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Radiation Oncology (London, England) Oct 2020To evaluate inter-fractional variations in bladder and rectum during prostate stereotactic body radiation therapy (SBRT) and determine dosimetric and clinical...
BACKGROUND
To evaluate inter-fractional variations in bladder and rectum during prostate stereotactic body radiation therapy (SBRT) and determine dosimetric and clinical consequences.
METHODS
Eighty-five patients with 510 computed tomography (CT) images were analyzed. Median prescription dose was 40 Gy in 5 fractions. Patients were instructed to maintain a full bladder and empty rectum prior to simulation and each treatment. A single reviewer delineated organs at risk (OARs) on the simulation (Sim-CT) and Cone Beam CTs (CBCT) for analyses.
RESULTS
Bladder and rectum volume reductions were observed throughout the course of SBRT, with largest mean reductions of 86.9 mL (19.0%) for bladder and 6.4 mL (8.7%) for rectum noted at fraction #5 compared to Sim-CT (P < 0.01). Higher initial Sim-CT bladder volumes were predictive for greater reduction in absolute bladder volume during treatment (ρ = - 0.69; P < 0.01). Over the course of SBRT, there was a small but significant increase in bladder mean dose (+ 4.5 ± 12.8%; P < 0.01) but no significant change in the D2cc (+ 0.8 ± 4.0%; P = 0.28). The mean bladder trigone displacement was in the anterior direction (+ 4.02 ± 6.59 mm) with a corresponding decrease in mean trigone dose (- 3.6 ± 9.6%; P < 0.01) and D2cc (- 6.2 ± 15.6%; P < 0.01). There was a small but significant increase in mean rectal dose (+ 7.0 ± 12.9%, P < 0.01) but a decrease in rectal D2cc (- 2.2 ± 10.1%; P = 0.04). No significant correlations were found between relative bladder volume changes, bladder trigone displacements, or rectum volume changes with rates of genitourinary or rectal toxicities.
CONCLUSIONS
Despite smaller than expected bladder and rectal volumes at the time of treatment compared to the planning scans, dosimetric impact was minimal and not predictive of detrimental clinical outcomes. These results cast doubt on the need for excessively strict bladder filling and rectal emptying protocols in the context of image guided prostate SBRT and prospective studies are needed to determine its necessity.
Topics: Aged; Aged, 80 and over; Cone-Beam Computed Tomography; Dose Fractionation, Radiation; Humans; Male; Middle Aged; Organs at Risk; Prospective Studies; Prostate; Prostatic Neoplasms; Radiosurgery; Radiotherapy Planning, Computer-Assisted; Radiotherapy, Image-Guided; Rectum; Urinary Bladder
PubMed: 33066781
DOI: 10.1186/s13014-020-01681-6 -
Journal of B.U.ON. : Official Journal... 2021Moderately accelerated hypofractionation (HypoAR) has been recently established as a standard radiotherapy scheme for low-risk prostate cancer. The application of...
PURPOSE
Moderately accelerated hypofractionation (HypoAR) has been recently established as a standard radiotherapy scheme for low-risk prostate cancer. The application of ultra-hypofractionated regimens (ultra-HypoAR), with fraction size above 5 Gy, is also widely tested.
METHODS
We applied Image Guided Radiation Therapy (IGRT) ultra-HypoAR delivered with Volumetric Modulated Arc Therapy (VMAT) technique in low-risk prostate cancer patients (5.75 Gy/fraction, 40.25 Gy total dose, two fractions per week). A comparative radiobiological analysis of Dose-Volume Ηistograms (DVH) obtained for target volumes and organs at risk was performed, investigating the advantages and disadvantages of ultra-HypoAR and conventional radiotherapy regimens (CRT). Early clinical results on efficacy and toxicity are also reported.
