scholarly journals CT-on-Rails versus in-Room CBCT for Online Daily Adaptive Proton Therapy of Head-and-Neck Cancers

Cancers ◽  
2021 ◽  
Vol 13 (23) ◽  
pp. 5991
Author(s):  
Konrad P. Nesteruk ◽  
Mislav Bobić ◽  
Arthur Lalonde ◽  
Brian A. Winey ◽  
Antony J. Lomax ◽  
...  
Keyword(s):  
Head And Neck ◽  
Proton Therapy ◽  
Good Alternative ◽  
Dose Distributions ◽  
Dose Volume Histograms ◽  
Dose Volume ◽  
Significant Difference ◽  
Clinically Significant ◽  
Adaptive Therapy ◽  
Virtual Ct

Purpose: To compare the efficacy of CT-on-rails versus in-room CBCT for daily adaptive proton therapy. Methods: We analyzed a cohort of ten head-and-neck patients with daily CBCT and corresponding virtual CT images. The necessity of moving the patient after a CT scan is the most significant difference in the adaptation workflow, leading to an increased treatment execution uncertainty σ. It is a combination of the isocenter-matching σi and random patient movements induced by the couch motion σm. The former is assumed to never exceed 1 mm. For the latter, we studied three different scenarios with σm = 1, 2, and 3 mm. Accordingly, to mimic the adaptation workflow with CT-on-rails, we introduced random offsets after Monte-Carlo-based adaptation but before delivery of the adapted plan. Results: There were no significant differences in accumulated dose-volume histograms and dose distributions for σm = 1 and 2 mm. Offsets with σm = 3 mm resulted in underdosage to CTV and hot spots of considerable volume. Conclusion: Since σm typically does not exceed 2 mm for in-room CT, there is no clinically significant dosimetric difference between the two modalities for online adaptive therapy of head-and-neck patients. Therefore, in-room CT-on-rails can be considered a good alternative to CBCT for adaptive proton therapy.

Analysis of the Physical and Radiobiological Equivalence of the Calculated and Measured Dose Distributions for Prostate Stereotactic Radiotherapy

2021 ◽  
Vol 66 (3) ◽  
pp. 68-75
Author(s):  
E. Sukhikh ◽  
L. Sukhikh ◽  
A. Vertinsky ◽  
P. Izhevsky ◽  
I. Sheino ◽  
...  
Keyword(s):  
Radiation Therapy ◽  
Dose Distribution ◽  
Three Dimensional ◽  
Anterior Wall ◽  
Dose Distributions ◽  
Stereotactic Radiation ◽  
Dose Volume Histograms ◽  
Dose Volume ◽  
Gamma Index ◽  
Measured Dose

Purpose: Carrying out the analysis of the physical and radiobiological equivalence of dose distributions obtained during the planning of hypofractionated stereotactic radiation therapy of the prostate cancer and verification using a three-dimensional cylindrical dosimeter. Material and Methods: Based on the anatomical data of twelve patients diagnosed with prostate carcinoma, stage T2N0M0 with low risk, plans were developed for stereotactic radiation therapy with volumetric modulates arc therapy (VMAT). The dose per fraction was 7,25 Gy for 5 fractions (total dose 36,25 Gy) with a normal photon energy of 10 MV. The developed plans were verified using a three-dimensional cylindrical ArcCHECK phantom. During the verification process, the three-dimensional dose distribution in the phantom was measured, based on which the values of the three-dimensional gamma index and the dose–volume histogram within each contoured anatomical structures were calculated with 3DVH software. The gamma index value γ (3 %, 2 mm, GN) at a threshold equal to 20 % of the dose maximum of the plan and the percentage of coincidence of points at least 95 % was chosen as a criterion of physical convergence of the calculated and measured dose distribution according to the recommendations of AAPM TG-218. To analyze the radiobiological equivalence of the calculated and measured dose distribution, the local control probability (TCP) and normal tissue complication probability (NTCP) criteria were used based on the calculated and measured dose–volume histograms. Contours of the target (PTV) and the anterior wall of the rectum were used for the analysis. The approach based on the concept of equivalent uniform dose (EUD) by A. Niemierko was used to calculate the values of TCP/NTCP criteria. Results: The results of physical convergence of plans for all patients on the contour of the whole body were higher than 95 % for the criteria γ (3 %, 2 mm, GN). The convergence along the PTV contour is in the range (75.5–95.2)%. The TCP and NTCP values obtained from the measured dose-volume histograms were higher than the planned values for all patients. It was found that the accelerator delivered a slightly higher dose to the PTV and the anterior wall of the rectum than originally planned. Conclusion: The capabilities of modern dosimetric equipment allow us move to the verification of treatment plans based on the analysis of TCP / NTCP radiobiological equivalence, taking into account the individual characteristics of the patient and the capabilities of radiation therapy equipment.

