Reflect on the DVH topic in week four. Summarize your interpretation and understanding of the readings. Provide Website URLs that support your summary and provide more insight to the rest of the class. Also, make sure you include when you would use each type of DVH.
There are many tools available to evaluate a radiation therapy treatment plan. In addition to the isodose lines and surfaces, which show areas of high, low, and uniform dose and their location in relation to the patient’s anatomy, the dose volume histogram (DVH) should also be reviewed when evaluating a plan or comparing plans.[1] A DVH is a graphic depiction of how much dose a structure is receiving in relation to its volume and allows the entire dose distribution for a structure to be seen in a single curve. There are 2 different types of DVHs; cumulative integral and differential.
A cumulative integral DVH shows the volume receiving a specified dose or higher as a function of dose.[1] The points on the curve depict the volume of the structure that is receiving the stated dose and, as such, it is commonly used to evaluate organs at risk because their mean dose, point dose, and volume receiving specific doses, among other things, are easily visualized on the cumulative DVH. A cumulative DVH can show the curves of many structures all at once, making it easy for the dosimetrist and physician to evaluate all the structures quickly.
A differential DVH shows the volume receiving a dose as a function of dose for a designated dose interval.[1] The more conformal and uniform the dose is, the thinner the peak will be on the DVH.[2] A differential DVH can only show one structure at a time. The differential DVH can be used to evaluate target structures easily, but because it lacks information such as maximum point dose and mean dose, it is not commonly used to evaluate normal critical structures and, thus, it is less frequently used, in general, to evaluate plans.
Reference
A cumulative integral DVH shows the volume receiving a specified dose or higher as a function of dose.[1] The points on the curve depict the volume of the structure that is receiving the stated dose and, as such, it is commonly used to evaluate organs at risk because their mean dose, point dose, and volume receiving specific doses, among other things, are easily visualized on the cumulative DVH. A cumulative DVH can show the curves of many structures all at once, making it easy for the dosimetrist and physician to evaluate all the structures quickly.
A differential DVH shows the volume receiving a dose as a function of dose for a designated dose interval.[1] The more conformal and uniform the dose is, the thinner the peak will be on the DVH.[2] A differential DVH can only show one structure at a time. The differential DVH can be used to evaluate target structures easily, but because it lacks information such as maximum point dose and mean dose, it is not commonly used to evaluate normal critical structures and, thus, it is less frequently used, in general, to evaluate plans.
Reference
- Khan FM. Electron Beam Therapy: The Physics of Radiation Therapy.5th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2014: 423-424.
- UNC Department of Radiation Oncology. Dosimetry online supplemental education. http://www.dosimetrypractice.com/M2-1.htm. Accessed April 18, 2017.