限局期前立腺癌に対する高線量強度変調放射線治療後の晩期直腸出血においてMLC幅が与える臨床的影響

京都大学0048新制・論文博士博士(医学)乙第13032号論医博第2114号新制||医||1016(附属図書館)32990横浜市立大学大学院医科学専攻(主査)教授 増永 慎一郎, 教授 坂井 義治, 教授 小川 修学位規則第4条第2項該当Doctor of Medical ScienceKyoto UniversityDFA

Dynamic tumor-tracking stereotactic body radiotherapy with real-time monitoring of liver tumors using a gimbal-mounted linac: A multi-institutional phase II study

[Background and purpose] This prospective multicenter phase II study aimed to evaluate the safety and efficacy of dynamic tumor tracking (DTT) stereotactic body radiotherapy (SBRT) with real-time monitoring of liver tumors using a gimbal-mounted system. [Materials and methods] Patients with < 4 primary or metastatic liver tumors with diameters ≤ 50 mm and expected to have a respiratory motion of ≥ 10 mm were eligible. The prescribed dose was 40 Gy in five fractions. The primary endpoint was local control (LC) at 2 years. The secondary endpoints were overall survival (OS), progression-free survival (PFS), treatment-related toxicity, and tracking accuracy. [Results] Between September 2015 and March 2019, 48 patients (48 lesions) with a median age of 74 years were enrolled from four institutions. Of these, 39 were diagnosed with hepatocellular carcinoma and nine with metastatic liver cancer. The median tumor diameter was 17.5 mm. DTT-SBRT was successfully performed in all patients; the median treatment time was 28 min/fraction. The median follow-up period was 36.5 months. The 2-year LC, OS, and PFS rates were 98.0 %, 88.8 %, and 55.1 %, respectively. Disease progression was observed in 33 (68.8 %) patients. One patient (0.2 %) had local recurrence, 31 (64.6 %) developed new hepatic lesions outside the irradiation field, and nine (18.8 %) had distant metastases (including overlap). Grade 3 late adverse events were observed in seven patients (14.5 %). No grade 4 or 5 treatment-related toxicity was observed. The median tracking accuracy was 2.9 mm. [Conclusion] Employing DTT-SBRT to treat liver tumors results in excellent LC with acceptable adverse-event incidence

A pilot study of highly hypofractionated intensity-modulated radiation therapy over 3 weeks for localized prostate cancer

The purpose of this pilot study was to evaluate the feasibility of highly hypofractionated intensity-modulated radiation therapy (IMRT) in 15 fractions over 3 weeks for treating localized prostate cancer based on prostate position-based image-guided radiation therapy. Twenty-five patients with National Comprehensive Cancer Network (NCCN) very low- to unfavorable intermediate-risk prostate cancer were enrolled in this study from April 2014 to September 2015 to receive highly hypofractionated IMRT (without intraprostatic fiducial markers) delivering 54 Gy in 15 fractions over 3 weeks. Patients with intermediate-risk disease underwent neoadjuvant androgen suppression for 4–8 months. Twenty-four patients were treated with highly hypofractionated IMRT, and one was treated with conventionally fractionated IMRT because the dose constraint of the small bowel seemed difficult to achieve during the simulation. Seventeen percent had very low- or low-risk, 42% had favorable intermediate-risk, and 42% had unfavorable intermediate-risk disease according to NCCN guidelines. The median follow-up period was 31 months (range, 24–42 months). No Grade ≥3 acute toxicity was observed, and the incidence rates of Grade 2 acute genitourinary and gastrointestinal toxicities were 21% and 4%, respectively. No Grade ≥2 late toxicity was observed. Biochemical relapse was observed in one patient at 15 months, and the biochemical relapse-free survival rate was 95.8% at 2 years. A prostate-specific antigen bounce of ≥0.4 ng/ml was observed in 11 patients (46%). The highly hypofractionated IMRT regimen is feasible in patients with localized prostate cancer and is more convenient than conventionally fractionated schedules for patients and health-care providers

