scholarly journals Options for Combining Altered Fractionation with IMRT

2008 ◽  
Vol 7 (6) ◽  
pp. 457-461 ◽  
Author(s):  
Aaron M. Allen ◽  
Luciant Wolfsberger ◽  
Roy B. Tishler ◽  
Laurence E. Court
Keyword(s):  
Hot Spots ◽  
Imrt Plan ◽  
Planning Time ◽  
Once Daily ◽  
Integral Dose ◽  
Altered Fractionation ◽  
Time To Completion ◽  
Concomitant Boost ◽  
Treatment Plans ◽  
Prescription Dose

We set out to investigate IMRT-based concomitant boost. Eight patients with stage III/IV squamous cell carcinoma of the head and neck treated with once daily with chemoradiotherapy at the Dana-Farber/Brigham and Women's Hospital had their treatment plans reviewed with IRB approval. Each case was replanned for treatment with a a concomitant boost regimen. Plans delivered 1.9 Gy in 30 fractions to 57 Gy with a boost of 1.5 Gy in 10 fractions for a total dose of 72 Gy. The boost was planned with both IMRT and 3-D conformal, to compare the two techniques. For each patient, both plans (IMRT-IMRT and IMRT-3DCRT) were evaluated for target and avoidance coverage, monitor units and integral dose. Finally, we evaluated the plans for time to completion. The IMRT-IMRT and IMRT-3-DCRT techniques were equivalent for target coverage. 100% coverage of the GTV and PTV was achieved with 97% of the prescription dose. Hot spots were seen 104% to 108% with IMRT-IMRT plan and from 102–111% with the IMRT-3DCRT plans. The IMRT-IMRT boost had double the monitor units as the 3-DCRT boosts. When the total monitor units from both the initial and boost portions of the plans were e combined there was not a significant differnce. There was a slight increase in integral dose with the IMRT-IMRT plans of mean 3.8%. Planning time was increased for the 3-DCRT boost as opposed to the IMRT boost (mean 3.5 hours vs. 1.5 hours). More time was needed for quality assurance of the IMRT-IMRT plans (3.0 hours vs. 1.5 hours for IMRT-3-DCRT). We found that both IMRT-based concomitant-boost strategies are achievable and produce good dosimetric results.

Effect of dose prescription and block margin on small field treatment planning

2011 ◽  
Vol 12 (1) ◽  
pp. 8-17 ◽  
Author(s):  
Summer R. Chaudhari ◽  
Margaret Reynolds ◽  
Patrick D. Higgins
Keyword(s):  
Hot Spots ◽  
High Dose ◽  
Target Coverage ◽  
Integral Dose ◽  
Good Target ◽  
Target Volumes ◽  
Small Fields ◽  
Dose Homogeneity ◽  
Prescription Dose ◽  
Small Targets

AbstractBackground and purpose: We evaluated the effect of block margin on small fields when point dose prescription (ICRU) or isodose line prescription (RTOG) formats are used.Material and methods: A total of 11 clinical SBRT cases, one 4-field prostate case and 2 phantom cases using 0, 0.5 or 1 cm block margins were analysed. Integral dose and target coverage were compared using DVHs and isodose volumes for either isodose line prescription (100% Rx dose to 95% PTV volume) or isocenter point prescription (100% Rx dose to the isocenter) were calculated.Results: Tight planning target margins using isodose line prescription leads to good target coverage but high dose heterogeneity with hot spots possibly exceeding 140% of the prescription dose for small target volumes. As block margin is increased, target coverage converges for the two methods but point dose prescriptions result in better dose homogeneity. For a given block margin, integral doses are consistently larger for isodose line prescription over point prescription, but are similar when block margins are adjusted to produce equal target coverage. As target size increases dose heterogeneity and integral dose differences disappear.Conclusions: For small targets, the ICRU point prescription method can produce comparable PTV coverage to the isodose line prescription method with less dose heterogeneity and comparable integral dose. Reduction of hot spots in potentially normal tissue and reporting clarity makes this internationally recommended prescription standard preferable.

Phase 3 comparison of high-dose once-daily (QD) thoracic radiotherapy (TRT) with standard twice-daily (BID) TRT in limited stage small cell lung cancer (LSCLC): CALGB 30610 (Alliance)/RTOG 0538.

