What is the optimum number of beams and energy for IMRT boost in prostate cancer? A plan comparison study

2009 ◽  
Vol 27 (15_suppl) ◽  
pp. e16158-e16158
Author(s):  
H. Kunhiparambath ◽  
R. Prabhakar ◽  
G. K. Rath ◽  
D. N. Sharma ◽  
P. Heera ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Maximum Dose ◽  
Target Volume ◽  
Seminal Vesicles ◽  
Integral Dose ◽  
Dose Volume ◽  
Carcinoma Prostate ◽  
Femoral Heads ◽  
Dose Homogeneity ◽  
The Mean

e16158 Background: Intensity Modulated Radiotherapy (IMRT) is used in carcinoma prostate to achieve better target coverage with less dose to critical organs thereby permitting dose escalation and eventually better therapeutic ratio. There is scarcity of literature evaluating beam number and energy in prostate cancer treated by IMRT. Aim of our study is to identify the optimal number of beams and energy in the boost treatment of prostate cancer by IMRT. Methods: Ten patients were included in this study. Initially a dose of 45 Gy in 25 fractions was delivered to the prostate, seminal vesicles and the nodes by 3DCRT. A boost dose of 27 Gy in 15 fractions was planned to the prostate and the seminal vesicles by sliding window IMRT. Four different sets of IMRT plans: 5, 7 and 9 field with 6 MV; 7 field with 15 MV were generated. The dose constraints to the critical structures and the target volume were based on standard guidelines. The mean dose, maximum dose, volume receiving the prescribed dose (V100), volume receiving > 107% and <95% of the prescribed dose were analyzed for CTV and planning target volume (PTV). The mean dose, volume receiving 100%, 50% and 30% of the prescribed dose were analyzed for the bladder and the rectum. Similarly, the mean dose and the maximum dose to the right and left femoral heads, monitor units (MU) and the integral dose were analyzed. SPSS V10.0 software was used for statistical analysis. Results: The seven beam plan provide better dose homogeneity to PTV and lesser doses to critical structures like bladder, rectum and femoral heads when 6 MV photon is used. 15 MV photons further improve the dose homogeneity and decrease the dose to critical structures. The Monitoring Units required to deliver the treatment and the Integral dose is significantly reduced by using 15 MV compared to 6 MV. Conclusions: The optimal IMRT plan for boost planning in carcinoma prostate is that uses 7 beams and higher energy. This yields lesser dose to surrounding critical structures with better target conformity. [Table: see text] No significant financial relationships to disclose.

scholarly journals A Deep Learning-Based Automated CT Segmentation of Prostate Cancer Anatomy for Radiation Therapy Planning-A Retrospective Multicenter Study

Diagnostics ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 959
Author(s):  
Timo Kiljunen ◽  
Saad Akram ◽  
Jarkko Niemelä ◽  
Eliisa Löyttyniemi ◽  
Jan Seppälä ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Deep Learning ◽  
Lymph Node ◽  
Seminal Vesicles ◽  
Dice Similarity Coefficient ◽  
Efficiency Gain ◽  
Data Set ◽  
Femoral Heads ◽  
The Mean ◽  
Penile Bulb

A commercial deep learning (DL)-based automated segmentation tool (AST) for computed tomography (CT) is evaluated for accuracy and efficiency gain within prostate cancer patients. Thirty patients from six clinics were reviewed with manual- (MC), automated- (AC) and automated and edited (AEC) contouring methods. In the AEC group, created contours (prostate, seminal vesicles, bladder, rectum, femoral heads and penile bulb) were edited, whereas the MC group included empty datasets for MC. In one clinic, lymph node CTV delineations were evaluated for interobserver variability. Compared to MC, the mean time saved using the AST was 12 min for the whole data set (46%) and 12 min for the lymph node CTV (60%), respectively. The delineation consistency between MC and AEC groups according to the Dice similarity coefficient (DSC) improved from 0.78 to 0.94 for the whole data set and from 0.76 to 0.91 for the lymph nodes. The mean DSCs between MC and AC for all six clinics were 0.82 for prostate, 0.72 for seminal vesicles, 0.93 for bladder, 0.84 for rectum, 0.69 for femoral heads and 0.51 for penile bulb. This study proves that using a general DL-based AST for CT images saves time and improves consistency.

