探寻以单光子发射计算机断层成像术/计算机断层成像术（SPECT/CT）射线探测为基础的剂量验证参数以及其评价前列腺癌粒子植入疗效的可行性。

应用SPECT/CT扫描一位前列腺癌粒子植入患者，将SPECT图像与CT图像融合，调整融合图像的放射性浓聚范围与术后计划中145 Gy、217.5 Gy等剂量线范围一致。并记录不同剂量时放射性浓聚计数值。观察两个计数值曲线包含的靶区及危及器官的范围，计算两种计数值放射性浓聚所包含的体积与靶体积之比。随访4年，确认患者肿瘤控制良好，无并发症。然后用以上等计数值曲线包绕靶区范围及浓聚体积与靶体积比评价另外一位前列腺癌患者并随访。

第一例患者SPECT/CT融合图像中与145 Gy等剂量曲线一致的计数值约为200，此曲线包含的体积与靶体积之比为106%，其范围累及部分直肠前壁。相当于217.5 Gy等剂量线的计数值为300，此曲线包含的体积与靶体积之比为58%，此曲线未包含尿道。第二例患者200等计数值曲线完全包绕靶区，累及部分直肠前壁，曲线内体积与靶体积之比为176%。300等计数值曲线范围累及部分尿道，曲线内体积与靶体积之比为74%。现患者术后3月，PSA降至正常。无排尿相关症状。

SPECT/CT可以探测到前列腺癌内¹²⁵I粒子的剂量分布并成像，将放射性浓聚程度与剂量关联，可能成为评价前列腺癌粒子植入疗效的新方法。

To study the dose evaluation parameter and assess the therapeutic effect of prostate brachytherapy based on SPECT/CT detection.

A patient with prostate cancer underwent ¹²⁵I seed implantation was scanned by SPECT/CT. The images of SPECT and CT were fused and adjusted the radioactivity concentration region to match 145Gy and 217.5Gy isodose line. The two-radioactivity density count values were recorded. The relationship between target, the organ at risk and region in the two count value lines was observed. Counted the ratio between the volume in the two count value lines and the target volume. After 4 years follow up, the patient showed a good tumor control and no complication. Then, evaluated a second patient with the count value line and the ratio used before and followed up.

The count value matched 145Gy isodose line in the first patient was 200. The ratio between the volume in this count value line and target volume was 106%. A little part of the anterior wall of the rectum was involved. The count value matched 217.5Gy isodose line in the first patient was 300. The ratio between the volume in this count value line and target volume was 58%. The urethra was avoided. The 200-count value line in the second patient covered the target completely and part of the anterior wall of the rectum was involved. The ratio between the volume in this count value line and target volume was 176%. The 300-count value line in the second patient covered part of the urethra. The ratio between the volume in this count value line and target volume was 74%. The second patient was followed up for three months till now. PSA declined to normal and no complications of rectum and urethra were observed.

The dose distribution of ¹²⁵I seed in the prostate cancer can be detected and imaged by SPECT/CT. SPECT/CT based dose verification may be a new method to access the therapeutic effect of prostate cancer brachytherapy if the radioactive count value and the dose were related.