2021 ◽  
Vol 39 (15_suppl) ◽  
pp. 8505-8505
Author(s):  
Jeffrey A Bogart ◽  
Xiaofei F. Wang ◽  
Gregory A. Masters ◽  
Junheng Gao ◽  
Ritsuko Komaki ◽  
...  
Keyword(s):  
Regional Lymph Node ◽  
Performance Status ◽  
Lymph Node Involvement ◽  
High Dose ◽  
Phase 3 ◽  
Ecog Performance Status ◽  
Once Daily ◽  
Concomitant Boost ◽  
Significant Difference ◽  
Grade 3

8505 Background: Although level 1 evidence is lacking, the majority of patients (pts) with LSCLC are treated with a high dose QD TRT regimen in clinical practice. CALGB 30610/RTOG 0538 was designed to determine if administering high dose TRT would improve overall survival (OS), compared with standard 45 Gy BID TRT, in LSCLC pts treated with chemoradiotherapy. Methods: Eligible pts had LSCLC, ECOG performance status (PS) 0-2 and regional lymph node involvement excluding contralateral hilar or supraclavicular nodes. This phase 3 trial was conducted in 2 stages. In the first stage, pts were randomized 1:1:1 to 45 Gy BID over 3 weeks, 70 Gy QD over 7 weeks, or 61.2 Gy concomitant boost (CB) over 5 weeks. For the second stage, the study planned discontinuation of one high dose arm based on interim toxicity analysis with patients then randomized 1:1 in the two remaining arms. TRT was given starting with either the 1st or 2nd (of 4 total) chemotherapy cycles. The primary endpoint was OS measured from date of randomization. Results: The trial opened 03/15/2008 and closed 12/01/2019 upon completing accrual, with the CB arm discontinued 3/11/2013 after interim analysis. This analysis includes 638 pts randomized to 45 Gy BID TRT (n = 313) or 70 Gy QD TRT (n = 325). Median age was 63 years (range 37-81), the majority of pts were Caucasian (86%), female (52%), and with ECOG PS 0-1 (95%). After median follow-up of 2.84 years (IQR:1.35 -5.61) for surviving pts, QD compared to BID did not result in a significant difference in OS (HR 0.94, 95% CI: 0.76-1.2, p = 0.9). Median, 2- and 4-year OS for QD were 30.5 months (95% CI: 24.4-39.6), 56% (95% CI: 0.51-0.62), and 39% (95% CI: 0.33-0.45), and for BID 28.7 months (95% CI: 26.2-35.5), 59% (95% CI: 0.53-0.65), and 35% (95% CI: 0.29-0.42). QD also did not result in a significant difference in PFS (HR 0.96, 95% CI: 0.78-1.18, p = 0.94). Most grade 3+ hematologic and non-hematologic adverse events (AEs) were similar between cohorts. Rates of grade 3+ febrile neutropenia, dyspnea, esophageal pain and dysphagia for QD were 12.6%,7%, 11.6% and 11.3%, and for BID 13.6%, 4%, 11.2 % and 9.5%. Grade 5 AEs were reported in 3.7% and 1.7% of the QD and BID cohorts, respectively. Results will be updated at presentation. Conclusions: High dose QD TRT to 70 Gy did not significantly improve OS compared with standard 45 Gy BID TRT. Nevertheless, favorable outcomes on the QD arm provide the most robust evidence available supporting high dose once-daily TRT as an acceptable option in LSCLC. Outcomes from this study, the largest conducted in LSCLC to date, will help guide TRT decisions for this patient population. Support: U10CA180821, U10CA180882; Clinical trial information: NCT00632853.

Risk of breast fibrosis following irradiation using a breast-specific SBRT system compared with conventional APBI.

2011 ◽  
Vol 29 (27_suppl) ◽  
pp. 116-116
Author(s):  
Z. A. Husain ◽  
S. J. Feigenberg ◽  
E. Nichols ◽  
J. Zhang ◽  
C. Yu ◽  
...  
Keyword(s):  
Normal Tissue Complication Probability ◽  
Tumor Location ◽  
Imaging Studies ◽  
Ipsilateral Breast ◽  
Treatment Plans ◽  
Prescription Dose ◽  
Irradiation Unit ◽  
Immobilization Device ◽  
Biologically Equivalent Dose ◽  
Breast Dosimetry