Evaluation and comparison of dosimetric parameters in PTV for prostate cancer via step and shoot IMRT and 3DCRT

2014 ◽  
Vol 6 (1) ◽  
pp. 1038-1048
Author(s):  
Shirani K ◽  
Nedaie H A ◽  
Banaee N ◽  
Hassani H ◽  
Samiei F ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Radiation Effects ◽  
Treatment Plan ◽  
Target Volume ◽  
Mean Value ◽  
High Dose ◽  
Integral Dose ◽  
Radiation Therapy Treatment Planning ◽  
Step And Shoot ◽  
The Mean

The aim of radiation therapy treatment planning is to achieve an optimal balance between delivering a high dose to target volume and a low dose to healthy tissues. The integral dose, conformity and homogeneity indexes, hence, are the important guidance for predicting the radiation effects and choosing the optimal treatment plan. The goal of this study is to compare and investigate the aforementioned parameters in 3DCRT vs. IMRT plan. In order to evaluate dosimetric parameters, data from five patients with prostate cancer, planned by IMRT and 3DCRT were obtained. Prescribed doses for IMRT procedure and 3DCRT were 80Gy and 70 Gy, respectively. Also, the target coverage was achieved with 95% of the prescribed dose to 95% of the PTV in 3DCRT and 95% of the prescribed dose to 98% of the PTV in IMRT method. A total of thirty IMRT and 3DCRT plans were performed for evaluation of dosimetric parameters (for each patient both treatment plans, step and shoot IMRT and 3DCRT with 6, 10 and 18MV energies) were done. The integral dose was calculated as the mean- dose times the volume of the structure. The mean integral dose (ID) received by rectum for 3DCRT was almost 1.01% greater than IMRT while in bladder mean value of ID for IMRT was approximately 1.68% higher than 3DCRT. For PTV in IMRT the ID of target volume had the biggest value (1.14%) compared to that of 3DCRT. Dose conformity in PTV volume in S.A.S and 3DCRT was almost equal. The same outcome was achieved in homogeneity index. The results of this study shows that IMRT method leads to adequate target dose coverage while the prescribed dose for this modality is higher than 3DCRT. IMRT has the ability of increasing the maximum dose to tumor region and improves conformity and homogeneity indexes in target volume and also reduces dose to OAR.

scholarly journals Toward a better prescription method for external radiotherapy

2017 ◽  
Vol 23 (1) ◽  
pp. 3-7
Author(s):  
Marzena Mrozowska ◽  
Paweł Kukołowicz
Keyword(s):  
Prostate Cancer ◽  
Effective Dose ◽  
Target Volume ◽  
External Radiotherapy ◽  
Median Dose ◽  
Equivalent Uniform Dose ◽  
Simple Method ◽  
Perfect Correlation ◽  
Dose Homogeneity ◽  
The Mean

Abstract Aim: The aim of the study was to compare several methods of dose prescription, the mean dose, the median dose, the effective dose and the generalized Equivalent Uniform Dose (gEUD). Background: The dose distribution in the planning target volume is never fully homogenous. Depending on the dose prescription method for the same prescribed dose different biologically equivalent doses are delivered. The latest ICRU Report 83 proposes to prescribe the dose to the median dose in the PTV. Several other methods are also in common use. It is important to know what are differences of doses actually delivered depending on the dose prescription method. Materials and methods: The study was performed for three groups of patients treated radically with external beams in Brzozow, over the 2012-2013 period. The groups were of patients with breast, lung and prostate cancer. There were 10 patients in each group. For each patient all metrics, i.e. the mean dose, the median dose, the effective dose and the generalized Equivalent Uniform Dose, were calculated. The influence of the dose homogeneity in the PTV on the results is also evaluated. The gEUD was used as a reference dose prescription method. Results: For all patients, an almost perfect correlation between the median dose and the gEUD was obtained. Worse correlation was obtained between other metrics and the gEUD. The median dose is almost always a little higher than the gEUD, but the ratio of these two values never exceeded 1.013. Conclusion: The median dose seems to be a good and simple method of dose prescription.

scholarly journals A novel index for assessing treatment plan quality in stereotactic radiosurgery

2018 ◽  
Vol 129 (Suppl1) ◽  
pp. 118-124 ◽  
Author(s):  
Alexis Dimitriadis ◽  
Ian Paddick
Keyword(s):  
Stereotactic Radiosurgery ◽  
Treatment Plan ◽  
Efficiency Index ◽  
Target Volume ◽  
Surrounding Tissue ◽  
Plan Quality ◽  
Multiple Target ◽  
Integral Dose ◽  
Plan Optimization ◽  
Dose Volume

