Dosimetric impact of gastrointestinal air column in radiation treatment of pancreatic cancer

Abstract

CBCT revealed large air column in GI structures; however, its impact is minimal for target coverage. Because of the inherent advantage of segmentation in IMRT, where only a small fraction of a given beam passes through the air column, this technique might have an advantage over 3DCRT in treating upper GI malignancies where the daily air column can have significant impact. Advances in knowledge: Radiation treatment of pancreatic cancer has significant challenges due to positioning, imaging of soft tissues and variability of air column in bowels. The dosimetric impact of variable air column is retrospectively studied using CBCT. Even though, the volume of air column changes by ± 80%, its dosimetric impact in IMRT is minimum.

Quantifying and Assessing the Dosimetric Impact of Changing Gas Volumes Throughout the Course of VMAT Radiation Therapy of Upper Gastrointestinal Tumors

“…Multiple studies have found that deviations in delivered dose occur in patients with upper GI cancer who present with varying abdominal gas volumes throughout treatment. 9 , 11 , 13 , 14 However, these studies either fail to report on the treatment technique used, assess intensity modulated radiation therapy, or simply determine their dosimetric differences to be clinically acceptable. The results of the few studies to focus on VMAT treatment delivery 10 , 12 provide support to the findings outlined in the present study.…”

“…Given the low incidence of patients with pancreatic cancer who are prescribed radical radiation therapy and the relatively recent implementation of VMAT as a feasible treatment option, only 8 patients were available to review. This is a common limitation for studies investigating pancreatic cancer, 9 , 10 , 11 , 12 resulting in the inability to assess the true implications of changing gas volumes for VMAT treatment delivery. Greater collaboration between institutions and pooling of data sets may be a viable option to help improve sample size and the quality of results.…”

“…Research investigating the presence and dosimetric impact of changing gas volumes on radiotherapy treatment for upper GI tumours shows varying results. [8][9][10][11][12][13][14] Interfractional fluctuations in gas volumes have been found to be significant during pancreatic irradiation. [8][9][10] While some studies have found significant variations in delivered dose to target volumes and OARs, they fail to report on treatment delivery techniques used and only assess the impact of gas on a weekly 13 and single fraction 14 basis.…”

Deep learning based synthetic CT from cone beam CT generation for abdominal paediatric radiotherapy

“…The abdominal and lower abdominal region is particularly susceptible to daily anatomical variations due to the presence of organs with variable filling, including the gastrointestinal (GI) tract, bowel, bladder, and rectum (Berger et al 2017). GI air volumes were shown to vary by up to ±80% throughout radiotherapy in adult pancreatic cancer patients (Estabrook et al 2018). In children with abdominal cancers, average GI air volume changes of 99.4 ± 126.9 ml (range: 216.7-454.7 ml) have been reported (Guerreiro et al 2019) as well as evidence that younger children under anaesthesia are the most predisposed to variability (Lim et al 2021.…”

Gas bubble motion artifact reduction through simultaneous motion estimation and image reconstruction

“…N-board cone-beam computed tomography (CBCT) is widely used in image-guided radiation therapy (IGRT) and shows the potential to aid in adaptive radiation therapy (ART) [1][2][3][4] . Its artifacts, range from those due to inherent limitation of imaging physics, such as scattering, beam hardening, to those caused by the long-time scanning process, such as patient respiratory motion, have been well studied [5][6][7] . Much work has been done on techniques to reduce these artifacts and improve the imaging quality.…”