Transcript
Good morning, everybody. Thank you for introducing me. For my presentation, I am going to talk about the imaging comparison between two techniques of multiple brain metastases treatment with a single isocenter DCA and multiple isocenter technique from the GammaKnife.
The multiple brain metastases software allows an automatic pairing of multiple brain metastases treatment. With the version 1.5, it's now possible to treat up to 15 lesions simultaneously. Okay. With the version 1.5, it's possible to treat up to 15 lesions simultaneously with only one isocenter and five arcs back and forth.
So the aim of our study was to evaluate [inaudible 00:01:03] by dosimetry comparison to our reference with the GammaKnife Perfexion. Twenty-two previous patients we treated with GammaKnife for 2 to 12 lesions are selected with a simple case [inaudible 00:01:20] metastasis far from each other to have a good confidence and the dosimetry indexes reported. We included 77 metastatic with different origin and with a dimension less than 3.0 centimeters for the major axis.
All treatments were replanned using the multiple brain mets. It's anatomically planning using a template. This is the [inaudible 00:01:59] multiple brain mets software. And for each patient, we tried three templates and we chose the best template according to the best activity index and the best organ at risk protection. And then, we customized the template in order to spare organ at risk like [inaudible 00:02:16]. The automatic treatment planning lasts about two minutes.
For the target we used the dosimetric indexes selected was the coverage index, the selectivity index, the gradient index, the maximum, and the mean dose. For this [inaudible 00:02:34] prescription for this index is the comparison was made with treatment planning on the GTV for GammaPlan and also on GTV for multiple brain mets [inaudible 00:02:45]. For the organ at risk we choose the mean and the maximum dose and the normal brain receiving at least 12 Gy. And the comparison was made with the treatment planning on GTV +1 millimeters for multiple brain mets and on GTV for GammaPlan in order to compare the [inaudible 00:03:06] and clinical conditions.
We used the Wilcoxon signed-rank test which was significant if the P-value was less than 0.05. For the main results, you first noticed that the dose prescription method is different. For the SIDCA wave we have a different mean and maximum dose. And here we have the DVH [inaudible 00:03:32] and we see that we have a different [inaudible 00:03:36].
We studied the selectivity index according to the major axis diameter, the volume, and the number of lesions. And the GammaKnife shows a better selectivity for lesions larger than 1 centimeter or 0.4 cubic centimeters. The single isocenter DCA showed a better selectivity for a lesion smaller than 1 centimeter, or 0.4 cubic centimeters. And we found no significant difference for the total group and according to the number of lesions.
For the gradient index, we have significant differences. It's always better for the [inaudible 00:04:20] in all cases. For instance, we had one case [inaudible 00:04:29] with multiple brain mets we can see [inaudible 00:04:34] isodose 12 Gy. One was with a GammaKnife. We don't have [inaudible 00:04:39].
For the organ at risk, this is normal brain receiving at least 12 Gy against a [inaudible 00:04:51] and the measure [inaudible 00:04:54] here. And in our institution, our clinical [inaudible 00:04:58] strength is that for one function the [inaudible 00:05:03] at least 12 Gy will not exceed 10 cubic centimeters. And this bar shows that these multiple brain mets with 10 cubic centimeters is a lesion larger than 1.8 centimeters or 2.5 cubic centimeters.
Concerning the beam on time, this histogram are purely meaningful. The average beam-on time is divided by 12 and [inaudible 00:05:33] multiple brain mets. It's about 12 minutes whereas we had the 90 minutes for less than 5 lesions for GammaPlan and more than [inaudible 00:05:52].
So, in conclusion, multiple brain mets in GammaPlan show similar coverage and selectivity. We have a better gradient for GammaKnife. [Inaudible 00:06:08] because there is real strength of the Gamma knife. The dose prescription method is different [inaudible 00:06:16]. For multiple brain mets version 1.5, we had some software difficulties to spare organ at risk. And we have a beam on time considerably reduced compared to GammaPlan.
So the single isocenter DCA would be interesting in some selected cases with a lesion smaller than 1.8 centimeters or 2.5 cubic centimeters and distant from each other and from organ at risk. If metastases are too close from organs at risk [inaudible 00:06:50] to use the cranial SRS software in complement of multiple brain mets.
