What is the conformity index?
Conformity index is introduced as an extension of section-by-section dosimetric analysis and dose-volume histograms and can be defined as an absolute value resulting from the ratio between a fraction of the tumour volume and the volume covered with the certain isodose line.
What is gradient index in radiotherapy?
Purpose: Steep dose falloff outside of tumors is a hallmark of stereotactic radiosurgery (SRS) and radiation therapy (SRT). Dose gradient index (DGI) quantifies the dose drop off. Tables of DGIs versus target volumes have been published for body. sites, but none is available for brain.
What is paddick conformity?
IAN PADDICK, M.SC. ✔ A conformity index is a measure of how well the volume of a radiosurgical dose distribution conforms to the size and shape of a target volume.
How do you calculate gradient index?
Gradient Index: GI = PIVhalfPIV where PIVhalf is the prescription isodose volume, at half the prescription isodose and PIV is the prescription isodose volume.
What is heterogeneity index?
The Heterogeneity Index (HI) is a dimensionless property that compares a specific property (e.g., porosity with the average porosity value).
What do you mean by heterogeneity?
Definition of heterogeneity : the quality or state of consisting of dissimilar or diverse elements : the quality or state of being heterogeneous cultural heterogeneity.
What is the difference between homogeneous and heterogeneous?
By definition, a pure substance or a homogeneous mixture consists of a single phase. A heterogeneous mixture consists of two or more phases. When oil and water are combined, they do not mix evenly, but instead form two separate layers.
What is the radiotherapy conformity index of unity?
Abstract. The radiotherapy conformity index (CI) is a useful tool to quantitatively assess the quality of radiotherapy treatment plans, and represents the relationship between isodose distributions and target volume. A conformity index of unity implies high planning target volume (PTV) coverage and minimal unnecessary irradiation
What do conformity index and homogeneity index tell us about breast radiotherapy?
AIM: The conformity index and the homogeneity index are two analysis tools of a treatment plan using conformal radiotherapy. The purpose of this article is an analysis of these two parameters in the assessment of the treatment plans in 58 patients undergoing postoperative radiotherapy of the whole breast.
What is the RTOG conformity index for radiation?
Radiation Therapy Oncology Group criteria. The RTOG “conformity index” (Eq. 1c) is easy to interpret. A conformity index equal to 1 corresponds to ideal conformation. A conformity index greater than 1 indicates that the irradiated volume is greater than the target volume and includes healthy tissues.
What can conformity indices tell us about irradiated tissue homogeneity?
An analysis of conformity indices for isodoses greater than the 95% isodose would provide information about the degree of homogeneity of irradiation of the target. For isodoses less than the 95% isodose, the indices could be used to evaluate the volume of healthy tissue irradiated.