In prone breast radiation, as the medial tangential beam usually passes through immobilization board and couch, it is necessary to quantify attenuation effect potential skin dose enhancement from these external structures. The studied consists of an insert on which contralateral rests a base indexed couch. Two different Varian couch systems were also studied. Transmission factors (TF) measured ...

Dear Editor, Over the last few years, medical LINAC manufacturers have started to offer couch tops or inserts designed for image-guided radiation therapy (IGRT). These couch tops have a homogeneous construction, with a carbon fiber shell and no metal components. Although the use of these couches may offer some advantages in image quality, it can have a potentially serious impact on skin sparing...

The dosimetric impact from devices external to the patient is a complex combination of increased skin dose, reduced tumor dose, and altered dose distribution. Although small monitor unit or dose corrections are routinely made for blocking trays, ion chamber correction factors, e.g., accounting for temperature and pressure, or tissue inhomogeneities, the dose perturbation of the treatment couch ...

The purpose of this study is to determine comparability of three different planar IMRT QA techniques: patient gantry angle composite (PGAC), single gantry angle composite (SGAC), and field by field (FBF), using MapCHECK 2 device and the γ test as performance metrics; and to assess the dependency of these techniques on intensity modulation, couch attenuation, and detector position (angular depen...

The aim of this study was to understand the difference between the measured and calculated irradiation attenuations obtained using two algorithms and to identify the influence of couch attenuation on patient dose verification. We performed eight tests of couch attenuation with two photon energies, two longitudinal couch positions, and two rail positions. The couch attenuation was determined usi...

The purpose of this study was to survey current departmental policies on treatment couch overrides and the values of table tolerances used clinically. A 25-question electronic survey on couch overrides and tolerances was sent to full members of the American Association of Physicists in Medicine (AAPM). The first part of the survey asked participants if table overrides were allowed at their inst...

Highly attenuating radiation treatment couches are no longer useful in the present era of radiotherapy utilizing IMRT and IGRT. Carbon fibers couch tops with its high tensile strength and low density present a useful alternative. The objective of the current study was to quantify the attenuation of megavoltage photons through a Brainlab imaging couch top and headrest at various angles and field...

In this study, we compared the motion accuracy of six degrees of freedom (6D) couch for precision radiotherapy with or without weights attached to the couch. Two digital cameras were focused on the iso-center of a linear accelerator. Images of a needle which had been fixed to the 6D couch were obtained using the cameras when the couch moved in translation and rotation around each axis. The thre...