การเปรียบเทียบตัวแปรเชิงรังสีคณิตของแผนรังสีรักษาระยะใกล้สำหรับมะเร็งปากมดลูกระหว่างวิธีใช้ภาพเอกซเรย์คอมพิวเตอร์กับวิธีใช้ภาพคลื่นเสียงความถี่สูงทางหน้าท้อง

Abstract

This research compares dosimetric parameters of a brachytherapy planning for cervical cancer between the volumetric computed tomography method and the transabdominal ultrasound point method. The computed tomography and transabdominal ultrasonography datasets were studied in 59 datasets from 38 patients which measured the cervical reference point from transabdominal ultrasonography. Each dataset was planned with two brachytherapy planning methods. The volume method from computed tomography prescribed that the HR-CTV was given a dose of at least 7 Gray, and the point-based from transabdominal ultrasonography prescribed that all cervical reference points received at least 7 Gray. Then compare the dosimetric variables. HR-CTV were determined by D100, D98, D95, D90 and D50. For organs at risk, including the bladder, rectum, and sigmoid colon, were determined by D0.1cc, D1cc, and D2cc. The results showed that in the HR-CTV, the mean D100, D98, D95, D90 and D50 from the brachytherapy planning using the transabdominal ultrasonography were 6.0±1.1 Gray, 7.0±1.2 Gray, 7.6±1.2 Gray, 8.2±1.2 Gray, and 13.1±1.9 Gray, respectively. In the computed tomography method, the mean D100, D98, D95, D90 and D50 were 5.0±0.3 Gray, 5.9±0.2 Gray, 6.4±0.1 Gray, 7.0±0.0 Gray, and 11.2±0.6 Gray, respectively. The relationship between the mean radiation dose at the cervical reference point and the HR-CTV was found. The mean radiation dose at the cervical reference point was close to D98 of the HR-CTV with a difference of 0.6±16.5 percent. For organ at risk consideration, mean bladder D0.1cc, D1cc, and D2cc from the planning using transabdominal ultrasonography method were 8.2±1.9 grey, 6.9±1.4 gray and 5.9±1.6 Gray respectively and from the volumetric image from computed tomography method, the values were 7.0±1.5 Gray, 5.6±1.1 Gray, and 4.9±0.9 Gray, respectively. Mean D0.1cc, D1cc, and D2cc of the rectum from the planning using transabdominal ultrasonography method were 5.0±1.5 Gray, 3.9±1.1 Gray, and 3.4±1.0 Gay. respectively and from the volumetric image from computed tomography method, the values were 4.3±1.3 Gray, 3.3±1.0 Gray, and 2.9±0.9 Gray, respectively. The mean D0.1cc, D1cc, and D2cc of the sigmoid colon from the planning using the transabdominal ultrasonography method were 5.6±1.7 Gray, 4.4±1.3 Gray, and 3.9±1.2 Gray respectively and from the volumetric image from computed tomography method, the values were 4.7±1.2 Gray, 3.7±0.9 Gray and 3.3±0.8 Gray, respectively. For the uniformity index and the conformal index, it was found that in the planning using the transabdominal ultrasonography method, the mean values were 0.29±0.10 and 0.32±0.06, respectively, and using volumetric computed tomography method, the mean values were 0.39±0.06 and 0.36. ±0.06, respectively. Both index of these two methods were statistically significant difference. From this comparative studied it was found that all dosimetric parameters in the brachytherapy planning using transabdominal ultrasonography method were statistically significantly higher than the volumetric computed tomography method.