Limits...
Technical advances and pitfalls in head and neck radiotherapy.

Parvathaneni U, Laramore GE, Liao JJ - J Oncol (2012)

Bottom Line: However, these benefits come with a serious and sobering price.Proton therapy has a theoretical physical advantage over photon therapy due to a lack of "exit dose".The purpose of this article is to review the literature, discuss the salient issues and make recommendations that address the gaps in knowledge.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiation Oncology, University of Washington, Seattle, WA 98195, USA.

ABSTRACT
Intensity Modulated Radiotherapy (IMRT) is the standard of care in the treatment of head and neck squamous cell carcinomas (HNSCC) based on level 1 evidence. Technical advances in radiotherapy have revolutionized the treatment of HNSCC, with the most tangible gain being a reduction in long term morbidity. However, these benefits come with a serious and sobering price. Today, there is a greater chance of missing the target/tumor due to uncertainties in target volume definition by the clinician that is demanded by the highly conformal planning process involved with IMRT. Unless this is urgently addressed, our patients would be better served with the historically practiced non conformal radiotherapy, than IMRT which promises lesser morbidity. Image guided radiotherapy (IGRT) ensures the level of set up accuracy warranted to deliver a highly conformal treatment plan and should be utilized with IMRT, where feasible. Proton therapy has a theoretical physical advantage over photon therapy due to a lack of "exit dose". However, clinical data supporting the routine use of this technology for HNSCC are currently sparse. The purpose of this article is to review the literature, discuss the salient issues and make recommendations that address the gaps in knowledge.

No MeSH data available.


Related in: MedlinePlus

Comparison of a HRT plan (a) with an IMRT plan (b). Red color wash is the high-risk clinical target volume (CTV 66). Green color wash is the low-risk target volume (CTV 54) for microscopic disease. CTV66 is covered conformally by the red 98% isodose line in the IMRT plan. In the HRT plan conformality is lacking as the 98% isodose line covers not only CTV66 but also CTV54 as well as normal tissue including the mandible and oral mucosa. The magenta isodose line is an undesirable 105% “hot spot” located on the mandible and in the posterior neck in conventional plan. There are no “hot spots” in the IMRT plan.
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fig1: Comparison of a HRT plan (a) with an IMRT plan (b). Red color wash is the high-risk clinical target volume (CTV 66). Green color wash is the low-risk target volume (CTV 54) for microscopic disease. CTV66 is covered conformally by the red 98% isodose line in the IMRT plan. In the HRT plan conformality is lacking as the 98% isodose line covers not only CTV66 but also CTV54 as well as normal tissue including the mandible and oral mucosa. The magenta isodose line is an undesirable 105% “hot spot” located on the mandible and in the posterior neck in conventional plan. There are no “hot spots” in the IMRT plan.

Mentions: IMRT is a conformal 3-dimensional technique capable of precisely targeting tumors while avoiding normal structures and is the current standard of care in the treatment of HNSCC. IMRT refers to a controlled modulation of intensity across each individual beam so that the desired high-dose distribution matches the tumor/target in all physical dimensions. Advances in computerized treatment planning systems utilizing complex inverse planning algorithms, along with hardware improvisations including high-resolution multi-leaf collimators, have made this technique readily available for routine use at most centers in the developed world. The major benefit of IMRT compared to HRT is the sparing of critical structures while conforming the desired high doses to the tumors; an example is seen in Figure 1.


Technical advances and pitfalls in head and neck radiotherapy.

Parvathaneni U, Laramore GE, Liao JJ - J Oncol (2012)

Comparison of a HRT plan (a) with an IMRT plan (b). Red color wash is the high-risk clinical target volume (CTV 66). Green color wash is the low-risk target volume (CTV 54) for microscopic disease. CTV66 is covered conformally by the red 98% isodose line in the IMRT plan. In the HRT plan conformality is lacking as the 98% isodose line covers not only CTV66 but also CTV54 as well as normal tissue including the mandible and oral mucosa. The magenta isodose line is an undesirable 105% “hot spot” located on the mandible and in the posterior neck in conventional plan. There are no “hot spots” in the IMRT plan.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3369487&req=5

fig1: Comparison of a HRT plan (a) with an IMRT plan (b). Red color wash is the high-risk clinical target volume (CTV 66). Green color wash is the low-risk target volume (CTV 54) for microscopic disease. CTV66 is covered conformally by the red 98% isodose line in the IMRT plan. In the HRT plan conformality is lacking as the 98% isodose line covers not only CTV66 but also CTV54 as well as normal tissue including the mandible and oral mucosa. The magenta isodose line is an undesirable 105% “hot spot” located on the mandible and in the posterior neck in conventional plan. There are no “hot spots” in the IMRT plan.
Mentions: IMRT is a conformal 3-dimensional technique capable of precisely targeting tumors while avoiding normal structures and is the current standard of care in the treatment of HNSCC. IMRT refers to a controlled modulation of intensity across each individual beam so that the desired high-dose distribution matches the tumor/target in all physical dimensions. Advances in computerized treatment planning systems utilizing complex inverse planning algorithms, along with hardware improvisations including high-resolution multi-leaf collimators, have made this technique readily available for routine use at most centers in the developed world. The major benefit of IMRT compared to HRT is the sparing of critical structures while conforming the desired high doses to the tumors; an example is seen in Figure 1.

Bottom Line: However, these benefits come with a serious and sobering price.Proton therapy has a theoretical physical advantage over photon therapy due to a lack of "exit dose".The purpose of this article is to review the literature, discuss the salient issues and make recommendations that address the gaps in knowledge.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiation Oncology, University of Washington, Seattle, WA 98195, USA.

ABSTRACT
Intensity Modulated Radiotherapy (IMRT) is the standard of care in the treatment of head and neck squamous cell carcinomas (HNSCC) based on level 1 evidence. Technical advances in radiotherapy have revolutionized the treatment of HNSCC, with the most tangible gain being a reduction in long term morbidity. However, these benefits come with a serious and sobering price. Today, there is a greater chance of missing the target/tumor due to uncertainties in target volume definition by the clinician that is demanded by the highly conformal planning process involved with IMRT. Unless this is urgently addressed, our patients would be better served with the historically practiced non conformal radiotherapy, than IMRT which promises lesser morbidity. Image guided radiotherapy (IGRT) ensures the level of set up accuracy warranted to deliver a highly conformal treatment plan and should be utilized with IMRT, where feasible. Proton therapy has a theoretical physical advantage over photon therapy due to a lack of "exit dose". However, clinical data supporting the routine use of this technology for HNSCC are currently sparse. The purpose of this article is to review the literature, discuss the salient issues and make recommendations that address the gaps in knowledge.

No MeSH data available.


Related in: MedlinePlus