Abstract：
BACKGROUND: Methods for accurate absolute dose (AD) calibration are essential for the proper functioning of radiotherapy treatment machines. Many systems do not conform to TG-51 calibration standards, and modifications are required. TG-21 calibration is also a viable methodology for these situations with the appropriate setup, equipment, and factors. It has been shown that both these methods result in minimal errors. A similar approach has been taken in calibrating the dose for a recent vault-free radiosurgery system.
OBJECTIVE: To evaluate modified TG-21 and TG-51 protocols for AD calibrations of the ZAP-X radiosurgery system using ion chambers, film, and thermoluminescent dosimeters (TLDs).
METHODS: The current treatment planning system for ZAP-X requires AD calibration at dmax (7 mm) and 450 mm source-to-axis distance. Both N D , w 60 C o [ G y / C ] $N_{D,w}^{{60}Co}[ {Gy/C} ]$ and Nx [R/C] calibration coefficients were provided by an accredited dosimetry calibration laboratory for a physikalisch technische werkstatten (PTW) 31010 chamber (0.125 cc). The vendor provides an f-bracket that can be mounted on the collimator. Various phantoms can then be attached to the f-bracket. A custom acrylic phantom was designed based on recommendations from TG-21 and technical report series-398 that places the chamber at 500 mm from the source with a depth of 44-mm acrylic and 456-mm SSD. Nx along with other TG-21 parameters was used to calculate the AD. Measurements using a PTW MP3-XS water tank and the same chamber were used to calculate AD using N D , w 60 C o $N_{D,w}^{{60}Co}$ and TG-51 factors. Dose verification was performed using Gafchromic film and 3rd party TLDs.
RESULTS: Measurements from TG-51, TG-21 (utilizing the custom acrylic phantom), film, and TLDs agreed to within ± 2%.
CONCLUSIONS: A modified TG-51 AD calculation in water is preferred but may not be practical due to the difficulty in tank setup. The TG-21 modified protocol using a custom acrylic phantom is an accurate alternative option for dose calibration. Both of these methods are within acceptable agreement and provide confidence in the system\'s AD calibration.
OBJECTIVE: To evaluate modified TG-21 and TG-51 protocols for AD calibrations of the ZAP-X radiosurgery system using ion chambers, film, and thermoluminescent dosimeters (TLDs).
METHODS: The current treatment planning system for ZAP-X requires AD calibration at dmax (7 mm) and 450 mm source-to-axis distance. Both N D , w 60 C o [ G y / C ] $N_{D,w}^{{60}Co}[ {Gy/C} ]$ and Nx [R/C] calibration coefficients were provided by an accredited dosimetry calibration laboratory for a physikalisch technische werkstatten (PTW) 31010 chamber (0.125 cc). The vendor provides an f-bracket that can be mounted on the collimator. Various phantoms can then be attached to the f-bracket. A custom acrylic phantom was designed based on recommendations from TG-21 and technical report series-398 that places the chamber at 500 mm from the source with a depth of 44-mm acrylic and 456-mm SSD. Nx along with other TG-21 parameters was used to calculate the AD. Measurements using a PTW MP3-XS water tank and the same chamber were used to calculate AD using N D , w 60 C o $N_{D,w}^{{60}Co}$ and TG-51 factors. Dose verification was performed using Gafchromic film and 3rd party TLDs.
RESULTS: Measurements from TG-51, TG-21 (utilizing the custom acrylic phantom), film, and TLDs agreed to within ± 2%.
CONCLUSIONS: A modified TG-51 AD calculation in water is preferred but may not be practical due to the difficulty in tank setup. The TG-21 modified protocol using a custom acrylic phantom is an accurate alternative option for dose calibration. Both of these methods are within acceptable agreement and provide confidence in the system\'s AD calibration.
摘要：
背景：准确的绝对剂量（AD）校准方法对于放射治疗机的正常运行至关重要。许多系统不符合TG-51校准标准，和修改是必需的。TG-21校准也是适用于这些情况的可行方法，设备,和因素。已经表明,这两种方法都导致最小的误差。在校准最近的无拱顶放射外科系统的剂量时，已经采取了类似的方法。
目的：为了评估使用离子室对ZAP-X放射外科系统进行AD校准的改良TG-21和TG-51方案，电影,和热释光剂量计（TLD）。
方法：ZAP-X的当前治疗计划系统需要在dmax（7mm）和450mm的源到轴距离进行AD校准。两个ND,w60Co[Gy/C]$N_{D，w}^{{60}Co}[{Gy/C}]$和Nx[R/C]校准系数由认可的剂量学校准实验室提供，用于物理检验技术（PTW）31010室（0.125cc）。供应商提供了可以安装在准直器上的f形支架。然后可以将各种体模附接到f形支架。根据TG-21和技术报告系列-398的建议设计了一个定制的丙烯酸体模，该腔室距离源头500毫米，深度为44毫米丙烯酸和456毫米SSD。Nx与其他TG-21参数一起用于计算AD。使用PTWMP3-XS水箱和相同腔室进行的测量用于使用ND计算AD，w60Co$N_{D，w}^{{60}Co}$和TG-51因素。使用Gafchrome胶片和第三方TLD进行剂量验证。
结果：来自TG-51，TG-21（使用定制丙烯酸体模）的测量值，电影,和TLD同意在±2%以内。
结论：在水中进行改进的TG-51AD计算是优选的，但由于储罐设置困难，可能不切实际。使用定制丙烯酸体模的TG-21修改方案是剂量校准的准确替代选择。这两种方法均在可接受的协议范围内，并对系统的AD校准提供了信心。
目的：为了评估使用离子室对ZAP-X放射外科系统进行AD校准的改良TG-21和TG-51方案，电影,和热释光剂量计（TLD）。
方法：ZAP-X的当前治疗计划系统需要在dmax（7mm）和450mm的源到轴距离进行AD校准。两个ND,w60Co[Gy/C]$N_{D，w}^{{60}Co}[{Gy/C}]$和Nx[R/C]校准系数由认可的剂量学校准实验室提供，用于物理检验技术（PTW）31010室（0.125cc）。供应商提供了可以安装在准直器上的f形支架。然后可以将各种体模附接到f形支架。根据TG-21和技术报告系列-398的建议设计了一个定制的丙烯酸体模，该腔室距离源头500毫米，深度为44毫米丙烯酸和456毫米SSD。Nx与其他TG-21参数一起用于计算AD。使用PTWMP3-XS水箱和相同腔室进行的测量用于使用ND计算AD，w60Co$N_{D，w}^{{60}Co}$和TG-51因素。使用Gafchrome胶片和第三方TLD进行剂量验证。
结果：来自TG-51，TG-21（使用定制丙烯酸体模）的测量值，电影,和TLD同意在±2%以内。
结论：在水中进行改进的TG-51AD计算是优选的，但由于储罐设置困难，可能不切实际。使用定制丙烯酸体模的TG-21修改方案是剂量校准的准确替代选择。这两种方法均在可接受的协议范围内，并对系统的AD校准提供了信心。
