Abstract
Objective To investigate the influence of cold weather on setup errors of patients with chest and pelvic disease in radiotherapy. Methods The image-guided data of the patients were collected from the Radiotherapy Center of Cancer Hospital Affiliated to Guangxi Medical University from October 2020 to February 2021. During this period, the cold weather days were December 15, 16, and 17, 2020, and January 7 and 8, 2021. For body fixation in radiotherapy, an integrated plate and a thermoplastic mold were employed in 18 patients with chest disease, while an integrated plate and a vacuum pad were applied in 19 patients with pelvic disease. All patients underwent cone beam computed tomography (CBCT) scans in the first five treatments and once a week thereafter. The obtained data were registered to the planning CT image to get the setup errors of the patient in the translational direction including X, Y, and Z axes and rotational direction including RX, RY, and RZ. Then, the Mann–Whitney U test was performed. The expansion boundary values of the chest and pelvis were calculated according to the formula MPTV=2.5∑+0.7δ. Results A total of 286 eligible results of CBCT scans were collected. There were 138 chest CBCT scans, including 26 taken in cold weather and 112 in usual weather, and 148 pelvic CBCT scans, including 33 taken in cold weather and 115 in usual weather. The X-, Y-, and Z-axis translational setup errors of patients with chest disease in the cold weather group were 0.16 (0.06, 0.32) cm, 0.25 (0.17, 0.52) cm, and 0.35 (0.21, 0.47) cm, respectively, and those in the usual weather group were 0.14 (0.08, 0.29) cm, 0.23 (0.13, 0.37) cm, and 0.18 (0.1, 0.35) cm, respectively. The results indicated that there was a statistical difference in the Z-axis translational error between the cold weather group and the usual weather group (U = 935.5; p=0.005 < 0.05), while there was no statistical difference in the rotational error between the two groups. The external boundary values of X, Y, and Z axes in the cold weather group were 0.57 cm, 0.92 cm, and 0.99 cm, respectively, and those in the usual weather group were 0.57 cm, 0.78 cm, and 0.68 cm, respectively. There was no significant difference in the translational and rotational errors of patients with pelvic disease between the cold weather group and the usual weather group (p < 0.05). The external boundary values of X, Y, and Z axes were 0.63 cm, 0.79 cm, and 0.68 cm in the cold weather group and 0.61 cm, 0.79 cm, and 0.61 cm in the usual weather group, respectively. Conclusion The setup error of patients undergoing radiotherapy with their bodies fixed by an integrated plate and a thermoplastic mold was greater in cold weather than in usual weather, especially in the ventrodorsal direction.
Highlights
Roentgen first discovered X-ray in 1985 and Madame Curie discovered radium in 1986
For patients with chest disease, the positioning mark point was delineated on the thermoplastic mold at the target area position using a pen; for patients with pelvic disease, the positioning mark point was made on the skin at the level of the tumor target area using a laser gun
Planning and Design. e CT simulated positioning images obtained by planning design were transmitted to the planning system (Philips Pinnacle 9.10) through the DICOM local area network to develop the radiotherapy plan. e target area was delineated regarding the ICRU83 reporting standard. e gross tumor volume (GTV), clinical target volume (CTV), planning tumor volume (PTV), and organ at risk (OAR) were delineated. e physicist completed the design of the plan, and the superior physician and physicist jointly completed the evaluation of the plan
Summary
Roentgen first discovered X-ray in 1985 and Madame Curie discovered radium in 1986. After more than a hundred years of development, tumor radiotherapy has become one of the important means to treat malignant tumors. With the progress of science and technology, PET/CT, MRI, and other equipment have promoted the diagnosis of tumors and delineation of target areas to the molecular level. Scholars have studied the effects of body weight [1,2,3], respiration [4,5,6], body position fixation, molds [7,8,9], registration mode between planning images and CT images [10,11,12], and whether to wear a mask during the epidemic of COVID-19 [13,14,15] on the setup repeatability. Erefore, this study aimed to investigate the influence of cold weather on setup errors in radiation therapy Few studies considered the weather conditions. erefore, this study aimed to investigate the influence of cold weather on setup errors in radiation therapy
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