116 Background: To determine the dosimetric characteristics and risk of breast fibrosis using a normal tissue complication probability (NTCP) model in conjunction with a novel preoperative stereotactic radiotherapy system called the GammaPod. Results are compared with linac based post-lumpectomy APBI plans for the same cohort. Methods: The GammaPod breast SBRT system consists of a Co-60 irradiation unit in combination with an immobilization device with embedded fiducials. Eight patients were enrolled in an IRB-approved protocol and underwent CT scans in the prone position with breast immobilization. A preoperative target (GTV) was synthesized to match the tumor location and volume reported in imaging studies obtained prior to surgery (0.3-2.4 cc). The GTV was expanded by 1.5 cm to create a CTV, and a PTV was created using an additional 0.3 cm margin. The PTV was prescribed 25.5 Gy in 3 fx, which is radiobiologically equivalent to conventional APBI doses of 38.5 Gy in 10 fx. Following the radioablative experience in NSCLC, we also planned to deliver 60.0 Gy to the GTV+0.3 cm as a simultaneous boost in conjunction with the 25.5 Gy PTV prescription dose. For comparison, linac-based treatment plans were created for the same cohort following NSABP B-39 guidelines. Whole breast dosimetry was analyzed in terms of biologically equivalent dose (BED) and Lyman NTCP analysis was performed. Results: The volume of ipsilateral breast receiving 10, 20, 50, and 100% of the prescribed dose was substantially smaller in GammaPod vs. APBI plans, with cohort averages of 19.3, 13.0, 7.1 and 4.0% vs. 75.8, 67.3, 48.1 and 27.6% respectively (p<0.001). Even though the PTV equivalent uniform BED (EUD) was substantially higher in GammaPod plans (87.9 Gy vs. 57.3 Gy), the ipsilateral breast EUD was still smaller in these plans, 18.9 ± 5.0 Gy vs. 47.2 ± 3.2 Gy (p<0.001). Corresponding NTCP predictions for breast fibrosis rates following GammaPod and APBI treatments were 0.2 ± 0.1% vs. 2.8 ± 0.8% (p<0.001), respectively. Conclusions: The GammaPod system improves upon traditional post-lumpectomy linac-based APBI by decreasing dose to the ipsilateral breast as well as the predicted rates of breast fibrosis.

Dosimetic quality and evolution of edema after prostate brachytherapy for small prostates: Implications for the use of newer isotopes.

2013 ◽  
Vol 31 (6_suppl) ◽  
pp. 232-232
Author(s):  
Konstantin Kovtun ◽  
Luciant D. Wolfsberger ◽  
Thomas Niedermayr ◽  
Emily Neubauer ◽  
Yonina R. Murciano-Goroff ◽  
...  
Keyword(s):  
Hot Spots ◽  
Transrectal Ultrasound ◽  
Prostate Brachytherapy ◽  
Short Term ◽  
Mri Scans ◽  
Operative Planning ◽  
Dosimetric Study ◽  
Prescription Dose ◽  
Iodine 125 ◽  
Ct And Mri

232 Background: Prostate brachytherapy is often avoided in men with small prostate volumes (PV) due to concerns about suboptimal dosimetry. We characterized prostate swelling and dosimetry in patients with small PVs compared with large PVs. Methods: We studied twenty-five patients with PV <25 cc (range 15.1-24.8) and sixty-five patients with PV >=25 cc (range 25.0-66.2) who underwent brachytherapy. Gland size was based on the contoured volume on a 3D transrectal ultrasound before the procedure. Ultrasound-guided brachytherapy was performed under intra-operative planning with loose Iodine-125 seeds to a prescription dose of 145 Gy. Patients underwent CT and MRI scans on post-implant Days 1 and 30 for dosimetric study. MRI was used to contour the prostate and then fused with the CT for dosimetry. Results: Small PVs had greater Day 1 post-implant swelling than patients with large PVs (32.5% increase in volume vs. 23.7%, p=0.04) but Day 30 swelling was minimal and not significantly different (4.4% increase in volume vs. 1.6%, p=0.44) for small and large PVs respectively. Small PVs had greater seed and needle density at implant (p<0.001). Small PV patients had larger Day 1 hot spots in the prostate at (V150 = 59.6% vs. 53.0, p=0 .022) which resolved by Day 30 (V150 = 70.9% vs. 67.1, p=0.20). Rectal and urethral doses were nearly identical by Day 30 (Small PV RV100 = 0.32 cc, Large PV RV100 = 0.33 cc, p=0.99; small PV UV150 = 0.20, large PV UV150 = 0.20, p=0.91). Day 1 swelling created cold areas (rate D90>140 Gy = 88.0% and 90.6% for the small and large PV groups respectively, p=0.71), but day 30 dosimetry was excellent (rate D90>140 Gy = 100% for both groups). Conclusions: While smaller prostates have more immediate post-operative swelling, good Day 30 dosimetry can be achieved in small prostates, which makes them excellent candidates for treatment with I-125 seeds (t½ = 60 days). Due to the increased short-term swelling, small prostates may be suboptimal candidates for implants done with shorter half-life sources such as cesium-131 (t½ = 9.7 days), where the majority of the dose may be delivered to an edematous gland.

scholarly journals Long-term Functional Outcomes and Patient Perspective Following Altered Fractionation Radiotherapy with Concomitant Boost for Oropharyngeal Cancer

