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Miura H.,Miyakojima IGRT Clinic
Journal of applied clinical medical physics / American College of Medical Physics | Year: 2014

The purpose of this study was to investigate the impact of Monte Carlo (MC) calculations and optimized dose definitions in stereotactic body radiotherapy (SBRT) for lung cancer patients. We used a retrospective patient review and basic virtual phantom to determine dose prescriptions. Fifty-three patients underwent SBRT. A basic virtual phantom had a gross tumor volume (GTV) of 10.0 mm with equivalent water density of 1.0 g/cm3, which was surrounded by equivalent lung surrounding the GTV of 0.25 g/cm3. D95 of the planning target volume (PTV) and D99 of the GTV were evaluated with different GTV sizes (5.0 to 30.0 mm) and different lung densities (0.05 to 0.45 g/cm3). Prescribed dose was defined as 95% of the PTV should receive 100% of the dose (48 Gy/4 fractions) using pencil beam (PB) calculation and recalculated using MC calculation. In the patient study, average doses to the D95 of the PTV and D99 of the GTV using the MC calculation plan were 19.9% and 10.2% lower than those by the PB calculation plan, respectively. In the phantom study, decreased doses to the D95 of the PTV and D99 of the GTV using the MC calculation plan were accompanied with changes GTV size from 30.0to 5.0 mm, which was decreased from 8.4% to 19.6% for the PTV and from 17.4%to 27.5% for the GTV. Similar results were seen with changes in lung density from 0.45 to 0.05 g/cm3, with doses to the D95 of the PTV and D99 of the GTV were decreased from 12.8% to 59.0% and from 7.6% to 44.8%, respectively. The decrease in dose to the PTV with MC calculation was strongly dependent on lung density. We suggest that dose definition to the GTV for lung cancer SBRT be optimized using MC calculation. Our current clinical protocol for lung SBRT is based on a prescribed dose of 44 Gy in 4 fractions to the GTV using MC calculation. Source


Of 127 lung cancer patients treated with stereotactic body radiation therapy over 4 years, 35 patients (58 ribs) experienced radiation associated rib fractures (RARF) that developed in second through eighth ribs. Three-year estimated incidence of G1 RARF was 40%. Out of eight factors examined, site of primary tumors was significant by both uni- and multivariate analyses. Patient instruction such as fall prevention and avoidance of twist motion should be necessary to prevent the G2 RARF. Source


Kishi K.,Wakayama Medical University | Sonomura T.,Wakayama Medical University | Shirai S.,Wakayama Medical University | Noda Y.,Wakayama Medical University | And 3 more authors.
Brachytherapy | Year: 2013

Purpose/Introduction: To safely irradiate retroperitoneal targets as paraaortic lymph node by separating abdominal at-risk organs from the target during irradiation, we created a percutaneous paravertebral approach of high-dose-rate brachytherapy with hyaluronate gel injection (HGI). We report a case treated with this technique. Methods and Materials: We encountered a patient with symptomatic regrowth of paraaortic lymph node metastasis from prostatic cancer. He had previously received 58.4. Gy of radiotherapy to the same region 12 months prior. Brachytherapy needles and a HGI needle were deployed via the paravertebral approach under local anesthesia at our outpatient clinic. Results: A single dose of 22.5Gy (equivalent to 60.94Gy in 2Gy per fraction schedule calculated at α/β=10) was delivered to the target, with preservation of the surrounding small intestine by HGI with D2cc (minimum dose to the most irradiated volume of 2mL) of 5.05Gy. Therapeutic ratio was 3.64 times higher for this brachytherapy plan compared with an intensity-modulated radiation therapy plan. At followup at 1 year after brachytherapy, the symptoms had disappeared, tumor size had reduced with no fluorodeoxyglucose accumulation, and prostate-specific antigen level had decreased. Conclusion: We consider that high-dose-rate brachytherapy with the HGI procedure offers effective treatment even in this type of reirradiation situation. © 2013 American Brachytherapy Society. Source


Oh R.,Miyakojima IGRT Clinic
Japanese Journal of Clinical Radiology | Year: 2016

In recent decades, the number of long-term cancer survivors has increased. This has caused increasing requests for the delivery of a second course of radiation to recurrent tumors that occurred in previous radiotherapy fields. Most radiation oncologists are reluctant to offer reirradiation due to a lack of experience and potential toxicity. We reviewed our experience during 6 years and analyzed the outcome which indicates the low toxicity of reirradiation by using modern techniques should allow the delivery of higher doses and, as a consequence, lead to an improvement in the reirradiation outcome. Source


Inoue T.,Miyakojima IGRT Clinic | Masai N.,Miyakojima IGRT Clinic | Oh R.-J.,Miyakojima IGRT Clinic | Shiomi H.,Miyakojima IGRT Clinic | Hashida N.,Osaka University
Journal of Radiation Research | Year: 2014

Swept source optical coherence tomography (SS-OCT) is a convenient method for precise, early-stage detection of choroidal metastatic lesions, involving assessment of tumor response, and for regular follow-up studies. Using information obtained with SS-OCT, we performed intensity-modulated radiotherapy (IMRT) for a patient with choroidal metastasis from breast cancer with more accuracy than had been previously possible. We made replanning adaptive radiotherapy (ART) three times based on the rapid tumor shrinkage detected by weekly assessments with SS-OCT. Accordingly, the planning target volume (PTV) decreased from 1.6 cm3 to 0.61 cm3 (38%), with 0.95 cm3 (59%) and 0.75 cm3 (46%) as intermediate values during the treatment course. The D0.1 cm3 of the right optic nerve was also reduced from 1.70 Gy/fraction to 0.69 Gy/faction, with 1.41 Gy/fraction and 1.29 Gy/fraction as intermediate values. Adaptive replanning IMRT made it possible to perform locally curative treatment of the metastatic choroidal lesion with a higher dose for the PTV, and a lower dose for organs at risk (OARs). © 2014 The Author 2014. Published by Oxford University Press on behalf of The Japan Radiation Research Society and Japanese Society for Radiation Oncology. Source

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