Prete J J, Prestidge B R, Bice W S, Friedland J L, Stock R G, Grimm P D
Department of Radiation Oncology, Wilford Hall Medical Center, San Antonio, TX 78236-5300, USA.
Int J Radiat Oncol Biol Phys. 1998 Mar 1;40(4):1001-5. doi: 10.1016/s0360-3016(97)00901-2.
To obtain data with regard to current physics and dosimetry practice in transperineal interstitial permanent prostate brachytherapy (TIPPB) in the U.S. by conducting a survey of institutions performing this procedure with the greatest frequency.
Seventy brachytherapists with the greatest volume of TIPPB cases in 1995 in the U.S. were surveyed. The four-page comprehensive questionnaire included questions on both clinical and physics and dosimetry practice. Individuals not responding initially were sent additional mailings and telephoned. Physics and dosimetry practice summary statistics are reported. Clinical practice data is reported separately.
Thirty-five (50%) surveys were returned. Participants included 29 (83%) from the private sector and 6 (17%) from academic programs. Among responding clinicians, 125I (89%) is used with greater frequency than 103Pd (83%). Many use both (71%). Most brachytherapists perform preplans (86%), predominately employing ultrasound imaging (85%). Commercial treatment planning systems are used more frequently (75%) than in-house systems (25%). Preplans take 2.5 h (avg.) to perform and are most commonly performed by a physicist (69%). A wide range of apparent activities (mCi) is used for both 125I (0.16-1.00, avg. 0.41) and 103Pd (0.50-1.90, avg. 1.32). Of those assaying sources (71%), the range in number assayed (1 to all) and maximum accepted difference from vendor stated activity (2-20%) varies greatly. Most respondents feel that the manufacturers criteria for source activity are sufficiently stringent (88%); however, some report that vendors do not always meet their criteria (44%). Most postimplant dosimetry imaging occurs on day 1 (41%) and consists of conventional x-rays (83%), CT (63%), or both (46%). Postimplant dosimetry is usually performed by a physicist (72%), taking 2 h (avg.) to complete. Calculational formalisms and parameters vary substantially. At the time of the survey, few institutions have adopted AAPM TG-43 recommendations (21%). Only half (50%) of those not using TG-43 indicated an intent to do so in the future. Calculated doses at 1 cm from a single 1 mCi apparent activity source permanently implanted varied significantly. For 125I, doses calculated ranged from 13.08-40.00 Gy and for 103Pd, from 3.10 to 8.70 Gy.
While several areas of current physics and dosimetry practice are consistent among institutions, treatment planning and dose calculation techniques vary considerably. These data demonstrate a relative lack of consensus with regard to these practices. Furthermore, the wide variety of calculational techniques and benchmark data lead to calculated doses which vary by clinically significant amounts. It is apparent that the lack of standardization with regard to treatment planning and dose calculation practice in TIPPB must be addressed prior to performing any meaningful comparison of clinical results between institutions.
通过对美国开展经会阴间质永久性前列腺近距离放射治疗（TIPPB）频率最高的机构进行调查，获取有关当前美国TIPPB物理和剂量测定实践的数据。
对1995年美国TIPPB病例量最大的70位近距离放射治疗师进行了调查。这份四页的综合问卷包括了临床以及物理和剂量测定实践方面的问题。最初未回复的人员收到了额外的邮件并被电话联系。报告了物理和剂量测定实践的汇总统计数据。临床实践数据另行报告。
共收回35份（50%）调查问卷。参与者包括29位（83%）来自私营部门的人员和6位（17%）来自学术项目的人员。在回复的临床医生中，125I（89%）的使用频率高于103Pd（83%）。许多人同时使用两者（71%）。大多数近距离放射治疗师进行预计划（86%），主要采用超声成像（85%）。商业治疗计划系统的使用频率（75%）高于内部系统（25%）。预计划平均需要2.5小时完成，最常见由物理学家进行（69%）。125I（0.16 - 1.00，平均0.41）和103Pd（0.50 - 1.90，平均1.32）使用的表观活度（mCi）范围很广。在进行源测定的人员中（71%），测定的源数量范围（1个至全部）以及与供应商声明活度的最大可接受差异（2% - 20%）差异很大。大多数受访者认为制造商的源活度标准足够严格（88%）；然而，一些人报告供应商并非总是符合他们的标准（44%）。大多数植入后剂量测定成像在第1天进行（41%），包括传统X射线（83%）、CT（63%）或两者皆有（46%）。植入后剂量测定通常由物理学家进行（72%），平均需要2小时完成。计算形式和参数差异很大。在调查时，很少有机构采用美国医学物理学会（AAPM）TG - 43建议（21%）。未使用TG - 43的人员中只有一半（50%）表示未来打算采用。对于永久植入的单个表观活度为1 mCi的源，在距离1 cm处计算得到的剂量差异显著。对于125I，计算得到的剂量范围为13.08 - 40.00 Gy，对于103Pd，为3.10至8.70 Gy。
虽然当前物理和剂量测定实践的几个方面在各机构之间是一致的，但治疗计划和剂量计算技术差异很大。这些数据表明在这些实践方面相对缺乏共识。此外，各种计算技术和基准数据导致计算得到的剂量在临床上有显著差异。显然，在对各机构的临床结果进行任何有意义的比较之前，必须解决TIPPB治疗计划和剂量计算实践缺乏标准化的问题。