Thank you very much [inaudible 00:06:59].
The multiple brain metastases software allows an automatic pairing of multiple brain metastases treatment. With the version 1.5, it's now possible to treat up to 15 lesions simultaneously. Okay. With the version 1.5, it's possible to treat up to 15 lesions simultaneously with only one isocenter and five arcs back and forth.
So the aim of our study was to evaluate [inaudible 00:01:03] by dosimetry comparison to our reference with the GammaKnife Perfexion. Twenty-two previous patients we treated with GammaKnife for 2 to 12 lesions are selected with a simple case [inaudible 00:01:20] metastasis far from each other to have a good confidence and the dosimetry indexes reported. We included 77 metastatic with different origin and with a dimension less than 3.0 centimeters for the major axis.
All treatments were replanned using the multiple brain mets. It's anatomically planning using a template. This is the [inaudible 00:01:59] multiple brain mets software. And for each patient, we tried three templates and we chose the best template according to the best activity index and the best organ at risk protection. And then, we customized the template in order to spare organ at risk like [inaudible 00:02:16]. The automatic treatment planning lasts about two minutes.
For the target we used the dosimetric indexes selected was the coverage index, the selectivity index, the gradient index, the maximum, and the mean dose. For this [inaudible 00:02:34] prescription for this index is the comparison was made with treatment planning on the GTV for GammaPlan and also on GTV for multiple brain mets [inaudible 00:02:45]. For the organ at risk we choose the mean and the maximum dose and the normal brain receiving at least 12 Gy. And the comparison was made with the treatment planning on GTV +1 millimeters for multiple brain mets and on GTV for GammaPlan in order to compare the [inaudible 00:03:06] and clinical conditions.
We used the Wilcoxon signed-rank test which was significant if the P-value was less than 0.05. For the main results, you first noticed that the dose prescription method is different. For the SIDCA wave we have a different mean and maximum dose. And here we have the DVH [inaudible 00:03:32] and we see that we have a different [inaudible 00:03:36].
We studied the selectivity index according to the major axis diameter, the volume, and the number of lesions. And the GammaKnife shows a better selectivity for lesions larger than 1 centimeter or 0.4 cubic centimeters. The single isocenter DCA showed a better selectivity for a lesion smaller than 1 centimeter, or 0.4 cubic centimeters. And we found no significant difference for the total group and according to the number of lesions.
For the gradient index, we have significant differences. It's always better for the [inaudible 00:04:20] in all cases. For instance, we had one case [inaudible 00:04:29] with multiple brain mets we can see [inaudible 00:04:34] isodose 12 Gy. One was with a GammaKnife. We don't have [inaudible 00:04:39].
For the organ at risk, this is normal brain receiving at least 12 Gy against a [inaudible 00:04:51] and the measure [inaudible 00:04:54] here. And in our institution, our clinical [inaudible 00:04:58] strength is that for one function the [inaudible 00:05:03] at least 12 Gy will not exceed 10 cubic centimeters. And this bar shows that these multiple brain mets with 10 cubic centimeters is a lesion larger than 1.8 centimeters or 2.5 cubic centimeters.
Concerning the beam on time, this histogram are purely meaningful. The average beam-on time is divided by 12 and [inaudible 00:05:33] multiple brain mets. It's about 12 minutes whereas we had the 90 minutes for less than 5 lesions for GammaPlan and more than [inaudible 00:05:52].
So, in conclusion, multiple brain mets in GammaPlan show similar coverage and selectivity. We have a better gradient for GammaKnife. [Inaudible 00:06:08] because there is real strength of the Gamma knife. The dose prescription method is different [inaudible 00:06:16]. For multiple brain mets version 1.5, we had some software difficulties to spare organ at risk. And we have a beam on time considerably reduced compared to GammaPlan.
So the single isocenter DCA would be interesting in some selected cases with a lesion smaller than 1.8 centimeters or 2.5 cubic centimeters and distant from each other and from organ at risk. If metastases are too close from organs at risk [inaudible 00:06:50] to use the cranial SRS software in complement of multiple brain mets.
Thank you very much [inaudible 00:06:59].