Center for Proton Therapy, Paul Scherrer Institut, Villigen, Switzerland.
Phys Med Biol. 2013 Aug 7;58(15):R131-60. doi: 10.1088/0031-9155/58/15/R131. Epub 2013 Jul 17.
Protons are an interesting modality for radiotherapy because of their well defined range and favourable depth dose characteristics. On the other hand, these same characteristics lead to added uncertainties in their delivery. This is particularly the case at the distal end of proton dose distributions, where the dose gradient can be extremely steep. In practice however, this gradient is rarely used to spare critical normal tissues due to such worries about its exact position in the patient. Reasons for this uncertainty are inaccuracies and non-uniqueness of the calibration from CT Hounsfield units to proton stopping powers, imaging artefacts (e.g. due to metal implants) and anatomical changes of the patient during treatment. In order to improve the precision of proton therapy therefore, it would be extremely desirable to verify proton range in vivo, either prior to, during, or after therapy. In this review, we describe and compare state-of-the art in vivo proton range verification methods currently being proposed, developed or clinically implemented.
质子是放射治疗中一种有趣的模式，因为它们具有明确的射程和有利的深度剂量特性。另一方面，这些相同的特性导致在输送过程中增加了不确定性。在质子剂量分布的远端尤其如此，那里的剂量梯度可能非常陡峭。然而，在实践中，由于对其在患者体内的确切位置的担忧，很少利用这种梯度来保护关键的正常组织。造成这种不确定性的原因包括 CT 亨氏单位到质子阻止本领的校准不准确和非唯一性、成像伪影（例如由于金属植入物）以及治疗过程中患者的解剖结构变化。因此，为了提高质子治疗的精度，非常希望在治疗前、治疗中或治疗后在体内验证质子射程。在这篇综述中，我们描述并比较了目前正在提出、开发或临床实施的先进的体内质子射程验证方法。
