Comparative dosimetry of brachytherapy treatment planning between a volume-based plan by CT and a point-based plan by TAUS in CT datasets for brachytherapy

Abstract

Aim: To evaluate comparative dosimetry of brachytherapy treatment planning between a volume-based plan by computed tomography (CT) and a point-based plan by transabdominal ultrasound (TAUS) in CT datasets for brachytherapy. Materials and methods: From 2019 to 2021, 59 different datasets of CT images were collected from 38 patients treated by intracavitary brachytherapy with tandem ovoid or tandem ring applicators. At that time, TAUS was performed to prevent uterine perforation and to evaluate topography of the cervix during application. In volume-based planning by CT, the target dose was used to keep the dose at 90% of high-risk clinical target volume (HR-CTV), to give a dose of at least 7Gy, while in the point-based plan by TAUS, the target dose was used to keep the minimum dose to eight cervix reference points (measured by TAUS), to give a dose of at least 7Gy. The doses to targets and organs at risk were evaluated and compared between volume-based planning by CT and the point-based plan by TAUS. Results: Of 59 fractions, a tandem ovoid applicator was used in 48 fractions (81·3%). In the volume-based plan by CT, the mean doses to HR-CTV(D90), intermediate-risk clinical target volume (IR-CTV)(D90), bladder(D2cc), rectum(D2cc) and sigmoid colon(D2cc) were 7·0, 3·9, 4·9, 2·9 and 3·3 Gy, respectively, while in the point-based plan by TAUS, the mean doses to HR-CTV(D90), IR-CTV(D90), bladder(D2cc), rectum(D2cc) and sigmoid colon(D2cc) were 8·2, 4·6, 5·9, 3·4 and 3·9 Gy, respectively. The percentages of mean dose differences between TAUS and CT of HR-CTV(D90), IR-CTV(D90), bladder(D2cc), rectum(D2cc) and sigmoid colon(D2cc) were 17·7, 19·5, 20·5, 19·5, 21·3 and 19·8%, respectively. With the target dose to the point-based plan by TAUS (7 Gy to the cervix reference points), this was close to D98 of HR-CTV with a mean percentage of difference of 0·6%. Findings: The point-based plan by TAUS showed higher values to targets and organs at risk than the volume-based plan by CT. With the point-based plan by TAUS, it was close to D98 of HR-CTV.

Integration of Ultrasound in Image-Guided Adaptive Brachytherapy in Cancer of the Uterine Cervix

“…Pintakham [94] performed a study to evaluate the dosimetry comparison of brachytherapy delineation using two distinct methods: a volume-based plan utilising computed tomography (CT) and a point-based plan employing transabdominal ultrasound (TAUS) in CT datasets for brachytherapy. The results showed that the point-based plan performed by TAUS had better outcomes for both the intended targets and the organs at risk, in comparison to the volume-based plan carried out by CT. TAUS's point-based technique led to a close closeness between D98 and HR-CTV.…”

Image-Guided Adaptive Brachytherapy in Cervical Cancer: Integration of Ultrasound

“…Pintakham [60] conducted a research to assess the dosimetry comparison of brachytherapy treatment planning using two different methods: a volume-based plan using computed tomography (CT) and a point-based plan utilising transabdominal ultrasonography (TAUS) in CT datasets for brachytherapy. The findings indicated that the point-based plan implemented by TAUS demonstrated superior values for both targets and organs at risk compared to the volume-based plan executed by CT. TAUS's point-based strategy resulted in a proximity of D98 to HR-CTV.…”