scholarly journals Decreasing the Dose to the Rectal Wall by Using a Rectal Retractor during Radiotherapy of Prostate Cancer: A Comparative Treatment Planning Study

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Kristina Nilsson ◽  
Andreas K. Johansson ◽  
Anders Montelius ◽  
Ingela Turesson ◽  
Risto O. Heikkinen ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Treatment Planning ◽  
Rectal Wall ◽  
Target Volume ◽  
Planning Study ◽  
Volumetric Arc Therapy ◽  
Dose Volume ◽  
Arc Therapy ◽  
Treatment Plans ◽  
Comparative Treatment

Aim. The aim of the study was to examine the dosimetric effect of rectal retraction, using a rectal retractor, by performing a comparative treatment planning study. Material and Methods. Treatment plans using volumetric arc therapy (VMAT) were produced for ten patients both with and without rectal retraction. A hypofractionation scheme of 42.7 Gy in seven fractions was used. The dose to the rectal wall was evaluated for both methods (with and without retraction) using four dose-volume criteria: V40.1 Gy, V38.3 Gy, V36.5 Gy, and V32.6 Gy. Results. The retraction of the rectal wall increased the distance between the rectal wall and the prostate. The rectal wall volume was reduced to zero for all dose-volume values except for V32.6 Gy, which was 0.2 cm3 in average when the rectal retractor was used. Conclusion. There was a significant decrease of V40.1 Gy, V38.3 Gy, V36.5 Gy, and V32.6 Gy when the rectal retractor was used without compromising the dose coverage of planning target volume (PTV).

scholarly journals EP-1884: Automated treatment planning of volumetric arc therapy for patient with prostate cancer

2018 ◽  
Vol 127 ◽  
pp. S1020
Author(s):  
M. Olminska ◽  
A. Skrobala ◽  
B. Pawalowski ◽  
T. Piotrowski
Keyword(s):  
Prostate Cancer ◽  
Treatment Planning ◽  
Volumetric Arc Therapy ◽  
Arc Therapy

Dosimetric comparison of RapidPlan and manually optimised volumetric modulated arc therapy plans in prostate cancer

2020 ◽  
pp. 1-8
Author(s):  
Loyce M. H. Chua ◽  
Eric P. P. Pang ◽  
Zubin Master ◽  
Rehena Sultana ◽  
Jeffrey K. L. Tuan ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Organs At Risk ◽  
Volumetric Modulated Arc Therapy ◽  
Target Volume ◽  
Plan Quality ◽  
Planning Time ◽  
Arc Therapy ◽  
Treatment Plans ◽  
The Mean ◽  
Time Required

Abstract Purpose: The aim of this study was to evaluate whether RapidPlan (RP) could generate clinically acceptable prostate volumetric modulated arc therapy (VMAT) plans. Methods: The in-house RP model was used to generate VMAT plans for 50 previously treated prostate cancer patients, with no additional optimisation being performed. The VMAT plans that were generated using the RP model were compared with the patients’ previous, manually optimised clinical plans (MP), none of which had been used for the development of the in-house RP prostate model. Differences between RP and MP in planning target volume (PTV) doses, organs at risk (OAR) sparing, monitor units (MU) and planning time required to produce treatment plans were analysed. Assessment of PTV doses was based on the conformation number (CN), homogeneity index (HI), D2%, D99% and the mean dose of the PTV. The OAR doses evaluated were the rectal V50 Gy, V65 Gy, V70 Gy and the mean dose, the bladder V65 Gy, V70 Gy and the mean dose, and the mean dose to both femurs. Results: D99% and mean dose of the PTV were lower for RP than for MP (p = 0·006 and p = 0·040, respectively).V50 Gy, V65 Gy and the mean dose to rectum were lower in RP than in MP (p < 0·001). V65 Gy, V70 Gy and the mean dose to bladder were lower in RP than in MP (p < 0·001). RP had enhanced the sparing of both femurs (p < 0·001) and significantly reduced the planning time to less than 5% of the time taken with MP. MU in RP was significantly higher than MP by an average of 52·5 MU (p < 0·001) and 46 out of the 50 RP plans were approved by the radiation oncologist. Conclusion: This study has demonstrated that VMAT plans generated using an in-house RP prostate model in a single optimisation for prostate patients were clinically acceptable with comparable or better plan quality compared to MP. RP can add value and improve treatment planning efficiency in a high-throughput radiotherapy department through reduced plan optimisation time while maintaining consistency in the plan quality.

