Harmony Search in Therapeutic Medical Physics - Music-Inspired Harmony Search Algorithm: Theory and Applications - page 188

Fig. 1. A cumulative dose-volume histogram (DVH)
Once the DVH is created, it can be analyzed by specifying two types of criteria:
volume and dose constraints. These parameters are standard nomenclature in the field
of radiation oncology. The first letter determines the type of constraint (dose or vol-
ume) and the following number identifies which value to look up from the DVH. For
example, if a physician would like to determine the V100 of the prostate, he would
like to know the volume of the prostate that receives 100% of the prescribed dose. On
the other hand, if the D90 is requested, the dose that 90% of the volume receives is
returned. Additionally, volume constraints (Vxxx) can also be specified in absolute
volume, as well as percent of the total volume. In this version of the constraint, the
standard notation is to append a “cc” after the number, i.e. D1cc (determine the dose
to 1 cc of the volume).
3 High Dose-Rate Prostate Brachytherapy
Brachytherapy is a form of radiation therapy in which sealed radioactive source(s) are
placed inside or on the body to irradiate tumors. With improved anatomical resolu-
tion, physicians are able to define target volumes more clearly with image guidance.
Brachytherapy can be used to treat these targets in a variety of situations such as in-
terstitial, intracavitary, intravascular or even on the surface of tumor.
In high dose-rate (HDR) prostate brachytherapy, approximately 15 to 25 catheters
are inserted into the target volume for treatment and a single source (commonly 192 Ir)
is moved to dwell positions within the catheters. Each position to which the source
can be advanced is known as a dwell position. The source remains in each position for
a specified amount of time. For each catheter, a step distance can be defined, in which
the source is retracted by the given distance in order to deliver a desired dose