OBJECTIVEStereotactic radiosurgery (SRS) is characterized by high levels of conformity and steep dose gradients from the periphery of the target to surrounding tissue. Clinical studies have backed up the importance of these factors through evidence of symptomatic complications. Available data suggest that there are threshold doses above which the risk of symptomatic radionecrosis increases with the volume irradiated. Therefore, radiosurgical treatment plans should be optimized by minimizing dose to the surrounding tissue while maximizing dose to the target volume. Several metrics have been proposed to quantify radiosurgical plan quality, but all present certain weaknesses. To overcome limitations of the currently used metrics, a novel metric is proposed, the efficiency index (η50%), which is based on the principle of calculating integral doses: η50% = integral doseTV/integral dosePIV50%.METHODSThe value of η50% can be easily calculated by dividing the integral dose (mean dose × volume) to the target volume (TV) by the integral dose to the volume of 50% of the prescription isodose (PIV50%). Alternatively, differential dose-volume histograms (DVHs) of the TV and PIV50% can be used. The resulting η50% value is effectively the proportion of energy within the PIV50% that falls into the target. This value has theoretical limits of 0 and 1, with 1 being perfect. The index combines conformity, gradient, and mean dose to the target into a single value. The value of η50% was retrospectively calculated for 100 clinical SRS plans.RESULTSThe value of η50% for the 100 clinical SRS plans ranged from 37.7% to 58.0% with a mean value of 49.0%. This study also showed that the same principles used for the calculation of η50% can be adapted to produce an index suitable for multiple-target plans (Gη12Gy). Furthermore, the authors present another adaptation of the index that may play a role in plan optimization by calculating and minimizing the proportion of energy delivered to surrounding organs at risk (OARη50%).CONCLUSIONSThe proposed efficiency index is a novel approach in quantifying plan quality by combining conformity, gradient, and mean dose into a single value. It quantifies the ratio of the dose “doing good” versus the dose “doing harm,” and its adaptations can be used for multiple-target plan optimization and OAR sparing.

Dosimetric evaluation of whole-pelvis radiation therapy of prostate cancers: clinical experience

2020 ◽  
pp. 1-15
Author(s):  
Ernest Osei ◽  
Hafsa Mansoor ◽  
Johnson Darko ◽  
Beverley Osei ◽  
Katrina Fleming ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Radiation Therapy ◽  
High Risk ◽  
Cancer Patients ◽  
Seminal Vesicles ◽  
Conformity Index ◽  
Prostate Bed ◽  
Risk Patients ◽  
Treatment Plans ◽  
The Mean

Abstract Background: The standard treatment modalities for prostate cancer include surgery, chemotherapy, hormonal therapy and radiation therapy or any combination depending on the stage of the tumour. Radiation therapy is a common and effective treatment modality for low-intermediate-risk patients with localised prostate cancer, to treat the intact prostate and seminal vesicles or prostate bed post prostatectomy. However, for high-risk patients with lymph node involvement, treatment with radiation will usually include treatment of the whole pelvis to cover the prostate and seminal vesicles or prostate bed and the pelvic lymph nodes followed by a boost delivery dose to the prostate and seminal vesicles or prostate bed. Materials and Methods: We retrospectively analysed the treatment plans for 179 prostate cancer patients treated at the cancer centre with the volumetric-modulated arc therapy (VMAT) technique via RapidArc using 6 MV photon beam. Patients were either treated with a total prescription dose of 78 Gy in 39 fractions for patients with intact prostate or 66 Gy in 33 fractions for post prostatectomy patients. Results: There were 114 (64%) patients treated with 78 Gy/39 and 65 (36%) treated with 66 Gy/34. The mean homogeneity index (HI), conformity index (CI) and uniformity index (UI) for the PTV-primary of patients treated with 78 Gy are 0.06 ± 0.01, 1.04 ± 0.01 and 0.99 ± 0.01, respectively, and the corresponding mean values for patients treated with 66 Gy are 0.06 ± 0.02, 1.05 ± 0.01 and 0.99 ± 0.01, respectively. The mean PTV-primary V95%, V100% and V105% are 99.5 ± 0.5%, 78.8 ± 12.2% and 0.1 ± 0.5%, respectively, for patients treated with 78 Gy and 99.3 ± 0.9%, 78.1 ± 10.6% and 0.1 ± 0.4%, respectively, for patients treated with 66 Gy. The rectal V50Gy, V65Gy, V66.6Gy, V70Gy, V75Gy and V80Gy are 26.8 ± 9.1%, 14.2 ± 5.3%, 13.1 ± 5.0%, 10.8 ± 4.3%, 6.9 ± 3.1% and 0.1 ± 0.1%, respectively, for patients treated with 78 Gy and 33.7 ± 8.4%, 14.1 ± 4.5%, 6.7 ± 4.5%, 0.0 ± 0.2%, 0.0% and 0.0%, respectively, for patients treated with 66 Gy. Conclusion: The use of VMAT technique for radiation therapy of high-risk prostate cancer patients is an efficient and reliable method for achieving superior dose conformity, uniformity and homogeneity to the PTV and minimal doses to the organs at risk. Results from this study provide the basis for the development and implementation of consistent treatment criteria in radiotherapy programs, have the potential to establish an evaluation process to define a consistent, standardised and transparent treatment path for all patients that reduces significant variations in the acceptability of treatment plans and potentially improve patient standard of care.

