scholarly journals Optimization of dose distributions of target volumes and organs at risk during stereotactic body radiation therapy for pancreatic cancer with dose-limiting auto-shells

2018 ◽  
Vol 13 (1) ◽  
Author(s):  
Yangsen Cao ◽  
Xiaofei Zhu ◽  
Xiaoping Ju ◽  
Yongming Liu ◽  
Chunshan Yu ◽  
...  
Keyword(s):  
Pancreatic Cancer ◽  
At Risk ◽  
Radiation Therapy ◽  
Stereotactic Body Radiation Therapy ◽  
Organs At Risk ◽  
Dose Distributions ◽  
Stereotactic Body Radiation ◽  
Target Volumes

scholarly journals Adrenal Stereotactic Body Radiation Therapy: The Effects of a Full and Empty Stomach on Radiation Dose to Organs at Risk

2021 ◽  
Author(s):  
Osamu Tanaka ◽  
Takuya Taniguchi ◽  
Kousei Ono ◽  
Shuto Nakaya ◽  
Takuji Kiryu ◽  
...  
Keyword(s):  
At Risk ◽  
Radiation Therapy ◽  
Stereotactic Body Radiation Therapy ◽  
Organs At Risk ◽  
Left Kidney ◽  
Empty Stomach ◽  
Full Group ◽  
Left Adrenal Gland ◽  
Stereotactic Body Radiation ◽  
Organ At Risk

Abstract BackgroundStereotactic Body Radiation Therapy (SBRT) has been reported to be curative in the treatment of oligometastases to the adrenal glands. However, the adrenals are surrounded by radiation-sensitive organs. We performed an Organ at Risk (OAR) analysis for SBRT to the left adrenal gland based on gastric state.Patients and MethodsTwenty random stomachs were divided into “empty” or “full” groups of 10 each based on size. The PTV dose was 54 Gy/6 fx and D 95 coverage of PTV(CTV) (the dose to 95% of the PTV volume). ResultsThe gastric OAR dose in the empty group was significantly lower than the full group. The OAR dose to the left kidney in the empty group was significantly higher than in the full group.ConclusionThe smaller the stomach size, the lower the dose to the stomach. It is therefore better to perform SBRT on patients with an empty stomach.

Stereotactic body radiation therapy for pancreatic cancer: Assessing motion with and without abdominal compression.

2016 ◽  
Vol 34 (4_suppl) ◽  
pp. 234-234 ◽  
Author(s):  
Priscilla K. Stumpf ◽  
Bernard Jones ◽  
Supriya K. Jain ◽  
Arya Amini ◽  
Dale A. Thornton ◽  
...  
Keyword(s):  
Pancreatic Cancer ◽  
Radiation Therapy ◽  
Stereotactic Body Radiation Therapy ◽  
Organs At Risk ◽  
Locally Advanced ◽  
Advanced Pancreatic Cancer ◽  
Free Breathing ◽  
Tumor Motion ◽  
Abdominal Compression ◽  
Stereotactic Body Radiation

234 Background: Stereotactic body radiation therapy (SBRT) is an emerging treatment option for locally advanced pancreatic cancer. This ablative therapy requires highly accurate delivery due to nearby organs at risk. To minimize tumor motion, our institution applies abdominal compression during computed tomography (CT) simulation. The purpose of this study is to evaluate the effect of compression in the context of pancreatic SBRT. Methods: In the last 6 months, 32 patients who completed SBRT to the pancreas at our institution were selected for analysis. In each patient, two 4DCT images were acquired, one with and one without abdominal compression. Abdominal compression was achieved with an indexed compression belt with a customized degree of inflation. Each patient had fiducial markers implanted in or near the pancreatic tumor prior to simulation. These fiducials were contoured on both planning CT scans for each gated phase. Motion was assessed by fiducial position changes throughout each gated phase. Results: In the anterior to posterior, transverse, and superior to inferior dimension, compression decreased motion in 19 of 32 cases (59%), 21 of 32 cases (66%), and 28 of 32 cases (88%) respectively. In the anterior to posterior (AP) dimension compression decreased motion by a mean of 0.43mm ± 1.7mm with a range of -2.1-6.5mm (p = 0.16). The mean decrease in motion with compression in the transverse dimension was 0.93mm ± 1.9mm with a range of -1.6-8.6mm (p = 0.01). In the superior to inferior dimension, compression decreased motion by a mean of 2.72mm ± 2.8mm with a range of -1.2-11.5mm (p < 0.001). Displacement of tissue due to compression led to increased patient AP separation at the level of T12 by a mean of 9.1±5.8mm (p < 0.001). Conclusions: Abdominal compression significantly reduced tumor motion in the superior to inferior and transverse directions for patients undergoing SBRT to the pancreas. This decrease in motion allows for significant reductions in the size of the volume necessary to treat the tumor. Given our findings, we would recommend using abdominal compression over free-breathing for pancreatic SBRT.

scholarly journals Comparison of two planning techniques (FiF/IMRT) for postoperative radiation therapy of prostate cancer

