introduction:  skin  sparing  is  one  of  the  most  desirable  characteristics  of  high  energy  photon  beams. however, the photons emerging from the target of linacs are contaminated by secondary  electrons  as  a  result  of  their  interactions  with  air,  collimators,  flattening  filter  and  any  other  objects in their path. this phenomenon tends to increase the skin dose received b...

BACKGROUND Patient-specific dose verification for treatment planning in helical tomotherapy is routinely performed using a homogeneous virtual water cylindrical phantom of 30 cm diameter and 18 cm length (Cheese phantom). Because of this small length, treatment with total marrow irradiation (TMI) requires multiple deliveries of the dose verification procedures to cover a wide range of the targe...

PURPOSE To directly measure skin dose using point-dosimeters from dental cone-beam CT (CBCT) scans. To compare the results among three different dental CBCT scanners and compare the CBCT results with those from a conventional panoramic and cephalomic dental imaging system. METHODS A head anthropomorphic phantom was used with nanoDOT dosimeters attached to specified anatomic landmarks of selec...

Methods: The Optic Nerve (ON) coil was constructed using two fiberglass formers that fit together to surround the entire head. The anterior former supports 26 overlapping coil elements in a mask arrangement as shown in Fig. 1. The posterior former supports the neck and head and houses two additional overlapped coil elements, totaling to 28 elements. In this design, the two formers can slide ove...

Neurofeedback- and brain-computer interface (BCI)-based interventions can be implemented using real-time analysis of magnetoencephalographic (MEG) recordings. Head movement during MEG recordings, however, can lead to inaccurate estimates of brain activity, reducing the efficacy of the intervention. Most real-time applications in MEG have utilized analyses that do not correct for head movement. ...

objective: different categories are available for estimating of radiation dose. radioisotopes with the same energy and almost the same physical properties have similar effects. monte carlo technique is a computerized method based on mathematical simulation of physical processes. the main purpose of this study is to show that beta particles are not able to penetrate deep into the water. also dif...

The performance of a cellular phone commercial helical antenna at 900 MHz band, both in free space and in the presence of a human head phantom was studied. Numerical simulation of the phone model for the latter case has been performed giving 3D radiation diagrams. The effect of the phantom head on radiation diagrams is presented. The relative amount of the EM power absorbed in the head was obta...

OBJECTIVE To evaluate three-dimensional translational setup errors and residual errors in image-guided radiosurgery, comparing frameless and frame-based techniques, using an anthropomorphic phantom. MATERIALS AND METHODS We initially used specific phantoms for the calibration and quality control of the image-guided system. For the hidden target test, we used an Alderson Radiation Therapy (ART...

BACKGROUND Electroencephalography (EEG) can capture the cortical response evoked by transcranial magnetic stimulation (TMS). The TMS pulse provokes a large artefact, which obscures the cortical response in the first milliseconds after TMS. Removing this artefact remains a challenge. METHODS We delivered monophasic and biphasic TMS to a melon as head phantom and to four healthy participants an...

annually, many people are irradiated for diagnostic and therapeutic purposes. assessment of radiation dose and its related risks to patients are important issues in radiation protection dosimetry. the complex mathematical calculations of the absorbed and effective doses are now done with computers. the calculations are performed with the help of anthropomorphic computational models of human bod...