In the latter experiences, the focal boost has been delivered with differential dose external beam radiation, differential HDR brachytherapy, and LDR brachytherapy.
Both high-dose-rate intracavitary brachytherapy and stereotactic radiosurgical boost have been shown to increase locoregional control rates when given as an adjuvant to external beam RT (Pai et al, 2002; Le et al, 2003; Lu et al, 2004).
20 HDR prostate brachytherapy, originally used as a boost together with external beam treatment, has been receiving more attention as monotherapy for suitable patients, due to its better-controlled dosimetry, no residual radioactivity, higher dose rate, and better suitability for low α/β ratio prostate cancer.
The fan-beam technology has been extended to a so-called cone-beam or a flash-beam technique.
Volume-dependent perfusion defects after irradiation of left-sided breast cancer using tangential photon beams to a dose of 50 Gy and electron boost of 16-18 Gy has been revealed for up to 40% of patients within 2 years after treatment [ 9].
High dose rate brachytherapy to a partial volume of the prostate has been used as a boost after external beam radiotherapy [93] and several ongoing phase I and II trials are investigating its use as a boost to the dominant intraprostatic lesion (NCT00807820, NCT01605097).
However intraoperative radiation therapy has been introduced by several groups including ours also in the treatment of extremity tumors [ 13- 16] to replace the external beam boost mainly because of its unique opportunity to guide a high single dose directly to the high risk region for close or positive margins under visual control during surgery.
Recently, sequential beam delivery techniques have been used in TBI.
Nearly half of the 761 beams have been checked by engineers; about 30 "severely" corroded beams have been found.
