Influential Factors on Outcomes in Stereotactic Ablative Radiotherapy for Adrenal Gland Metastases: HVR Report
Creators: name: Velázquez Miranda, Santiago. Dept. of Medical Physics. Virgen del Rocio University Hospital, Sevilla, Spain.
Publisher: name: Zenodo
Year: 2024

description: Purpose/Objective

Adrenal glands are situated within the inverted cone-shaped space delimited by Gerota's and Zuckerland's fascias. The displacement of the kidneys and adrenal glands within this space is predominantly governed by diaphragmatic movements. However, these movements are inherently asynchronous and are susceptible to influence from intra-abdominal pressure dynamics and peristalsis. This inherent complexity poses challenges during the 4DCT simulation process. In this study, we propose a novel strategy for controlling suprarenal movement utilizing a combination of CT, MRI, and ConeBeamCT imaging modalities in the context of stereotactic ablative radiotherapy (SABR) for the treatment of adrenal oligometastases.

Material/Methods

In our institution, we routinely employ SlowCT registration with conventional diagnostic CT (field of view 240mm and contrast enhancement) during treatment simulation for patients with adrenal metastases, utilizing our patented stereotactic system, 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 and reducing movement of abdominal organs ( see fig 1)

To further optimize immobilization, lateral compressions in the area between the iliac crest and floating ribs are once again employed, eliminating the need for an anterior compressor. This method effectively repositions the kidney superiorly within the Gerota and Zuckerland's space, thereby reducing its mobility (see fig. 2). Compared to alternative dampening techniques, this approach enhances patient comfort, minimizes invasiveness, and shortens treatment duration.

It's important to highlight that Exacradle is carbon-free and compatible with MRI environments, allowing for precise volume delineation.

Our treatment planning strategy involves utilizing non-coplanar beams to achieve a high dosage gradient. ConeBeamCT scans are routinely acquired before and after each session to accurately capture inter-fractional and intra-fractional variability. Additionally, we conduct daily image-guided radiation therapy (IGRT) verification to ensure precise patient positioning.

Results

Nineteen patients with adrenal oligometastases underwent Stereotactic Ablative Radiotherapy (SABR). The median Clinical Target Volume (CTV) volume was 13 cc, and the median follow-up duration was 10 months. No instances of local failure or Grade IV toxicity were recorded. The mean post-treatment Image-Guided Radiation Therapy (IGRT) correction values were as follows: lateral 1.5±1.8 mm, longitudinal 1.3±1.7 mm, and vertical 1.81±1.5 mm. The duration of irradiation ranged from start to end was 5.3±3.2 minutes for doses between 16-21 Gy, with a relative increase in volume between Gross Tumor Volume (GTV) and Internal Target Volume (ITV) of 37.7%.

Conclusion

In conclusion, the Exacradle abdominal dampening procedure offers a valuable solution for achieving reproducible, comfortable, and effective Stereotactic Ablative Radiotherapy (SABR) treatments in patients with adrenal oligometastases. Exacradle successfully addresses the issue of synchronous kidney movements, ensuring consistent 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. Overall, Exacradle represents a promising advancement in SABR techniques for adrenal oligometastases, offering a patient-centered approach to treatment delivery that prioritizes both efficacy and comfort.