Stereotactic Radiotherapy of Central Nervous System and Head and Neck Lesions, Using a Conformal Intensity-Modulated Radiotherapy System (PeacockTM System)

Abstract

The objective of this article is to evaluate single-fraction or fractionated stereotactic radiotherapy of central nervous system (CNS) and head and neck lesions using intensity-modulated radiotherapy (IMRT) with a commercially available system (Peacocktrade mark, Nomos Corporation, Sewickley, PA). This system allows tomotherapeutic delivery of intensity-modulated radiation, that is, the slice-by-slice treatment of the volume of interest with an intensity-modulated beam, making the delivery of highly conformal radiation to the target possible in both single or multiple fractions mode. During an 18-month period, 43 (21 males and 22 females) patients were treated, using a removable cranial screw-fixation device. Ages ranged from 10 to 77 years (mean, 52.2; median, 53.5). Intra- and extra-axial lesions, including head and neck malignancies and spine metastases, were treated. Clinical target volume ranged from 0.77 to 195 cm(3) (mean, 47.8; median, 29.90). The dose distribution was normalized to the maximum and was prescribed, in most cases, at the 80% or 90% isodose line (range, 65 to 96%; median, 85%; mean, 83.4%) and ranged from 14 to 80 Gy (mean, 48; median, 50). The number of fractions ranged from 1 to 40 (mean, 23; median, 25). In all but one patient, 90% of the prescription isodose line covered 100% of the clinical target volume. The heterogeneity index (the ratio between the maximum radiation dose and the prescribed dose) ranged between 1.0 and 1.50, whereas the conformity index (the ratio between the volume encompassed by the prescription isodose line and the clinical target volume) ranged between 1.0 and 4.5. There were no complications related to the radiation treatment. With a median follow-up of 6 months, more than 70% of our patients showed decreased lesion size. Stereotactic IMRT of CNS and head and neck lesions can be delivered safely and accurately. The Peacock system delivers stereotactic radiation in single or multiple fractions and has no volume limitations. It has been used to treat intracranial, head and neck, and spinal lesions. The option of fractionation, the lack of volume constraint, and the capability of treating intracranial, head and neck, and spinal pathology make stereotactic IMRT a valuable adjunct to established stereotactic radiotherapy systems delivering convergent-beam irradiation using the Linac or Gamma Knife. In a clinical setting that offers Linac, Gamma Knife radiosurgery, and conformal stereotactic radiotherapy, the latter may have advantages for treating large (> 25-cm(3)) and irregular lesions, especially when fractionation is considered useful.

Conservative thickness layers in Mohs micrographic surgery

“…a,b) which, in our experience, leads to a cosmetically appropriate outcome and helps avoid a more invasive reconstruction. In our practice, when CTL clears a tumor on the nose, we consider dermabrasion to improve second intention healing in a similar manner as reported with the carbon dioxide laser . Dermabrasion is best done on the distal nose and nasal alae due to the sebaceous nature of these sites.…”

Hypofractionated intensity modulated radiotherapy with temozolomide in newly diagnosed glioblastoma multiforme

“…Standard RT for GBM was arrived at in the 1970s and consists of 60 Gy delivered in 30 fractions of 2 Gy each for a total of 6 weeks [3–5]. Clearly in the last 10–15 years there have been great advances in imaging of the area to be irradiated as well as advances in the more precise delivery of radiation using three dimensional (3D) conformal and intensity modulated radiation therapy (IMRT) techniques [6]. IMRT is widely regarded as a technique that enables delivery of very conformal radiation to a target while limiting radiation deposition on surrounding structures at risk; IMRT has been considered and used for GBM.…”