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Dose Reduction to the Scalp with Hippocampal Sparing Is Achievable with Intensity Modulated Radiotherapy.

ABSTRACT: We evaluated the feasibility of combined hippocampal- and scalp-sparing intensity-modulated radiotherapy (IMRT) plans. This study included 7 patients who received conventional palliative whole brain radiation treatment (WBRT) for brain metastasis. The brain, hippocampus, and scalp were contoured and replanned with intensity modulated radiation therapy. The prescription dose was 30 Gray (Gy) in 10 fractions with hippocampus and normal structure constraints per the Radiation Therapy Oncology Group (RTOG) 0933 protocol. Further planning was done to minimize the scalp dose while maintaining the dose constraints for the hippocampus. Dose volume histograms were obtained from conventional opposed lateral fields, IMRT and compared. Planning target volume (PTV) coverage for all plans fell within the RTOG 0933 critical structure acceptable variation category. When compared to traditional opposed lateral fields, the IMRT plan with combined hippocampal- and scalp-sparing constraints was able to significantly reduce the max and mean scalp dose as well as the percentage of scalp receiving 10 and 20 Gy by 46% and 35%, respectively, while maintaining acceptable RTOG 0933 hippocampal dose variations. We conclude that acceptable PTV coverage and sparing of the scalp and hippocampus can be accomplished using a 9-field non-coplanar IMRT plan. Prospective study is warranted to understand the impact on radiation induced alopecia.

SUBMITTER: Witek M

PROVIDER: S-EPMC6020831 | biostudies-literature | 2014 Aug

REPOSITORIES: biostudies-literature

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Dose Reduction to the Scalp with Hippocampal Sparing Is Achievable with Intensity Modulated Radiotherapy.

Witek Matthew M Vahknenko Yelena Y Siglin Joshua J Harrison Amy A Xiao Ying Y Lui Haison H Andrews David D Shi Wenyin W

International journal of medical physics, clinical engineering and radiation oncology 20140801 3

We evaluated the feasibility of combined hippocampal- and scalp-sparing intensity-modulated radiotherapy (IMRT) plans. This study included 7 patients who received conventional palliative whole brain radiation treatment (WBRT) for brain metastasis. The brain, hippocampus, and scalp were contoured and replanned with intensity modulated radiation therapy. The prescription dose was 30 Gray (Gy) in 10 fractions with hippocampus and normal structure constraints per the Radiation Therapy Oncology Group ...[more]

PMID: 29963335

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Project description:The purpose of this study was to retrospectively investigate the accuracy, plan quality, and efficiency of using intensity-modulated arc therapy (IMAT) for whole brain radiotherapy (WBRT) patients with sparing not only the hippocampus (following RTOG 0933 compliance criteria) but also other organs at risk (OARs). A total of 10 patients previously treated with nonconformal opposed laterals whole-brain radiotherapy (NC-WBRT) were retrospectively replanned for hippocampal sparing using IMAT treatment planning. The hippocampus was volumetrically contoured on fused diagnostic T1-weighted MRI with planning CT images and hippocampus avoidance zone (HAZ) was generated using a 5 mm uniform margin around the hippocampus. Both hippocampi were defined as one paired organ. Whole brain tissue minus HAZ was defined as the whole-brain planning target volume (WB-PTV). Highly conformal IMAT plans were generated in the Eclipse treatment planning system for Novalis TX linear accelerator consisting of high-definition multileaf collimators (HD-MLCs: 2.5 mm leaf width at isocenter) and 6 MV beam for a prescription dose of 30 Gy in 10 fractions following RTOG 0933 dosimetric criteria. Two full coplanar arcs with orbits avoidance sectors were used. In addition to RTOG criteria, doses to other organs at risk (OARs), such as parotid glands, cochlea, external/middle ear canals, skin, scalp, optic pathways, brainstem, and eyes/lens, were also evaluated. Subsequently, dose delivery efficiency and accuracy of each IMAT plan was assessed by delivering quality assurance (QA) plans with a MapCHECK device, recording actual beam-on time and measuring planed vs. measured dose agreement using a gamma index. On IMAT plans, following RTOG 0933 dosimetric criteria, the maximum dose to WB-PTV, mean WB-PTV D2%, and mean WB-PTV D98% were 34.9 ± 0.3 Gy, 33.2 ± 0.4 Gy, and 26.0± 0.4Gy, respectively. Accordingly, WB-PTV received the prescription dose of 30Gy and mean V30 was 90.5% ± 0.5%. The D100%, and mean and maximum doses to hippocampus were 8.4 ± 0.3 Gy, 11.2 ± 0.3 Gy, and 15.6 ± 0.4 Gy, on average, respectively. The mean values of homogeneity index (HI) and conformity index (CI) were 0.23 ± 0.02 and 0.96 ± 0.02, respectively. The maximum point dose to WB-PTV was 35.3 Gy, well below the optic pathway tolerance of 37.5 Gy. In addition, compared to NC-WBRT, dose reduction of mean and maximum of parotid glands from IMAT were 65% and 50%, respectively. Ear canals mean and maximum doses were reduced by 26% and 12%, and mean and maximum scalp doses were reduced by 9 Gy (32%) and 2 Gy (6%), on average, respectively. The mean dose to skin was 9.7 Gy with IMAT plans compared to 16 Gy with conventional NC-WBRT, demonstrating that absolute reduction of skin dose by a factor of 2. The mean values of the total number of monitor units (MUs) and actual beam on time were 719 ± 44 and 2.34 ± 0.14 min, respectively. The accuracy of IMAT QA plan delivery was (98.1 ± 0.8) %, on average, with a 3%/3 mm gamma index passing rate criteria. All of these plans were considered clinically acceptable per RTOG 0933 criteria. IMAT planning provided highly conformal and homogenous plan with a fast and effective treatment option for WBRT patients, sparing not only hippocampi but also other OARs, which could potentially result in an additional improvement of the quality life (QoL). In the future, we plan to evaluate the clinical potential of IMAT planning and treatment option with hippocampal and other OARs avoidance in our patient's cohort and asses the QoL of the WBRT patients, as well as simultaneous integrated boost (SIB) for the brain metastases diseases.

