ESTRO 2024 - Abstract Book

S5477

RTT - Patient care, preparation, immobilisation and IGRT verification protocols

ESTRO 2024

370

Digital Poster

Impact of two different Immobilization devices in reducing set-up errors during pelvic radiotherapy

Amna Abdullah Al Ajmi, Devisree Cheerathuvalappil, Abid Ali Mirza, Abishek Vidhyadharan, Nadeem Pervez, Zahid Al Mandhari

Sultan Qaboos comprehensive cancer care and research center, Radiation Therapy, Muscat, Oman

Purpose/Objective:

Immobilization devices plays an important role in reducing set-up errors during pelvic radiotherapy treatment. Selection of particular immobilization device must be comfortable for the patient and easy to use as well.To address this issue, a study conducted to assess and compare the potential variations between the Orfit knee and leg positioning cushion (Orfit KR) and the AIO indexable knee and foot frame, along with knee rest and footrest (AIO KR+FR) immobilization systems for pelvic radiotherapy treatment

Material/Methods:

Data was retrospectively collected from the ARIA system for a period of 8 months, involving 100 consecutive patients who received pelvic external beam radiotherapy using VarianTruebeam. Among these patients, 50 were positioned using an Orfit KR, while the remaining 50 patients were immobilized using an AIO KR+FR.The set-up corrections were performed offline based on the departmental protocol using anterior MV- lateral KV pairs, as well as cone-Beam computed tomograghy (CBCT) images

Results:

A total of 2463 CBCT images were analyzed. All data were carefully reviewed and recorded on an excel sheet, including translational and rotational shifts. Random errors were observed during the analysis process.The average standard deviation of random translational errors was found to be 0.446219mm for the Orfit KR cushion and 0.41526mm for the AIO KR + FR system. In terms of random rotational errors, the Orfit KR exhibited an average of 0.7705°, while the AIO KR + FR system showed an average of 0.838029°

Conclusion:

The AIO KR+FR demonstrated slightly lower random translational errors compared to the Orfit KR in our study, while the Orfit KR demonstrates slightly lower random rotational errors. These findings suggest that both immobilization systems, the AIO KR+FR and Orfit KR, have similar performance in minimizing set-up errors during pelvic radiotherapy treatment. The implementation of the surface guided Radiotherapy ( SGRT) system has also been proposed to minimize translational and rotational errors.A prospective study is being considered to confirm the findings and provide more comprehensive evidence on the effectiveness of these interventions