disease tends to recur in a treated field with a frequency which is inversely related to dose and approaches zero at a dose of approximately 4000 rads, delivered at the rate of about 1000 rads/week. Such doses make the use of megavoltage X-ray beams mandatory to avoid severe skin reactions, but are other wise well tolerated by the normal tissues. The inverse relation ship of recurrence rate to ...

The purpose of this paper is to describe the reproducibility of liver position using Active Breathing Coordinator in a larger series of patients with more advanced liver cancer, consecutively planned for SBRT delivered in six fractions over two weeks. In this study, repeat megavoltage (MV) verification imaging, real-time beams-eye-view MV movies, conventional kV fluoroscopy, cone beam kV fluoro...

Objective: Using Megavoltage photons generated by medical linear accelerator is a common modality for the treatment of malignant. The crucial problem for using photon beams >8MV is the photoneutron yields that increase the risk of secondary cancer that treated with high-energy photon beams. The contaminated neutrons produced in different components of the accelerator head and rely on many param...

Objective: Using Megavoltage photons generated by medical linear accelerator is a common modality for the treatment of malignant. The crucial problem for using photon beams >8MV is the photoneutron yields that increase the risk of secondary cancer that treated with high-energy photon beams. The contaminated neutrons produced in different components of the accelerator head and rely on many param...

BACKGROUND Radiation-sensitive polymer gels are among the most promising three-dimensional dose verification tools and tissue-like phantom developed to date. OBJECTIVE The aim of this study is an investigating of percentage depth dose enhancement within the gel medium with used of conformal distribution gold nanoparticle as contrast agents by high atomic number material. METHODS In this wor...

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...

This study proposes a new method for removal of metal artifacts from megavoltage cone beam computed tomography (MVCBCT) and kilovoltage CT (kVCT) images. Both images were combined to obtain prior image, which was forward projected to obtain surrogate data and replace metal trace in the uncorrected kVCT image. The corrected image was then reconstructed through filtered back projection. A similar...

The dosimetric stability of six TomoTherapy units was analyzed to investigate changes in performance over time and with system upgrades. Energy and output were tracked using monitor chamber signal, onboard megavoltage computed tomography (MVCT) detector profile, and external ion chamber measurements. The systems (and monitoring periods) include three Hi-Art (67, 61, and 65 mos.), two TomoHDA (3...

In the megavoltage energy range although the mass attenuation coefficients of different bones do not vary by more than 10%, it has been estimated that a simple tissue model containing a single-bone composition could cause errors of up to 10% in the calculated dose distribution. In the kilovoltage energy range, the variation in mass attenuation coefficients of the bones is several times greater,...