Project description:Coplanar extended-field intensity-modulated radiation therapy (EF-IMRT) targeting the whole-pelvic and para-aortic lymph nodes in patients with advanced cervical cancer results in impaired creatinine clearance. An improvement in renal function cannot be expected unless low-dose (approximately 10 Gy) kidney exposure is reduced. The dosimetric method should be considered during EF-IMRT planning to further reduce low-dose exposure to the kidneys. To assess the usefulness of non-coplanar EF-IMRT with kidney-avoiding beams to spare the kidneys during cervical carcinoma treatment in dosimetric analysis between non-coplanar and coplanar EF-IMRT, we compared the doses of the target organ and organs at risk, including the kidney, in 10 consecutive patients. To estimate the influence of EFRT on renal dysfunction, creatinine clearance values after treatment were also examined in 18 consecutive patients. Of these 18 patients, 10 patients who were included in the dosimetric analysis underwent extended field radiation therapy (EFRT) with concurrent chemotherapy, and eight patients underwent whole-pelvis radiation therapy with concurrent chemotherapy to treat cervical carcinoma between April 2012 and March 2015 at our institution. In the dosimetric analysis, non-coplanar EF-IMRT was effective at reducing low-dose (approximately 10 Gy) exposure to the kidneys, thus maintaining target coverage and sparing other organs at risk, such as the small bowel, rectum, and bladder, compared with coplanar EF-IMRT. Renal function in all 10 patients who underwent EFRT, including coplanar EF-IMRT (with kidney irradiation), was low after treatment, and differed significantly from that of the eight patients who underwent WPRT (no kidney irradiation) 6 months after the first day of treatment (P = 0.005). In conclusion, non-coplanar EF-IMRT should be considered in patients with advanced cervical cancer, particularly in patients with a long life expectancy or with pre-existing renal dysfunction.

