What is beam profile in radiotherapy?
A beam profile is the graphical representation of the relative dose versus the dis- tance from the central axis at a specific depth. The penumbra region, usually defined as the region between the 80% and the 20% relative dose in the beam profile, is an intrinsic characteristic of any beam, whether photon or electron.
What is DMAX radiotherapy?
DMAX may refer to: Dmax, Maximum point dose to an organ or tumor target in radiotherapy cancer treatment. In densitometry of optics and imaging “D-max” refers to maximum optical density: The greatest achievable opaqueness or optical absorbency.
What is off axis ratio in radiotherapy?
Off-axis ratio is defined as the dose profile normalized to its maximum dose value. Sensitivity studies were done for three scenarios: oscillating the fluctuation regions of two off-axis profiles, shifting the profiles, and rotating the profiles.
Does PDD increase with beam energy?
We notice from Fig. 2 that PDD rate increases with photon beam energy while it decreases with irradiation field size.
What is difference between SSD and sad in radiotherapy?
Modern photon beam radiotherapy is carried out with a variety of beam energies and field sizes under one of two set-up conventions: a constant source to surface distance (SSD) for all beams or an isocentric set-up with a constant source to axis distance (SAD).
What does the D stand for in DMAX?
Maximum Densities (digital scanner quality)
What is wedge angle?
According to the International Commission on Radiation Units and Measurements, the wedge angle is defined as the angle at which an isodose curve is tilted at the central axis of the beam at a specified depth (usually 10 cm) [5].
How do you measure a beam?
The beam diameter is simply twice the beam radius, and can be measured anywhere along the propagation axis. The focal spot size can therefore be very small, and when it is, the beam size varies very rapidly along the propagation axis.
What is the difference between SSD and sad?
What is four field box technique in radiotherapy?
The conventional four field box technique with parallel opposed AP-PA fields and two lateral opposed fields achieves better dose distribution than the parallel opposed AP-PA field technique in terms of tumor coverage and a relatively reduced dose to the normal tissues.
How is PDD measured?
PDDs were measured at 100 cm source-to-surface distance (SSD), for fields of size: 5 cm × 5 cm, 10 cm × 10 cm, 20 cm × 20 cm, 30 cm × 30 cm, and 40 cm × 40 cm. PDDs were measured at all available dose rates for 6 FFF and 10 FFF as PDD curves smoothing vary with dose rate.
What is FSD in radiotherapy?
[*A frequently used alternative term for the ‘focus to skin distance’ ( FSD ) is the ‘source to skin distance’ ( SSD ).] 4.4. Manual calculation of the ‘depth dose’ The radiation dose that is prescribed by the oncologist is the dose to the point of treatment.
Are D-Max and Colorado the same?
The Isuzu D-Max is a pickup truck manufactured since 2002 by Isuzu Motors. The first and second-generation model shared its platform with the Chevrolet Colorado. In Australasia between 2003 and 2008, the D-Max was marketed as the Holden Rodeo, but then was relaunched as the Holden Colorado.
What is a 64 degree wedge used for?
A 64 degree wedge is best used for very short distance shots, or shots where a lot of height is needed. Generally, if you are about 5 yards away from the green, or are on the far side of the green, this club will benefit you greatly. Any distance beyond 40 yards and this club will come up short for green shots.
What is collimator scatter?
the collimator scatter factor (Sc) is commonly called the output factor or head scatter factor, and may be defined as the ratio of the output in air for a given field to that for the reference field (e.g., 10 × 10 cm2) with a buildup cap of a size large enough to provide electronic equilibrium (2).