van Wagenberg Teun, Fonseca Gabriel Paiva, Voncken Robert, van Beveren Celine, van Limbergen Evert, Lutgens Ludy, Vanneste Ben G L, Berbee Maaike, Reniers Brigitte, Verhaegen Frank
Department of Radiation Oncology (Maastro), GROW School for Oncology and Reproduction, Maastricht University Medical Centre+, Maastricht, The Netherlands.
Department of Radiation Oncology (Maastro), GROW School for Oncology and Reproduction, Maastricht University Medical Centre+, Maastricht, The Netherlands; Department of Human Structure and Repair; Department of Radiation Oncology, Ghent University Hospital, Gent, Belgium.
Brachytherapy. 2023 Mar-Apr;22(2):269-278. doi: 10.1016/j.brachy.2022.11.012. Epub 2023 Jan 9.
Even though High Dose Rate (HDR) brachytherapy has good treatment outcomes in different treatment sites, treatment verification is far from widely implemented because of a lack of easily available solutions. Previously it has been shown that an imaging panel (IP) near the patient can be used to determine treatment parameters such as the dwell time and source positions in a single material pelvic phantom. In this study we will use a heterogeneous head phantom to test this IP approach, and simulate common treatment errors to assess the sensitivity and specificity of the error-detecting capabilities of the IP.
A heterogeneous head-phantom consisting of soft tissue and bone equivalent materials was 3D-printed to simulate a base of tongue treatment. An High Dose Rate treatment plan with 3 different catheters was used to simulate a treatment delivery, using dwell times ranging from 0.3 s to 4 s and inter-dwell distances of 2 mm. The IP was used to measure dwell times, positions and detect simulated errors. Measured dwell times and positions were used to calculate the delivered dose.
Dwell times could be determined within 0.1 s. Source positions were measured with submillimeter accuracy in the plane of the IP, and average distance accuracy of 1.7 mm in three dimensions. All simulated treatment errors (catheter swap, catheter shift, afterloader errors) were detected. Dose calculations show slightly different distributions with the measured dwell positions and dwell times (gamma pass rate for 1 mm/1% of 96.5%).
Using an IP, it was possible to verify the treatment in a realistic heterogeneous phantom and detect certain treatment errors.
尽管高剂量率（HDR）近距离放射治疗在不同治疗部位都有良好的治疗效果，但由于缺乏易于获得的解决方案，治疗验证尚未得到广泛应用。此前已表明，患者附近的成像板（IP）可用于在单一材料盆腔体模中确定治疗参数，如驻留时间和源位置。在本研究中，我们将使用异质头部体模来测试这种IP方法，并模拟常见的治疗错误，以评估IP错误检测能力的敏感性和特异性。
3D打印一个由软组织和等效骨材料组成的异质头部体模，以模拟舌根部治疗。使用具有3种不同导管的高剂量率治疗计划来模拟治疗过程，驻留时间范围为0.3秒至4秒，驻留间隔为2毫米。使用IP测量驻留时间、位置并检测模拟错误。测量的驻留时间和位置用于计算输送剂量。
驻留时间可在0.1秒内确定。在IP平面内，源位置的测量精度可达亚毫米级，三维平均距离精度为1.7毫米。所有模拟的治疗错误（导管交换、导管移位、后装治疗机错误）均被检测到。剂量计算显示，测量的驻留位置和驻留时间的剂量分布略有不同（1毫米/1%时的伽马通过率为96.5%）。
使用IP能够在逼真的异质体模中验证治疗并检测某些治疗错误。