scholarly journals Dosimetric comparison of MR-linac-based IMRT and conventional VMAT treatment plans for prostate cancer

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Vanessa Da Silva Mendes ◽  
Lukas Nierer ◽  
Minglun Li ◽  
Stefanie Corradini ◽  
Michael Reiner ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Target Volume ◽  
Planning System ◽  
Treatment Planning System ◽  
Target Coverage ◽  
Treatment Delivery ◽  
Ptv Margin ◽  
Delivery Times ◽  
Low Field ◽  
Treatment Plans

Abstract Background The aim of this study was to evaluate and compare the performance of intensity modulated radiation therapy (IMRT) plans, planned for low-field strength magnetic resonance (MR) guided linear accelerator (linac) delivery (labelled IMRT MRL plans), and clinical conventional volumetric modulated arc therapy (VMAT) plans, for the treatment of prostate cancer (PCa). Both plans used the original planning target volume (PTV) margins. Additionally, the potential dosimetric benefits of MR-guidance were estimated, by creating IMRT MRL plans using smaller PTV margins. Materials and methods 20 PCa patients previously treated with conventional VMAT were considered. For each patient, two different IMRT MRL plans using the low-field MR-linac treatment planning system were created: one with original (orig.) PTV margins and the other with reduced (red.) PTV margins. Dose indices related to target coverage, as well as dose-volume histogram (DVH) parameters for the target and organs at risk (OAR) were compared. Additionally, the estimated treatment delivery times and the number of monitor units (MU) of each plan were evaluated. Results The dose distribution in the high dose region and the target volume DVH parameters (D98%, D50%, D2% and V95%) were similar for all three types of treatment plans, with deviations below 1% in most cases. Both IMRT MRL plans (orig. and red. PTV margins) showed similar homogeneity indices (HI), however worse values for the conformity index (CI) were also found when compared to VMAT. The IMRT MRL plans showed similar OAR sparing when the orig. PTV margins were used but a significantly better sparing was feasible when red. PTV margins were applied. Higher number of MU and longer predicted treatment delivery times were seen for both IMRT MRL plans. Conclusions A comparable plan quality between VMAT and IMRT MRL plans was achieved, when applying the same PTV margin. However, online MR-guided adaptive radiotherapy allows for a reduction of PTV margins. With a red. PTV margin, better sparing of the surrounding tissues can be achieved, while maintaining adequate target coverage. Nonetheless, longer treatment delivery times, characteristic for the IMRT technique, have to be expected.

Bony-based and prostate-based image guidance for lo-calized prostate cancer radiotherapy

2020 ◽  
Vol 8 (1) ◽  
Author(s):  
Saulo Santos Fortes ◽  
Luiz Antonio Ribeiro Da Rosa
Keyword(s):  
Prostate Cancer ◽  
Normal Tissue ◽  
Bone Structure ◽  
Absorbed Dose ◽  
Target Volume ◽  
Image Guided Radiotherapy ◽  
Beam Modulation ◽  
Significant Difference ◽  
Treatment Volume ◽  
Treatment Plans

