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Dosimetric evaluation of an ipsilateral intensity modulated radiotherapy beam arrangement for parotid malignancies.

Yirmibesoglu E, Fried DV, Kostich M, Rosenman J, Shockley W, Weissler M, Zanation A, Chera B - Radiol Oncol (2013)

Bottom Line: Dose, volume statistics for the planning target volumes (PTVs) and planning risk volumes (PRVs) were compared for the four treatment techniques.Wedge pair plans inadequately covered the deep aspect of the PTV.The mean doses to the brainstem, spinal cord, ipsilateral temporal lobe, cerrebellum and ipsilateral cochlea were similar among the four techniques.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiation Oncology, Kocaeli University Faculty of Medicine, Kocaeli, Turkey ; Department of Radiation Oncology, University of North Carolina Hospitals, Chapel Hill, NC, USA.

ABSTRACT

Background: We conducted a dosimetric comparison of an ipsilateral beam arrangement for intensity modulated radiotherapy (IMRT) with off-axis beams.

Patients and methods: Six patients who received post-operative radiotherapy (RT) for parotid malignancies were used in this dosimetric study. Four treatment plans were created for each CT data set (24 plans): 1) ipsilateral 4-field off-axis IMRT (4fld-OA), 2) conventional wedge pair (WP), 3) 7 field co-planar IMRT (7fld), and 4) ipsilateral co-planar 4-field quartet IMRT (4fld-CP). Dose, volume statistics for the planning target volumes (PTVs) and planning risk volumes (PRVs) were compared for the four treatment techniques.

Results: Wedge pair plans inadequately covered the deep aspect of the PTV. The 7-field IMRT plans delivered the largest low dose volumes to normal tissues. Mean dose to the contralateral parotid was highest for 7 field IMRT. Mean dose to the contralateral submandibular gland was highest for 7 field IMRT and WP. 7 field IMRT plans had the highest dose to the oral cavity. The mean doses to the brainstem, spinal cord, ipsilateral temporal lobe, cerrebellum and ipsilateral cochlea were similar among the four techniques.

Conclusions: For postoperative treatment of the parotid bed, 4-field ipsilateral IMRT techniques provided excellent coverage while maximally sparing the contralateral parotid gland and submandibular gland.

No MeSH data available.


Related in: MedlinePlus

Dose volume histogram of the Planning Target Volume (PTV) for wedge pair (WP), 7-field IMRT (7fld), 4-field co-planar (4fld-CP), and 4-field off-axis (4fld-OA) IMRT plans.
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f2-rado-47-04-411: Dose volume histogram of the Planning Target Volume (PTV) for wedge pair (WP), 7-field IMRT (7fld), 4-field co-planar (4fld-CP), and 4-field off-axis (4fld-OA) IMRT plans.

Mentions: Dose volume data for the PTV are listed in Table 1 and related dose volume histograms in Figure 2. Representative isodose distributions for the four treatment plans are depicted in Figure 3. The PTV coverage was similar for both the 7 field and 4 field IMRT plans. As expected, the medial aspect of the PTV (i.e. deep aspect of the post-surgical parotid bed) was inadequately covered with the wedge pair plans (Figure 3, A & E). Dose statistics regarding the conformality of the high dose (i.e. 100% and 95% of the prescription dose) and the integral dose are shown in Table 2. The wedge pair had the worst coverage of the PTV in terms of dose covered by 100% and 95% of the prescription. The wedge pair and 7-field IMRT plans had the least high dose delivered to normal tissues, and the four field plans had much less low dose (i.e. integral dose) delivered to normal tissues.


Dosimetric evaluation of an ipsilateral intensity modulated radiotherapy beam arrangement for parotid malignancies.

Yirmibesoglu E, Fried DV, Kostich M, Rosenman J, Shockley W, Weissler M, Zanation A, Chera B - Radiol Oncol (2013)

Dose volume histogram of the Planning Target Volume (PTV) for wedge pair (WP), 7-field IMRT (7fld), 4-field co-planar (4fld-CP), and 4-field off-axis (4fld-OA) IMRT plans.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC3814288&req=5

f2-rado-47-04-411: Dose volume histogram of the Planning Target Volume (PTV) for wedge pair (WP), 7-field IMRT (7fld), 4-field co-planar (4fld-CP), and 4-field off-axis (4fld-OA) IMRT plans.
Mentions: Dose volume data for the PTV are listed in Table 1 and related dose volume histograms in Figure 2. Representative isodose distributions for the four treatment plans are depicted in Figure 3. The PTV coverage was similar for both the 7 field and 4 field IMRT plans. As expected, the medial aspect of the PTV (i.e. deep aspect of the post-surgical parotid bed) was inadequately covered with the wedge pair plans (Figure 3, A & E). Dose statistics regarding the conformality of the high dose (i.e. 100% and 95% of the prescription dose) and the integral dose are shown in Table 2. The wedge pair had the worst coverage of the PTV in terms of dose covered by 100% and 95% of the prescription. The wedge pair and 7-field IMRT plans had the least high dose delivered to normal tissues, and the four field plans had much less low dose (i.e. integral dose) delivered to normal tissues.

Bottom Line: Dose, volume statistics for the planning target volumes (PTVs) and planning risk volumes (PRVs) were compared for the four treatment techniques.Wedge pair plans inadequately covered the deep aspect of the PTV.The mean doses to the brainstem, spinal cord, ipsilateral temporal lobe, cerrebellum and ipsilateral cochlea were similar among the four techniques.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiation Oncology, Kocaeli University Faculty of Medicine, Kocaeli, Turkey ; Department of Radiation Oncology, University of North Carolina Hospitals, Chapel Hill, NC, USA.

ABSTRACT

Background: We conducted a dosimetric comparison of an ipsilateral beam arrangement for intensity modulated radiotherapy (IMRT) with off-axis beams.

Patients and methods: Six patients who received post-operative radiotherapy (RT) for parotid malignancies were used in this dosimetric study. Four treatment plans were created for each CT data set (24 plans): 1) ipsilateral 4-field off-axis IMRT (4fld-OA), 2) conventional wedge pair (WP), 3) 7 field co-planar IMRT (7fld), and 4) ipsilateral co-planar 4-field quartet IMRT (4fld-CP). Dose, volume statistics for the planning target volumes (PTVs) and planning risk volumes (PRVs) were compared for the four treatment techniques.

Results: Wedge pair plans inadequately covered the deep aspect of the PTV. The 7-field IMRT plans delivered the largest low dose volumes to normal tissues. Mean dose to the contralateral parotid was highest for 7 field IMRT. Mean dose to the contralateral submandibular gland was highest for 7 field IMRT and WP. 7 field IMRT plans had the highest dose to the oral cavity. The mean doses to the brainstem, spinal cord, ipsilateral temporal lobe, cerrebellum and ipsilateral cochlea were similar among the four techniques.

Conclusions: For postoperative treatment of the parotid bed, 4-field ipsilateral IMRT techniques provided excellent coverage while maximally sparing the contralateral parotid gland and submandibular gland.

No MeSH data available.


Related in: MedlinePlus