RESULTS
We calculated the Normalized Total Dose (NTD) and NTD with time correction (NTD_T)-based biological Dose- Volume Histograms (bDVH) for bladder and rectum tissue late effects (α/β=4 Gy) and early effects (α/β=10 Gy). Ultra-HypoAR produced a significantly lower biological dose burden than CRT, for both early and late responding tissue components of the bladder and rectum, whether calculated for time-correction or not (p<0.0001). Our clinical experience showed that the ultra-HypoAR regimen produced minimal early and late radiation sequelae. The median PSA levels dropped from 9.1 to 0.75 and 0.45 ng/ml at 6 and 12 months, respectively, after the end of therapy.
CONCLUSIONS
In conclusion, radiobiological analysis of DVHs and preliminary clinical experience predict a better efficacy and low early and late toxicity profile for the tested seven-fraction VMAT ultra-HypoAR regimen with IGRT.
Topics: Aged; Aged, 80 and over; Dose Fractionation, Radiation; Humans; Male; Middle Aged; Prostatic Neoplasms; Radiation Dose Hypofractionation
PubMed: 34268959
DOI: No ID Found -
Journal of Applied Clinical Medical... Jun 2010The objective was to evaluate the performance of a high-definition multileaf collimator (MLC) of 2.5 mm leaf width (MLC2.5) and compare to standard 5 mm leaf width MLC... (Randomized Controlled Trial)
Randomized Controlled Trial
The objective was to evaluate the performance of a high-definition multileaf collimator (MLC) of 2.5 mm leaf width (MLC2.5) and compare to standard 5 mm leaf width MLC (MLC5) for the treatment of intracranial lesions using dynamic conformal arcs (DCA) technique with a dedicated radiosurgery linear accelerator. Simulated cases of spherical targets were created to study solely the effect of target volume size on the performance of the two MLC systems independent of target shape complexity. In addition, 43 patients previously treated for intracranial lesions in our institution were retrospectively planned using DCA technique with MLC2.5 and MLC5 systems. The gross tumor volume ranged from 0.07 to 40.57 cm3 with an average volume of 5.9 cm3. All treatment parameters were kept the same for both MLC-based plans. The plan evaluation was performed using figures of merits (FOM) for a rapid and objective assessment on the quality of the two treatment plans for MLC2.5 and MLC5. The prescription isodose surface was selected as the greatest isodose surface covering >or= 95% of the target volume and delivering 95% of the prescription dose to 99% of target volume. A Conformity Index (CI) and conformity distance index (CDI) were used to quantifying the dose conformity to a target volume. To assess normal tissue sparing, a normal tissue difference (NTD) was defined as the difference between the volume of normal tissue receiving a certain dose utilizing MLC5 and the volume receiving the same dose using MLC2.5. The CI and normal tissue sparing for the simulated spherical targets were better with the MLC2.5 as compared to MLC5. For the clinical patients, the CI and CDI results indicated that the MLC2.5 provides better treatment conformity than MLC5 even at large target volumes. The CI's range was 1.15 to 2.44 with a median of 1.59 for MLC2.5 compared to 1.60-2.85 with a median of 1.71 for MLC5. Improved normal tissue sparing was also observed for MLC2.5 over MLC5, with the NTD always positive, indicating improvement, and ranging from 0.1 to 8.3 for normal tissue receiving 50% (NTV50), 70% (NTV70) and 90% (NTV90) of the prescription dose. The MLC2.5 has a dosimetric advantage over the MLC5 in Linac-based radiosurgery using DCA method for intracranial lesions, both in treatment conformity and normal tissue sparing when target shape complexity increases.
Topics: Brain Neoplasms; Dose Fractionation, Radiation; Humans; Prognosis; Radiosurgery; Radiotherapy Planning, Computer-Assisted; Radiotherapy, Intensity-Modulated
PubMed: 20717077
DOI: 10.1120/jacmp.v11i3.3040 -
Radiation Oncology (London, England) Jun 2022Delivered organs at risk (OARs) dose may vary from planned dose due to interfraction and intrafraction motion during kidney SABR treatment. Cases of bowel stricture...
BACKGROUND
Delivered organs at risk (OARs) dose may vary from planned dose due to interfraction and intrafraction motion during kidney SABR treatment. Cases of bowel stricture requiring surgery post SABR treatment were reported in our institution. This study aims to provide strategies to reduce dose deposited to OARs during SABR treatment and mitigate risk of gastrointestinal toxicity.
