Pediatric Craniospinal Irradiation - The implementation and Use of Normal Tissue Complication Probability in Comparing Photon versus Proton Planning

Evaluating the efficacy of radiotherapy in patients with embryonal tumor with multilayered rosettes: A systematic review and meta-analysis

Background

Embryonal tumor with multilayered rosettes (ETMR) is a rare and deadly pediatric central nervous system tumor often seen before the age of 3. ETMR consists of embryonal tumors with abundant neuropil and true rosettes, ependymoblastoma, and medulloepithelioma. The 5-year survival rate has been reported to be between 0% and 30%. Treatment of ETMR is very unstandardized and typically consists of surgical resection, chemotherapy, and radiotherapy. A systematic review was performed to better understand treatment-related outcome trends.

Methods

The authors performed a PRISMA guidelines-based systematic review of the literature. Survival curve analysis using Kaplan-Meier curves and Cox proportional hazards models were used to estimate survival rates between 2 groups and multiple risk factors, respectively.

Results

The average survival time was 31.1 months in patients treated with radiotherapy compared to 11.2 months in patients who did not. Radiotherapy was a significant covariate on overall survival (P < .001) with an 82% lower risk of death compared to patients who did not receive radiotherapy. The average survival time for patients with focal radiotherapy was 35.8 months compared to 29.8 months in patients with CSI radiotherapy, but there was a great number of patients with pretreatment metastasis in the CSI group. In patients without pretreatment metastasis, focal radiotherapy had non-inferior outcomes for survival rates and times.

Conclusions

Patients treated with radiotherapy in addition to chemotherapy demonstrated a significantly higher survival time. For patients with no metastasis prior to treatment, focal radiotherapy should be strongly considered.

A dosimetric comparison of non-coplanar volumetric modulated arc therapy and non-coplanar fixed field intensity modulated radiation therapy in hippocampus-avoidance whole-brain radiation therapy with a simultaneous integrated boost for brain metastases

Objective

The aim of this study was to investigate the dosimetric differences between non-coplanar volumetric modulated arc therapy (VMAT) and non-coplanar fixed-field intensity-modulated radiotherapy (IMRT) in hippocampus-avoidance whole-brain radiation therapy with a simultaneous integrated boost (HA-WBRT+SIB) for brain metastases using the Monaco treatment planning system (TPS).

Method

A total of 22 patients with brain metastases were retrospectively enrolled. Two radiotherapy treatment plans were designed for each patient: non-coplanar VMAT and non-coplanar fixed field IMRT. The dose distribution of targets and organs at risk (OAR), the number of monitor units (MUs), and pre-treatment plan verification were compared between the two plans while meeting the prescribed dose requirements of the target volume.

Results

There were no significant differences in V50, V55, Dmax, heterogeneity index (HI) and conformity index (CI) of target PGTV between the two plans (p>0.05). For PTV-brain-SIB, there was no significant difference in D98% between IMRT and VMAT (p=0.103). VMAT significantly improved the V30 of PTV-brain-SIB (p<0.001), decreased HI (p=0.003), and increased CI (p<0.001). There were no significant differences in the Dmax to the brain stem, left and right lens, optic chiasm, pituitary gland, and left and right hippocampus between the two plans (p>0.05). Compared with IMRT, VMAT significantly reduced the Dmax to the left and right eyes (p<0.001) and significantly increased the Dmax to the right inner ear (p=0.010). There was no significant difference in the Dmax to the left inner ear between VMAT and IMRT (p=0.458). Compared with IMRT, VMAT significantly reduced the Dmax to the left optic nerve (p=0.006), but significantly increased the Dmax to the right optic nerve (p=0.001). There was no significant difference in the Dmax to the left and right hippocampus between VMAT and IMRT (p>0.05), but VMAT significantly increased the D100% (p<0.05) compared with IMRT. Compared with VMAT, IMRT significantly reduced the MU (p<0.001) but VMAT has a higher treatment efficiency than IMRT, with an average reduction of 41 seconds (294.1 ± 16.4 s for VMAT, 335.8 ± 34.9 s for IMRT, p<0.001). Under the conditions of 3%/2 mm, and 2%/2 mm, the gamma passing rate of the IMRT QA was improved compared to VMAT, with an average increase of 0.6%, p=0.013, and 1.7%, p<0.001, respectively.

Conclusion

Both non-coplanar VMAT and non-coplanar fixed field IMRT based on the Monaco TPS produce clinically acceptable results for HA-WBRT+SIB in patients with brain metastases. Compared with IMRT, VMAT has better dose distribution in the target volume and treatment efficiency, but IMRT can better protect the hippocampus and reduce the number of MUs.

