{'fraction_non_alphanumeric': 0.03954802259887006, 'fraction_numerical': 0.02401129943502825, 'mean_word_length': 4.8312757201646095, 'pattern_counts': {'":': 0, '<': 3, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
The clinical application of in-house double lower limb auxiliary device in treating pelvic tumors.

OBJECTIVE
Patient positioning accuracy is critical in radiotherapy. To improve the patient positioning accuracy, a double lower limb auxiliary device has been developed to fix pelvis patients to treatment couch. A clinical study for comparing new device to conventional devices has been performed.


MATERIALS AND METHODS
Thirty patients with pelvic tumor were randomly divided into conventional thermoplastic membrane fixation group (conventional fixing group) and conventional thermoplastic membrane plus lower limb auxiliary fixture group (auxiliary fixing group). The setup error was acquired by simulator position alignment with center field digital radiograph reconstruction (DRR) image from treatment planning system, The correlations between the conventional fixing group and the auxiliary fixing group were analyzed using Pearson's Chi-squared test.


RESULTS
Set-up errors in conventional fixing group and auxiliary fixing group were respectively 3.8 ± 1.5 mm and 1.4 ± 0.9 mm (P< 0.02), 5.4 ± 2.5 mm and 1.2 ± 1.2mm (P < 0.001), 2.2 ± 1.3 mm and 1.9 ± 1.0 mm (P < 0.05) in the bilateral, superior-inferior and anterior-posterior direction.


CONCLUSION
The double lower limbs auxiliary device can reduce pelvic patient positioning errors. It is very helpful in improving the daily clinical setup accuracy.