February 22, 2013

Today, we will be discussing some specific HDR treatment types (external applicator, permanent & temporary interstitial implants, and intracavitary applicators.

• External applicators & molds

1.      Used in topical brachytherapy.

2.      Commonly treated areas include skin, oral cavity, nasal cavity, hard palate, and orbital cavity (eye).

• Permanent interstitial implants

1.      When tumor is inaccessible, making removal impossible or impractical.

2.      CT guided.

3.      Uses a gunlike applicator

4.      Common for deep seated tumors in the pelvis, abdomen, and lung.

• Temporary interstitial implants

1.      Used in areas where there is no body cavity or orifice to accept the sources.

2.      Boost fields often use this application.

3.      Commonly used in breast and chest wall irradiation, as well as with cancers of the rectum, prostate, vagina, and urethra.

• Intracavitary applicators

1.      Most are designed for gynecological use.

2.      Most common are the tandem and ovoids.

• Tandem & ovoids

1.      The tandem is a long narrow tube inserted into the opening of the cervix into the uterus.

2.      Ovoids are oval shaped and inserted into the lateral fornices of the vagina.

3.      They are stabilized by packing with sterile gauze that helps to displace the rectum and bladder from the sources (lower dose received).

4.      2-3 day placement for treatment.

Reflections:

It is good HDR has so many applications.  Not all linear accelerators have electron therapy built in which means the clinic can buy an HDR and be able to treat superficial lesions that they couldn’t do with typical external photon beam therapy.  Also, it is able to go get inside of the body without irradiating a large volume of tissue that doesn’t need irradiation.

When I looked up "HDR cancer" on google images, I found images of a prostate with the catheters and I was surprised by the picture.  I assumed that the prostate didn't get HDR treatment since I have only seen external beam therapy.  Though I didn't see HDR treatments for breast until I went to Nevada Cancer Center.  Though as can be read up above there are HDR treatments for the rectum, prostate, vagina, and urethra.