Dysphagia ◽  
2012 ◽  
Vol 27 (4) ◽  
pp. 481-490 ◽  
Author(s):  
Bena Cartmill ◽  
Petrea Cornwell ◽  
Elizabeth Ward ◽  
Wendy Davidson ◽  
Sandro Porceddu
Keyword(s):  
Oropharyngeal Cancer ◽  
Functional Outcomes ◽  
Patient Perspective ◽  
Altered Fractionation ◽  
Concomitant Boost

scholarly journals Gamma Knife Radiosurgery for Trigeminal Neuralgia: A Comparison of Dose Protocols

2019 ◽  
Vol 9 (6) ◽  
pp. 134 ◽  
Author(s):  
Warren Boling ◽  
Minwoo Song ◽  
Wendy Shih ◽  
Bengt Karlsson
Keyword(s):  
Patient Satisfaction ◽  
Pain Relief ◽  
Trigeminal Neuralgia ◽  
Gamma Knife Radiosurgery ◽  
Sensory Disturbance ◽  
Kaplan Meier ◽  
Facial Numbness ◽  
Satisfaction With Treatment ◽  
Treatment Plans ◽  
Prescription Dose

Purpose: A variety of treatment plans including an array of prescription doses have been used in radiosurgery treatment of trigeminal neuralgia (TN). However, despite a considerable experience in the radiosurgical treatment of TN, an ideal prescription dose that balances facial dysesthesia risk with pain relief durability has not been determined. Methods and Materials: This retrospective study of patients treated with radiosurgery for typical TN evaluates two treatment doses in relation to outcomes of pain freedom, bothersome facial numbness, and patient satisfaction with treatment. All patients were treated with radiosurgery for intractable and disabling TN. A treatment dose protocol change from 80 to 85 Gy provided an opportunity to compare two prescription doses. The variables evaluated were pain relief, treatment side-effect profile, and patient satisfaction. Results: Typical TN was treated with 80 Gy in 26 patients, and 85 Gy in 37 patients. A new face sensory disturbance was reported after 80 Gy in 16% and after 85 Gy in 27% (p = 0.4). Thirteen failed an 80 Gy dose whereas seven failed an 85 Gy dose. Kaplan–Meier analysis found that at 29 months 50% failed an 80 Gy treatment compared with 79% who had durable pain relief after 85 Gy treatment (p = 0.04). Conclusion: The 85 Gy dose for TN provided a more durable pain relief compared to the 80 Gy one without a significantly elevated occurrence of facial sensory disturbance.

scholarly journals PS1 - 189 A Universal Predictive Model for Dose Fall-Off in MLC-Based Stereotactic Brain Radiosurgery

2016 ◽  
Vol 43 (S4) ◽  
pp. S8-S8
Author(s):  
M. Ruschin ◽  
A. Sahgal ◽  
H. Soliman ◽  
B. Chugh ◽  
S. Myrehaug ◽  
...  
Keyword(s):  
Clinical Decision Making ◽  
Treatment Plan ◽  
Clinical Decision ◽  
Target Volume ◽  
Adjustment Factor ◽  
Ongoing Work ◽  
Toxicity Risk ◽  
Treatment Plans ◽  
Prescription Dose ◽  
Prediction Band

Predictive modeling of dose fall-off in radiosurgery could assist in clinical decision-making when prescribing a treatment plan with minimized toxicity risk. The purpose of this study is to develop a predictive dose fall-off model. Materials/Methods: We retrospectively reviewed treatment plans from 257 patients (365 lesions) with total doses ranging from 20 to 35Gy in 5 fractions. For each plan, we measured both total volume of the external contour (EXT) and BrainMinusPTV (BMP) receiving P=20% to P=80% of the prescription dose. The model has form y=Fa(PTV)b+/-delta. y=volume of EXT or BMP (cc’s); a and b are curve-fitting coefficients; PTV=total planning target volume (cc’s); F is an adjustment factor (>1) to account for number of targets; delta is the 95% prediction band. F, a, b, and delta were modeled such that dose-fall can be forecast for any PTV and dose level. Results: The model coefficients were as follows: Coefficient EXT BMP a 19927(100×P)exp(-2) 17122(100×P)exp(-2) b 0.42(100×P)exp(0.17) 0.63 F -0.0156×(100×P)+2.5517 delta 384467×(100×P)exp(-2.3159) The table can be used to determine the model for any P from 20% to 80%. Example: the EXT receiving 50%, P=0.5, a=8.0, b=0.82, F=1.8, delta=45. Thus, EXT-50=8(PTV0.82) or 1.8×8(PTV0.82) for 1-3 or >3 targets, respectively,+/-45cc’s. The model was verified against published values of dose fall-off from linacs. Conclusion: A predictive dose fall-off model was generated for linac-based radiosurgery. The model can be used for quality assurance or for inter-institutional comparisons. Ongoing work is being conducted to extend the model to a SRS cones system.

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