scholarly journals Stereotactic body radiotherapy with a single isocentre for multiple pulmonary metastases

2020 ◽  
Vol 6 (4) ◽  
pp. 20190121
Author(s):  
Ryuji Nakamura ◽  
Jun Sugawara ◽  
Satoshi Yamaguchi ◽  
Hisao Kakuhara ◽  
Koyo Kikuchi ◽  
...  
Keyword(s):  
Stereotactic Body Radiotherapy ◽  
Pulmonary Metastases ◽  
Target Volume ◽  
Conformity Index ◽  
Left Shoulder ◽  
Dose Volume ◽  
Lower Lung ◽  
The Mean ◽  
The Individual ◽  
Individual Tumour

A 45-year-old male developed a second set of pulmonary metastases 5 years after surgery for extraskeletal mucinous chondrosarcoma of the left shoulder. He already underwent a lobectomy and two segmentectomies for a first set of pulmonary metastases 2 years ago. The closely grouped three nodules within the left lower lung formed a planning target volume (PTV) for stereotactic body radiotherapy (SBRT) with a single isocentre, which was focused on the centre of the largest nodule (the simultaneous plan). Dose-volume histogram analysis confirmed that the plan was superior to an alternative plan, in which SBRT plans would have been produced for each individual tumour (the individual plan). The mean, maximum and minimum PTV doses were 54.0, 57.5 and 47.3 Gy, respectively, in the simultaneous plan, and 65.6, 87.2 and 52.3 Gy, respectively, in the individual plan. The homogeneity index, conformity index, and the maximum dose delivered to the surrounding healthy lung were 1.21, 0.71, and 37.7 Gy, respectively, in the simultaneous plan and 1.66, 4.44, and 46.2 Gy, respectively, in the individual plan. The patient developed Grade two pneumonitis, but remained healthy until 4 years after the SBRT. When multiple closely grouped metastases are treated using SBRT, the use of a single isocentre should be considered.

Is it possible to get adequate dose coverage of a clinical target volume (CTV) to account for the possible extra capsular extension in early-stage prostate cancer by low dose rate (LDR) brachytherapy?

2011 ◽  
Vol 29 (7_suppl) ◽  
pp. 98-98
Author(s):  
E. P. Saibishkumar ◽  
D. Iupati ◽  
J. Borg ◽  
K. Fernandes
Keyword(s):  
Prostate Cancer ◽  
Early Stage ◽  
Univariate Analysis ◽  
Target Volume ◽  
Implantation Technique ◽  
Prostate Brachytherapy ◽  
Exact Test ◽  
Ldr Brachytherapy ◽  
Adequate Dose ◽  
The Mean

98 Background: There is no consensus for the definition and evaluation of CTV in post-implant setting for LDR prostate brachytherapy to account for extra capsular extension in clinically localized prostate cancer. In this study, we defined a CTV and evaluated its dosimetry in the post implant CT/MR scans done at 1 month after the LDR brachytherapy procedure. Methods: The initial consecutive 71 patients who underwent LDR brachytherapy under a single physician at Princess Margaret Hospital from June 2009 to July 2010 were included in this retrospective study. On the post implant MRI, the CTV was created by adding 3mm uniform margins around the prostate but respecting the anatomical boundaries like bone, bladder and rectum. Post implant dosimetry was based on CT/MR fusion using the dosimetric parameters V80, V90, V100, V150, V200, D80, D90 and D100. Implants were qualified as optimal if their V100 was >85% and D90 was >90% for both prostate and CTV. Univariate analysis was performed to evaluate associations of factors with V100 and D90 for the CTV using Wilcoxon rank sum test and Fisher's exact test. Results: The mean (SD) prostate V100 and D90 were 95.5% (4.2) and 117% (10) respectively with only 1 patient having sub optimal implant (V100 <85% and D90 <90%). The mean (SD) V100 and D90 for the CTV were also acceptable at 90.6% (4.9) and 103% (9), respectively. Six patients had V100 <85% and 7 patients had D90 <90% for the CTV. On univariate analysis, edema and seed implantation technique correlated with sub-optimal implant for the CTV. The mean (SD) edema for patients with V100 <85% was 18% (10) and with D90 <90% was 15% (12). The corresponding values for the optimal implants both in terms of V100 and D90 were 3% (13). Patients implanted with exclusively loose seeds (15 patients only) had higher incidence of sub-optimal implants (26%) compared to patients who had strands on the antero-lateral margins (56 patients; 3.5%). Conclusions: In this study, adequate dose coverage of CTV was achieved in most patients with current technique but implants with optimal dosimetry to prostate still may have sub-optimal D90 and V100 for the CTV. No significant financial relationships to disclose.

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