Dosimetric and radiobiological comparison of IMRT, VMAT, and helical tomotherapy planning techniques in hippocampal sparing whole brain radiotherapy with simultaneous integrated boost for multiple brain metastases

To compare treatment planning and dosimetric outcomes for hippocampal sparing whole brain radiotherapy (WBRT) with the simultaneous integrated boost (SIB) in brain metastasis (BM) patients using tumour control probability (TCP) and normal tissue complication probability (NTCP) formalism between IMRT, VMAT, and HT techniques. In this retrospective study, the treatment data of 20 BM patients who typically received whole brain radiation with SIB treatment were used. Prescription doses of 30 Gy and 36 Gy was delivered in 10 fractions for WBRT and SIB, respectively. Niemierko and LKB models were applied for calculating TCP and NTCP. All the plans were evaluated for the RTOG 0933 protocol criteria and found acceptable. Additionally, the homogeneity of the PTV boost is 0.07 ± 0.01, 0.1 ± 0.04, and 0.08 ± 0.02 for IMRT, VMAT, and HT, respectively (P < 0.05). The percentage of TCP for the PTV boost was 99.99 ± 0.003, 99.98 ± 0.004, and 99.99 ± 0.002 of IMRT, VMAT, and HT, respectively, (P < 0.005). The NTCP value of the lenses was higher with the VMAT plan as compared to IMRT and HT Plans. The hippocampal NTCP values are equal in all three planning proficiencies. The techniques like IMRT, VMAT, and HT can reduce the dose received by hippocampus to the dosimetric threshold during the delivery of WBRT with hippocampal sparing and can simultaneously boost multiple metastases. Overall, the high-quality dose distribution, TCP, and NTCP comparison between all three planning techniques show that the HT technique has better results when compared to the VMAT and IMRT techniques.

Comparison of passive-scattered and intensity-modulated proton beam therapy of craniospinal irradiation with proton beams for pediatric and young adult patients with brain tumors

PURPOSE

To investigate the dose stability of craniospinal irradiation based on irradiation method of proton beam therapy (PBT).

METHODS AND MATERIALS

Twenty-four pediatric and young adult brain tumor patients (age: 1-24 years) were examined. Treatment method was passive-scattered PBT (PSPT) in 8 patients and intensity-modulated PBT (IMPT) in 16 patients. The whole vertebral body (WVB) technique was used in 13 patients whose ages were younger than 10, and vertebral body sparing (VBS) technique was used for the remaining 11 patients aged 10 and above. Dose stability of planning target volume (PTV) against set-up error was investigated.

RESULTS

The minimum dose (Dmin) of IMPT was higher than that of PSPT (p = 0.01). Inhomogeneity index (INH) of IMPT was lower than that of PSPT (p = 0.004). When the irradiation field of the cervical spinal cord level (C level) was shifted, the maximum dose (Dmax) was lower in IMPT, and mean dose (Dmean) was higher than PSPT as movement became greater to the cranial-caudal direction (p = 0.000-0.043). Dmin was higher and INH was lower in IMPT in all directions (p = 0.000-0.034). When the irradiation field of the lumber spinal cord level (L level) was shifted, Dmax was lower in IMPT as movement became greater to the cranial direction (p = 0.000-0.028). Dmin was higher and INH was lower in IMPT in all directions (p = 0.000-0.022).

CONCLUSIONS

The PTV doses of IMPT and PSPT are robust and stable in both anterior-posterior and lateral directions at both C level and L level, but IMPT is more robust and stable than PSPT for cranial-caudal movements.

TRIAL REGISTRY

Clinical Trial Registration number: No. 04-03.

Comparison of Craniospinal Irradiation Using Proton Beams According to Irradiation Method and Initial Experience Treating Pediatric Patients

Purpose

This study compared craniospinal irradiation using proton beam therapy (PBT) according to irradiation method and investigated the initial effects.

Methods and Materials

Twenty-four pediatric patients (1-24 years old) who received proton craniospinal irradiation were examined. Passive scattered PBT (PSPT) and intensity modulated PBT (IMPT) were used in 8 and 16 patients, respectively. The whole vertebral body technique was used for 13 patients <10 years old, and the vertebral body sparing (VBS) technique was used for the remaining 11 patients aged ≥10 years. The follow-up period was 17 to 44 (median, 27) months. Organ-at-risk and planning target volume (PTV) doses and other clinical data were examined.

Results

The maximum lens dose using IMPT was lower than that using PSPT (P = .008). The mean thyroid, lung, esophagus, and kidney doses were lower in patients treated using the VBS technique compared with the whole vertebral body technique (all P < .001). The minimum PTV dose of IMPT was higher than that of PSPT (P = .01). The inhomogeneity index of IMPT was lower than that of PSPT (P = .004).