METHODS
Small bowel (SB), large bowel (LB) and stomach (STO) were delineated on the last cone beam CT (CBCT) acquired before any dose had been delivered (PRE CBCT) and on the first CBCT acquired after any dose had been delivered (MID CBCT). OAR interfraction and intrafraction motion were estimated from the shortest distance between OAR and the internal target volume (ITV). Adaptive radiation therapy (ART) was used if dose limits were exceeded by projecting the planned dose on the anatomy of the day.
RESULTS
In 36 patients, OARs were segmented on 76 PRE CBCTs and 30 MID CBCTs. Interfraction motion was larger than intrafraction motion in STO (p-value = 0.04) but was similar in SB (p-value = 0.8) and LB (p-value = 0.2). LB was inside the planned 100% isodose in all PRE CBCTs and MID CBCTs in the three patients that suffered from bowel stricture. SB D0.03cc was exceeded in 8 fractions (4 patients). LB D1.5cc was exceeded in 4 fractions (2 patients). Doses to OARs were lowered and limits were all met with ART on the anatomy of the day.
CONCLUSIONS
Interfraction motion was responsible for OARs overdosage. Dose limits were respected by using ART with the anatomy of the day.
Topics: Constriction, Pathologic; Dose Fractionation, Radiation; Humans; Kidney; Radiotherapy Planning, Computer-Assisted; Radiotherapy, Intensity-Modulated
PubMed: 35761291
DOI: 10.1186/s13014-022-02041-2 -
Radiation Oncology (London, England) Jul 2015Accelerated partial breast irradiation (APBI) with balloon and strut adjusted volume implants (SAVI) show promising results with excellent tumor control and minimal... (Comparative Study)
Comparative Study
PURPOSE
Accelerated partial breast irradiation (APBI) with balloon and strut adjusted volume implants (SAVI) show promising results with excellent tumor control and minimal toxicity. Knowing the factors that contribute to a high skin dose, rib dose, and D95 coverage may reduce toxicity, improve tumor control, and help properly predict patient outcomes following APBI.
METHODS AND MATERIALS
A retrospective analysis of 594 patients treated with brachytherapy based APBI at a single institution from May 2008 to September 2014 was grouped by applicator subtype. Patients were treated to a total of 34 Gy (3.4 Gy x 10 fractions over 5 days delivered BID) targeting a planning target volume (PTV) 1.0 cm beyond the lumpectomy cavity using a high dose rate source.
RESULTS
SAVI devices had the lowest statistically significant values of DmaxSkin (81.00 ± 29.83), highest values of D90 (101.50 ± 3.66), and D95 (96.09 ± 4.55). SAVI-mini devices had the lowest statistically significant values of DmaxRib (77.66 ± 32.92) and smallest V150 (18.01 ± 3.39). Multi-lumen balloons were able to obtain the smallest V200 (5.89 ± 2.21). Strut-based applicators were more likely to achieve a DmaxSkin and a DmaxRib less than or equal to 100 %. The effect of PTV on V150 showed a strong positive relationship (p < .001). PTV and DmaxSkin showed a weak negative relationship in multi-lumen applicators (p = .016) and SAVI-mini devices (p < .001). PTV and DmaxRib showed a weak negative relationship in multi-lumen applicators (p = .009), SAVI devices (p < .001), and SAVI-mini devices (p < .001).
CONCLUSION
PTV volume is strongly correlated with V150 in all devices and V200 in strut based devices. Larger PTV volumes result in greater V150 and V200, which could help predict potential risks for hotspots and resulting toxicities in these devices. PTV volume is also weakly negatively correlated with max skin dose and max rib dose, meaning that as the PTV volumes increase one can expect slightly smaller max skin and rib doses. Strut based applicators are significantly more effective in keeping skin and rib dose constraints under 125 and 100 % when compared to any balloon based applicator.
