasms. An ideal target volume is covered by 80% isodose volume with 3-4 arcs and a single isocenter. Sixteen patients have been treated to date at our institution, including one patient with brain metastases, two patients with meningiomas, one patient with lymphoma and 12 patients with astrocytomas. The majority of tumors have been treated with single isocenter but some as large as 7 cm have been treated safely with two isocenters.

Original languageEnglish (US)
Pages (from-to)127-133
Number of pages7
JournalMedical Dosimetry
Issue number2
StatePublished - Jan 1 1997
Externally publishedYes


  • Malignant neoplasm
  • Output factors
  • Tissue maximum ratios

ASJC Scopus subject areas

  • Radiological and Ultrasound Technology
  • Oncology
  • Radiology Nuclear Medicine and imaging

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