Conclusions

IMPT is better than PSPT at reducing the dose to the lens. The VBS technique can decrease the doses to neck-chest-abdomen organs. The PTV coverage of IMPT is superior to that of PSPT.

Comparison of Acute Hematological Adverse Reactions Induced by Craniospinal Irradiation With Intensity-Modulated Radiotherapy and Conventional Radiotherapy

Background

With the update of equipment, the hospital base of this study began to adopt craniospinal irradiation (CSI) intensity-modulated radiotherapy (IMRT) in May 2018 to replace the traditional CSI conventional radiotherapy (CRT) technology. The purpose of this study was designed to compare the differences in acute hematological adverse reactions induced by CSI-IMRT and CSI-CRT.

Methods

The clinical data and hematological data of 102 patients with central nervous system malignant tumors who underwent CSI treatment at the 900th Hospital of Joint Logistics Support Force of PLA from January 2008 to August 2022 were analyzed retrospectively. The patients included 63 men and 39 women, aged 3 to 56 years old. On the basis of the radiotherapy technique used, the patients were divided into the CSI-IMRT group (38 cases) and CSI-CRT group (64 cases). Acute hematological adverse reactions during radiotherapy were compared between the two groups according to the Common Terminology Criteria for Adverse Events version 4.0. The Mann-Whitney U test was used to compare the measurement data, and the χ² test was used to compare the count data.

Results

No significant difference was found between the CSI-IMRT group and the CSI-CRT group in terms of sex, histopathological type, tumor location, spinal cord invasion, surgery, and the Eastern Cooperative Oncology Group score (χ² = 0.004 to 6.213; all P > .05). No significant difference was found in onset time of myelosuppression (11 days (interquartile range [IQR]: 7 to 14; minimum [min] to maximum [max]: 0 to 26) vs 8 days (IQR: 7 to 15; min to max: 3 to 29)) and nadir time of myelosuppression (21 days (IQR: 18 to 25; min to max: 12 to 35) vs 22 days (IQR: 15 to 25; min to max: 12 to 36)) between the CSI-IMRT group and the CSI-CRT group (Z = -0.856, -0.248; all P > .05). There were no significant differences in the incidence of decreased white blood cell counts (WBC), platelet counts, and hemoglobin concentration between the CSI-IMRT group and the CSI-CRT group, 86.8% (33/38) vs 78.1% (50/64), 57.9% (22/38) vs 42.2% (27/64), 57.9% (22/38) vs 53.1% (34/64); χ² = 1.195, 2.357, 0.219; all P > .05. There were no significant differences in the incidence of decreased WBC, platelet counts, and hemoglobin concentration (severe myelosuppression) in grades III and IV, 23.7% (9/38) vs 21.9% (14/64), 7.9% (3/38) vs 3.1% (2/64), 5.3% (2/38) vs 9.4% (6/64); χ² = 0.045, 1.164, 0.558; all P > .05.

Conclusions

There was no significant difference in the incidence of myelosuppression and severe myelosuppression (grade III or above) induced by CSI-IMRT and CSI-CRT. CSI-IMRT is worthy of further clinical application.

A Dosimetric and Radiobiological Comparison of Intensity Modulated Radiotherapy, Volumetric Modulated Arc Therapy and Helical Tomotherapy Planning Techniques in Synchronous Bilateral Breast Cancer

OBJECTIVE

The present investigation intends to identify the optimal radiotherapy treatment plan for synchronous bilateral breast cancer (SBBC) using dosimetric and radiobiological indexes for three techniques, namely, helical tomotherapy (HT), volumetric modulated arc therapy (VMAT), and intensity-modulated radiotherapy (IMRT).

METHODS

Twenty SBBC treated female patients treatment planning data (average age of 52.5 years) were used as the sample for the present study. Three different plans were created using 50 Gy in a 25 fraction dose regime. Poisson, Niemierko, and LKB models were applied for calculating normal tissue complication probability (NTCP) and tumour control probability (TCP).

RESULT

The target average dose comparison between IMRT with HT and VMAT with HT was highly substantial (P=0.001). The percentage of TCP for IMRT, VMAT, and HT in the Poisson model were 93.70±0.28, 94.68±0.30, and 94.34±0.57, respectively (p<0.05). The dose maximum was lower for the whole lung in the HT plan, with an average dose of 49.31Gy±3.9 (p<0.009). The NTCP values of both Niemierko and LKB models were lower for the heart, lungs, and liver for the IMRT plan.

CONCLUSION

The sparing of organs at risk was higher in the HT plan dosimetrically, and the TCP was higher in the three techniques. The comparison between the three techniques shows that the IMRT and HT techniques could be considered for treating SBBC.