The use of RapidArc volumetric-modulated arc therapy to deliver stereotactic radiosurgery and stereotactic body radiotherapy to intracranial and extracranial targets.

Twenty-three targets in 16 patients treated with stereotactic radiosurgery (SRS) or stereotactic body radiotherapy (SBRT) were analyzed in terms of dosimetric homogeneity, target conformity, organ-at-risk (OAR) sparing, monitor unit (MU) usage, and beam-on time per fraction using RapidArc volumetric-modulated arc therapy (VMAT) vs. multifield sliding-window intensity-modulated radiation therapy (IMRT). Patients underwent computed tomography simulation with site-specific immobilization.

Real-time tumor tracking using implanted positron emission markers: concept and simulation study.

The delivery accuracy of radiation therapy for pulmonary and abdominal tumors suffers from tumor motion due to respiration. Respiratory gating should be applied to avoid the use of a large target volume margin that results in a substantial dose to the surrounding normal tissue. Precise respiratory gating requires the exact spatial position of the tumor to be determined in real time during treatment.

Gene expression profiling of in vitro radiation resistance in cervical carcinoma: a feasibility study.

Objective(s): To determine the feasibility of integrating an in vitro chemo-radiation response assay (IVRRA) with a gene microarray system to investigate the molecular patterns of expression that contribute to radiation resistance in cervical cancer.

Methods: Viable primary untreated cervical cancer specimens were obtained and exposed to gamma irradiation at a dose of 3 Gy in the IVRRA to determine in vitro radiation sensitivity. RNA was purified for microarray analysis with the Affymetrix Human Genome U95A Array carrying more than 12,000 gene probes.

Use of Yttrium-90 TheraSphere for the treatment of unresectable hepatocellular carcinoma.

This is a retrospective analysis of a new treatment modality, intra-arterial administration of Yttrium-90 TheraSphere, for unresectable hepatocellular carcinoma (HCC). Patients with HCC not amenable to surgical treatment who had satisfactory physiological function without comorbid disease or significant pulmonary shunting were eligible for treatment. Patients were categorized into complete, partial, or no response based on serum alpha-fetoprotein (AFP) levels and CT or MRI imaging.

Treatment planning considerations of reshapeable automatic intensity modulator for intensity modulated radiation therapy.

As compared with multi-leaf collimator based intensity modulated radiation therapy (IMRT) techniques, physical modulators have the major advantage of temporally invariant intensity map delivery which makes it more flexible with monitor unit rate, simpler resolution of interrupted treatment and easier implementation and use with respiratory gating. However, traditional physical modulator techniques require long fabrication time and operator intervention during treatments. It has been previously proposed [Xu et al.

Intensity-modulated radiotherapy for previously irradiated, recurrent head-and-neck cancer.

The purpose of this work is to evaluate our initial experience in treating previously irradiated, recurrent head-and-neck cancers using intensity-modulated radiotherapy (IMRT). Between July 1997 and September 1999, 12 patients with previously irradiated, locally recurrent head-and-neck cancers were treated with IMRT. These included cancers of the nasopharynx, oropharynx, hypopharynx, larynx, paranasal sinus, skin of the head-and-neck region, and malignant melanoma.