Risk-Adapted SABR for Ultra-Central Lung Tumors Attaining High BED10 to Targets in a Steep Dose-Response Window of 72-105 Gy under Tumor Tracking: A Planning Study

PURPOSE/OBJECTIVE(S)

Higher rate of durable local control in stereotactic ablative radiotherapy (SABR) for ultra-central lung tumors (UCLTs) strongly correlates to a BED10 ≥ 100 Gy to the tumors. However, higher rates of grade 5 toxicities are reported to be directly associated with higher dose to the organs at risk (OARs) abutting or in close distance to the UCLTs, including trachea, proximal bronchial tree (PBT) and esophagus. This study evaluated two risk-adapted SABR schemes in a steep dose-response window of BED10 at 72 -105 Gy with isotoxic optimization and dynamic tumor tracking to safely attain high BED10 to the tumors while keeping dose to the OARs within evidence-based tolerances.

MATERIALS/METHODS

A total of 12-16 patients are included for planning under two risk-adapted-SABR schemes of 60 Gy in 8 (scheme A) and15 (scheme B) fractions to attain high BED10 of ≥100 Gy to the distal sections of the PTV and yet potent BED10 at 72-84 Gy to the proximal sections of the PTV. Such inhomogeneous dose plans use a 3-5 mm GTV to PTV margins under a scenario that patients have at least one fiducial marker placed in or near the GTV for real-time tumor tracking on a robotic SRS-SABR system. All plans used fixed cone collimators and a planning tool's dose calculation to reach highest BED10 dose coverage achievable to the target volumes while respecting the OAR dose tolerances, including V105 Gy, V100 Gy, V84 Gy and V72 Gy in BED10 for target volumes and the maximum EQD2 dose tolerances (α/β = 3 Gy) in D0.03cc for the trachea/PBT ≤80.5-82.5 Gy and esophagus ≤64.0-77.6 Gy in scheme-A; and trachea/PBT≤97.7 Gy and esophagus ≤64.3 Gy in scheme-B. Median and range of plan dosimetry metrics are compared between the two schemes.

RESULTS

For scheme-A, mean BED10 to PTV are 118.0 Gy (median) in105.5-133.5 Gy (range), and mean BED10 dose to GTV are 132.2 (118.3-149.4 Gy). EQD2 dose to trachea are 80.5 Gy (68.0-81.7 Gy), PBT 80.5 Gy (49.1-82.2 Gy), esophagus 67.2 Gy (51.6-77.3 Gy). PTV coverage by BED10 of 72 Gy, 84 Gy, 100 Gy and 105 Gy are 98.9% (87.5-100%), 97.1% (81.8-99.8%), 91.9% (72.5-98.6%) and 85.3% (68.5-97.9%). For scheme-B, mean BED10 to PTV are 102.2 Gy (93.4-106.0 Gy), and mean BED10 dose to GTV are 115.4 (103.4-117.3 Gy). EQD2 dose to trachea are 73.3 Gy (67.5-96.3 Gy), PBT 90.9 Gy (74.4-97.2 Gy), esophagus 61.4 Gy (41.9-64.1 Gy). PTV coverage by BED10 of 72 Gy, 84 Gy, 100 Gy and 105 Gy are 100% (94.9-100%), 95.5% (83.9-99.0%), 54.8% (31.2-65.4%) and 42.8% (17.9-53.2%).

CONCLUSION

Two risk-adapted SABR of 7.5 Gyx8 and 4 Gyx15 are implemented for treating ultra-central lung tumors with BED10 ≥100 Gy to the distal sections of PTV and yet attain potent BED10 ≥72-84 Gy to the proximal sections of PTV that abut or overlap with trachea, proximal bronchial tree or esophagus. Accurate dose calculation by a planning tool and real-time tumor tracking are essential for safe and accurate delivery of such high-risk SABR treatments.

