Contents
What does isodose mean?
: of or relating to points or zones in a medium that receive equal doses of radiation.
What is isodose planning?
An isodose plan is a graphic display of patient’s anatomy to include the distribution of radiation based on a prescribed dose and plan of care created by a radiation oncologist.
What is penumbra in radiotherapy?
Abstract. In external beam therapy, radiation penumbra is one of the factors which hinder the confinement of the dose to tumour volume and cause unnecessary irradiation of the surrounding normal tissues in the penumbral region.
What is Isocenter Photogrammetry?
Isocenter in aerial photography: it is a point where a line cuts an angle of 90 degree of tier/2. It is the point on the aerial photo platform that directly falls on a line half-way between the Principal point and the Nadir point.
How often can you bill 77338?
Do not bill CPT 77338 with CPT 77385; also, do not bill CPT 77338 more than once per IMRT plan, unless an exceptional circumstance should arise; for example, if the beneficiary was in a car accident after the device was designed, and as a result, suffered injuries that may impact the construction of the device, a …
How is penumbra reduced?
Penumbra width is decreased using compensating filter and intensity modulation technique. Penumbra width is improved by removing the flattening filter of linac. Increasing SDD results in decreasing geometric penumbra width. Penumbra width is increased by increasing depth and field size.
How is the depth of an isodose curve normalized?
The depth dose values of the curves are normalized: 1) At the point of maximum dose on the central axis (Dmax) 2) At a fixed distance along the central axis in the irradiated medium (SAD). 7. Isodose chart Co60 10*10cm SSD =80cm SAD 8. BEAM PROFILE The dose variation across the field at a specified depth. 9.
Which is the function of variation in thedose curve?
DefinitionIsodose curves are the lines joiningthe points of equal PercentageDepth Dose (PDD), therefore ameans of mapping variation in thedose as a function of depth andtransverse distance from the centralaxis of the beam. 3 4. Depends upon• Beam energy (quality)• Field size• SSD• Attenuating factors• Source geometry/collimation 4
Why are isodose curves distended outside the primary beam?
As expected, the isodose curves outside the primary beam (e.g., 10% and 5%) are greatly distended in the case of orthovoltage radiation. Thus, one disadvantage of the orthovoltage beams is the increased scattered dose to tissue outside the treatment region.
What is the wedge angle of an isodose curve?
Isodose Curve Effected by Wedge Filter Normalized to dmax without wedge Normalized to dmax with wedge (open field)d = 10 cm wedge wedge angle angle Wedge Angle : ICRU #24: The angle through which an isodose curve is titled at the central ray of a beam at a specified depth. (10 cm) 9 10.