scholarly journals Proton therapy for non-squamous cell carcinoma of the head and neck: planning comparison and toxicity

2019 ◽  
Vol 60 (5) ◽  
pp. 612-621 ◽  
Author(s):  
Hiromitsu Iwata ◽  
Toshiyuki Toshito ◽  
Kensuke Hayashi ◽  
Maho Yamada ◽  
Chihiro Omachi ◽  
...  
Keyword(s):  
Quality Of Life ◽  
Squamous Cell Carcinoma ◽  
Cell Carcinoma ◽  
Head And Neck ◽  
Squamous Cell ◽  
Proton Therapy ◽  
Patient Specific ◽  
Dose Distributions

Abstract To investigate optimal treatment planning using proton beams for non-squamous cell carcinoma of the head and neck (NSCHN), the dose distributions of plans involving pencil beam scanning (PBS) with or without a patient-specific aperture system (PSAS), passive-scattering proton therapy (PSPT) and X-ray intensity-modulated radiotherapy (IMRT) were compared. As clinical results, toxicities of PBS with PSAS, including changes in quality of life, were reported. Between April 2014 and August 2016, a total of 30 patients were treated using PBS with PSAS. In 20 patients selected at random, the dose distributions of PBS with or without the PSAS, PSPT and IMRT plans were compared. Neutron exposure by proton therapy was calculated using a Monte Carlo simulation. Toxicities were scored according to CTCAE ver. 4.0. Patients completed EORTC quality of life survey forms (QLQ-C30 and QLQ-HN35) before and 0–12 months after proton therapy. The 95% conformity number of PBS with the PSAS plan was the best, and significant differences were detected among the four plans (P < 0.05, Bonferroni tests). Neutron generation by PSAS was ~1.1-fold higher, but was within an acceptable level. No grade 3 or higher acute dermatitis was observed. Pain, appetite loss and increased weight loss were more likely at the end of treatment, but recovered by the 3 month follow-up and returned to the pretreatment level at the 12 month follow-up. PBS with PSAS reduced the penumbra and improved dose conformity in the planning target volume. PBS with PSAS was tolerated well for NSCHN.

WE-A-17A-12: The Influence of Eye Plaque Design On Dose Distributions and Dose- Volume Histograms

2014 ◽  
Vol 41 (6Part28) ◽  
pp. 490-490
Author(s):  
P Aryal ◽  
JA Molloy ◽  
MJ Rivard
Keyword(s):  
Dose Distributions ◽  
Dose Volume Histograms ◽  
Dose Volume ◽  
Eye Plaque

Challenges and Differences in External Radiation Therapy for Retinoblastoma: From Standard Techniques to New Developments

2015 ◽  
Vol 103 (5) ◽  
pp. 438-442
Author(s):  
Ayşe Hiçsönmez ◽  
Yıldız Güney ◽  
Ayşen Dizman ◽  
Bahar Dirican ◽  
Yakup Arslan ◽  
...  
Keyword(s):  
Bone Growth ◽  
External Beam Radiotherapy ◽  
Intensity Modulated Radiotherapy ◽  
Target Volume ◽  
Dose Volume Histograms ◽  
Normal Tissues ◽  
Dose Volume ◽  
Significant Difference ◽  
Treatment Plans ◽  
External Radiation Therapy

Aims The purpose of this study is to calculate the treatment plans and to compare the dose distributions and dose-volume histograms (DVH) for 6 external radiotherapy techniques for the treatment of retinoblastoma as well as intensity-modulated radiotherapy (IMRT) and fractionated stereotactic radiotherapy (Cyberknife). Methods Treatment plans were developed using 6 techniques, including an en face electron technique (ET), an anterior and lateral wedge photon technique (LFT), a 3D conformal (6 fields) technique (CRT), an inverse plan IMRT, tomotherapy, and conventional focal stereotactic external beam radiotherapy with Cyberknife (SBRT). Dose volume analyses were carried out for each technique. Results All techniques except electron provided similar target coverage. When comparing conformal plan with IMRT and SBRT, there was no significant difference in planning target volume dose distribution. The mean volume of ipsilateral bony orbit received more than 20 Gy, a suggested threshold for bone growth inhibition. The V20 Gy was 73% for the ET, 57% for the LFT, 87% for the CRT, 65% for the IMRT, 66% for the tomotherapy, and 2.7% for the SBRT. Conclusions This work supports the potential use of IMRT and SBRT to spare normal tissues in these patients.

Elective nodal irradiation for prostate cancer patients: Comparison of available dynamic techniques.