2020 ◽  
Vol 48 (2-3) ◽  
pp. 47-53
Author(s):  
Nevena Obajdin ◽  
Keyword(s):  
Prostate Cancer ◽  
At Risk ◽  
Radiation Therapy ◽  
Organs At Risk ◽  
Planning Techniques ◽  
Dose Distributions ◽  
Dose Volume ◽  
Significant Difference ◽  
Target Volumes ◽  
Planning Technique

Introduction: Within the past two decades, we made significant progress in radiation therapy for prostate cancer. At UH Rijeka IMRT became the technique of choice for radiation therapy following radical prostatectomy since 2016. Previously, an advanced 3-DCRT technique using the field-in-field (FiF) method was used for dose distribution optimization around target volumes and organs-at-risk. This research has been performed to investigate the influence of planning technique choice (FiF or IMRT) on coverage of target volumes with prescribed dose and organs-at-risk sparing. Materials and methods: Comparison of dose distributions calculated using FiF and IMRT techniques was performed retrospectively for ten patients who underwent postoperative radiotherapy. The prescribed dose for all patients was delivered using IMRT, and for this research, we also calculated dose distributions using the FiF technique. For FiF and IMRT techniques, we used linear accelerator photon beams. To determine the influence of planning technique on dose distribution parameters related to target volumes (GTV, CTV, PTV1, PTV2) were analyzed. For organs-at-risk sparing evaluation (rectum, bladder, femoral heads), we used dose-volume constraints. Results and discussion: The analysis of parameters related to target volumes has shown that most of them had no statistically significant difference (V100%(GTV), V100%(CTV), V95%(PTV2), V95%(PTV1)). For both planning techniques, internationally set dose constraints were achieved. Statistically, we found a significant difference for V100%(PTV2), p=0,000534, and V100%(PTV1), p=0,042944 in favor of IMRT. A statistically significant difference (p=0,045966) was found for the volume of the rectum, which receives 40Gy, and for the volume of femoral heads, which receives 30Gy (p=0,000385), where the sparing is better for IMRT. For dose-volume constraints related to the bladder, no statistically significant differences were found. Conclusion: Results of this research show a statistically significant difference for V100% target volume coverage for PTV1 and PTV2, with better dose coverage accomplished by IMRT. Concerning organs-at-risk sparing, a statistically significant difference in favor of IMRT was found for rectum volume, which receives 40Gy. Expectedly, IMRT was superior to the FiF technique. However, differences between the two planning techniques were relatively small, which points to the fact that the FiF technique is viable as a technique of choice.

scholarly journals A Collimator Setting Optimization Algorithm for Dual-Arc Volumetric Modulated Arc Therapy in Pancreas Stereotactic Body Radiation Therapy

2019 ◽  
Vol 18 ◽  
pp. 153303381987076 ◽  
Author(s):  
Xinyi Li ◽  
Jackie Wu ◽  
Manisha Palta ◽  
You Zhang ◽  
Yang Sheng ◽  
...  
Keyword(s):  
At Risk ◽  
Radiation Therapy ◽  
Optimization Algorithm ◽  
Stereotactic Body Radiation Therapy ◽  
Organs At Risk ◽  
Volumetric Modulated Arc Therapy ◽  
Target Dose ◽  
Stereotactic Body Radiation ◽  
Complexity Score ◽  
Arc Therapy

Purpose: To optimize collimator setting to improve dosimetric quality of pancreas volumetric modulated arc therapy plan for stereotactic body radiation therapy. Materials and Methods: Fifty-five volumetric modulated arc therapy cases in stereotactic body radiation therapy of pancreas were retrospectively included in this study with internal review board approval. Different from the routine practice of initializing collimator settings with a template, the proposed algorithm simultaneously optimizes the collimator angles and jaw positions that are customized to the patient geometry. Specifically, this algorithm includes 2 key steps: (1) an iterative optimization algorithm via simulated annealing that generates a set of potential collimator settings from 39 cases with pancreas stereotactic body radiation therapy, and (2) a multi-leaf collimator modulation scoring system that makes the final decision of the optimal collimator settings (collimator angles and jaw positions) based on organs at risk sparing criteria. For validation, the other 16 cases with pancreas stereotactic body radiation therapy were analyzed. Two plans were generated for each validation case, with one plan optimized using the proposed algorithm ( Planopt) and the other plan with the template setting ( Planconv). Each plan was optimized with 2 full arcs and the same set of constraints for the same case. Dosimetric results were analyzed and compared, including target dose coverage, conformity, organs at risk maximum dose, and modulation complexity score. All results were tested by Wilcoxon signed rank tests, and the statistical significance level was set to .05. Results: Both plan groups had comparable target dose coverage and mean doses of all organs at risk. However, organs at risk (stomach, duodenum, large/small bowel) maximum dose sparing ( D0.1 cc and D0.03 cc) was improved in Planopt compared to Planconv. Planopt also showed lower modulation complexity score, which suggests better capability of handling complex shape and sparing organs at risk . Conclusions: The proposed collimator settings optimization algorithm successfully improved dosimetric performance for dual-arc pancreas volumetric modulated arc therapy plans in stereotactic body radiation therapy of pancreas. This algorithm has the capability of immediate clinical application.

Sign in / Sign up

Export Citation Format

Share Document