Thermoplastic patient fixation: influence on chest wall and target motion during radiotherapy of lung cancer.
OBJECTIVE
Several methods have been developed to reduce tumor motions and patient movements during radiotherapy of lung cancer. In this study, a multislice CT-based analysis was performed to examine the effect of a thermoplastic patient immobilization system on the chest wall and tumor motions.


METHODS
Ten patients with stage II-IV lung cancer were enrolled into the study. According to tumor localization, five patients had peripheral, and five patients central lung cancer (T2-T4). In total, six series of measurements were made with a multislice CT scanner, both with and without mask fixation, in normal breathing, at maximal tidal volume inhalation, and at maximal tidal volume exhalation.


RESULTS
Movements of chest wall, diaphragm and tumor, with and without mask, under different breathing conditions were registered. With the use of the immobilization system, no significant difference was found in diaphragmatic movements (mean deviation of diaphragm: 41.7-40.5 mm to the right, and 40.5-36.8 mm to the left side) and in tumor motions (mean deviation of tumor: 15.3-12.4 mm in craniocaudal, and 11.5-8.8 mm in posterolateral direction, mean medial deviation: 4.6-4.1 mm, mean lateral deviation: 7.2-5 mm). Significant differences were observed concerning tumor motions in anteroposterior direction (mean: 8.9-6.3 mm) and transverse chest movements in anteroposterior direction.


CONCLUSIONS
Besides the advantage of optimal patient positioning, the movements of the bony chest wall can be considerably reduced by using the immobilization system. However, this fixation system has limitations concerning its suitability for minimizing tumor motions.
Kovacs
Arpad
A
Health Science Center, University of Kaposvar, Hungary.
Hadjiev
Janaki
J
Lakosi
Ferenc
F
Vallyon
Marta
M
Cselik
Zsolt
Z
Bogner
Peter
P
Horvath
Akos
A
Repa
Imre
I
D000230:Adenocarcinoma / Q000000981:diagnostic imaging / Q000473:pathology / Q000532:radiotherapy*; D000328:Adult; D000368:Aged; D002294:Carcinoma, Squamous Cell / Q000000981:diagnostic imaging / Q000473:pathology / Q000532:radiotherapy*; D004867:Equipment Design; D005260:Female; D006801:Humans; D007103:Immobilization / Q000295:instrumentation*; D008175:Lung Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology / Q000532:radiotherapy*; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D020266:Radiotherapy, Conformal / Q000295:instrumentation*; D015656:Respiratory Mechanics / Q000502:physiology; D036542:Tomography, Spiral Computed