Topics: Adult; Aged; Aged, 80 and over; Brachytherapy; Breast Neoplasms; Catheters; Dose Fractionation, Radiation; Equipment Design; Female; Humans; Mastectomy, Segmental; Middle Aged; Organs at Risk; Radiation Injuries; Radiometry; Radiotherapy, Adjuvant; Retrospective Studies; Ribs; Skin; Tumor Burden
PubMed: 26227388
DOI: 10.1186/s13014-015-0468-7 -
The British Journal of Radiology Mar 2020We compared the sensitivity of intensity modulated proton therapy (IMPT) and photon volumetric modulated arc therapy (VMAT) plans to setup uncertainties in locally... (Comparative Study)
Comparative Study
OBJECTIVE
We compared the sensitivity of intensity modulated proton therapy (IMPT) and photon volumetric modulated arc therapy (VMAT) plans to setup uncertainties in locally advanced non-small cell lung cancer (NSCLC) using probabilistic scenarios.
METHODS
Minimax robust (MM) and planning target volume (PTV) optimised IMPT and VMAT nominal plans were created with physical dose of 70 Gy in 35 fractions in 10 representative patients. Using population data of setup errors, a fractionated treatment course was simulated, summed (D) and compared to the nominal plan. Three treatment-course simulations were done for each plan. Target robustness criteria were: dose deviation of ≤5% to clinical target volume (CTV) D and CTV V ≥ 99.9%. Voxelwise simulation repeatability was analysed using Bland-Altman plots. Acceptable limits of agreement were 2% of the prescription dose.
RESULTS
All D met target robustness criteria. While fraction VMAT and MM-IMPT doses were excellent, simulated fraction doses in PTV-IMPT were suboptimal. Almost all (>99%) of VMAT and MM-IMPT fraction doses met both target robustness criteria. For PTV-IMPT, only 96.9 and 80.3% of fractions met CTVD and V criteria respectively. Simulation repeatability was excellent (limits of agreement range: 0.41-1.1 Gy) with strong positive correlations.
CONCLUSION
When considering the whole treatment course, setup errors do not influence robustness irrespective of planning techniques used. However, on a fraction level, VMAT and MM-IMPT plans are superior compared to PTV-IMPT plans.
ADVANCES IN KNOWLEDGE
Probabilistic analysis provides a fast and practical method for evaluating VMAT and IMPT plan sensitivity against setup uncertainty. VMAT and robust-optimised IMPT plans have comparable sensitivity to setup uncertainties in conventionally fractionated treatment for NSCLC.
Topics: Carcinoma, Non-Small-Cell Lung; Dose Fractionation, Radiation; Humans; Lung Neoplasms; Photons; Proton Therapy; Radiotherapy Setup Errors; Radiotherapy, Intensity-Modulated; Reproducibility of Results; Sensitivity and Specificity; Uncertainty
PubMed: 31977241
DOI: 10.1259/bjr.20190584 -
Radiation Oncology (London, England) Jan 2017Intraoperative radiotherapy differs from conventional, fractionated radiotherapy in several aspects that may influence its biological effect. The radiation quality... (Review)
Review
Intraoperative radiotherapy differs from conventional, fractionated radiotherapy in several aspects that may influence its biological effect. The radiation quality influences the relative biologic effectiveness (RBE), and the role of the five R's of radiotherapy (reassortment, repair, reoxygenation, repopulation, radiosensitivity) is different. Furthermore, putative special biological effects and the small volume receiving a high single dose may be important. The present review focuses on RBE, repair, and repopulation, and gives an overview of the other factors that potentially contribute to the efficacy. The increased RBE should be taken into account for low-energy X-rays while evidence of RBE < 1 for high-energy electrons at higher doses is presented. Various evidence supports a hypothesis that saturation of the primary DNA double-strand break (DSB) repair mechanisms leads to increasing use of an error-prone backup repair system leading to genomic instability that may contribute to inactivate tumour cells at high single doses. Furthermore, the elimination of repopulation of residual tumour cells in the tumour bed implies that some patients are likely to have very few residual tumour cells which may be cured even by low doses to the tumour bed. The highly localised dose distribution of IORT has the potential to inactivate tumour cells while sparing normal tissue by minimising the volume exposed to high doses. Whether special effects of high single doses also contribute to the efficacy will require further experimental and clinical studies.
