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Comparative analysis between 5 mm and 7.5 mm collimators in CyberKnife radiosurgery for trigeminal neuralgia.

Sudahar H, Kurup PG, Murali V, Velmurugan J - J Med Phys (2013)

Bottom Line: The 6 Gy dose volumes in 7.5 mm plans were 1.53 and 1.34 times higher than the 5 mm plan and the bi-collimator plans respectively.The treatment time parameters were lesser for 7.5 mm collimators.Since, the normal tissue dose is pretty high in 7.5 mm collimator plans, the use of it in TN plans can be ruled out though the treatment time is lesser for these 7.5 mm collimator plans.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiotherapy, Apollo Speciality Hospital, Chennai, Tamil Nadu, India.

ABSTRACT
Trigeminal neuralgia (TN) is treated in CyberKnife (Accuray Inc, Sunnyvale, USA) with the 5 mm collimator whose dosimetric inaccuracy is higher than the other available collimators. The 7.5 mm collimator which is having less dosimetric uncertainty can be an alternative for 5 mm collimator provided the dose distribution with 7.5 mm collimator is acceptable. Aim of this study is to analyze the role of 7.5 mm collimator in CyberKnife treatment plans of TN. The treatment plans with 5 mm collimators were re-optimized with 7.5 mm collimator and a bi-collimator system (5 mm and 7.5 mm). The treatment plans were compared for target coverage, brainstem doses, and the dose to normal tissues. The target and brainstem doses were comparable. However, the conformity indices were 2.31 ± 0.52, 2.40 ± 0.87 and 2.82 ± 0.51 for 5 mm, bi-collimator (5mm and 7.5 mm), 7.5 mm collimator plans respectively. This shows the level of dose spillage in 7.5 mm collimator plans. The 6 Gy dose volumes in 7.5 mm plans were 1.53 and 1.34 times higher than the 5 mm plan and the bi-collimator plans respectively. The treatment time parameters were lesser for 7.5 mm collimators. Since, the normal tissue dose is pretty high in 7.5 mm collimator plans, the use of it in TN plans can be ruled out though the treatment time is lesser for these 7.5 mm collimator plans.

No MeSH data available.


Related in: MedlinePlus

An axial dose distribution comparison between 5 mm collimator plan (a), 5-7.5 mm bi-collimator plan (b), and 7.5 mm collimator plan (c)
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Figure 1: An axial dose distribution comparison between 5 mm collimator plan (a), 5-7.5 mm bi-collimator plan (b), and 7.5 mm collimator plan (c)

Mentions: The mean volume of the trigeminal nerve target was 36.9 ± 3.4 mm3. The mean prescription volume, which is nothing but the V100% was 71.7 ± 7.8% volume of the nerve target. Dose distribution comparison between the treatment plans by 5 mm collimator, 5 mm and 7.5 mm collimators and 7.5 mm collimator for a sample case is shown in Figure 1.


Comparative analysis between 5 mm and 7.5 mm collimators in CyberKnife radiosurgery for trigeminal neuralgia.

Sudahar H, Kurup PG, Murali V, Velmurugan J - J Med Phys (2013)

An axial dose distribution comparison between 5 mm collimator plan (a), 5-7.5 mm bi-collimator plan (b), and 7.5 mm collimator plan (c)
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3775035&req=5

Figure 1: An axial dose distribution comparison between 5 mm collimator plan (a), 5-7.5 mm bi-collimator plan (b), and 7.5 mm collimator plan (c)
Mentions: The mean volume of the trigeminal nerve target was 36.9 ± 3.4 mm3. The mean prescription volume, which is nothing but the V100% was 71.7 ± 7.8% volume of the nerve target. Dose distribution comparison between the treatment plans by 5 mm collimator, 5 mm and 7.5 mm collimators and 7.5 mm collimator for a sample case is shown in Figure 1.

Bottom Line: The 6 Gy dose volumes in 7.5 mm plans were 1.53 and 1.34 times higher than the 5 mm plan and the bi-collimator plans respectively.The treatment time parameters were lesser for 7.5 mm collimators.Since, the normal tissue dose is pretty high in 7.5 mm collimator plans, the use of it in TN plans can be ruled out though the treatment time is lesser for these 7.5 mm collimator plans.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiotherapy, Apollo Speciality Hospital, Chennai, Tamil Nadu, India.

ABSTRACT
Trigeminal neuralgia (TN) is treated in CyberKnife (Accuray Inc, Sunnyvale, USA) with the 5 mm collimator whose dosimetric inaccuracy is higher than the other available collimators. The 7.5 mm collimator which is having less dosimetric uncertainty can be an alternative for 5 mm collimator provided the dose distribution with 7.5 mm collimator is acceptable. Aim of this study is to analyze the role of 7.5 mm collimator in CyberKnife treatment plans of TN. The treatment plans with 5 mm collimators were re-optimized with 7.5 mm collimator and a bi-collimator system (5 mm and 7.5 mm). The treatment plans were compared for target coverage, brainstem doses, and the dose to normal tissues. The target and brainstem doses were comparable. However, the conformity indices were 2.31 ± 0.52, 2.40 ± 0.87 and 2.82 ± 0.51 for 5 mm, bi-collimator (5mm and 7.5 mm), 7.5 mm collimator plans respectively. This shows the level of dose spillage in 7.5 mm collimator plans. The 6 Gy dose volumes in 7.5 mm plans were 1.53 and 1.34 times higher than the 5 mm plan and the bi-collimator plans respectively. The treatment time parameters were lesser for 7.5 mm collimators. Since, the normal tissue dose is pretty high in 7.5 mm collimator plans, the use of it in TN plans can be ruled out though the treatment time is lesser for these 7.5 mm collimator plans.

No MeSH data available.


Related in: MedlinePlus