Comparison of multileaf collimator and conventional circular collimator systems in Cyberknife stereotactic radiotherapy

Multileaf collimator (MLC) technology has been newly introduced with the Cyberknife system. This study investigated the advantages of this system compared with the conventional circular collimator (CC) system. Dosimetric comparisons of MLC and CC plans were carried out. First, to investigate suitable target sizes for the MLC mode, MLC and CC plans were generated using computed tomography (CT) images from 5 patients for 1, 3, 5 and 7 cm diameter targets. Second, MLC and CC plans were compared in 10 patients, each with liver and prostate targets. For brain targets, doses to the brain could be spared in MLC plans better than in CC plans (P ≤ 0.02). The MLC mode also achieved more uniform dose delivery to the targets. The conformity index in MLC plans was stable, irrespective of the target size (P = 0.5). For patients with liver tumors, the MLC mode achieved higher target coverage than the CC mode (P = 0.04). For prostate tumors, doses to the rectum and the conformity index were lowered in MLC plans compared with in CC plans (P ≤ 0.04). In all target plans, treatment times in MLC plans were shorter than those in CC plans (P < 0.001). The newly introduced MLC technology can reduce treatment time and provide favorable or comparable dose distribution for 1-7 cm targets. In particular, the MLC mode has dosimetric advantage for targets near organs at risk. Therefore, the MLC mode is recommended as the first option in stereotactic body radiotherapy.

CyberKnife radiotherapy for malignant fibrous histiocytoma of the chest wall: A case report and review of the literature

Malignant fibrous histiocytoma (MFH) is the most common type of soft tissue sarcoma, but rarely originates in the chest wall. Surgical resection is considered to be the most reliable treatment, however, no consensus has been reached concerning the best treatment for unresectable MFH. The current study presents the case of a 77-year-old male with MFH of the chest wall. The patient developed a painless mass and intermittent fever over a four-month period. A computed tomography scan demonstrated a large inhomogeneous lesion in the right chest wall, which was subsequently diagnosed via biopsy as a MFH. Since the tumor was an unresectable mass, CyberKnife^® radiotherapy was conducted. Following the treatment, a marked reduction in the tumor size was observed with a tolerable level of toxicity. The sequencing analysis also revealed an in-frame deletion (delE746-A750) in exon 19 of the epidermal growth factor receptor gene. Based on this result, gefitinib was administered to the patient at a dose of 250 mg/day.

Stereotactic Body Radiotherapy (SBRT) for primary and recurrent head and neck tumors

Stereotactic Body Radiotherapy (SBRT) is increasingly used to treat a variety of head and neck tumors as a result of its highly conformal dose distributions and stereotactic spatial accuracy in delivery. Our experience and other previous reports have shown that SBRT is technically feasible, well-tolerated and compares favorably to other alternatives of salvage therapy in the management of patients with recurrent and/or previously irradiated head and neck cancers. Furthermore, it has the advantage of a shorter treatment schedule, greater compliance, and safe delivery in the outpatient setting. This affords an opportunity to introduce SBRT as a definitive treatment in select patients. This review presents an overview of the use of SBRT for managing head and neck tumors by highlighting the existing indications and the expanding role of SBRT in managing these patients.