Topics: Dose Fractionation, Radiation; Dose-Response Relationship, Radiation; Humans; Intraoperative Period; Neoplasms; Relative Biological Effectiveness
PubMed: 28107823
DOI: 10.1186/s13014-016-0750-3 -
Lung Cancer (Amsterdam, Netherlands) Jun 2021To explore the efficacy and toxicities of split-course hypo-fractionated radiotherapy with concurrent chemotherapy (HFRT-CHT) with intensity modulated radiotherapy...
Hypo-fractionated radiotherapy with concurrent chemotherapy for locoregional recurrence of non-small cell lung cancer after complete resection: A prospective, single-arm, phase II study (GASTO-1017).
OBJECTIVES
To explore the efficacy and toxicities of split-course hypo-fractionated radiotherapy with concurrent chemotherapy (HFRT-CHT) with intensity modulated radiotherapy (IMRT) technique in non-small cell lung cancer (NSCLC) patients with postoperative locoregional recurrence (LRR).
MATERIALS AND METHODS
NSCLC patients were eligible if confirmed as LRR disease without distant metastasis after complete resection. HFRT-CHT using IMRT technique was administered with 51 Gy in 17 fractions or 40 Gy in 10 fractions as the first course followed by a break. Patients with no disease progression and no persistent Grade ≥2 toxicities had the second course of 15 Gy in 5 fractions or 28 Gy in 7 fractions as a boost. The primary endpoint was progression-free survival (PFS).
RESULTS
Fifty-eight patients were enrolled and analyzed. With a median follow-up of 23.9 months for all, the 2-year and 3-year PFS rate was 59.7 % and 46.4 %, the 2-year and 3-year OS rate was 72.5 % and 52.2 %, respectively, and a favorable objective response rate of 95.9 % was obtained after the whole courses protocol. Grade 3 acute pneumonitis and esophagitis occurred in 2 (3.4 %) and 7 (12.1 %) patients, and fatal pneumonitis was reported in one case (1.7 %). Exploratory subgroup analysis showed that performance status (PS) (PS 0 vs. 1: 2-year PFS, 88.1 % vs. 46.9 %,P = 0.001; 2-year OS, 100 % vs. 59.4 %, P < 0.001), recurrence site (single vs. multiple: 2-year PFS, 93.8 % vs. 47.4 %, P = 0.008; 2-year OS, 100 % vs. 63.0 %, P = 0.001), and gross tumor volume (GTV) (<50cm vs. ≥ 50cm: 2-year PFS, 70.6 % vs. 46.2 %, P = 0.024; 2-year OS, 85.6 % vs. 57.4 %, P = 0.034) were significantly associated with PFS and OS.
CONCLUSION
Split-course HFRT-CHT with IMRT technique achieved promising disease control and satisfactory survival with moderate toxicities in postoperative LRR of NSCLC. Good PS, a single recurrence site and GTV<50cm tended to have prolonged PFS and OS. Early detection of LRR may improve the efficacy of HFRT-CHT.
Topics: Antineoplastic Combined Chemotherapy Protocols; Carcinoma, Non-Small-Cell Lung; Dose Fractionation, Radiation; Humans; Lung Neoplasms; Neoplasm Recurrence, Local; Prospective Studies
PubMed: 33933895
DOI: 10.1016/j.lungcan.2021.04.020 -
International Journal of Radiation... Feb 2010To investigate the safety and efficacy of proton beam therapy (PBT) in patients with large hepatocellular carcinoma (HCC).
PURPOSE
To investigate the safety and efficacy of proton beam therapy (PBT) in patients with large hepatocellular carcinoma (HCC).
