Development and evaluation of a novel water-based pigment marker for radiation therapy skin marking.

Skin marks are widely used in external radiation therapy to ensure the accuracy of the irradiation position. However, conventional skin markers contain harmful substance, so we developed an alternative skin marker. The purpose of this study was to investigate the feasibility of using a novel water-based pigment marker comprising safe materials commonly used in cosmetics for clinical radiation therapy. We investigated various properties of the marker, namely marker longevity, color variety, line visibility, ink bleeding, and line durability, and improved the marker in response to the feel when drawing or being drawn on. The durability of the ink was evaluated by simultaneously applying the new marker and oil-based pen and comparing the period until the marks faded and became invisible. In clinical trial, we applied marks on the skin of 56 patients over three months to observe symptoms and visible changes in the skin. There were no complications of discomfort or pain, owing to the improvements in the marker tip. The marks drawn on the arms of volunteers with the new marker and the oil-based pen remained visible for a mean of 7.2 days and 3.6 days, respectively (P value < 0.001). The percentages of participants with no symptoms and no visible changes were 100%, respectively. We developed an alternative skin marker that complies with current regulatory standards by excluding crystal violet. The newly developed marker has features suitable for clinical use, such as resistance to smudging and water, marker tip shape and texture, and color variations.

Experience with Photodynamic Therapy Using Indocyanine Green Liposomes for Refractory Cancer.

We reported the development of an effective cancer treatment using a multidisciplinary treatment, including photodynamic therapy (PDT) with indocyanine green (ICG) liposomes and a combination of Lentinula edodes mycelia (LEM) and hydrogen gas inhalation therapy. ICG liposomes were prepared by adding 5 mg of ICG to 50 mL liposomes. Later, 25 mL of ICG liposomes were diluted with 250 mL of 5% glucose solution and administered intravenously to the patient. We selected the multi-laser delivery system (MLDS), a laser irradiator for performing PDT. Further, the patients received a combination of LEM and hydrogen gas inhalation therapy throughout the treatment. We reported two cases of PDT therapy, one with middle intrathoracic esophagus carcinoma and the other with hypopharyngeal cancer. In the first case, the MLDS laser was directly attached to the endoscope and directed to the cancer area with wavelengths of 810 nm. After the treatment, a biopsy demonstrated no tumor recurrence. In the second case, the patient was treated with endovascular PDT using ICG liposomes and MLDS fiber optics. Later, tumor shrinkage was demonstrated after the first round and disappeared after six months. In conclusion, the present findings suggest that the effect of PDT using ICG liposomes with LEM and hydrogen gas may eradicate cancer without burdening patients by enhancing tumor immunity.

Estimation of extremely small field radiation dose for brain stereotactic radiotherapy using the Vero4DRT system.

The purpose of this study was a dosimetric validation of the Vero4DRT for brain stereotactic radiotherapy (SRT) with extremely small fields calculated by the treatment planning system (TPS) iPlan (Ver.4.5.1; algorithm XVMC). Measured and calculated data (e.g. percentage depth dose [PDD], dose profile, and point dose) were compared for small square fields of 30 × 30, 20 × 20, 10 × 10 and 5 × 5 mm2 using ionization chambers of 0.01 or 0.04 cm3 and a diamond detector. Dose verifications were performed using an ionization chamber and radiochromic film (EBT3; the equivalent field sizes used were 8.2, 8.7, 8.9, 9.5, and 12.9 mm2) for five brain SRT cases irradiated with dynamic conformal arcs. The PDDs and dose profiles for the measured and calculated data were in good agreement for fields larger than or equal to 10 × 10 mm2 when an appropriate detector was chosen. The dose differences for point doses in fields of 30 × 30, 20 × 20, 10 × 10 and 5 × 5 mm2 were +0.48%, +0.56%, -0.52%, and +11.2% respectively. In the dose verifications for the brain SRT plans, the mean dose difference between the calculated and measured doses were -0.35% (range, -0.94% to +0.47%), with the average pass rates for the gamma index under the 3%/2 mm criterion being 96.71%, 93.37%, and 97.58% for coronal, sagittal, and axial planes respectively. The Vero4DRT system provides accurate delivery of radiation dose for small fields larger than or equal to 10 × 10 mm2.

Accuracy of image guidance using free-breathing cone-beam computed tomography for stereotactic lung radiotherapy.

Movement of the target object during cone-beam computed tomography (CBCT) leads to motion blurring artifacts. The accuracy of manual image matching in image-guided radiotherapy depends on the image quality. We aimed to assess the accuracy of target position localization using free-breathing CBCT during stereotactic lung radiotherapy. The Vero4DRT linear accelerator device was used for the examinations. Reference point discrepancies between the MV X-ray beam and the CBCT system were calculated using a phantom device with a centrally mounted steel ball. The precision of manual image matching between the CBCT and the averaged intensity (AI) images restructured from four-dimensional CT (4DCT) was estimated with a respiratory motion phantom, as determined in evaluations by five independent operators. Reference point discrepancies between the MV X-ray beam and the CBCT image-guidance systems, categorized as left-right (LR), anterior-posterior (AP), and superior-inferior (SI), were 0.33 ± 0.09, 0.16 ± 0.07, and 0.05 ± 0.04 mm, respectively. The LR, AP, and SI values for residual errors from manual image matching were -0.03 ± 0.22, 0.07 ± 0.25, and -0.79 ± 0.68 mm, respectively. The accuracy of target position localization using the Vero4DRT system in our center was 1.07 ± 1.23 mm (2 SD). This study experimentally demonstrated the sufficient level of geometric accuracy using the free-breathing CBCT and the image-guidance system mounted on the Vero4DRT. However, the inter-observer variation and systematic localization error of image matching substantially affected the overall geometric accuracy. Therefore, when using the free-breathing CBCT images, careful consideration of image matching is especially important.