Kaliyaperumal Venkatesan, Banerjee Susovan, Kataria Tejinder, Abraham Susan K, Kamaraj Dayanithi, Tamilselvan Singaravelu, Gupta Deepak, Bisht Shyam Singh, Narang Kushal, Shishak Sorun
Division of Radiation Oncology, Medanta Cancer Institute, Medanta the Medicity, Gurgaon, Haryana, India.
J Med Phys. 2022 Oct-Dec;47(4):322-330. doi: 10.4103/jmp.jmp_50_22. Epub 2023 Jan 10.
The goal of this study is to discuss the commissioning and dosimetric parameters achieved during the clinical implementation of an indigenously developed intracavitary (IC) plus interstitial (IS) template for high dose rate (HDR) image-guided brachytherapy (IGBT) in cancer (Ca) cervix. We want to discuss our achieved values of cumulative equi-effective doses (EQD2) for high-risk clinical target volume (HRCTV) and organ at risk (OAR) and compare it with available published results.
Medanta anterior oblique/lateral oblique template has a total of 19 needles including the central tandem. For commissioning the template with needles, the indigenously made acrylic phantom was used. Oblique and straight needles were placed inside the acrylic phantom and a computed tomography (CT) scan was performed. Sixteen patients were treated in HDR IGBT using this template after external-beam radiotherapy. The IGBT plans were evaluated based on EQD2 of target coverage i.e., dose received by 98% (D_HRCTV), 90% (D_HRCTV), and 50% (D_HRCTV) volume of HRCTV, and dose received by 2 cc (D) and 0.1 cc (D) of OAR using linear quadratic (LQ) radiobiological model.
The autoradiographic in radiochromic film shows that the distance between the needle tip and the middle of the source position is 6 mm. The mean D98%_HRCTV and D90%_HRCTV was 76.8 Gy (range: 70-87.7 Gy, < 0.01) and 84.49 Gy (range: 76.6-96.7 Gy, < 0.01), respectively. Mean EQD2 of D2cc of the bladder, rectum, and sigmoid was 85.6 Gy (range: 77.5-99.6 Gy, < 0.03), 74.3 Gy (range: 70.9-76.7 Gy, < 0.05), and 58.3 Gy (range: 50.6-67.9 Gy, = 0.01), respectively. The mean total reference air kerma at a 1 m distance is 0.489cGy (range: 0.391-0.681cGy).
The indigenously developed template could attain satisfactory standards in terms of set parameters for commissioning and acceptable dose volume relations in our clinical use for treating the advanced Ca cervix patients who need IC + IS type of HDR IGBT. The comparative analysis with contemporary applicators was acceptable.
本研究的目的是探讨在临床应用国产腔内（IC）加组织间（IS）模板进行宫颈癌高剂量率（HDR）图像引导近距离放疗（IGBT）过程中所实现的调试和剂量学参数。我们希望讨论高危临床靶区（HRCTV）和危及器官（OAR）的累积等效有效剂量（EQD2）的实现值，并将其与已发表的结果进行比较。
Medanta前后斜位/侧斜位模板共有19根针，包括中央串联针。为了用针调试模板，使用了国产丙烯酸模体。将斜针和直针放置在丙烯酸模体内并进行计算机断层扫描（CT）。16例患者在体外放疗后使用该模板进行HDR IGBT治疗。基于靶区覆盖的EQD2评估IGBT计划，即HRCTV的98%（D_HRCTV）、90%（D_HRCTV）和50%（D_HRCTV）体积所接受的剂量，以及使用线性二次（LQ）放射生物学模型评估OAR的2 cc（D）和0.1 cc（D）所接受的剂量。
放射变色胶片的放射自显影片显示针尖与源位置中点之间的距离为6 mm。HRCTV的平均D98%和D90%分别为76.8 Gy（范围：70 - 87.7 Gy，<0.01）和84.49 Gy（范围：76.6 - 96.7 Gy，<0.01）。膀胱、直肠和乙状结肠的D2cc的平均EQD2分别为85.6 Gy（范围：77.5 - 99.6 Gy，<0.03）、74.3 Gy（范围：70.9 - 76.7 Gy，<0.05）和58.3 Gy（范围：50.6 - 67.9 Gy，=0.01）。在1 m距离处的平均总参考空气比释动能为0.489 cGy（范围：0.391 - 0.681 cGy）。
在我们临床用于治疗需要IC + IS型HDR IGBT的晚期宫颈癌患者时，国产模板在调试设置参数和可接受的剂量体积关系方面能够达到令人满意的标准。与当代施源器的比较分析是可以接受的。