An important modality for the treatment of prostate cancer is teletherapy. The use of image-guided radiotherapy (IGRT) is a valuable tool in this treatment. This study retrospectively compared how repositioning the patient based on bone structure (B-ISO) and the prostate itself (P-ISO) affected the volumetric dose in the rectum, bladder, and clinical treatment volume (CTV). Additionally, the probability of normal tissue complication (NTCP) for the rectum was computed. We evaluated 155 cone-beam computed tomography (CBCT) from 8 patients. The treatment plans used beam modulation techniques. The planning target volume (PTV) margin adopted in both scenarios was 1 cm. The organs of interest were outlined over each CBCT and then treatment plans were applied so that the absorbed dose could be computed. NTCP values were calculated for the rectum. Analyzing dose-volume metrics published by the Quantitative Analysis of Normal Tissue Effects in the Clinic (QUANTEC), there was no significant difference between the two repositioning strategies for the rectum and bladder. There was a slight degradation in CTV coverage for the B-ISO strategy, but still with adequate coverage. Analysis of the uniform equivalent dose (EUD) and NTCP for the rectum showed little sensitivity to the strategy used. The present study showed that the use of CBCT in radiotherapy for prostate cancer treatment did not significantly improve volumetric doses for the rectum, bladder, and CTV, as well as NTCP for the rectum.

scholarly journals Treatment planning comparison of volumetric modulated arc therapy with Trilogy and Halcyon for bilateral breast cancer

2021 ◽  
Author(s):  
Tao Sun ◽  
Xiutong Lin ◽  
Guifang Zhang ◽  
Qingtao Qiu ◽  
Chengqiang Li ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Treatment Planning ◽  
Volumetric Modulated Arc Therapy ◽  
Bilateral Breast Cancer ◽  
Planning System ◽  
Skin Dose ◽  
Delivery Time ◽  
Dose Volume ◽  
Arc Therapy ◽  
The Mean

Abstract Background: The Halcyon is a new machine from the Varian company. The purpose of this study was to evaluate the dosimetry of the Halcyon in treatment of bilateral breast cancer with volumetric modulated arc therapy. Methods: On CT images of 10 patients with bilateral breast cancer, four Halcyon plans with different setup fields were generated, and dosimetric comparisons using Bonferroni’s multiple comparisons test were conducted among the four plans. Whole and partial arc plans on the Trilogy and the Halcyon, referred to as T-4arc, T-8arc, H-4arc and H-8arc, were designed. The prescription dose was 50 Gy in 2-Gy fractions. All plans were designed with the Eclipse version 15.5 treatment planning system. The dosimetric differences between whole and partial arc plans in the same accelerator were compared using the Mann-Whitney U test. The better Halcyon plan was selected for the further dosimetric comparison of the plan quality and delivery efficiency between the Trilogy and the Halcyon. Results:Halcyon plans with high‐quality megavoltage cone beam CT setup fields increased the Dmean, D2 and V107 of the planning target volume (PTV) and the V5 and Dmean of the heart, left ventricle (LV) and lungs compared with other Halcyon setup plans. The mean dose and low dose volume of the heart, lungs and liver were significantly decreased in T-8arc plans compared to T-4arc plans. In terms of the V5, V20, V30, V40 and Dmean of the heart, the V20, V30, V40 and Dmean of the LV, the V30, V40, Dmax and Dmean of the left anterior descending artery (LAD), and the V5 and V40 of lungs, H-8arc was significantly higher than H-4arc (p<0.05). Compared with the Trilogy’s plans, the Halcyon’s plans reduced the high-dose volume of the heart and LV but increased the mean dose of the heart. For the dose of the LAD and the V20 and V30 of lungs, there was no significant difference between the two accelerators. Compared with the Trilogy, plans on the Halcyon significantly increased the skin dose but also significantly reduced the delivery time. Conclusion: For the Halcyon, the whole-arc plans have more dosimetric advantages than partial-arc plans in bilateral breast cancer radiotherapy. Although the mean dose of the heart and the skin dose are increased, the doses of the cardiac substructure and other OARs are comparable to the Trilogy, and the delivery time is significantly reduced.

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