**3. Volume-based IGBT for cervical cancer**

The concepts of volume-based brachytherapy in magnetic resonance imaging (MRI) started by the publications of the Groupe European de Curietherapie and the European Society for Radiotherapy and Oncology GEC-ESTRO in 2005–2006 to propose the definitions of targets (high-risk clinical target volume; HR-CTV and intermediate-risk clinical target volume; IR-CTV) and normal tissues (Organs at risk (OARs); bladder, rectum and sigmoid) with dose constraints for evaluation [10, 11]. Moreover, the additional concepts of HR-CTV were extrapolated to CT since 2007 and developed to many international publications [12–15]. **Figure 2** shows the HR-CTV and IR-CTV according to GEC-ESTRO recommendations.

In comparison to conventional brachytherapy (point A), IGBT keeps the cumulatively curative dose to the target (HR-CTV) while sparing the cumulative dose to normal tissues [16–19]. After the first clinical results of IGBT were reported by Pötter et al. in 2007, many institutes started to develop IGBT around the world [20]. The selected publications of IGBT are shown in **Table 1** and shown promising results in local control and toxicity.

*Ultrasound-Guided Brachytherapy for Cervical Cancer - A Tool for Quality Improvement… DOI: http://dx.doi.org/10.5772/intechopen.101853*

#### **Figure 2.**

*HR-CTV and IR-CTV on MRI and CT related to GEC-ESTRO recommendations from the division of radiation oncology, Department of Radiology, Faculty of Medicine, Chiang Mai University.*


*BT, brachytherapy, CT, computed tomography, GI, gastrointestinal toxicity, GU, genitourinary toxicity, MRI, magnetic resonance imaging, IPSA, inverse planning simulated annealing.*

#### **Table 1.**

*Selected studies of IGBT.*

## **4. Clinical results of ultrasound in brachytherapy for cervical cancer**

Ultrasound in medicine was firstly developed by the military (as "sonar") and was firstly investigated in the 1940s by the method of echo-reflection to detect tumors, exudates, or abscesses [31]. Ultrasound developed very much in obstetrics and gynecology to evaluate the growing fetus and examinations in gynecological conditions [32]. Using ultrasound in clinical practice of brachytherapy divides into three aspects a) applicator guidance, b) CT-based contouring, and c) planning process. The most common use of ultrasound in brachytherapy for cervical cancer is to guide insertion of intrauterine tandem to prevent uterine perforation. Although, in this era, the incidence of uterine perforation was 3% from Segedin et al. [33]. The use of ultrasound can support accurate and safe application in brachytherapy procedures in cervical cancer. Moreover, ultrasound can help the practitioner to adjust the applicator to be a suitable position before patient transportation to the next steps. **Figure 3** shows uterine perforation by TAUS.

#### **Figure 3.**

*Uterine perforation during insertion by TAUS from The Division of Radiation Oncology, Department of Radiology, Faculty of Medicine, Chiang Mai University.*


*BT, brachytherapy; CT, computed tomography; FU, follow up; GI, gastrointestinal; GU, genitourinary; IGBT, imageguided brachytherapy; MRI, magnetic resonance imaging; TAUS, transabdominal ultrasound; TRUS, transrectal ultrasound.*

#### **Table 2.**

*Selected studies showed progression of US guidance in brachytherapy.*

#### *Ultrasound-Guided Brachytherapy for Cervical Cancer - A Tool for Quality Improvement… DOI: http://dx.doi.org/10.5772/intechopen.101853*

To guide CT-based contouring is very new for using ultrasound. This comes from the pain point of CT-based contouring is an overestimation in comparison to MRIbased contouring [12]. To find the support equipment, some researchers found that the US in transabdominal (TAUS) or transrectal (TRUS) approaches showed a correlation in measurement with MRI [34–37]. Moreover, the publication from Schmid et al. showed TRUS is superior to CT as it yields systematically smaller deviations from MRI, with good to excellent image quality [38] and Mahanshetty et al. published the correlation of MRI-based contouring versus CT-based contouring supported by TRUS [37]. In recently, the latest publication from IBS-GEC ESTRO-ABS recommended TRUS to support CT-based contouring in IGBT for cervical cancer [39].

The use of TAUS in the planning process was firstly developed by Peter MacCallum Cancer Center, Melbourne, Australia [40]. This process developed from the measurement by TAUS showed a correlation to MRI [35]. In Peter MacCallum Cancer Center, the cooperation of TAUS and MRI (in first application) supported the high-end treatment in brachytherapy for cervical cancer. With this implementation, international publications were reported to support TAUS in brachytherapy [34, 35, 40, 41]. In 2014, they published a survival outcome that showed a 5-year overall survival rate of 65% [42].

The developments of US guidance for brachytherapy are concluded in **Table 2**.
