Background: Megavoltage beams used in radiotherapy are contaminated with secondary electrons. Different parts of linac head and air above patient act as a source of this contamination. This contamination can increase damage to skin and subcutaneous tissue during radiotherapy. Monte Carlo simulation is an accurate method for dose calculation in medical dosimetry and has an important role in opt...

Cherenkov radiation is induced when charged particles travel through dielectric media (such as biological tissue) faster than the speed of light through that medium. Detection of this radiation or excited luminescence during megavoltage external beam radiotherapy (EBRT) can allow emergence of a new approach to superficial dose estimation, functional imaging, and quality assurance for radiation ...

PURPOSE To estimate the doses to the heart and coronary arteries from common breast cancer radiotherapy (RT) regimens used worldwide from the 1950s to the 1990s. METHODS AND MATERIALS Virtual simulation and computed tomography planning were used to reconstruct the megavoltage and electron regimens. Manual planning was used for the orthovoltage and brachytherapy regimens. Several sources of va...

Considering internal organ motion and tumor regression, it is controversial to use intensity-modulated radiation therapy (IMRT) in definitive radiotherapy for cervical cancer. In this study, we evaluated the efficacy and toxicity of IMRT combined with dose-escalated intracavitary brachytherapy (ICBT) for cervical cancer. In total, 373 consecutive FIGO-stage-IIB cervical cancer patients treated ...

OBJECTIVE To determine if subsets of patients may benefit from smaller or larger margins when using laser setup and bony anatomy verification of breast tumour bed (TB) boost radiotherapy (RT). METHODS Verification imaging data acquired using cone-beam CT, megavoltage CT or two-dimensional kilovoltage imaging on 218 patients were used (1574 images). TB setup errors for laser-only setup (dlaser...

The imaging characteristics of an arc-shaped xenon gas ionization chamber for the purpose of megavoltage CT imaging were investigated. The detector consists of several hundred 320 microm thick gas cavities separated by thin tungsten plates of the same thickness. Dose response, efficiency and resolution parameters were calculated using Monte Carlo simulations. The calculations were compared to m...

PURPOSE To compare the sensitivity of flatness based energy metrics versus an attenuation based metric (percent depth dose) as a function of energy changes from the linac's nominal clinical energy. METHODS Energy changes were accomplished by adjusting the bending magnet current (BMI) ±15% away from the value used clinically. Two metrics for flatness, relative flatness in the central 80% of th...