dose to the patient from a mv portal image

by Zoila Jakubowski 9 min read

Modeling dose distributions from portal dose images …

33 hours ago Post-treatment dose verification refers to the process of reconstructing delivered dose distributions internal to a patient from information obtained during the treatment. ... at the portal image plane is equal to the portal dose image, the PEF is then back-projected through the … >> Go To The Portal


What is portal dosimetry and how does it work?

Varian’s Portal Dosimetry serves as a method to QA IMRT/VMAT plans which have constant dose modulation. As opposed to using a phantom and ionization chamber for pre-treatment verification, a portal imager made of amorphous silicon is used to produce the portal dose image in calibration units (CU).

How do I perform an IMRT QA using portal dosimetry with mosaiq?

To perform an IMRT QA using Portal Dosimetry with Mosaiq, the treatment plan must first be imported into Mosaiq. Head over to the treatment machine, and enter the room to shift the couch out (longitudinal) to prevent any collision. Use Mosaiq to open up the patient’s chart, and enter into QA mode in RO treat.

Why are portal Films important in breast cancer treatment?

Even though radiation therapy has improved greatly in recent years so that there is less damage to healthy tissue, this is dependent on the radiation reaching its target, something that can change. Portal films are particularly important in women who have left-sided breast cancer.

What are calibration units (cu) for portal imaging?

As opposed to using a phantom and ionization chamber for pre-treatment verification, a portal imager made of amorphous silicon is used to produce the portal dose image in calibration units (CU). CU is an absolute unit that is calibrated, though will vary between institutions, so that 1 CU equals approximately 1 Gy.

Why is a portal image important?

Careful portal images are essential to properly positioning the radiation beam to take advantage of the shape of the chest during the breath hold. Protecting the Heart During Radiation for Breast Cancer: Resiratory Gating.

What happens when you take a port film of your breast?

When taking a port film of your breast, you may have some radiation exposure to your breast that did not have surgery. In addition, the breast that is receiving radiation takes in a small dose of X-ray energy during the portal imaging procedure. This dose of radiation can be calculated into your total prescribed dose, so your treatments won't exceed the amount of radiation that is needed for treatment. If you have a radiation dosimeter implanted at your treatment site, your radiation technician can verify the actual dose that your tissue received at each session.

What is a radiation port film?

Learn about our Medical Review Board. Doru Paul, MD. on November 18, 2019. A radiation port film or portal image is an X-ray that is taken to ensure that radiation targets a tumor or tumor cavity while minimizing exposure to healthy tissues. During breast radiation, your radiation oncologist will check a radiation port film ...

Why do we need to repeat radiation port films?

The need for repeated radiation port films can be annoying due to the extra time it takes during radiation , but is essential to make sure the radiation reaches its intended target while avoiding healthy tissues and organs.

Why do you need a port film?

Port films are done to make sure that you and the radiation machine are properly aligned to each other. These port films ensure your safety and help your radiation technician stay on target ...

Do port films show cancer?

That said, they don't track your progress during treatment—meaning they do not show if any cancer is present.

Can radiation be absorbed through a porthole?

Only a small beam of sunlight can come through a porthole, and only a specific amount of radiation will be beamed at a targeted area of your body. The skin over your tumor site is the porthole through which radiation enters your breast.