ConPas：一种用于双侧颈部治疗的三维适形腮腺保留照射技术，可作为调强放疗的替代方案。
ConPas: a 3-D conformal parotid gland-sparing irradiation technique for bilateral neck treatment as an alternative to IMRT.
作者信息
Wiggenraad Ruud, Mast Mirjam, van Santvoort Jan, Hoogendoorn Marc, Struikmans Henk
机构信息
Department of Radiotherapy, The Hague Medical Center, The Hague, The Netherlands.
出版信息
Strahlenther Onkol. 2005 Oct;181(10):673-82. doi: 10.1007/s00066-005-1413-8.
BACKGROUND AND PURPOSE
Intensity-modulated radiotherapy (IMRT) is used in most reported techniques for bilateral neck irradiation that aim at parotid gland sparing. A relatively simple conformal parotid-sparing technique (ConPas) was developed that uses no beam-intensity modulation. The purpose of this paper is to demonstrate, in patients with larynx or hypopharynx carcinoma, that ConPas enables adequate coverage of the primary tumor and the bilateral neck nodes, while keeping the mean parotid dose (MPD) < 26 Gy.
PATIENTS AND METHODS
Treatment plans using ConPas and the conventional technique (using one anteroposterior supraclavicular and two lateral beams) were computed for ten consecutive patients with T1-4 N0-1 larynx or hypopharynx carcinoma (not T1 glottic). A dose of 46 Gy was prescribed to the primary tumor and the bilateral neck nodes, planned either with the conventional technique or ConPas, followed by a boost up to 70 Gy with a simple two-field technique. The target coverage of both techniques was compared using the V(95), the percentage of the planning target volume (PTV) of the primary tumor and nodal regions receiving at least 95% of the prescribed elective dose. The MPDs and the normal-tissue complication probabilities (NTCPs) of the parotid glands were compared using either technique including the boost up to 70 Gy. Dosimetric verification of the technique has been carried out, using ionization chamber measurements and film dosimetry.
RESULTS
The mean V(95) was 85.2% and 91.2% (p = 0.08), the mean MPD 38.7 Gy and 25.4 Gy (p < 0.001), and the mean NTCP for the parotid glands 0.87 and 0.22 (p < 0.001) for the conventional technique and ConPas, respectively. The dosimetric verification shows a good agreement between dose calculation and measurement.
CONCLUSION
ConPas enables adequate target coverage and clinically relevant parotid sparing in bilateral neck irradiation without beam-intensity modulation.
背景与目的
在大多数已报道的旨在保留腮腺的双侧颈部照射技术中，调强放疗（IMRT）被广泛应用。我们开发了一种相对简单的保留腮腺的适形技术（ConPas），该技术不使用射束强度调制。本文的目的是在喉癌或下咽癌患者中证明，ConPas能够在保持腮腺平均剂量（MPD）<26 Gy的同时，充分覆盖原发肿瘤和双侧颈部淋巴结。
患者与方法
为连续10例T1 - 4 N0 - 1期喉癌或下咽癌（非T1声门型）患者计算了使用ConPas和传统技术（使用一个前后位锁骨上野和两个侧野）的治疗计划。对原发肿瘤和双侧颈部淋巴结处方剂量为46 Gy，分别采用传统技术或ConPas进行计划，随后采用简单的两野技术推量至70 Gy。使用V(95)比较两种技术的靶区覆盖情况，V(95)即原发肿瘤和淋巴结区域的计划靶体积（PTV）中接受至少95%处方选择性剂量的百分比。比较两种技术包括推量至70 Gy时腮腺的MPD和正常组织并发症概率（NTCP）。使用电离室测量和胶片剂量测定法对该技术进行了剂量验证。
结果
传统技术和ConPas的平均V(95)分别为85.2%和91.2%（p = 0.08），平均MPD分别为38.7 Gy和25.4 Gy（p < 0.001），腮腺的平均NTCP分别为0.87和0.22（p < 0.001）。剂量验证显示剂量计算与测量结果具有良好的一致性。
结论
ConPas在不进行射束强度调制的双侧颈部照射中能够实现充分的靶区覆盖和具有临床意义的腮腺保留。
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