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SU-E-J-124: Assessment of Intrafraction and Interfraction Motion in Cranial SRT Using Tomotherapy
D Barbee1,2, K Rasmussen1,2, R Bartlett1,2
1Long Island Radiation Therapy, Lake Success, NY.
Medical Physics
|May 19, 2017
Summary
Thermoplastic mask immobilization is superior to frameless systems for stereotactic radiotherapy, significantly reducing intrafraction motion and improving patient setup accuracy during TomoTherapy treatments.
Area of Science:
- Medical Physics
- Radiation Oncology
- Medical Imaging
Background:
- Stereotactic radiotherapy demands precise patient positioning and immobilization due to steep dose gradients.
- Accurate patient immobilization is critical for effective dose delivery in radiotherapy.
Purpose of the Study:
- To evaluate intrafraction and interfraction patient motion with two immobilization devices during TomoTherapy.
- Compare the efficacy of frameless Aktina PinPoint system versus thermoplastic mask immobilization.
Main Methods:
- 60 brain metastases patients treated on MVCT-imaged TomoTherapy.
- Immobilization using Aktina PinPoint or thermoplastic mask with bite block.
- MVCT images analyzed for intrafraction motion; phantom study assessed imaging/registration accuracy.
Main Results:
- Phantom study showed a total workflow error of 0.11 ± 0.09 mm.
- Mask immobilization resulted in less intrafraction motion (1.29 ± 1.18 mm) than Aktina (2.58 ± 2.29 mm).
- 95% of intrafraction motion with masks was within 2 mm, compared to 75% with Aktina.
Conclusions:
- Thermoplastic mask immobilization is more effective than the Aktina PinPoint system.
- Masks better prevent intrafraction motion and reduce interfraction setup differences.
- Masks offer superior immobilization for stereotactic radiotherapy.