Correlation between urinary dose and delayed radiation cystitis after 78 Gy intensity-modulated radiotherapy for high-risk prostate cancer: A 10-year follow-up study of genitourinary toxicity in clinical practice

Purpose: To investigate the factors associated with the risk of long-term genitourinary (GU) toxicity among high-risk prostate cancer (PC) patients treated with high-dose intensity-modulated radiotherapy (IMRT). Methods and materials: Between 2000 and 2011, PC patients treated with 78 Gy in 39 fractions delivered by IMRT combined with neo-adjuvant hormonal therapy were selected from among our database. GU toxicities and clinical factors, as well as separate anatomical urinary structures, were evaluated in terms of their associations. Results: A total of 309 patients was included in this study. The median follow-up was 104 months (range: 24–143 months). The most frequently observed late grade ≥2 GU toxicity was hematuria (11.2%: 10-year actuarial risk) with radiation cystitis observed in the majority of patients. In univariate analysis, late grade ≥2 hematuria was associated with the exposure to doses >75 Gy (V75) of the bladder neck and V70 of the bladder wall, as well as with T stage. V75 of the bladder neck remained significant in multivariate analysis (p = 0.049). Conclusions: At the 10-year follow up of high-dose IMRT, a major concern was proved to be delayed cystitis related to the higher volume of bladder neck dose exposed excess over 75 Gy

Dosimetric evaluation of the Acuros XB algorithm for a 4MV photon beam in head and neck intensity-modulated radiation therapy

In this study, we assessed the differences in the dose distribution of a 4 MV photon beam among different calculation algorithms: the Acuros XB (AXB) algorithm, the analytic anisotropic algorithm (AAA), and the pencil beam convolution (PBC) algorithm (ver. 11.0.31), in phantoms and in clinical intensity-modulated radiation therapy (IMRT) plans. Homogeneous and heterogeneous, including middle-, low-, and high-density, phantoms were combined to assess the percentage depth dose and lateral dose profiles among AXB, AAA, and PBC. For the phantom containing the low-density area, AXB was in agreement with measurement within 0.5%, while the greatest differences between the AAA and PBC calculations and measurement were 2.7% and 3.6%, respectively. AXB showed agreement with measurement within 2.5% at the high-density area, while AAA and PBC overestimated the dose by more than 4.5% and 4.0%, respectively. Furthermore, 15 IMRT plans, calculated using AXB, for oropharyngeal, hypopharyngeal, and laryngeal carcinomas were analyzed. The dose prescription was 70 Gy to 50% of the planning target volume (PTV70). Subsequently, each plan was recalculated using AAA and PBC while maintaining the AXB-calculated monitor units, leaf motion, and beam arrangement. Additionally, nine hypopharyngeal and laryngeal cancer patients were analyzed in terms of PTV70 for cartilaginous structures (PTV70_cartilage). The doses covering 50% to PTV70 calculated by AAA and PBC were 2.1% ± 1.0% and 3.7% ± 0.8% significantly higher than those using AXB, respectively (p < 0.01). The increases in doses to PTV70_cartilage calculated by AAA and PBC relative to AXB were 3.9% and 5.3% on average, respectively, and were relatively greater than those in the entire PTV70. AXB was found to be in better agreement with measurement in phantoms in heterogeneous areas for the 4 MV photon beam. Considering AXB as the standard, AAA and PBC overestimated the IMRT dose for head and neck cancer. The dosimetric differences should not be ignored, particularly with cartilaginous structures in PTV

災害ハザード・リスク・復興過程等に関する情報の統合型データ・ベースシステム(クロスメディア・データベース)の構築(4)

