CAJ | 학술논문

目的利用CT模拟机定位技术及治疗计划系统分析鼻咽癌常规放疗面颈联合野照射时肿瘤靶区及颅底剂量欠量问题,并分析采用不同处方剂量点造成的靶区剂量分布差别.方法选择11例接受常规放疗的首程鼻咽癌患者,普通模拟机定位,将通过科查房的面颈野边界应用细铅丝在面罩上标记,然后在CT模拟机上采取和普通模拟机定位相同的治疗体位及固定方式进行扫描,获取的图像通过网络系统传输至治疗计划系统.由医生在数字莺建图像上根据细铅丝的位置复制出面颈联合野,同时在横断面上逐层勾画鼻咽原发肿瘤GTV及照射野内的蝶骨体、斜坡等靶区.取两个处方剂量点分别位于第1颈椎前(代表鼻咽深度)和第3颈椎前(代表上颈深度).按临床要求以处方剂量点36 Gy分18次为面颈联合野的处方剂量,由计划系统分别计算原发肿瘤及颅底的剂量.结果以鼻咽深度为处方剂量点时,95%体积的GTV实际受量为33.31～35.54 Gy,中位值为34.83 Gy;95%体积的颅底实际受量为17.76～34.60 Gy,中位值为30.28 Gy.当以上颈深度为处方剂量点时,95%体积的GTV实际受量为31.43～33.36 Gy,中位值为32.44 Gy;95%体积的颅底实际受量为16.52～32.60 Gy,中位值为28.52 Gy.结论鼻咽癌常规放疗采用面颈联合野无论采用鼻咽还是上颈部为处方剂量计算深度均会造成GTV及颅底剂量低于处方剂量,后者尤为明显.提示临床实施常规放疗时应以鼻咽深度为处方剂量点,同时应结合临床情况酌情考虑对颅底受侵患者疗终给予适当补量.
목적 이용CT모의궤정위기술급치료계화계통분석비인암상규방료면경연합야조사시종류파구급로저제량흠량문제,병분석채용불동처방제량점조성적파구제량분포차별.방법 선택11례접수상규방료적수정비인암환자,보통모의궤정위,장통과과사방적면경야변계응용세연사재면조상표기,연후재CT모의궤상채취화보통모의궤정위상동적치료체위급고정방식진행소묘,획취적도상통과망락계통전수지치료계화계통.유의생재수자앵건도상상근거세연사적위치복제출면경연합야,동시재횡단면상축층구화비인원발종류GTV급조사야내적접골체、사파등파구.취량개처방제량점분별위우제1경추전(대표비인심도)화제3경추전(대표상경심도).안림상요구이처방제량점36 Gy분18차위면경연합야적처방제량,유계화계통분별계산원발종류급로저적제량.결과 이비인심도위처방제량점시,95%체적적GTV실제수량위33.31～35.54 Gy,중위치위34.83 Gy;95%체적적로저실제수량위17.76～34.60 Gy,중위치위30.28 Gy.당이상경심도위처방제량점시,95%체적적GTV실제수량위31.43～33.36 Gy,중위치위32.44 Gy;95%체적적로저실제수량위16.52～32.60 Gy,중위치위28.52 Gy.결론 비인암상규방료채용면경연합야무론채용비인환시상경부위처방제량계산심도균회조성GTV급로저제량저우처방제량,후자우위명현.제시림상실시상규방료시응이비인심도위처방제량점,동시응결합림상정황작정고필대로저수침환자료종급여괄당보량.
Objective To evaluate the dose distribution of the target volume and the cranial base in nasopharyngeal carcinoma ( NPC ) treated with facial-cervical fields, and to analyze the differences of dose distribution using different isoeenters with the CT-simulator and treatment planning system (TPS). Methods Eleven patients with nasopharyngeal carcinoma were treated by conventional radiotherapy as their primary treatment. All patients were simulated by the conventional simulator and the field borders were marked with thin lead wires on the mask. Then the patients were scanned by the CT-sim with the same immobilization. The planning CT images were transferred to the TPS and the field borders were copied on the DRR, and then GTV and the cranial base were contoured on the coronal CT slices. Two isoeenters were chosen, including one in front of the 1 st cervical vertebra to measeure the depth of the nasopharynx and the other in front of the 3rd cervical vertebra to measure the depth of the upper neck. The prescription dose of 36 Gy was given in 18 fractions. Dose distributions of GTV and the cranial base were calculated with TPS. Results The actual dose of 95% volume of GTV was 33.31 -35.54 Gy (median 34.83 Gy) and 31.43 -33.36 Gy (median 32.44 Gy) when the isoeenters were set in the nasopharynx and the superior neck, respectively. The corre-sponding actual dose of 95% volume of the cranial base was 17.76 - 34.60 Gy ( median 30.28 Gy ) and 16.52 -32.60 Gy (median 28.52 Gy), respectively. Conclusions For NPC patients treated with conven-tional radiotherapy using facial-cervical fields, the actual dose of GTV and the cranial base is lower than the prescribed dose whenever the isocenter is set in the nasopharynx or the upper neck,which is more significant in the latter. The isocenter should be set in the nasopharynx when the conventional radiotherapy is applied and a boost of 4- 8 Gy should be given when the cranial base is involved.