Investigations of line scanning proton therapy with dynamic multi-leaf collimator.

Purpose: Scanning proton therapy has dosimetric advantage over passive treatment, but has a large penumbra in low-energy region. This study investigates the penumbra reduction when multi-leaf collimators (MLCs) are used for line scanning proton beams and secondary neutron production from MLCs.

Methods: Scanning beam plans with and without MLC shaping were devised.

Proton range verification in inhomogeneous tissue: Treatment planning system vs. measurement vs. Monte Carlo simulation.

In particle radiotherapy, range uncertainty is an important issue that needs to be overcome. Because high-dose conformality can be achieved using a particle beam, a small uncertainty can affect tumor control or cause normal-tissue complications. From this perspective, the treatment planning system (TPS) must be accurate.

Cumulative dose on fractional delivery of tomotherapy to periodically moving organ: a phantom QA suggestion.

This study was conducted to evaluate the cumulative dosimetric error that occurs in both target and surrounding normal tissues when treating a moving target in multifractional treatment with tomotherapy. An experiment was devised to measure cumulative error in multifractional treatments delivered to a horseshoe-shaped clinical target volume (CTV) surrounding a cylinder shape of organ at risk (OAR). Treatments differed in jaw size (1.

Analysis of changes in dose distribution due to respiration during IMRT.

Purpose: Intensity modulated radiation therapy (IMRT) is a high precision therapy technique that can achieve a conformal dose distribution on a given target. However, organ motion induced by respiration can result in significant dosimetric error. Therefore, this study explores the dosimetric error that result from various patterns of respiration.

Development of a video-guided real-time patient motion monitoring system.

Purpose: The authors developed a video image-guided real-time patient motion monitoring (VGRPM) system using PC-cams, and its clinical utility was evaluated using a motion phantom.

Methods: The VGRPM system has three components: (1) an image acquisition device consisting of two PC-cams, (2) a main control computer with a radiation signal controller and warning system, and (3) patient motion analysis software developed in-house. The intelligent patient motion monitoring system was designed for synchronization with a beam on/off trigger signal in order to limit operation to during treatment time only and to enable system automation.

Variation of small bowel sparing with small bowel displacement system according to the physiological status of the bladder during radiotherapy for cervical cancer.

Objective: To evaluate the reproducibility of small bowel displacement system (SBDS) volumetrically using weekly CT throughout a regimen of radiotherapy for the treatment of cervical cancer.

Methods: From October 2004 to January 2005, 10 consecutive patients who received pelvic radiation therapy for uterine cervical carcinoma with the SBDS were included in this study. With the patient laid prone on the conventional simulator table, the Styrofoam compression device is placed under the lower abdomen of the patient.