METHODS AND MATERIALS
Twenty-two patients with HCC larger than 10 cm were treated with proton beam therapy at our institution between 1985 and 2006. Twenty-one of the 22 patients were not surgical candidates because of advanced HCC, intercurrent disease, or old age. Median tumor size was 11 cm (range, 10-14 cm), and median clinical target volume was 567 cm(3) (range, 335-1,398 cm(3)). Hepatocellular carcinoma was solitary in 18 patients and multifocal in 4 patients. Tumor types were nodular and diffuse in 18 and 4 patients, respectively. Portal vein tumor thrombosis was present in 11 patients. Median total dose delivered was 72.6 GyE in 22 fractions (range, 47.3-89.1 GyE in 10-35 fractions).
RESULTS
The median follow-up period was 13.4 months (range, 1.5-85 months). Tumor control rate at 2 years was 87%. One-year overall and progression-free survival rates were 64% and 62%, respectively. Two-year overall and progression-free survival rates were 36% and 24%, respectively. The predominant tumor progression pattern was new hepatic tumor development outside the irradiated field. No late treatment-related toxicity of Grade 3 or higher was observed.
CONCLUSIONS
The Bragg peak properties of PBT allow for improved conformality of the treatment field. As such, large tumor volumes can be irradiated to high doses without significant dose exposure to surrounding normal tissue. Proton beam therapy therefore represents a promising modality for the treatment of large-volume HCC. Our study shows that PBT is an effective and safe method for the treatment of patients with large HCC.
Topics: Aged; Aged, 80 and over; Carcinoma, Hepatocellular; Dose Fractionation, Radiation; Female; Follow-Up Studies; Humans; Liver Neoplasms; Male; Middle Aged; Portal Vein; Proton Therapy; Protons; Survival Rate; Thrombosis
PubMed: 19427743
DOI: 10.1016/j.ijrobp.2009.02.030 -
Radiation Oncology (London, England) Feb 2023The main challenge in follow-up duration of patients with brain metastases after stereotactic radiotherapy is to distinguish between pseudo-progression and tumor...
BACKGROUND
The main challenge in follow-up duration of patients with brain metastases after stereotactic radiotherapy is to distinguish between pseudo-progression and tumor recurrence. The objective of this study is to retrospectively analyze the predictive factors.
METHODS
The study included 123 patients with enlarged brain metastases after hypo-fractionated radiotherapy in our center from March 2009 to October 2019, and the baseline clinical features, radiotherapy planning parameters, and enhanced magnetic resonance imaging before and after radiation therapy were analyzed. Logistic regression was performed to compare the differences between groups. Independent risk factors with P < 0.05 and associated with recurrence were used to establish a nomogram prediction model and validated by Bootstrap repeated sampling, which was validated in an internal cohort (n = 23) from October 2019 to December 2021.
RESULTS
The median follow-up time was 68.4 months (range, 8.9-146.2 months). A total of 76 (61.8%) patients were evaluated as pseudo-progression, 47 patients (38.2%) were evaluated as tumor recurrence. The median time to pseudo-progression and tumor recurrence were 18.3 months (quartile range, 9.4-27.8 months) and 12.9 months (quartile range, 8.7-19.6 months) respectively. Variables associated with tumor recurrence included: gross tumor volume ≥ 6 cc, biological effective dose < 60 Gy, target coverage < 96% and no targeted therapy. The area under curve values were 0.730 and 0.967 in the training and validation cohorts, respectively. Thirty-one patients received salvage therapy in the tumor recurrence group. The survival time in pseudo-progression and tumor recurrence groups were 66.3 months (95% CI 56.8-75.9 months) and 39.6 months (95% CI 29.2-50.0 months, respectively; P = 0.001).
CONCLUSIONS
Clinical and dosimetry features of hypo-fractionated radiation therapy based on enhanced brain magnetic resonance can help distinguish pseudo-progression from tumor recurrence after hypo-fractionated radiotherapy for brain metastases. Gross tumor volume, biological effective dose, target coverage, and having received targeted therapy or not were factors associated with the occurrence of tumor recurrence, and the individual risk could be estimated by the nomogram effectively.
Topics: Humans; Neoplasm Recurrence, Local; Retrospective Studies; Treatment Outcome; Brain Neoplasms; Radiosurgery; Dose Fractionation, Radiation
PubMed: 36788610
DOI: 10.1186/s13014-023-02214-7