Positional repeatability and variation in internal and external markers during volumetric-modulated arc therapy under end-exhalation breath-hold conditions for pancreatic cancer patients

Sasaki, Makoto; Kishi, Noriko; Ono, Tomohiro; Ashida, Ryo; Yoshimura, Masataka; Nakata, Masao; Mizutani, Takashi; Sugimoto, Naotoshi

doi:10.21203/rs.3.rs-19263/v1

Cited by 2 publications

(3 citation statements)

References 17 publications

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“…Patients held their breath according to the operator's instruction only without visual feedback. This was done in accordance with a previous study where further details can be found 32 …”

Section: Methodsmentioning

confidence: 89%

“…This was done in accordance with a previous study where further details can be found. 32 The gross tumor volume (GTV) included the primary tumor and metastatic lymph nodes. The clinical target volume (CTV) was defined as the GTV plus a 5 mm margin and the potential para-aortic lymph node and neuroplexus involvement between the celiac axis and the superior mesenteric artery.…”

Section: Initial Planning Ct Acquisition Contouring and Daily Cbct Ac...mentioning

confidence: 99%

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Potential utility of cone‐beam CT‐guided adaptive radiotherapy under end‐exhalation breath‐hold conditions for pancreatic cancer

Ogawa

Nakamura

Iramina

et al. 2022

J Applied Clin Med Phys

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Purpose The purpose of this study was to demonstrate the potential utility of cone‐beam computed tomography (CBCT)‐guided online adaptive radiotherapy (ART) under end‐exhalation breath‐hold (EE‐BH) conditions for pancreatic cancer (PC). Methods Eleven PC patients who underwent 15‐fraction volumetric‐modulated arc therapy under EE‐BH conditions were included. Planning CT images and daily 165 CBCT images were imported into a dedicated treatment planning system. The prescription dose was set to 48 Gy in 15 fractions. The reference plan was automatically generated along with predefined clinical goals. After segmentation was completed on CBCT images, two different plans were generated: One was an adapted (ADP) plan in which re‐optimization was performed on the anatomy of the day, and the other was a scheduled (SCH) plan, which was the same as the reference plan. The dose distributions calculated using the synthetic CT created from both planning CT and CBCT were compared between the two plans. Independent calculation‐based quality assurance was also performed for the ADP plans, with a gamma passing rate of 3%/3 mm. Results All clinical goals were successfully achieved during the reference plan generation. Of the 165 sessions, gross tumor volume D 98% and clinical target volume D 98% were higher in 100 (60.1%) and 122 (74.0%) ADP fractions. In each fraction, the V 3 Gy < 1 cm 3 of the stomach and duodenum was violated in 47 (28.5%) and 48 (29.1%), respectively, of the SCH fractions, whereas no violations were observed in the ADP fractions. There were statistically significant differences in the dose–volume indices between the SCH and ADP fractions ( p < 0.05). The gamma passing rates were above 95% in all ADP fractions. Conclusions The CBCT‐guided online ART under EE‐BH conditions successfully reduced the dose to the stomach and duodenum while maintaining target coverage.

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“…Patients held their breath according to the operator's instruction only without visual feedback. This was done in accordance with a previous study where further details can be found 32 …”

Section: Methodsmentioning

confidence: 89%

Section: Initial Planning Ct Acquisition Contouring and Daily Cbct Ac...mentioning

confidence: 99%

Potential utility of cone‐beam CT‐guided adaptive radiotherapy under end‐exhalation breath‐hold conditions for pancreatic cancer

Ogawa

Nakamura

Iramina

et al. 2022

J Applied Clin Med Phys

View full text Add to dashboard Cite

show abstract

“…There are many reports on internal errors in external radiation therapy for LAPC, [17][18][19][20] and many problems need to be solved. It has been pointed out that changes in GI tract density are more affected by particle therapy.…”

Section: Discussionmentioning

confidence: 99%

Dosimetric impact of simulated changes in large bowel content during proton therapy with simultaneous integrated boost for locally advanced pancreatic cancer

Narita

Katō

Takemasa

et al. 2021

J Applied Clin Med Phys

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To investigate the dosimetric impact of changes in the large bowel content during proton therapy (PT) with simultaneous integrated boost (SIB) for locally advanced pancreatic cancer (LAPC). Materials and methods: Fifteen patients with LAPC were included in this study. The SIB method was performed using five fields according to our standard protocol. A total dose of 67.5 Gy(relative biological effectiveness [RBE]) was prescribed in 25 fractions using the SIB method. A dose of 45 Gy(RBE) was prescribed for the entire planning target volume (PTV) by using four main fields. The remaining 22.5 Gy(RBE) was prescribed to the PTV excluding for the gastrointestinal tract using one subfield. Five simulated doses were obtained by the forward dose calculations with the Hounsfield units (HU) override to the large bowel to 50, 0, −100, −500, and −1000, respectively. The dose-volume indices in each plan were compared using the 50 HU plan as a reference. Results: At D 98 of the clinical target volume (CTV) and spinal cord-D 2cc , when the density of the large bowel was close to that of gas, there were significant differences compared to the reference plan (p < 0.05). By contrast, no significant difference was observed in stomach-D 2cc duodenum-D 2cc , small bowel-D 2cc , kidneys-V 18 , and liver-D mean under any of the conditions. There were no cases in which the dose constraint of organs at risk, specified by our institution, was exceeded. Conclusion: Density change in the large bowel was revealed to significantly affect the doses of the CTV and spinal cord during PT with SIB for LAPC. For beam arrangement,it is important to select a gantry angle that prevents the large bowel from passing as much as possible. If this is unavoidable, it is important to carefully observe the gas image on the beam path during daily image guidance and to provide adaptive re-planning as needed.

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Positional repeatability and variation in internal and external markers during volumetric-modulated arc therapy under end-exhalation breath-hold conditions for pancreatic cancer patients

Cited by 2 publications

References 17 publications

Potential utility of cone‐beam CT‐guided adaptive radiotherapy under end‐exhalation breath‐hold conditions for pancreatic cancer

Potential utility of cone‐beam CT‐guided adaptive radiotherapy under end‐exhalation breath‐hold conditions for pancreatic cancer

Dosimetric impact of simulated changes in large bowel content during proton therapy with simultaneous integrated boost for locally advanced pancreatic cancer

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