title: Intensity-modulated radiotherapy.
abstract: Intensity-modulated radiotherapy represents a recent advancement in conformal radiotherapy. It employs specialized computer-driven technology to generate dose distributions that conform to tumor targets with extremely high precision. Treatment planning is based on inverse planning algorithms and iterative computer-driven optimization to generate treatment fields with varying intensities across the beam section. Combinations of intensity-modulated fields produce custom-tailored conformal dose distributions around the tumor, with steep dose gradients at the transition to adjacent normal tissues. Thus far, data have demonstrated improved precision of tumor targeting in carcinomas of the prostate, head and neck, thyroid, breast, and lung, as well as in gynecologic, brain, and paraspinal tumors and soft tissue sarcomas. In prostate cancer, intensity-modulated radiotherapy has resulted in reduced rectal toxicity and has permitted tumor dose escalation to previously unattainable levels. This experience indicates that intensity-modulated radiotherapy represents a significant advancement in the ability to deliver the high radiation doses that appear to be required to improve the local cure of several types of tumors. The integration of new methods of biologically based imaging into treatment planning is being explored to identify tumor foci with phenotypic expressions of radiation resistance, which would likely require high-dose treatments. Intensity-modulated radiotherapy provides an approach for differential dose painting to selectively increase the dose to specific tumor-bearing regions. The implementation of biologic evaluation of tumor sensitivity, in addition to methods that improve target delineation and dose delivery, represents a new dimension in intensity-modulated radiotherapy research.
authors: Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, New York 10021, USA.
authors: Steven A
authors: SA
authors: Leibel
authors: Zvi
authors: Z
authors: Fuks
authors: Michael J
authors: MJ
authors: Zelefsky
authors: Suzanne L
authors: SL
authors: Wolden
authors: Kenneth E
authors: KE
authors: Rosenzweig
authors: Kaled M
authors: KM
authors: Alektiar
authors: Margie A
authors: MA
authors: Hunt
authors: Ellen D
authors: ED
authors: Yorke
authors: Linda X
authors: LX
authors: Hong
authors: Howard I
authors: HI
authors: Amols
authors: Chandra M
authors: CM
authors: Burman
authors: Andrew
authors: A
authors: Jackson
authors: Gikas S
authors: GS
authors: Mageras
authors: Thomas
authors: T
authors: LoSasso
authors: Laura
authors: L
authors: Happersett
authors: Spiridon V
authors: SV
authors: Spirou
authors: Chen-Shou
authors: CS
authors: Chui
authors: C Clifton
authors: CC
authors: Ling
mesh_terms: D000008:Abdominal Neoplasms / Q000532:radiotherapy; D002289:Carcinoma, Non-Small-Cell Lung / Q000532:radiotherapy; D006801:Humans; D008175:Lung Neoplasms / Q000532:radiotherapy; D008297:Male; D009303:Nasopharyngeal Neoplasms / Q000532:radiotherapy; D009369:Neoplasms / Q000532:radiotherapy*; D011471:Prostatic Neoplasms / Q000532:radiotherapy; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D020266:Radiotherapy, Conformal / Q000379:methods*