2011 ◽  
Vol 29 (7_suppl) ◽  
pp. 96-96
Author(s):  
H. Urbanczyk ◽  
L. Hawrylewicz ◽  
R. Kulik ◽  
K. Szczepanik ◽  
J. Ciechowicz ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Regional Lymph Node ◽  
Organs At Risk ◽  
Static Field ◽  
Dose Volume Histograms ◽  
Intensity Modulated ◽  
Dose Volume ◽  
Dynamic Techniques ◽  
Node Metastases ◽  
Clinically Significant

96 Background: The few recent studies showed that regional lymph node metastases of prostate cancer (PCa) could be successfully treated. It means that role of pelvic nodes (PN) irradiation could increase in next period. A problem is rectal and bladder toxicities of this treatment. Intensity modulated dynamic irradiation techniques (DT) may potentially help to reduce treatment related side effects. The aim of study is to compare three different radiotherapy techniques: conformal (CRT), static field intensity modulated (SF IMRT) and rapid arc (RA) for elective pelvic lymph nodes irradiation. Methods: We analyzed CRT, IMRT and RA plans of irradiation PN for ten patients. PTVs included PN iliac, iliac external upper then acetabulum, iliac internal and obturatory. Prescribed doses were 44 Gy/22 fractions. We compared the doses delivered to PTV rectum and bladder using dose volume histograms. The U Mann-Whitney, W Shapiro-Wilk and ANOVA rang Kruskal-Wallis tests were used for statistical analysis. Results: The median PTV doses were not statistically different in analyzed plans. The minimum doses for PTV were significantly lower in IMRT and RA plans but the differences were not clinically significant. Maximum doses were significantly higher for CRT plans. The doses calculated for rectum and bladder were statistically significantly lower for dynamic techniques in whole range of volumes and doses. SF IMRT is the most efficient technique in reducing the dose to bladder. The doses observed in half of the rectum and bladder volumes bladder were also statistically significant different (p=0.002 for rectum and 0.001 for bladder). The median doses for rectum were 43.6 Gy for CRT plans, 33.5 Gy for IMRT and 37.9 Gy for RA, median doses calculated for bladder were 44 Gy for CRT, 35.6 Gy for IMRT and 39.6 Gy for RA. Conclusions: CRT does not allow to reduce the dose to organs at risk. Both DT reduce the doses to bladder and rectum while maintaining the high homogenous dose to PTV. SF IMRT is more efficient in reducing the dose to bladder than RA. SF IMRT technique seems to be better than Rapid Arc for PN irradiation. It is probably because the nodal PTVs are large and their structures are complicated. No significant financial relationships to disclose.

534 Analysis of dose volume histograms in proton therapy for prostate cancer

2003 ◽  
Vol 1 (5) ◽  
pp. S161-S162 ◽  
Author(s):  
K. Nihei ◽  
T. Nishio ◽  
S. Ishikura ◽  
M. Kawashima ◽  
T. Ogino
Keyword(s):  
Prostate Cancer ◽  
Proton Therapy ◽  
Dose Volume Histograms ◽  
Dose Volume

scholarly journals Radiation associated brain image changes after proton therapy for skull base head and neck cancers

2020 ◽  
Author(s):  
Grete May Engeseth ◽  
Sonja Stieb ◽  
Abdallah Sherif Radwan Mohamed ◽  
Renjie He ◽  
Camilla Hanquist Stokkevåg ◽  
...  
Keyword(s):  
Head And Neck ◽  
Skull Base ◽  
Frontal Lobe ◽  
Temporal Lobe ◽  
Proton Therapy ◽  
Cox Regression ◽  
Maximum Size ◽  
Post Contrast ◽  
Dose Volume ◽  
The Brain

AbstractBackground and purposeTo characterize patterns and outcomes of brain MR image changes after proton therapy (PT) for skull base head and neck cancer (HNC).Material and methods127 patients treated with PT for HNC who had received at least 40 Gy(RBE) to the brain and had ≥ 1 follow-up MRI > 6 months after PT were analyzed. MRIs were reviewed for radiation- associated image changes (RAIC). MRIs were rigidly registered to planning CTs, and RAIC were contoured on T1 (post-contrast) and T2 weighted sequences, and dose-volume parameters extracted. Probability of RAIC over time was calculated using multistate analysis. Univariate/multivariate analyses were performed using Cox Regression. Recursive partitioning analysis was used to investigate dose-volume correlates of RAIC development.Results17.3% developed RAIC. All RAIC events were asymptomatic and occurred in the temporal lobe (14), frontal lobe (6) and cerebellum (2). The median volume of the RAIC on post-contrast T1 was 0.5 cc at their maximum size. The RAIC spontaneously resolved in 27.3%, progressed in 27.3% and improved or were stable in 29.6% of patients. The 3-year actuarial rate of developing RAIC was 14.3%. Brain and RAIC lesion doses were generally higher for temporal lobe RAIC compared to frontal lobe RAIC. RAIC was observed in 63% of patients when V67 Gy(RBE) of the brain ≥ 0.17 cc.ConclusionRAIC lesions after PT were asymptomatic and either resolved or regressed in the majority of the patients. The estimated dose–volume correlations confirm the importance of minimizing focal high doses to brain when achievable.

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