Case Study Of IMRT

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IMRT patients but remained within the dose TD 5/5 and Quantec constraints6. For the contralateral parotid, the mean dose for the IMRT was 1707 cGy compared to the wedged pair dose of 294cGy. The Quantec mean dose for unilateral parotid is 2000cGy and the TD 5/5 is 3200 cGy. Both are within limits to prevent xerostomia. The submandibular is another area that can cause dry mouth if the dose is over the TD 5/5 of 3900 cGy. For the IMRT the mean dose for the contralateral submandibular was 1788 cGy and for the wedged pair 444 cGy. So again, the dose is within the constraint for complicated side effects. The contralateral parotid and submandibular are important to prevent xerostomia and improve quality of life. Curative patients have long …show more content…

The mean PTV of the IMRT plan 6347 cGy and the wedge pair mean is 6414 cGy. The total mean dose that is trying to be achieved is 6167 cGy. The PTV had a sharper dose fall off to the PTV after the prescription dose was achieved than the wedged pair did. Discussion By just looking at the mean dose of the OAR, the wedge pair is a better option in planning. However, after evaluating the DVH and isodose distribution, the assessment becomes more complex. The conformality of IMRT is much better planning method to navigate the complex contour of the neck and the OARs that must have dose constraints to reduce side effect and increase quality. In the head and neck region, there are other considerations for dose constraint and accurate treatment of the tumor volume. Anatomical and set-up error can cause an increased dose of OARs and reduced tumor dose9. Changes in anatomy over the over the course of treatment such as tumor and lymph node shrinkage and weight loss can change the dosimetry.9 This is important in planning. With IMRT, daily imaging is often incorporated and includes IGRT. IGRT method can reduce the error in set-up and help to treat the tumor volume more accurately. Another methods treatment to consider is proton therapy. A pencil beam proton therapy can guide the beam to cover the PTV. There is a sharp fall off with proton therapy which makes it possible for the target volume to be covered and the OARs to give little or no dose.

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