Project description:ObjectiveThis study aimed to evaluate the efficacy and safety of simultaneous integrated boost intensity-modulated radiotherapy (SIB-IMRT) versus standard-dose intensity-modulated radiotherapy (SD-IMRT) in the treatment of locally advanced esophageal squamous cell carcinoma.MethodsFrom July 2003 to March 2014, 1748 patients in a single center who received definitive chemoradiotherapy were included in the analysis. A total of 109 patients who underwent SIB-IMRT and fulfilled all inclusion and exclusion criteria were identified as the study group. A total of 266 patients who underwent SD-IMRT (60 Gy/30 fractions, 2 Gy/fraction, 1 time/day, 5 times/week) during the same period were selected as the control group. Propensity score matching (PSM) was used to balance the baseline characteristics. Survival status, treatment failure mode, and the occurrence of adverse events were compared between the two groups.ResultsThere were more women and more cervical and upper thoracic cancers (P = 0.038, < 0.001, respectively) in the SIB-IMRT group before case matching. The median progression-free survival (PFS) in the SD-IMRT and SIB-IMRT groups was 22 and 19 months, respectively, and the median overall survival duration was 24 and 22 months, respectively, with χ2 = 0.244 and P = 0.621. After PSM of 1:1, 138 patients entered the final analysis (69 cases from each group). The median PFS of the SD-IMRT group and the SIB-IMRT group was 13 and 18 months, respectively, with χ2 = 8.776 and P = 0.003. The 1‑, 3‑, and 5‑year overall survival rates were 66.7, 21.7, and 8.7% and 65.2, 36.2, and 27.3%, respectively, and the median overall survival duration was 16 and 22 months, respectively, with χ2 = 5.362 and P = 0.021. Treatment failure mode: 5‑year local regional recurrence rates of SD-IMRT and SIB-IMRT were 50.7 and 36.2%, respectively, with χ2 = 2.949 and P = 0.086. The 5‑year distant metastasis rates of the two groups were 36.2 and 24.6%, respectively, with χ2 = 2.190 and P = 0.139.Adverse events3 patients experienced grade 4-5 toxicity (2.2%), including one case of grade 4 radiation esophagitis and two cases of grade 5 radiation pneumonitis, all in the SD-IMRT group; 14 patients experienced grade 3 adverse events (10.1%), primarily including radiation esophagitis, radiation pneumonitis, and hematological toxicity.ConclusionThe technique of SIB-IMRT was safe and reliable compared with SD-IMRT. In addition, SIB-IMRT had locoregional control advantages and potential survival benefits.

Project description:BACKGROUND:Concomitant chemo-radiotherapy is the reference treatment for non-resectable locally-advanced Non-Small Cell Lung Cancer (NSCLC). Increasing radiotherapy total dose in the whole tumour volume has been shown to be deleterious. Functional imaging with positron emission tomography (PET/CT) offers the potential to identify smaller and biologically meaningful target volumes that could be irradiated with larger doses without compromising Organs At Risk (OAR) tolerance. This study investigated four scenarios, based on 18FDG and 18F-miso PET/CT, to delineate the target volumes and derive radiotherapy plans delivering up to 74Gy. METHOD:Twenty-one NSCLC patients, selected from a prospective phase II trial, had 18FDG- and 18F-miso PET/CT before the start of radiotherapy and 18FDG PET/CT during the radiotherapy (42Gy). The plans were based planned on a standard plan delivering 66 Gy (plan 1) and on three different boost strategies to deliver 74Gy total dose in pre-treatment 18FDG hotspot (70% of SUVmax) (plan 2), pre-treatment 18F-miso target (SUVmax?>?1.4) (plan 3) and per-treatment 18FDG residual (40% of SUVmax). (plan 4). RESULTS:The mean target volumes were 4.8 cc (± 1.1) for 18FDG hotspot, 38.9 cc (± 14.5) for 18F-miso and 36.0 cc (± 10.1) for per-treatment 18FDG. In standard plan (66 Gy), the mean dose covering 95% of the PTV (D95%) were 66.5 (± 0.33), 66.1 (± 0.32) and 66.1 (± 0.32) Gy for 18FDG hotspot, 18F-miso and per-treatment 18FDG. In scenario 2, the mean D95% was 72.5 (± 0.25) Gy in 18FDG hotspot versus 67.9 (± 0.49) and 67.9 Gy (± 0.52) in 18F-miso and per-treatment 18FDG, respectively. In scenario 3, the mean D95% was 72.2 (± 0.27) Gy to 18F-miso versus 70.4 (± 0.74) and 69.5Gy (± 0.74) for 18FDG hotspot and per-treatment 18FDG, respectively. In scenario 4, the mean D95% was 73.1 (± 0.3) Gy to 18FDG per-treatment versus 71.9 (± 0.61) and 69.8 (± 0.61) Gy for 18FDG hotspot and 18F-miso, respectively. The dose/volume constraints to OARs were matched in all scenarios. CONCLUSION:Escalated doses can be selectively planned in NSCLC target volumes delineated on 18FDG and 18F-miso PET/CT functional images. The most relevant strategy should be investigated in clinical trials. TRIAL REGISTRATION:(RTEP5, NCT01576796 , registered 15 june 2012).

Dataset Information

Dose Reduction to the Scalp with Hippocampal Sparing Is Achievable with Intensity Modulated Radiotherapy.

Publications

Dose Reduction to the Scalp with Hippocampal Sparing Is Achievable with Intensity Modulated Radiotherapy.

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