Key Factors Affecting Outcomes in Stereotactic Ablative Radiotherapy for vertebral metastases : HVR Report

Purpose/Objective

Stereotactic Body Radiotherapy Treatment (SBRT) for vertebral metastases presents significant dosimetric and immobilization challenges. Doses administered to these metastases, covering a substantial portion of the vertebra or the entire structure, often exceed tolerance thresholds for neighboring critical organs such as the spinal cord, esophagus, or kidneys.

To address this issue, we've utilized the Exacradle. This innovative device provides a distinctive patient indexing solution, utilizing strategically positioned components between the iliac crest and floating ribs. This patented technology ensures a comfortable experience for patients by leveraging naturally compliant soft tissue regions, effectively mitigating the risk of cranio-caudal or yaw displacement ( see Fig 1). Moreover, its MRI compatibility, attributed not only to its dielectric materials but also to its geometry, ensures seamless registration between CT and MRI scans acquired in identical positions (see Fig. 2).

In this study, we delve into the simulation and Image-Guided Radiation <(IGRT) process of SBRT for vertebral metastases at HUVR

Material/Methods

The simulation of SBRT treatment for patients with vertebral metastases at HUVR is conducted as follows:
1. Index the eXaCradle cradle with the bars in a distant area from the irradiation area.
2. Place a pillow instead of the headrest.
3. Lay the patient down with arms downward so that the armpits touch the sides of the eXaCradle.
4. Mark the iliac crests and costal arches on the skin and note the eXaCradle number between marks.
5. Lift the patient with one person pressing firmly on the knees towards the stretcher, to maintain the position of the buttocks.
6. Place the posterior actuators between the iliac crest and the costal arch in the position noted in step 4 (see fig 1). Remove the pillow and insert the headrest until the elbows rest on the upper vertex of the headrest. Right hand over left.
7. Lift the patient with pressure on the knees, moisten the eXaCradle, and insert the MoldCare from the elbows, marking the epitricleal area towards the caudal area without reaching the posterior actuators.
8. Place the arch as a stereotactic reference one vertebra above.
9. Perform a 1 mm CT acquisition for calculation. Subsequently, elevate the table according to the scanogram until the CT center is located in the spinal cord and high-resolution CT is performed (see Fig. 3).
10. Magnetic Resonance, if necessary after observing the high-resolution CT and FOV of 240.

Following this preparation, 30 CBCT scans were meticulously scrutinized using the TRUEBEAM system, allowing for a comprehensive analysis of IGRT displacements, including their means and deviations, which were then tabulated for further examination.

Results

Table 1 offers an overview of IGRT displacements, highlighting the effectiveness of SBRT of vertebral metastasis with Exacradle.

Conclusion

In conclusion, the Exacradle successfully addresses the issue of ensuring consistent vertebral immobilization for precise tumor targeting while minimizing radiation exposure to healthy tissues. This approach not only enhances treatment efficacy but also improves patient comfort throughout the treatment process. By providing a comfortable and reliable setup, Exacradle promotes treatment compliance and reduces the risk of treatment-related side effects.