Effect of nerve root block guided by ultrasound on cervicogenic pain and its influence on immune function

Cervicogenic pain is a common chronic disease that needs individualized treatment according to the place of pain. This study aimed to observe the effect of ultrasound-guided nerve root block in the treatment of cervicogenic pain and its influence on immune function. A total of 30 patients (group A) with cervical discogenic pain (CDP) were treated by selective cervical nerve root block and 30 patients (group B) with CDP were treated with cervical spinal block under the X-ray C-arm guidance. The two groups of patients were examined with regard to the analgesic effect by Numerical Rating Scale (NRS), and the changes in the preoperative and postoperative range of motion in the neck (ROM). In addition, weekly pain attacks and the duration of each attack were recorded. The content of CD3+, CD4+ and CD8+ in the peripheral blood T lymphocyte subsets in the two groups was evaluated by flow cytometry. The levels of these subsets were compared 24 h before treatment, 24 h after treatment, 3 days (d) after treatment and 7 d after treatment. At the time periods of 24 h, 3 d, and 7 d after treatment, the NRS of the two groups decreased significantly compared with before treatment (P less than 0.01). The changes of the ROM, the number of weekly pain attacks, the duration of each pain attack, and the stiffness of the head and neck were significantly lower in the two groups compared with those prior to the treatment (P less than 0.05). In group A and group B, the number of CD3+, CD4+ and CD8+ T cells 24 h and 3 d after treatment increased significantly compared with that noted before treatment (P less than 0.05). Seven days after treatment, the levels of CD3+, CD4+ and CD8+ T cells in the peripheral blood T lymphocytes of group A were significantly higher than those of group B (P less than 0.05). Selective cervical nerve root block under ultrasound is an effective method for the treatment of cervical discogenic pain. The effect is better than that of the X-ray C-arm-guided cervical block method. The mechanism of selective cervical nerve root block under ultrasound may be related to the regulation of the content of CD3+, CD4+, CD8+ T cells in the peripheral blood T lymphocyte subsets and the enhancement of cellular immunity.

Structure-charge transport relationship of 5,15-dialkylated porphyrins

5,15-Dialkyl-substituted porphyrins that are symmetrically capped with ethyl (C(2)-Por), butyl (C(4)-Por) and hexyl (C(6)-Por) were synthesized and characterized. Molecular structure versus physical property relationship has been established through the analysis of planar charge transport using thin film transistor (TFT) structure.

Method for measurement of the density of thin films of small organic molecules

An accurate and sensitive method is reported to measure the thin-film density of vacuum-deposited, small-molecular organic semiconductor materials. A spectrophotometer and surface profiler had been used to determine the mass and thickness of organic thin film, respectively. The calculated density of tris-(8-hydroxyquinolato) aluminum (Alq(3)) thin film was 1.31+/-0.01 gcm(3). Vacuum pressures and thin-film growth rates are found to have less impact on the thin-film density of organic material. However, the thin-film density of organic material strongly depends on its chemical structure and molecular weight. Specifically, the chemical structure determines the density of organic material that affects the molecular volume and intermolecular stacking.

High-efficiency red electrophosphorescence based on neutral bis(pyrrole)-diimine platinum(ii) complex

Efficient red electroluminescence from the excimer or oligomer of neutral phosphorescent bis(pyrrole)-diimine Pt(II) complex has been achieved with maximum external quantum efficiency, luminous efficiency, power efficiency and brightness of 6.5%, 9.0 cd A(-1), 4.0 lm W(-1) and 11 100 cd m(-2), respectively.

Tetradentate Schiff base platinum(ii) complexes as new class of phosphorescent materials for high-efficiency and white-light electroluminescent devicesElectronic supplementary information (ESI) available: synthesis and spectroscopic, thermal (TGA), photophysical, electrochemical and EL characterization; CIF. See http://www.rsc.org/suppdata/cc/b4/b402318h/

The capabilities of readily prepared and sublimable Pt(II) Schiff base triplet emitters as OLED dopants have been examined; maximum luminous and power efficiencies and luminance of 31 cd A(-1), 14 lm W(-1), and 23,000 cd m(-2), respectively, and white EL (CIE: 0.33, 0.35) by simultaneous host/dopant emission, have been achieved.