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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

The graph between the volume dose index and the corresponding target doses in all the collimator plans
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Figure 2: The graph between the volume dose index and the corresponding target doses in all the collimator plans

Mentions: As far as the target dose coverage is concerned, all the three plans were yielding similar results. The mean value of the D98% was 48.8 ± 3.8 Gy, 50.1 ± 4.0 Gy, and 49.7 ± 3.9 Gy respectively for 5 mm collimator plan, 5 mm and 7.5 mm collimators plan and 7.5 mm collimator plan. Similarly, D10% values were 72.1 ± 2.1 Gy, 70.4 ± 2.6 Gy and 69.1 ± 2.9 Gy respectively for 5 mm, 5 mm and 7.5 mm, 7.5 mm collimator plans. The graph between the volume dose index and the target doses are shown in Figure 2. The maximum, minimum and the mean target doses along with the conformity index and homogeneity index are given in Table 1. The conformity index for the 5 mm plan is found to be the smallest when compared to the other two plans. The mean conformity indices were 2.31 ± 0.52, 2.40 ± 0.87 and 2.82 ± 0.51 for 5 mm, 5 mm and 7.5 mm, 7.5 mm collimator plans respectively. However, the 7.5 mm plan is more homogeneous than the other two plans.


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)

The graph between the volume dose index and the corresponding target doses in all the collimator plans
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 2: The graph between the volume dose index and the corresponding target doses in all the collimator plans
Mentions: As far as the target dose coverage is concerned, all the three plans were yielding similar results. The mean value of the D98% was 48.8 ± 3.8 Gy, 50.1 ± 4.0 Gy, and 49.7 ± 3.9 Gy respectively for 5 mm collimator plan, 5 mm and 7.5 mm collimators plan and 7.5 mm collimator plan. Similarly, D10% values were 72.1 ± 2.1 Gy, 70.4 ± 2.6 Gy and 69.1 ± 2.9 Gy respectively for 5 mm, 5 mm and 7.5 mm, 7.5 mm collimator plans. The graph between the volume dose index and the target doses are shown in Figure 2. The maximum, minimum and the mean target doses along with the conformity index and homogeneity index are given in Table 1. The conformity index for the 5 mm plan is found to be the smallest when compared to the other two plans. The mean conformity indices were 2.31 ± 0.52, 2.40 ± 0.87 and 2.82 ± 0.51 for 5 mm, 5 mm and 7.5 mm, 7.5 mm collimator plans respectively. However, the 7.5 mm plan is more homogeneous than the other two plans.

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