本年度はクロスメディアデータベースに新たに災害後の地域の復興プロセス・モニタリングシステムの追加を行った。このシステムにより、災害復興プロセスのモニタリングに不可欠な被災地の日々の画像を蓄積していく事が可能になる。また、システムの整備に加えて、神戸市長田区御蔵地区(阪神・淡路大震災の被災地)、台湾・中寮郷永平村(1999年台湾集集地震の被災地)、三宅村(2000年三宅島噴火災害の被災地)でこれまで観測されてきた復興プロセスのデジタルデータのアーカイビングも実施した。During the 2006-2007 academic year, a recovery process monitoring system was installed into the XMDB as a subsystem. Daily images of disaster impacted area have been monitored as a basic datasets enabling to analyze recovery process from disaster. Three sets of digital images showing recovery process at the disaster impacted area such as Kobe-Japan, Chungliao-Taiwan and Miyake Island-Japan were also archived into the XMDB. Geo-int database concept framework using a geo-lactation as the key for relating all kinds of information were developed. Possibility of implementing the geo-int concept database was tested in disaster response of 2007 Noto Earthquake Disaster.本年度はクロスメディアデータベースに新たに災害後の地域の復興プロセス・モニタリングシステムの追加を行った。このシステムにより、災害復興プロセスのモニタリングに不可欠な被災地の日々の画像を蓄積していく事が可能になる。また、システムの整備に加えて、神戸市長田区御蔵地区(阪神・淡路大震災の被災地)、台湾・中寮郷永平村(1999年台湾集集地震の被災地)、三宅村(2000年三宅島噴火災害の被災地)でこれまで観測されてきた復興プロセスのデジタルデータのアーカイビングも実施した。During the 2006-2007 academic year, a recovery process monitoring system was installed into the XMDB as a subsystem. Daily images of disaster impacted area have been monitored as a basic datasets enabling to analyze recovery process from disaster. Three sets of digital images showing recovery process at the disaster impacted area such as Kobe-Japan, Chungliao-Taiwan and Miyake Island-Japan were also archived into the XMDB. Geo-int database concept framework using a geo-lactation as the key for relating all kinds of information were developed. Possibility of implementing the geo-int concept database was tested in disaster response of 2007 Noto Earthquake Disaster

Impact of prostate position-based image-guidance in intensity-modulated radiation therapy for localized prostate cancer

[Background/purpose] The long-term clinical impact of prostate position-based image-guided radiotherapy (IGRT) for localized prostate cancer remains unclear. [Materials and methods] We retrospectively compared clinical outcomes following intensity-modulated radiation therapy (IMRT) with cone-beam computed tomography-based prostate position-based IGRT (P-IGRT) or without P-IGRT (non-P-IGRT). From June 2011, we applied P-IGRT in IMRT for intermediate-risk (IR) prostate cancer (PCa) (D’Amico risk classification) (76 Gy in 38 fractions, with smaller margins). Clinical outcomes of patients who received P-IGRT between June 2011 and June 2019 were retrospectively compared with those of patients with IR PCa who received IMRT without P-IGRT between October 2002 and May 2011 in our institution (74 Gy in 37 fractions). [Results] A total of 222 consecutive patients were analyzed: 114 in the P-IGRT cohort and 108 in the non-P-IGRT cohort. The median follow-up period after IMRT was 7.1 years for the P-IGRT cohort and 10.8 years for the non-P-IGRT cohort. The biochemical failure-free rate was significantly better in the P-IGRT cohort (94.9% for the P-IGRT cohort vs 82.7% for the non-P-IGRT cohort at 10 years, p = 0.041). The rate of rectal bleeding which needs intervention including the use of suppositories was significantly lower in the P-IGRT cohort (p < 0.001). [Conclusions] The use of P-IGRT with higher doses and smaller margins was correlated with significantly better biochemical control, and a lower incidence of rectal bleeding in IMRT for intermediate-risk prostate cancer. The enhanced accuracy using P-IGRT has the potential to independently improve disease control and reduce late rectal bleeding