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 does SRS mean in oncology?

Gamma Knife stereotactic radiosurgery Stereotactic radiosurgery (SRS) uses many precisely focused radiation beams to treat tumors and other problems in the brain, neck, lungs, liver, spine and other parts of the body. It is not surgery in the traditional sense because there’s no incision.

What is gradient index in radiotherapy?

A dose gradient index (GI) is proposed that can be used to compare treatment plans of equal conformity. The steep dose gradient outside the radiosurgical target is one of the factors that makes radiosurgery possible.

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.

What is the homogeneity index?

Homogeneity Index (HI) is an objective tool to analyz the uniformity of dose distribution in the target volume. Various formulae have been described in literature for its calculation but there is paucity of data regarding the ideal formula and the factors affecting this index.

What does it mean to conform to society?

Conformity
Conformity is the act of matching attitudes, beliefs, and behaviors to group norms, politics or being like-minded. People often choose to conform to society rather than to pursue personal desires – because it is often easier to follow the path others have made already, rather than forging a new one.

What is the difference between SBRT and SRS?

SRS, usually limited to brain lesions, is an extreme example of SBRT in that the entire dose is typically given in a single fraction. SBRT is defined as treatment of tumors outside of the brain with 1–5 dose fractions.

What is difference between SRS and SRT?

SRS is delivered in one high dose treatment. SRT delivers radiation therapy in smaller amounts over several treatment sessions. Both SRS and SRT deliver similar total doses of radiation, but SRT allows the healthy tissues time to recover between treatment sessions.

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?

Purpose/Objectives: Heterogeneity index (HI) has been described in the literature as a tool for evaluating dose gradients within a planning target volume (PTV). HI may be expressed as D1/D95 where D1 and D95 equal the dose encompassing 1% and 95% of the target volume.

Why is conformity a bad thing?

Normative conformity is the tendency to behave in certain ways in order to be accepted by a group. Of the two, normative conformity may be the most dangerous, as it can motivate someone to go along with a group even if they know the group is wrong.

How is conformity measured in a SRS plan?

SRS treatment plans require a high degree of conformity to minimize damage to the tissues that surround the target area. Clinically, this conformity is evaluated using a combination of visual inspection of the plan and evaluation of the dose-volume histograms (DVHs).

How are dose gradient index and conformity index related?

The conformity index (CI) quantifies how closely the radiation prescription (Rx) dose conforms to the size and shape of the target. 8 Dose gradient index (DGI) quantifies the dose falloff outside of the target. 9 Historically, the conformity of the dose was the key component of SRS/SRT.

Is the conformity index independent of target volume?

No acceptable limits for the new conformity index were defined by Paddick. Once again, the. conformity index is not independent of target volume: the average conformity for all the targets. was 55.6%, whereas the average conformity for targets smaller than 1 cm3 was 48.7%.

Which is a crucial component of SRS / SRT?

The crucial component of SRS/SRT is precise delivery of the radiation dose to the target conformally with rapid dose falloff into the surrounding normal tissues.